diff --git a/build.gradle.kts b/build.gradle.kts
index 55248f61..2fad1935 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -6,7 +6,7 @@ import org.jetbrains.dokka.gradle.DokkaTask
 plugins {
     id("org.jetbrains.kotlin.jvm") version "1.7.22"
     id("org.jetbrains.dokka") version "1.7.20"
-    id("org.sonarqube") version "4.3.1.3277" // https://plugins.gradle.org/plugin/org.sonarqube
+    id("org.sonarqube") version "4.4.1.3373" // https://plugins.gradle.org/plugin/org.sonarqube
     //id("org.sonarqube") version "3.5.0.2730" // supports java 8, dropped with 4.1
     id("maven-publish")
     id("java-library")
@@ -158,12 +158,17 @@ repo?.run { // tasks for publishing on maven repo
 val isRunningOnGithub = System.getenv("CI")?.toBoolean() ?: false
 println("isRunningOnGithub=$isRunningOnGithub")
 
+// https://docs.gradle.org/current/userguide/jacoco_plugin.html
+jacoco {
+    // https://mvnrepository.com/artifact/org.jacoco/jacoco-maven-plugin
+    toolVersion = "0.8.11"
+}
+
 // required for sonarqube code coverage
 // https://docs.sonarqube.org/latest/analysis/test-coverage/java-test-coverage
 tasks.jacocoTestReport {
     dependsOn(tasks.test)
     // https://stackoverflow.com/questions/67725347/jacoco-fails-on-gradle-7-0-2-and-kotlin-1-5-10
-    //version = "0.8.7"
     reports {
         xml.required.set(true)
         csv.required.set(false)
@@ -175,18 +180,19 @@ tasks.jacocoTestReport {
 // https://docs.sonarqube.org/latest/analysis/scan/sonarscanner-for-gradle/
 // configure token with 'publish analysis' permission in file ~/.gradle/gradle.properties:
 // systemProp.sonar.login=<token>
-sonar {
-    properties {
-        property("sonar.host.url", "https://sonarcloud.io")
-        property("sonar.projectKey", "gmuth_ipp-client-kotlin")
-        property("sonar.organization", "gmuth")
-        //property("sonar.verbose", "true")
-        //property("sonar.junit.reportPaths", "build/test-results/test")
-        //property("sonar.jacoco.reportPaths", "build/jacoco/test.exec")
-        //property("sonar.coverage.jacoco.xmlReportPaths", "build/reports/jacoco/test/")
-    }
-}
-
+//sonar {
+//    properties {
+//        property("sonar.host.url", "https://sonarcloud.io")
+//        property("sonar.projectKey", "gmuth_ipp-client-kotlin")
+//        property("sonar.organization", "gmuth")
+//        //property("sonar.verbose", "true")
+//        //property("sonar.junit.reportPaths", "build/test-results/test")
+//        //property("sonar.jacoco.reportPaths", "build/jacoco/test.exec")
+//        //property("sonar.coverage.jacoco.xmlReportPaths", "build/reports/jacoco/test/")
+//    }
+//}
+
+// https://docs.sonarsource.com/sonarqube/latest/analyzing-source-code/scanners/sonarscanner-for-gradle/
 tasks.sonar {
     dependsOn(tasks.jacocoTestReport) // for coverage
 }
diff --git a/gradle.properties b/gradle.properties
index c878a2c2..7fdb1fbf 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -7,4 +7,9 @@ org.gradle.jvmargs=-XX:MetaspaceSize=512M -XX:MaxMetaspaceSize=512M
 # java -XX:+PrintFlagsFinal -version|grep MaxHeapSize
 # Oracle-arm 11.0.5: MaxHeapSize = 2147483648
 
-#org.gradle.daemon=false
\ No newline at end of file
+#org.gradle.daemon=false
+
+# sonarcloud
+systemProp.sonar.host.url=https://sonarcloud.io
+systemProp.sonar.projectKey=gmuth_ipp-client-kotlin
+systemProp.sonar.organization=gmuth
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/ColorMode.kt b/src/main/kotlin/de/gmuth/ipp/attributes/ColorMode.kt
index 1e2a21aa..fcdb2321 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/ColorMode.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/ColorMode.kt
@@ -33,7 +33,6 @@ class ColorMode(private val keyword: String) : IppAttributeBuilder {
                 else "Required attribute not found (print-color-mode-supported or output-mode-supported)"
             )
         },
-        Keyword,
-        keyword
+        Keyword, keyword
     )
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/CommunicationChannel.kt b/src/main/kotlin/de/gmuth/ipp/attributes/CommunicationChannel.kt
index 2f57d458..fd276c3f 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/CommunicationChannel.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/CommunicationChannel.kt
@@ -29,5 +29,4 @@ class CommunicationChannel(
             }
         }
     }
-
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/Marker.kt b/src/main/kotlin/de/gmuth/ipp/attributes/Marker.kt
index a34fa5fd..52ee08b8 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/Marker.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/Marker.kt
@@ -35,9 +35,9 @@ class Marker(
         UNKNOWN("#?");
 
         companion object {
-            val log = getLogger(Color::class.java.name)
+            private val logger = getLogger(Color::class.java.name)
             fun fromString(code: String) = values().find { it.code == code.uppercase() }
-                ?: UNKNOWN.apply { log.warning { "Unknown color code: $code" } }
+                ?: UNKNOWN.apply { logger.warning { "Unknown color code: $code" } }
         }
     }
 
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/MediaMargin.kt b/src/main/kotlin/de/gmuth/ipp/attributes/MediaMargin.kt
index 5f1c4742..87edd91e 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/MediaMargin.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/MediaMargin.kt
@@ -7,7 +7,7 @@ package de.gmuth.ipp.attributes
 import de.gmuth.ipp.core.IppAttribute
 import de.gmuth.ipp.core.IppTag.Integer
 
-open class MediaMargin(
+class MediaMargin(
     val left: Int? = null,
     val right: Int? = null,
     val top: Int? = null,
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/MediaSize.kt b/src/main/kotlin/de/gmuth/ipp/attributes/MediaSize.kt
index ff56ea8e..b3b4f8eb 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/MediaSize.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/MediaSize.kt
@@ -13,11 +13,11 @@ import de.gmuth.ipp.core.IppTag.Integer
 
 // unit: 1/100 mm, e.g. 2540 = 1 inch
 class MediaSize(val xDimension: Int, val yDimension: Int) : IppAttributeBuilder {
-    override fun buildIppAttribute(printerAttributes: IppAttributesGroup) =
-        IppAttribute(
-            "media-size", BegCollection, IppCollection(
-                IppAttribute("x-dimension", Integer, xDimension),
-                IppAttribute("y-dimension", Integer, yDimension)
-            )
+    override fun buildIppAttribute(printerAttributes: IppAttributesGroup) = IppAttribute(
+        "media-size", BegCollection,
+        IppCollection(
+            IppAttribute("x-dimension", Integer, xDimension),
+            IppAttribute("y-dimension", Integer, yDimension)
         )
+    )
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/MediaSource.kt b/src/main/kotlin/de/gmuth/ipp/attributes/MediaSource.kt
index 3a58a057..56f6db60 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/MediaSource.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/MediaSource.kt
@@ -8,25 +8,33 @@ import de.gmuth.ipp.core.IppAttribute
 import de.gmuth.ipp.core.IppAttributeBuilder
 import de.gmuth.ipp.core.IppAttributesGroup
 import de.gmuth.ipp.core.IppTag.Keyword
-import java.util.logging.Logger.getLogger
 
-open class MediaSource(val keyword: String) : IppAttributeBuilder {
+class MediaSource(val keyword: String) : IppAttributeBuilder {
 
-    val log = getLogger(javaClass.name)
+    companion object {
+        @JvmField
+        val Auto = MediaSource("auto")
+
+        @JvmField
+        val Main = MediaSource("main")
+
+        @JvmField
+        val Manual = MediaSource("manual")
+
+        @JvmField
+        val Envelope = MediaSource("envelope")
+
+        @JvmField
+        val Alternate = MediaSource("alternate")
+
+        @JvmField
+        val ByPassTray = MediaSource("by-pass-tray")
+
+        @JvmField
+        val LargeCapacity = MediaSource("large-capacity")
+    }
 
     override fun buildIppAttribute(printerAttributes: IppAttributesGroup) =
         IppAttribute("media-source", Keyword, keyword)
-            .apply { validateSource(printerAttributes) }
-
-    private fun validateSource(printerAttributes: IppAttributesGroup) {
-        val mediaSourceSupported = printerAttributes["media-source-supported"]
-        if (mediaSourceSupported == null) {
-            log.fine { "printer does not provide attribute 'media-source-supported'" }
-        } else {
-            if (!mediaSourceSupported.values.contains(keyword)) {
-                log.warning { "media-source '$keyword' not supported by printer" }
-                log.warning { mediaSourceSupported.toString() }
-            }
-        }
-    }
+
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/PrinterState.kt b/src/main/kotlin/de/gmuth/ipp/attributes/PrinterState.kt
index 79301679..bf06529d 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/PrinterState.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/PrinterState.kt
@@ -22,7 +22,7 @@ enum class PrinterState(val code: Int) : IppAttributeBuilder {
         IppAttribute("printer-state", IppTag.Enum, code)
 
     companion object {
-        private fun fromInt(code: Int) = values().single { it.code == code }
+        fun fromInt(code: Int) = values().single { it.code == code }
         fun fromAttributes(attributes: IppAttributesGroup) = fromInt(attributes.getValue("printer-state"))
     }
 
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/PrinterType.kt b/src/main/kotlin/de/gmuth/ipp/attributes/PrinterType.kt
index a7ac2380..64a2b8aa 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/PrinterType.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/PrinterType.kt
@@ -11,13 +11,10 @@ import de.gmuth.ipp.core.IppTag
 import java.util.logging.Level
 import java.util.logging.Level.INFO
 import java.util.logging.Logger
-import java.util.logging.Logger.getLogger
 
 // https://www.cups.org/doc/spec-ipp.html
 class PrinterType(val value: Int) : IppAttributeBuilder {
 
-    val log = getLogger(javaClass.name)
-
     enum class Capability(val bit: Int, val description: String) {
         IsAPrinterClass(0, "Is a printer class."),
         IsARemoteDestination(1, "Is a remote destination."),
diff --git a/src/main/kotlin/de/gmuth/ipp/attributes/TemplateAttributes.kt b/src/main/kotlin/de/gmuth/ipp/attributes/TemplateAttributes.kt
index eb1a16b4..485f72c9 100644
--- a/src/main/kotlin/de/gmuth/ipp/attributes/TemplateAttributes.kt
+++ b/src/main/kotlin/de/gmuth/ipp/attributes/TemplateAttributes.kt
@@ -52,9 +52,13 @@ object TemplateAttributes {
     fun mediaSource(keyword: String) =
         IppAttribute("media-source", Keyword, keyword)
 
+    @JvmStatic // input tray
+    fun mediaColWithSource(mediaSource: MediaSource) =
+        MediaCollection(source = mediaSource)
+
     @JvmStatic // input tray
     fun mediaColWithSource(keyword: String) =
-        MediaCollection(source = MediaSource(keyword))
+        mediaColWithSource(MediaSource(keyword))
 
     @JvmStatic // unit: hundreds of mm
     fun mediaColWithSize(xDimension: Int, yDimension: Int) =
diff --git a/src/main/kotlin/de/gmuth/ipp/client/CupsClient.kt b/src/main/kotlin/de/gmuth/ipp/client/CupsClient.kt
index 20ce87b1..862ca218 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/CupsClient.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/CupsClient.kt
@@ -25,7 +25,7 @@ class CupsClient(
 ) {
     constructor(host: String = "localhost") : this(URI.create("ipp://$host"))
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     val config: IppConfig by ippClient::config
     var userName: String? by config::userName
     var cupsClientWorkDirectory = File("CUPS/${cupsUri.host}")
@@ -40,7 +40,7 @@ class CupsClient(
 
     private fun cupsPrinterUri(printerName: String) =
         cupsUri.run { URI("$scheme://$host${if (port > 0) ":$port" else ""}/printers/$printerName") }
-            .apply { log.finer { "cupsPrinterUri($printerName) = $this" } }
+            .apply { logger.finer { "cupsPrinterUri($printerName) = $this" } }
 
     val version: String by lazy {
         getPrinters().run {
@@ -70,7 +70,7 @@ class CupsClient(
                 .apply { workDirectory = cupsClientWorkDirectory }
         } catch (clientErrorNotFoundException: ClientErrorNotFoundException) {
             with(getPrinters()) {
-                if (isNotEmpty()) log.warning { "Available CUPS printers: ${map { it.name }}" }
+                if (isNotEmpty()) logger.warning { "Available CUPS printers: ${map { it.name }}" }
             }
             throw clientErrorNotFoundException
         }
@@ -105,7 +105,7 @@ class CupsClient(
 
     fun deletePrinter(printerName: String) =
         exchange(cupsPrinterRequest(CupsDeletePrinter, printerName))
-            .apply { log.info { "Printer deleted: $printerName" } }
+            .apply { logger.info { "Printer deleted: $printerName" } }
 
     // https://www.cups.org/doc/spec-ipp.html#CUPS_CREATE_LOCAL_PRINTER
     fun createLocalPrinter(
@@ -126,7 +126,7 @@ class CupsClient(
                 ppdName
             )
         ).run {
-            log.info { "$statusMessage ${printerGroup.getValues<Any>("printer-uri-supported")}" }
+            logger.info { "$statusMessage ${printerGroup.getValues<Any>("printer-uri-supported")}" }
             return IppPrinter(printerGroup, ippClient)
         }
     }
@@ -219,18 +219,18 @@ class CupsClient(
         ppdName = "everywhere"
     ).apply {
         updateAttributes("printer-name")
-        log.info(toString())
-        log.info { "CUPS now generates IPP Everywhere PPD." } // https://github.com/apple/cups/issues/5919
+        logger.info(toString())
+        logger.info { "CUPS now generates IPP Everywhere PPD." } // https://github.com/apple/cups/issues/5919
         do {
             updateAttributes("printer-make-and-model")
             Thread.sleep(500)
         } while (!makeAndModel.text.lowercase().contains("everywhere"))
-        log.info { "Make printer permanent." }
+        logger.info { "Make printer permanent." }
         exchange(
             cupsPrinterRequest(CupsAddModifyPrinter, printerName)
                 .apply { printerGroup.attribute("printer-is-temporary", IppTag.Boolean, false) }
         )
-        log.info { "Make printer operational." }
+        logger.info { "Make printer operational." }
         enable()
         resume()
         updateAttributes()
@@ -263,7 +263,7 @@ class CupsClient(
         )
             .onEach { job -> // update attributes and lookup job owners
                 if (updateJobAttributes) job.updateAttributes()
-                log.info { job.toString() }
+                logger.info { job.toString() }
                 job.getOriginatingUserNameOrAppleJobOwnerOrNull()?.let { jobOwners.add(it) }
             }
             .onEach { job -> // keep stats and save documents
@@ -272,9 +272,9 @@ class CupsClient(
                     .apply { numberOfSavedDocuments.addAndGet(size) }
             }
             .apply {
-                log.info { "Found ${jobOwners.size} job ${if (jobOwners.size == 1) "owner" else "owners"}: $jobOwners" }
-                log.info { "Found $size jobs (which=$whichJobs) where $numberOfJobsWithoutDocuments jobs have no documents" }
-                log.info { "Saved $numberOfSavedDocuments documents of ${size.minus(numberOfJobsWithoutDocuments.toInt())} jobs with documents to directory: ${cupsServer.workDirectory}" }
+                logger.info { "Found ${jobOwners.size} job ${if (jobOwners.size == 1) "owner" else "owners"}: $jobOwners" }
+                logger.info { "Found $size jobs (which=$whichJobs) where $numberOfJobsWithoutDocuments jobs have no documents" }
+                logger.info { "Saved $numberOfSavedDocuments documents of ${size.minus(numberOfJobsWithoutDocuments.toInt())} jobs with documents to directory: ${cupsServer.workDirectory}" }
             }
     }
 
@@ -292,10 +292,10 @@ class CupsClient(
     ) {
         createSubscription(whichJobEvents, notifyLeaseDuration = leaseDuration)
             .pollAndHandleNotifications(pollEvery, autoRenewSubscription = autoRenewLease) { event ->
-                log.info { event.toString() }
+                logger.info { event.toString() }
                 with(event.getJob()) {
                     while (isIncoming()) {
-                        log.info { toString() }
+                        logger.info { toString() }
                         Thread.sleep(1000)
                         updateAttributes()
                     }
@@ -319,7 +319,7 @@ class CupsClient(
             if (documents.isNotEmpty() && onSuccessUpdateJobAttributes) job.updateAttributes()
             true
         } catch (ippExchangeException: IppExchangeException) {
-            log.info { "Get documents for job #${job.id} failed: ${ippExchangeException.message}" }
+            logger.info { "Get documents for job #${job.id} failed: ${ippExchangeException.message}" }
             ippExchangeException.httpStatus!! != 401
         }
 
@@ -327,7 +327,7 @@ class CupsClient(
             val configuredUserName = config.userName
             jobOwners.forEach {
                 config.userName = it
-                log.fine { "set userName '${config.userName}'" }
+                logger.fine { "set userName '${config.userName}'" }
                 if (getDocuments()) return@forEach
             }
             config.userName = configuredUserName
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppClient.kt b/src/main/kotlin/de/gmuth/ipp/client/IppClient.kt
index c75da00c..7db3b36c 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppClient.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppClient.kt
@@ -27,7 +27,7 @@ import javax.net.ssl.HttpsURLConnection
 typealias IppResponseInterceptor = (request: IppRequest, response: IppResponse) -> Unit
 
 open class IppClient(val config: IppConfig = IppConfig()) : IppExchange {
-    protected val log: Logger = getLogger(javaClass.name)
+    protected val logger: Logger = getLogger(javaClass.name)
 
     var responseInterceptor: IppResponseInterceptor? = null
     var saveMessages: Boolean = false
@@ -72,9 +72,9 @@ open class IppClient(val config: IppConfig = IppConfig()) : IppExchange {
 
     override fun exchange(request: IppRequest): IppResponse {
         val ippUri: URI = request.printerOrJobUri
-        log.finer { "send '${request.operation}' request to $ippUri" }
+        logger.finer { "Send '${request.operation}' request to $ippUri" }
         val response = httpPost(toHttpUri(ippUri), request)
-        log.fine { "$ippUri: $request => $response" }
+        logger.fine { "$ippUri: $request => $response" }
         if (saveMessages) {
             fun file(suffix: String) = File(saveMessagesDirectory, "${request.requestId}-${request.operation}.$suffix")
             request.saveBytes(file("request"))
@@ -109,27 +109,25 @@ open class IppClient(val config: IppConfig = IppConfig()) : IppExchange {
         }
     }
 
-    protected fun validateResponse(request: IppRequest, response: IppResponse) {
-        with(response) {
-            if (status == ClientErrorBadRequest) request.log(log, SEVERE, prefix = "BAD-REQUEST: ")
-            if (containsGroup(Unsupported)) unsupportedGroup.values.forEach { log.warning() { "unsupported: $it" } }
-            if (!isSuccessful()) {
-                IppRegistrationsSection2.validate(request)
-                if (throwWhenNotSuccessful) {
-                    throw if (status == ClientErrorNotFound) ClientErrorNotFoundException(request, response)
-                    else IppExchangeException(request, response)
-                }
+    private fun validateResponse(request: IppRequest, response: IppResponse) = response.run {
+        if (status == ClientErrorBadRequest) request.log(logger, SEVERE, prefix = "BAD-REQUEST: ")
+        if (containsGroup(Unsupported)) unsupportedGroup.values.forEach { logger.warning() { "Unsupported: $it" } }
+        if (!isSuccessful()) {
+            IppRegistrationsSection2.validate(request)
+            if (throwWhenNotSuccessful) {
+                throw if (status == ClientErrorNotFound) ClientErrorNotFoundException(request, response)
+                else IppExchangeException(request, response)
             }
         }
     }
 
-    protected fun toHttpUri(ippUri: URI): URI = with(ippUri) {
+    private fun toHttpUri(ippUri: URI): URI = with(ippUri) {
         val scheme = scheme.replace("ipp", "http")
         val port = if (port == -1) 631 else port
         URI.create("$scheme://$host:$port$rawPath")
     }
 
-    protected fun HttpURLConnection.configure(chunked: Boolean) {
+    private fun HttpURLConnection.configure(chunked: Boolean) {
         config.run {
             connectTimeout = timeout.toMillis().toInt()
             readTimeout = timeout.toMillis().toInt()
@@ -143,58 +141,42 @@ open class IppClient(val config: IppConfig = IppConfig()) : IppExchange {
         setRequestProperty("Accept-Encoding", "identity") // avoid 'gzip' with Androids OkHttp
     }
 
-    protected fun HttpURLConnection.validateResponse(
+    private fun HttpURLConnection.validateResponse(
         request: IppRequest,
         contentStream: InputStream?,
         cause: Exception? = null
-    ) =
-        when {
-            responseCode == 401 -> with(request) {
-                "User \"$requestingUserName\" is not authorized for operation $operation on $printerOrJobUri"
-            }
-
-            responseCode == 426 -> {
-                "HTTP status $responseCode, $responseMessage, Try ipps://${request.printerOrJobUri.host}"
-            }
-
-            responseCode != 200 -> {
-                "HTTP request failed: $responseCode, $responseMessage"
-            }
-
-            contentType != null && !contentType.startsWith(APPLICATION_IPP) -> {
-                "Invalid Content-Type: $contentType"
-            }
-
-            cause != null -> cause.message
-
-            else -> null
-        }?.let {
-            throw IppExchangeException(
-                request,
-                response = null,
-                responseCode, // HTTP
-                httpHeaderFields = headerFields,
-                httpStream = contentStream,
-                message = it,
-                cause = cause
-            )
-        }
+    ) = when {
+        responseCode == 401 -> with(request) { "User \"$requestingUserName\" is not authorized for operation $operation on $printerOrJobUri" }
+        responseCode == 426 -> "HTTP status $responseCode, $responseMessage, Try ipps://${request.printerOrJobUri.host}"
+        responseCode != 200 -> "HTTP request failed: $responseCode, $responseMessage"
+        contentType != null && !contentType.startsWith(APPLICATION_IPP) -> "Invalid Content-Type: $contentType"
+        cause != null -> cause.message
+        else -> null
+    }?.let {
+        throw IppExchangeException(
+            request,
+            response = null,
+            responseCode, // HTTP
+            httpHeaderFields = headerFields,
+            httpStream = contentStream,
+            message = it,
+            cause = cause
+        )
+    }
 
-    protected fun decodeContentStream(
+    private fun decodeContentStream(
         request: IppRequest,
         httpStatus: Int,
         contentStream: InputStream
     ) = IppResponse().apply {
-        try {
-            read(contentStream)
-        } catch (throwable: Throwable) {
+        try { read(contentStream) }
+        catch (throwable: Throwable) {
             throw IppExchangeException(
-                request, this, httpStatus, message = "failed to decode ipp response", cause = throwable
+                request, this, httpStatus, message = "Failed to decode ipp response", cause = throwable
             ).apply {
                 if (onExceptionSaveMessages)
                     saveMessages("decoding_ipp_response_${request.requestId}_failed")
             }
         }
     }
-
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppDocument.kt b/src/main/kotlin/de/gmuth/ipp/client/IppDocument.kt
index 139065ca..d656becd 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppDocument.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppDocument.kt
@@ -21,7 +21,7 @@ class IppDocument(
     private val inputStream: InputStream
 ) {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     val number: Int
         get() = attributes.getValue("document-number")
@@ -35,9 +35,9 @@ class IppDocument(
     var file: File? = null
 
     fun readBytes() = inputStream.readBytes()
-        .also { log.fine { "Read ${it.size} bytes of $this" } }
+        .also { logger.fine { "Read ${it.size} bytes of $this" } }
 
-    fun filenameSuffix() = when (format) {
+    internal fun filenameSuffix() = when (format) {
         "application/pdf", "application/vnd.cups-pdf" -> "pdf"
         "application/octet-stream" -> "bin"
         "application/postscript" -> "ps"
@@ -75,7 +75,7 @@ class IppDocument(
         if (file.isFile && !overwrite) throw IOException("File '$file' already exists")
         copyTo(file.outputStream())
         this.file = file
-        log.info { "Saved $this" }
+        logger.info { "Saved $file" }
     }
 
     fun runCommand(commandToHandleFile: String) =
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppExchangeException.kt b/src/main/kotlin/de/gmuth/ipp/client/IppExchangeException.kt
index e5aabaa1..c1cdabe0 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppExchangeException.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppExchangeException.kt
@@ -32,11 +32,11 @@ open class IppExchangeException(
         IppExchangeException(request, response) {
         init {
             require(response.status == ClientErrorNotFound)
-            { "ipp response status is not ClientErrorNotFound: ${response.status}" }
+            { "IPP response status is not ClientErrorNotFound: ${response.status}" }
         }
     }
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     companion object {
         fun defaultMessage(request: IppRequest, response: IppResponse?) = StringBuilder().run {
@@ -53,11 +53,11 @@ open class IppExchangeException(
 
     fun log(logger: Logger, level: Level = INFO) = logger.run {
         log(level) { message }
-        request.log(log, level, prefix = "REQUEST: ")
-        response?.log(log, level, prefix = "RESPONSE: ")
+        request.log(this@IppExchangeException.logger, level, prefix = "REQUEST: ")
+        response?.log(this@IppExchangeException.logger, level, prefix = "RESPONSE: ")
         httpStatus?.let { log(level) { "HTTP-Status: $it" } }
         httpHeaderFields?.let { for ((key: String?, value) in it) log(level) { "HTTP: $key = $value" } }
-        httpStream?.let { log.log(level) { "HTTP-Content:\n" + it.bufferedReader().use { it.readText() } } }
+        httpStream?.let { this@IppExchangeException.logger.log(level) { "HTTP-Content:\n" + it.bufferedReader().use { it.readText() } } }
     }
 
     fun saveMessages(
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppInspector.kt b/src/main/kotlin/de/gmuth/ipp/client/IppInspector.kt
index eff78037..4753c252 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppInspector.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppInspector.kt
@@ -12,7 +12,7 @@ import java.net.URI
 import java.util.logging.Logger.getLogger
 
 object IppInspector {
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     var directory: String = "inspected-printers"
 
     const val pdfA4 = "blank_A4.pdf"
@@ -28,14 +28,14 @@ object IppInspector {
      * - Hold-Job, Release-Job, Cancel-Job
      */
     private fun IppPrinter.inspect(cancelJob: Boolean) {
-        log.info { "Inspect printer $printerUri" }
+        logger.info { "Inspect printer $printerUri" }
 
         val printerModel = with(StringBuilder()) {
             if (isCups()) append("CUPS-")
             append(makeAndModel.text.replace("\\s+".toRegex(), "_"))
             toString()
         }
-        log.info { "Printer model: $printerModel" }
+        logger.info { "Printer model: $printerModel" }
 
         ippClient.saveMessages = true
         ippClient.saveMessagesDirectory = File(directory, printerModel).createDirectoryIfNotExists()
@@ -43,25 +43,25 @@ object IppInspector {
 
         attributes.run {
             // Media
-            if (containsKey("media-supported")) log.info { "Media supported: $mediaSupported" }
-            if (containsKey("media-ready")) log.info { "Media ready: $mediaReady" }
-            if (containsKey("media-default")) log.info { "Media default: $mediaDefault" }
+            if (containsKey("media-supported")) logger.info { "Media supported: $mediaSupported" }
+            if (containsKey("media-ready")) logger.info { "Media ready: $mediaReady" }
+            if (containsKey("media-default")) logger.info { "Media default: $mediaDefault" }
             // URIs
-            log.info { "Communication channels supported:" }
-            communicationChannelsSupported.forEach { log.info { "  $it" } }
-            log.info { "Document formats: $documentFormatSupported" }
+            logger.info { "Communication channels supported:" }
+            communicationChannelsSupported.forEach { logger.info { "  $it" } }
+            logger.info { "Document formats: $documentFormatSupported" }
         }
 
         val pdfResource = when {
             !attributes.containsKey("media-ready") -> {
-                log.warning { "media-ready not supported" }
+                logger.warning { "media-ready not supported" }
                 pdfA4
             }
 
             mediaReady.contains("iso-a4") || mediaReady.contains("iso_a4_210x297mm") -> pdfA4
             mediaReady.contains("na_letter") || mediaReady.contains("na_letter_8.5x11in") -> "blank_USLetter.pdf"
             else -> {
-                log.warning { "No PDF available for media '$mediaReady', trying A4" }
+                logger.warning { "No PDF available for media '$mediaReady', trying A4" }
                 pdfA4
             }
         }
@@ -72,21 +72,21 @@ object IppInspector {
 
     private fun IppPrinter.runInspectionWorkflow(pdfResource: String, cancelJob: Boolean) {
 
-        log.info { "> Get printer attributes" }
+        logger.info { "> Get printer attributes" }
         getPrinterAttributes()
 
         if (supportsOperations(CupsGetPPD)) {
-            log.info { "> CUPS Get PPD" }
+            logger.info { "> CUPS Get PPD" }
             savePPD(file = File(workDirectory, "0-${name.text}.ppd"))
         }
 
         if (supportsOperations(IdentifyPrinter)) {
             val action = with(identifyActionsSupported) { if (contains("sound")) "sound" else first() }
-            log.info { "> Identify by $action" }
+            logger.info { "> Identify by $action" }
             identify(action)
         }
 
-        log.info { "> Validate job" }
+        logger.info { "> Validate job" }
         val response = try {
             validateJob(
                 jobName("Validation"),
@@ -99,38 +99,38 @@ object IppInspector {
         } catch (ippExchangeException: IppExchangeException) {
             ippExchangeException.response
         }
-        log.info { response.toString() }
+        logger.info { response.toString() }
 
-        log.info { "> Print job $pdfResource" }
+        logger.info { "> Print job $pdfResource" }
         printJob(
             IppInspector::class.java.getResourceAsStream("/$pdfResource"),
             jobName(pdfResource),
 
             ).run {
-            log.info { toString() }
+            logger.info { toString() }
 
-            log.info { "> Get jobs" }
+            logger.info { "> Get jobs" }
             for (job in getJobs()) {
-                log.info { "$job" }
+                logger.info { "$job" }
             }
 
             if (supportsOperations(HoldJob, ReleaseJob)) {
-                log.info { "> Hold job" }
+                logger.info { "> Hold job" }
                 hold()
-                log.info { "> Release job" }
+                logger.info { "> Release job" }
                 release()
             }
 
             if (cancelJob) {
-                log.info { "> Cancel job" }
+                logger.info { "> Cancel job" }
                 cancel()
             }
 
-            log.info { "> Update job attributes" }
+            logger.info { "> Update job attributes" }
             updateAttributes()
 
             ippClient.saveMessages = false
-            log.info { "> Wait for termination" }
+            logger.info { "> Wait for termination" }
             waitForTermination()
         }
     }
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppJob.kt b/src/main/kotlin/de/gmuth/ipp/client/IppJob.kt
index 31f70e0b..a2fbba4a 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppJob.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppJob.kt
@@ -8,6 +8,7 @@ import de.gmuth.ipp.attributes.JobState
 import de.gmuth.ipp.attributes.JobState.*
 import de.gmuth.ipp.core.*
 import de.gmuth.ipp.core.IppOperation.*
+import de.gmuth.ipp.core.IppStatus.SuccessfulOk
 import de.gmuth.ipp.core.IppTag.*
 import java.io.File
 import java.io.FileInputStream
@@ -23,17 +24,21 @@ import java.util.logging.Logger.getLogger
 class IppJob(
     val printer: IppPrinter,
     val attributes: IppAttributesGroup,
-    subscriptionAttributes: IppAttributesGroup? = null
 ) : IppExchange by printer {
 
+    private val logger = getLogger(javaClass.name)
+    var subscription: IppSubscription? = null
+
+    constructor(printer: IppPrinter, response: IppResponse) : this(printer, response.jobGroup) {
+        if (response.status != SuccessfulOk) logger.warning { "Job response status: ${response.status}" }
+        if (response.containsGroup(Subscription)) subscription = IppSubscription(printer, response.subscriptionGroup)
+    }
+
     companion object {
         var defaultDelay: Duration = Duration.ofSeconds(1)
         var useJobOwnerAsUserName: Boolean = false
     }
 
-    private val log = getLogger(javaClass.name)
-    var subscription: IppSubscription? = subscriptionAttributes?.let { IppSubscription(printer, it) }
-
     //--------------
     // IppAttributes
     //--------------
@@ -147,16 +152,16 @@ class IppJob(
 
     @JvmOverloads
     fun waitForTermination(delay: Duration = defaultDelay) {
-        log.info { "Wait for termination of job #$id" }
+        logger.info { "Wait for termination of job #$id" }
         var lastPrinterString = ""
         var lastJobString = toString()
-        log.info { lastJobString }
+        logger.info { lastJobString }
         while (!isTerminated()) {
-            Thread.sleep(delay.toMillis())
+            Thread.sleep(delay.toMillis()) // no coroutines (http, ssl and stream parsing also require JVM)
             updateAttributes()
             if (toString() != lastJobString) {
                 lastJobString = toString()
-                log.info { lastJobString }
+                logger.info { lastJobString }
             }
             if (isProcessingStopped() || lastPrinterString.isNotEmpty()) {
                 printer.updateAttributes(
@@ -164,12 +169,12 @@ class IppJob(
                 )
                 if (printer.toString() != lastPrinterString) {
                     lastPrinterString = printer.toString()
-                    log.info { lastPrinterString }
+                    logger.info { lastPrinterString }
                 }
             }
             if (isProcessing() && lastPrinterString.isNotEmpty()) lastPrinterString = ""
         }
-        if (isAborted()) log(log)
+        if (isAborted()) log(logger)
     }
 
     //-------------------
@@ -182,12 +187,12 @@ class IppJob(
 
     @JvmOverloads
     fun cancel(messageForOperator: String? = null): IppResponse { // RFC 8011 4.3.3
-        if (isCanceled()) log.warning { "Job #$id is already 'canceled'" }
-        if (isProcessingToStopPoint()) log.warning { "Job #$id is already 'processing-to-stop-point'" }
+        if (isCanceled()) logger.warning { "Job #$id is already 'canceled'" }
+        if (isProcessingToStopPoint()) logger.warning { "Job #$id is already 'processing-to-stop-point'" }
         val request = ippRequest(CancelJob).apply {
             messageForOperator?.let { operationGroup.attribute("message", TextWithoutLanguage, it) }
         }
-        log.info { "Cancel job #$id" }
+        logger.info { "Cancel $this" }
         return exchange(request)
     }
 
@@ -202,9 +207,8 @@ class IppJob(
         documentName: String? = null,
         documentNaturalLanguage: String? = null
     ) {
-        val request = documentRequest(SendDocument, lastDocument, documentName, documentNaturalLanguage).apply {
-            documentInputStream = inputStream
-        }
+        val request = documentRequest(SendDocument, lastDocument, documentName, documentNaturalLanguage)
+            .apply { documentInputStream = inputStream }
         attributes.put(exchange(request).jobGroup)
     }
 
@@ -227,9 +231,8 @@ class IppJob(
         documentName: String? = null,
         documentNaturalLanguage: String? = null
     ) {
-        val request = documentRequest(SendURI, lastDocument, documentName, documentNaturalLanguage).apply {
-            operationGroup.attribute("document-uri", Uri, documentUri)
-        }
+        val request = documentRequest(SendURI, lastDocument, documentName, documentNaturalLanguage)
+            .apply { operationGroup.attribute("document-uri", Uri, documentUri) }
         attributes.put(exchange(request).jobGroup)
     }
 
@@ -274,7 +277,7 @@ class IppJob(
         return IppSubscription(printer, subscriptionAttributes).apply {
             subscription = this
             if (notifyEvents != null && !events.containsAll(notifyEvents)) {
-                log.warning { "Server ignored some notifyEvents $notifyEvents, subscribed events: $events" }
+                logger.warning { "Server ignored some notifyEvents $notifyEvents, subscribed events: $events" }
             }
         }
     }
@@ -301,10 +304,9 @@ class IppJob(
 
     @JvmOverloads
     fun cupsGetDocument(documentNumber: Int = 1): IppDocument {
-        log.fine { "CupsGetDocument #$documentNumber for job #$id" }
-        val response = exchange(ippRequest(CupsGetDocument).apply {
-            operationGroup.attribute("document-number", Integer, documentNumber)
-        })
+        logger.fine { "CupsGetDocument #$documentNumber for job #$id" }
+        val response = exchange(ippRequest(CupsGetDocument)
+            .apply { operationGroup.attribute("document-number", Integer, documentNumber) })
         return IppDocument(this, response.jobGroup, response.documentInputStream!!)
     }
 
@@ -327,7 +329,7 @@ class IppJob(
     //-----------------------
 
     fun printerDirectory() =
-        printer.printerDirectory(printerUri.toString().substringAfterLast("/"))
+        printer.printerDirectory(printerUri.toString().substringAfterLast(File.separator))
 
     private fun ippRequest(operation: IppOperation, requestedAttributes: List<String>? = null) =
         printer.ippRequest(
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppPrinter.kt b/src/main/kotlin/de/gmuth/ipp/client/IppPrinter.kt
index e870a81f..3cbf3730 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppPrinter.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppPrinter.kt
@@ -11,7 +11,6 @@ import de.gmuth.ipp.attributes.PrinterState.*
 import de.gmuth.ipp.core.*
 import de.gmuth.ipp.core.IppOperation.*
 import de.gmuth.ipp.core.IppStatus.ClientErrorNotFound
-import de.gmuth.ipp.core.IppStatus.SuccessfulOk
 import de.gmuth.ipp.core.IppTag.*
 import de.gmuth.ipp.iana.IppRegistrationsSection2
 import java.io.*
@@ -33,7 +32,7 @@ class IppPrinter(
     requestedAttributesOnInit: List<String>? = null
 ) : IppExchange {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     var workDirectory: File = createTempDirectory().toFile()
 
     companion object {
@@ -60,27 +59,27 @@ class IppPrinter(
     }
 
     init {
-        log.fine { "create IppPrinter for $printerUri" }
+        logger.fine { "create IppPrinter for $printerUri" }
         require(printerUri.scheme.startsWith("ipp")) { "uri scheme unsupported: ${printerUri.scheme}" }
         if (printerUri.scheme == "ipps") ippConfig.trustAnyCertificateAndSSLHostname()
         if (!getPrinterAttributesOnInit) {
-            log.fine { "getPrinterAttributesOnInit disabled => no printer attributes available" }
+            logger.fine { "getPrinterAttributesOnInit disabled => no printer attributes available" }
         } else if (attributes.isEmpty()) {
             try {
                 updateAttributes(requestedAttributesOnInit)
                 if (isStopped()) {
-                    log.fine { toString() }
-                    alert?.let { log.info { "alert: $it" } }
-                    alertDescription?.let { log.info { "alert-description: $it" } }
+                    logger.fine { toString() }
+                    alert?.let { logger.info { "alert: $it" } }
+                    alertDescription?.let { logger.info { "alert-description: $it" } }
                 }
             } catch (ippExchangeException: IppExchangeException) {
                 if (ippExchangeException.statusIs(ClientErrorNotFound))
-                    log.severe { ippExchangeException.message }
+                    logger.severe { ippExchangeException.message }
                 else {
-                    log.severe { "Failed to get printer attributes on init. Workaround: getPrinterAttributesOnInit=false" }
+                    logger.severe { "Failed to get printer attributes on init. Workaround: getPrinterAttributesOnInit=false" }
                     ippExchangeException.response?.let {
-                        if (it.containsGroup(Printer)) log.info { "${it.printerGroup.size} attributes parsed" }
-                        else log.warning { "RESPONSE: $it" }
+                        if (it.containsGroup(Printer)) logger.info { "${it.printerGroup.size} attributes parsed" }
+                        else logger.warning { "RESPONSE: $it" }
                     }
                 }
                 throw ippExchangeException
@@ -260,7 +259,7 @@ class IppPrinter(
     ) =
         file.also {
             cupsGetPPD(it.outputStream())
-            log.info { "Saved PPD: $it" }
+            logger.info { "Saved PPD: $it" }
         }
 
     //------------------------------------------
@@ -364,7 +363,7 @@ class IppPrinter(
             // put attribute in operation or job group?
             val groupTag = IppRegistrationsSection2.selectGroupForAttribute(attribute.name) ?: Job
             if (!containsGroup(groupTag)) createAttributesGroup(groupTag)
-            log.finer { "$groupTag put $attribute" }
+            logger.finer { "$groupTag put $attribute" }
             getSingleAttributesGroup(groupTag).put(attribute)
         }
     }
@@ -389,7 +388,7 @@ class IppPrinter(
         limit: Int? = null,
         requestedAttributes: List<String>? = getJobsRequestedAttributes
     ): Collection<IppJob> {
-        log.fine { "getJobs(whichJobs=$whichJobs, requestedAttributes=$requestedAttributes)" }
+        logger.fine { "getJobs(whichJobs=$whichJobs, requestedAttributes=$requestedAttributes)" }
         val request = ippRequest(GetJobs, requestedAttributes = requestedAttributes).apply {
             operationGroup.run {
                 whichJobs?.keyword?.let {
@@ -408,6 +407,13 @@ class IppPrinter(
     fun getJobs(whichJobs: WhichJobs? = null, vararg requestedAttributes: String) =
         getJobs(whichJobs, requestedAttributes = requestedAttributes.toList())
 
+    //------------
+    // Cancel jobs
+    //------------
+
+    fun cancelJobs(whichJobs: WhichJobs) =
+        getJobs(whichJobs).forEach { it.cancel() }
+
     //----------------------------
     // Create-Printer-Subscription
     //----------------------------
@@ -484,19 +490,14 @@ class IppPrinter(
         checkIfValueIsSupported("charset-supported", attributesCharset)
     })
 
-    private fun exchangeForIppJob(request: IppRequest): IppJob {
-        val response = exchange(request)
-        if (response.status != SuccessfulOk) log.warning { "Job response status: ${response.status}" }
-        if (request.containsGroup(Subscription) && !response.containsGroup(Subscription)) {
-            request.log(log, WARNING, prefix = "REQUEST: ")
-            val events: List<String> = request.subscriptionGroup.getValues("notify-events")
-            throw IppException("printer/server did not create subscription for events: ${events.joinToString(",")}")
-        }
-        val subscriptionsAttributes = response.run {
-            if (containsGroup(Subscription)) subscriptionGroup else null
+    private fun exchangeForIppJob(request: IppRequest) =
+        IppJob(this, exchange(request)).apply {
+            if (request.containsGroup(Subscription) && subscription == null) {
+                request.log(logger, WARNING, prefix = "REQUEST: ")
+                val events: List<String> = request.subscriptionGroup.getValues("notify-events")
+                throw IppException("printer/server did not create subscription for events: ${events.joinToString(",")}")
+            }
         }
-        return IppJob(this, response.jobGroup, subscriptionsAttributes)
-    }
 
     private fun checkIfValueIsSupported(supportedAttributeName: String, value: Any) =
         IppValueSupport.checkIfValueIsSupported(attributes, supportedAttributeName, value)
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppSubscription.kt b/src/main/kotlin/de/gmuth/ipp/client/IppSubscription.kt
index 6e6c728e..f62c978e 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppSubscription.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppSubscription.kt
@@ -24,16 +24,12 @@ class IppSubscription(
     val attributes: IppAttributesGroup
 ) : IppExchange by printer {
 
-    private val log = getLogger(javaClass.name)
-
+    private val logger = getLogger(javaClass.name)
     private var lastSequenceNumber: Int = 0
     private var leaseStartedAt = now()
 
     init {
-        if (attributes.size <= 1) {
-            updateAttributes()
-            log.info { toString() }
-        }
+        if (attributes.size <= 1) updateAttributes()
     }
 
     val id: Int
@@ -61,11 +57,12 @@ class IppSubscription(
     // RFC 3995 11.2.4.1.2: 'subscription-template', 'subscription-description' or 'all' (default)
 
     @JvmOverloads
-    fun getSubscriptionAttributes(requestedAttributes: List<String>? = null) =
-        exchange(ippRequest(GetSubscriptionAttributes, requestedAttributes = requestedAttributes)).subscriptionGroup
+    fun getSubscriptionAttributes(requestedAttributes: List<String>? = null) = exchange(
+        subscriptionRequest(GetSubscriptionAttributes, requestedAttributes = requestedAttributes)
+    )
 
     fun updateAttributes() {
-        attributes.put(getSubscriptionAttributes())
+        attributes.put(getSubscriptionAttributes().subscriptionGroup)
     }
 
     //------------------
@@ -73,7 +70,7 @@ class IppSubscription(
     //------------------
 
     fun getNotifications(notifySequenceNumber: Int? = lastSequenceNumber + 1): List<IppEventNotification> {
-        val request = ippRequest(GetNotifications).apply {
+        val request = subscriptionRequest(GetNotifications).apply {
             operationGroup.run {
                 attribute("notify-subscription-ids", Integer, id)
                 notifySequenceNumber?.let { attribute("notify-sequence-numbers", Integer, it) }
@@ -89,27 +86,27 @@ class IppSubscription(
     // Cancel-Subscription
     //--------------------
 
-    fun cancel() =
-        exchange(ippRequest(CancelSubscription))
+    fun cancel() = exchange(subscriptionRequest(CancelSubscription))
 
     //-------------------
     // Renew-Subscription
     //-------------------
 
-    fun renew(leaseDuration: Duration? = null) =
-        exchange(ippRequest(RenewSubscription).apply {
+    fun renew(leaseDuration: Duration? = null) = exchange(
+        subscriptionRequest(RenewSubscription).apply {
             createSubscriptionAttributesGroup(notifyLeaseDuration = leaseDuration)
-        }).also {
-            leaseStartedAt = now()
-            updateAttributes()
-            log.info { "renewed $this" }
         }
+    ).also {
+        leaseStartedAt = now()
+        updateAttributes()
+        logger.fine { "renewed $this" }
+    }
 
     //-----------------------
     // Delegate to IppPrinter
     //-----------------------
 
-    protected fun ippRequest(operation: IppOperation, requestedAttributes: List<String>? = null) =
+    private fun subscriptionRequest(operation: IppOperation, requestedAttributes: List<String>? = null) =
         printer.ippRequest(operation, requestedAttributes = requestedAttributes)
             .apply { operationGroup.attribute("notify-subscription-id", Integer, id) }
 
@@ -127,19 +124,19 @@ class IppSubscription(
     fun pollAndHandleNotifications(
         pollEvery: Duration = ofSeconds(5), // should be larger than 1s
         autoRenewSubscription: Boolean = false,
-        handleNotification: (event: IppEventNotification) -> Unit = { log.info { it.toString() } }
+        handleNotification: (event: IppEventNotification) -> Unit = { logger.info { it.toString() } }
     ) {
         fun expiresAfterDelay() = !leaseDuration.isZero && now().plus(pollEvery).isAfter(expiresAt.minusSeconds(2))
         try {
             pollHandlesNotifications = true
             while (pollHandlesNotifications) {
-                if (expired()) log.warning { "subscription #$id has expired" }
+                if (expired()) logger.warning { "subscription #$id has expired" }
                 getNotifications().forEach { handleNotification(it) }
                 if (expiresAfterDelay() && autoRenewSubscription) renew(leaseDuration)
                 Thread.sleep(pollEvery.toMillis())
             }
         } catch (clientErrorNotFoundException: ClientErrorNotFoundException) {
-            log.info { clientErrorNotFoundException.response!!.statusMessage.toString() }
+            logger.info { clientErrorNotFoundException.response!!.statusMessage.toString() }
         }
     }
 
diff --git a/src/main/kotlin/de/gmuth/ipp/client/IppValueSupport.kt b/src/main/kotlin/de/gmuth/ipp/client/IppValueSupport.kt
index 9d60e890..8563aa01 100644
--- a/src/main/kotlin/de/gmuth/ipp/client/IppValueSupport.kt
+++ b/src/main/kotlin/de/gmuth/ipp/client/IppValueSupport.kt
@@ -14,11 +14,12 @@ import java.util.logging.Logger.getLogger
 
 object IppValueSupport {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
-    fun checkIfValueIsSupported(printerAttributes: IppAttributesGroup, attribute: IppAttribute<Any>) {
+    fun checkIfValueIsSupported(printerAttributes: IppAttributesGroup, attribute: IppAttribute<*>) {
         val supportedAttribute = printerAttributes["${attribute.name}-supported"]
-        supportedAttribute?.let { checkIfValueIsSupported(printerAttributes, supportedAttribute.name, attribute.value) }
+        if (supportedAttribute == null) logger.warning { "${attribute.name}-supported not available in printer attributes" }
+        else checkIfValueIsSupported(printerAttributes, supportedAttribute.name, attribute.value as Any)
     }
 
     fun checkIfValueIsSupported(
@@ -54,9 +55,10 @@ object IppValueSupport {
 
             IppTag.Enum, Charset, NaturalLanguage, MimeMediaType, Keyword, Resolution -> when (supportedAttributeName) {
                 "media-col-supported" -> with(value as IppCollection) {
-                    members.filter { !supportedAttribute.values.contains(it.name) }
-                        .forEach { log.warning { "member unsupported: $it" } }
-                    // all member names must be supported
+                    members
+                        .onEach { checkIfValueIsSupported(printerAttributes, it) }
+                        .filter { !supportedAttribute.values.contains(it.name) }
+                        .forEach { logger.warning { "media-col member unsupported: $it" } }
                     supportedAttribute.values.containsAll(members.map { it.name })
                 }
 
@@ -75,13 +77,14 @@ object IppValueSupport {
             else -> null
         }
         when (attributeValueIsSupported) {
-            null -> log.warning { "unable to check if value '$value' is supported by $supportedAttribute" }
-            true -> log.fine { "$supportedAttributeName: $value" }
+            null -> logger.warning { "Unable to check if value '$value' is supported by $supportedAttribute" }
+            true -> logger.finer { "$value is supported according to $supportedAttributeName" }
             false -> {
-                log.warning { "according to printer attributes value '${supportedAttribute.enumNameOrValue(value)}' is not supported." }
-                log.warning { "$supportedAttribute" }
+                logger.warning { "According to printer attributes value '${supportedAttribute.enumNameOrValue(value)}' is not supported." }
+                logger.warning { "$supportedAttribute" }
             }
         }
         return attributeValueIsSupported
+            .also { logger.finest { "is $supportedAttributeName(${supportedAttribute.tag})? $value -> $attributeValueIsSupported" } }
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppAttribute.kt b/src/main/kotlin/de/gmuth/ipp/core/IppAttribute.kt
index b8c683d1..e2592363 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppAttribute.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppAttribute.kt
@@ -15,7 +15,7 @@ import java.util.logging.Logger.getLogger
 
 data class IppAttribute<T>(val name: String, val tag: IppTag) : IppAttributeBuilder {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     val values: MutableCollection<T> = mutableListOf()
 
@@ -40,7 +40,7 @@ data class IppAttribute<T>(val name: String, val tag: IppTag) : IppAttributeBuil
         when {
             attribute.name.isNotEmpty() -> throw IppException("For additional '$name' values attribute name must be empty")
             attribute.values.size != 1 -> throw IppException("Expected 1 additional value, not ${attribute.values.size}")
-            attribute.tag != tag -> log.warning { "$name: ignore additional value \"$attribute\" - tag is not '$tag'" }
+            attribute.tag != tag -> logger.warning { "$name: ignore additional value \"$attribute\" - tag is not '$tag'" }
             else -> {
                 attribute.tag.validateValueClass(attribute.values.single() as Any)
                 values.add(attribute.values.single() as T)
@@ -85,5 +85,4 @@ data class IppAttribute<T>(val name: String, val tag: IppTag) : IppAttributeBuil
             }
         }
     }
-
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppAttributesGroup.kt b/src/main/kotlin/de/gmuth/ipp/core/IppAttributesGroup.kt
index e46e7112..1873282f 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppAttributesGroup.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppAttributesGroup.kt
@@ -17,7 +17,7 @@ import java.util.logging.Logger.getLogger
 
 class IppAttributesGroup(val tag: IppTag) : LinkedHashMap<String, IppAttribute<*>>() {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     var onReplaceWarn: Boolean = false
 
     init {
@@ -26,7 +26,7 @@ class IppAttributesGroup(val tag: IppTag) : LinkedHashMap<String, IppAttribute<*
 
     fun put(attribute: IppAttribute<*>) = put(attribute.name, attribute).also {
         if (it != null && onReplaceWarn) {
-            log.warning { "replaced '$it' with '${attribute.values.joinToString(",")}' in group $tag" }
+            logger.warning { "replaced '$it' with '${attribute.values.joinToString(",")}' in group $tag" }
         }
     }
 
@@ -83,7 +83,7 @@ class IppAttributesGroup(val tag: IppTag) : LinkedHashMap<String, IppAttribute<*
 
     fun saveText(file: File) = file.apply {
         bufferedWriter().use { write(it) }
-        log.info { "Saved $path" }
+        logger.info { "Saved $path" }
     }
 
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppInputStream.kt b/src/main/kotlin/de/gmuth/ipp/core/IppInputStream.kt
index f429853f..482788e9 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppInputStream.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppInputStream.kt
@@ -13,7 +13,7 @@ import java.util.logging.Logger.getLogger
 
 class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputStream) {
 
-    internal val log = getLogger(javaClass.name)
+    internal val logger = getLogger(javaClass.name)
 
     // character encoding for text and name attributes, RFC 8011 4.1.4.1
     internal lateinit var attributesCharset: Charset
@@ -21,13 +21,13 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
     fun readMessage(message: IppMessage) {
         with(message) {
             version = "${readUnsignedByte()}.${readUnsignedByte()}"
-            log.finest { "version = $version" }
+            logger.finest { "version = $version" }
 
             code = readUnsignedShort()
-            log.finest { "code = $code ($codeDescription)" }
+            logger.finest { "code = $code ($codeDescription)" }
 
             requestId = readInt()
-            log.finest { "requestId = $requestId" }
+            logger.finest { "requestId = $requestId" }
         }
 
         lateinit var currentGroup: IppAttributesGroup
@@ -42,7 +42,7 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
 
                     tag.isValueTag() -> {
                         val attribute = readAttribute(tag)
-                        log.finest { attribute.toString() }
+                        logger.finest { attribute.toString() }
                         if (attribute.name.isNotEmpty()) {
                             currentGroup.put(attribute)
                             currentAttribute = attribute
@@ -55,8 +55,8 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
         } catch (throwable: Throwable) {
             if (throwable !is EOFException) readBytes().apply {
                 if (isNotEmpty()) {
-                    log.warning { "Skipped $size unparsed bytes" }
-                    hexdump { log.finest { it } }
+                    logger.warning { "Skipped $size unparsed bytes" }
+                    hexdump { logger.finest { it } }
                 }
             }
             throw IppException("Failed to read ipp message", throwable)
@@ -64,7 +64,7 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
     }
 
     internal fun readTag() = IppTag.fromByte(readByte()).apply {
-        if (isDelimiterTag()) log.finest { "--- $this ---" }
+        if (isDelimiterTag()) logger.finest { "--- $this ---" }
     }
 
     internal fun readAttribute(tag: IppTag) = IppAttribute<Any>(name = readString(), tag).apply {
@@ -162,7 +162,7 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
                     readCollection()
                 } else {
                     // Xerox B210: workaround for invalid 'media-col' without members
-                    log.warning { "Invalid value length for IppCollection, trying to recover" }
+                    logger.warning { "Invalid value length for IppCollection, trying to recover" }
                     IppCollection()
                 }
             }
@@ -172,8 +172,8 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
                 readLengthAndValue().apply {
                     if (isNotEmpty()) {
                         val level = if (tag == Unsupported_) Level.FINEST else Level.WARNING
-                        log.log(level) { "Ignore $size value bytes tagged '$tag'" }
-                        hexdump { log.log(level) { it } }
+                        logger.log(level) { "Ignore $size value bytes tagged '$tag'" }
+                        hexdump { logger.log(level) { it } }
                     }
                 }
             }
@@ -217,7 +217,7 @@ class IppInputStream(inputStream: BufferedInputStream) : DataInputStream(inputSt
             if (!this) { // unexpected value length
                 reset() // revert 'readShort()'
                 with("Expected value length of $expected bytes but found $length") {
-                    if (throwException) throw IppException(this) else log.warning { this }
+                    if (throwException) throw IppException(this) else logger.warning { this }
                 }
             }
         }
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppMessage.kt b/src/main/kotlin/de/gmuth/ipp/core/IppMessage.kt
index 1102159a..29a2ac85 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppMessage.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppMessage.kt
@@ -13,7 +13,7 @@ import java.util.logging.Logger.getLogger
 
 abstract class IppMessage() {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     var code: Int? = null // unsigned short (16 bits)
     var requestId: Int? = null
     var version: String? = null
@@ -112,12 +112,12 @@ abstract class IppMessage() {
     }
 
     fun read(file: File) {
-        log.fine { "Read file ${file.absolutePath}: ${file.length()} bytes" }
+        logger.fine { "Read file ${file.absolutePath}: ${file.length()} bytes" }
         read(FileInputStream(file))
     }
 
     fun decode(byteArray: ByteArray) {
-        log.fine { "Decode ${byteArray.size} bytes" }
+        logger.fine { "Decode ${byteArray.size} bytes" }
         read(ByteArrayInputStream(byteArray))
     }
 
@@ -126,16 +126,16 @@ abstract class IppMessage() {
     // ------------------------
 
     protected fun copyDocumentStream(outputStream: OutputStream): Long {
-        if (documentInputStreamIsConsumed) log.warning { "documentInputStream is consumed" }
+        if (documentInputStreamIsConsumed) logger.warning { "documentInputStream is consumed" }
         return documentInputStream!!.copyTo(outputStream).apply {
-            log.fine { "consumed documentInputStream: $this bytes" }
+            logger.fine { "consumed documentInputStream: $this bytes" }
             documentInputStreamIsConsumed = true
         }
     }
 
     fun saveDocumentStream(file: File) {
         copyDocumentStream(file.outputStream())
-        log.info { "saved ${file.length()} document bytes to file ${file.path}" }
+        logger.info { "saved ${file.length()} document bytes to file ${file.path}" }
     }
 
     fun saveBytes(file: File) =
@@ -143,7 +143,7 @@ abstract class IppMessage() {
             throw IppException("No raw bytes to save. You must call read/decode or write/encode before.")
         } else {
             file.writeBytes(rawBytes!!)
-            log.info { "Saved ${file.path} (${file.length()} bytes)" }
+            logger.info { "Saved ${file.path} (${file.length()} bytes)" }
         }
 
     protected fun write(bufferedWriter: BufferedWriter, title: String) {
@@ -161,7 +161,7 @@ abstract class IppMessage() {
 
     fun saveText(file: File) = file.apply {
         bufferedWriter().use { write(it, title = "# File: ${file.name}") }
-        log.info { "Saved $path (${length()} bytes)" }
+        logger.info { "Saved $path (${length()} bytes)" }
     }
 
     // -------
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppOutputStream.kt b/src/main/kotlin/de/gmuth/ipp/core/IppOutputStream.kt
index 4094819a..b061729c 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppOutputStream.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppOutputStream.kt
@@ -13,7 +13,7 @@ import java.util.logging.Logger.getLogger
 
 class IppOutputStream(outputStream: OutputStream) : DataOutputStream(outputStream) {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     // Charset for text and name attributes, RFC 8011 4.1.4.1
     internal lateinit var attributesCharset: Charset
@@ -22,13 +22,13 @@ class IppOutputStream(outputStream: OutputStream) : DataOutputStream(outputStrea
         attributesCharset = operationGroup.getValue("attributes-charset")
 
         writeVersion(version ?: throw IppException("missing version"))
-        log.finest { "version = $version" }
+        logger.finest { "version = $version" }
 
         writeShort(code ?: throw IppException("missing operation or status code"))
-        log.finest { "code = $code ($codeDescription)" }
+        logger.finest { "code = $code ($codeDescription)" }
 
         writeInt(requestId ?: throw IppException("missing requestId"))
-        log.finest { "requestId = $requestId" }
+        logger.finest { "requestId = $requestId" }
 
         for (group in attributesGroups) {
             writeTag(group.tag)
@@ -51,7 +51,7 @@ class IppOutputStream(outputStream: OutputStream) : DataOutputStream(outputStrea
     }
 
     internal fun writeTag(tag: IppTag) {
-        if (tag.isDelimiterTag()) log.finest { "--- $tag ---" }
+        if (tag.isDelimiterTag()) logger.finest { "--- $tag ---" }
         writeByte(tag.code.toInt())
     }
 
@@ -63,7 +63,7 @@ class IppOutputStream(outputStream: OutputStream) : DataOutputStream(outputStrea
     }
 
     internal fun writeAttribute(attribute: IppAttribute<*>) {
-        log.finest { "$attribute" }
+        logger.finest { "$attribute" }
         with(attribute) {
             if (values.isEmpty() || tag.isOutOfBandTag()) {
                 writeTag(tag)
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppRequest.kt b/src/main/kotlin/de/gmuth/ipp/core/IppRequest.kt
index 729b7980..233b45ef 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppRequest.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppRequest.kt
@@ -20,9 +20,8 @@ class IppRequest : IppMessage {
             when {
                 containsKey("printer-uri") -> getUriValue("printer-uri")
                 containsKey("job-uri") -> getUriValue("job-uri")
-                else -> throw IppException("Missing 'printer-uri' or 'job-uri' in IppRequest").also {
-                    log(logger, Level.WARNING)
-                }
+                else -> throw IppException("Missing 'printer-uri' or 'job-uri' in IppRequest")
+                    .also { log(logger, Level.WARNING) }
             }
         }
 
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppResponse.kt b/src/main/kotlin/de/gmuth/ipp/core/IppResponse.kt
index 43b857fa..f7dc41c3 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppResponse.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppResponse.kt
@@ -4,7 +4,7 @@ package de.gmuth.ipp.core
  * Copyright (c) 2020-2023 Gerhard Muth
  */
 
-import de.gmuth.ipp.core.IppTag.*
+import de.gmuth.ipp.core.IppTag.Unsupported
 import java.nio.charset.Charset
 
 class IppResponse : IppMessage {
@@ -22,9 +22,6 @@ class IppResponse : IppMessage {
     val statusMessage: IppString
         get() = operationGroup.getValue("status-message")
 
-    val jobGroups: Collection<IppAttributesGroup>
-        get() = getAttributesGroups(Job)
-
     val unsupportedGroup: IppAttributesGroup
         get() = getSingleAttributesGroup(Unsupported)
 
@@ -41,5 +38,4 @@ class IppResponse : IppMessage {
     ) : super(version, requestId, charset, naturalLanguage) {
         code = status.code
     }
-
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/core/IppTag.kt b/src/main/kotlin/de/gmuth/ipp/core/IppTag.kt
index 4f6d7ecc..e640f6e0 100644
--- a/src/main/kotlin/de/gmuth/ipp/core/IppTag.kt
+++ b/src/main/kotlin/de/gmuth/ipp/core/IppTag.kt
@@ -70,7 +70,7 @@ enum class IppTag(
     override fun toString() = registeredName
 
     fun registeredSyntax() = when (this) {
-        // iana registered syntax doesn't care about language
+        // IANA registered syntax doesn't care about language
         NameWithoutLanguage, NameWithLanguage -> "name"
         TextWithoutLanguage, TextWithLanguage -> "text"
         else -> registeredName
@@ -87,5 +87,4 @@ enum class IppTag(
         fun fromString(name: String): IppTag =
             values().singleOrNull { it.registeredName == name } ?: throw IppException("Unknown tag name '$name'")
     }
-
 }
\ No newline at end of file
diff --git a/src/main/kotlin/de/gmuth/ipp/iana/IppRegistrationsSection2.kt b/src/main/kotlin/de/gmuth/ipp/iana/IppRegistrationsSection2.kt
index 2a6b76b4..05623b74 100644
--- a/src/main/kotlin/de/gmuth/ipp/iana/IppRegistrationsSection2.kt
+++ b/src/main/kotlin/de/gmuth/ipp/iana/IppRegistrationsSection2.kt
@@ -14,7 +14,7 @@ import java.util.logging.Logger.getLogger
 // https://www.iana.org/assignments/ipp-registrations/ipp-registrations.xml#ipp-registrations-2
 object IppRegistrationsSection2 {
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     data class Attribute(
         val collection: String,
@@ -103,7 +103,7 @@ object IppRegistrationsSection2 {
     }
 
     fun resolveAlias(name: String) = (aliasMap[name] ?: name).also {
-        if (aliasMap.containsKey(name)) log.finer { "'$name' resolves to '$it'" }
+        if (aliasMap.containsKey(name)) logger.finer { "'$name' resolves to '$it'" }
     }
 
     fun getAttribute(name: String, resolveAlias: Boolean = true) =
@@ -126,10 +126,10 @@ object IppRegistrationsSection2 {
         if (tag.isOutOfBandTag()) return
         val syntax = syntaxForAttribute(name, true)
         if (syntax == null) {
-            log.fine { "no syntax found for '$name'" }
+            logger.fine { "no syntax found for '$name'" }
             unknownAttributes.add(name)
         } else if (!syntax.contains(tag.registeredSyntax())) {
-            log.warning { "$name ($tag) does not match iana registered syntax '$syntax'" }
+            logger.warning { "$name ($tag) does not match iana registered syntax '$syntax'" }
         }
     }
 
@@ -145,16 +145,16 @@ object IppRegistrationsSection2 {
     fun validate(ippAttribute: IppAttribute<*>) = with(ippAttribute) {
         checkSyntaxOfAttribute(name, tag)
         if (isCollection()) validate(name, values as List<IppCollection>)
-        if (!tag.isOutOfBandTag() && values.isEmpty()) log.warning { "'$name' ($tag) has no values" }
-        if (values.size > 1 && attributeIs1setOf(name) == false) log.warning { "'$name' is not registered as '1setOf'" }
+        if (!tag.isOutOfBandTag() && values.isEmpty()) logger.warning { "'$name' ($tag) has no values" }
+        if (values.size > 1 && attributeIs1setOf(name) == false) logger.warning { "'$name' is not registered as '1setOf'" }
     }
 
     @Suppress("UNCHECKED_CAST")
     fun validate(name: String, ippCollections: List<IppCollection>) {
-        log.finer { "validate collection '$name'" }
+        logger.finer { "validate collection '$name'" }
         val resolvedName = resolveAlias(name)
         for (ippCollection in ippCollections) {
-            log.finer { "         ${ippCollection.members.size} members" }
+            logger.finer { "         ${ippCollection.members.size} members" }
             for (member in ippCollection.members) {
                 if (member.isCollection()) {
                     validate("$resolvedName/${member.name}", member.values as List<IppCollection>)
@@ -168,8 +168,8 @@ object IppRegistrationsSection2 {
     fun logUnknownAttributes() {
         with(unknownAttributes.toMutableList()) {
             sort()
-            log.info { "$size unknown attributes:" }
-            forEach { log.info { "- $it" } }
+            logger.info { "$size unknown attributes:" }
+            forEach { logger.info { "- $it" } }
         }
     }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/de/gmuth/ipp/client/CupsClientTests.kt b/src/test/kotlin/de/gmuth/ipp/client/CupsClientTests.kt
index 4b1a8dc2..7f27be39 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/CupsClientTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/CupsClientTests.kt
@@ -15,7 +15,7 @@ import kotlin.test.assertFailsWith
 import kotlin.test.assertTrue
 
 class CupsClientTests {
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     val ippClientMock = IppClientMock("printers/CUPS")
     val cupsClient = CupsClient(URI.create("ipps://cups"), ippClient = ippClientMock)
 
@@ -29,7 +29,7 @@ class CupsClientTests {
     fun getPrinters() {
         ippClientMock.mockResponse("Cups-Get-Printers.ipp")
         cupsClient.getPrinters().run {
-            forEach { log.info { it.toString() } }
+            forEach { logger.info { it.toString() } }
             assertEquals(12, size)
         }
     }
@@ -38,7 +38,7 @@ class CupsClientTests {
     fun getPrinter() {
         ippClientMock.mockResponse("Get-Printer-Attributes.ipp", "printers/CUPS_HP_LaserJet_100_color_MFP_M175")
         cupsClient.getPrinter("ColorJet_HP").run {
-            log(log)
+            log(logger)
             assertEquals("HP LaserJet 100 color MFP M175", makeAndModel.text)
             assertEquals(PrinterState.Idle, state)
             assertEquals(5, markers.size)
diff --git a/src/test/kotlin/de/gmuth/ipp/client/IppClientMock.kt b/src/test/kotlin/de/gmuth/ipp/client/IppClientMock.kt
index 7bce2f73..2531da7c 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/IppClientMock.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/IppClientMock.kt
@@ -36,13 +36,13 @@ class IppClientMock(var directory: String = "printers") : IppClient() {
     // when used with real http, responses are frequently created and garbage collected
     // however references to attribute groups are kept in IPP objects
     // changes to an attribute group would affect other tests as well
-    // therefor it's important to produce a fresh response for each call
+    // therefor it's important to produce a fresh response for each mocked call
 
     override fun httpPost(httpUri: URI, request: IppRequest) = IppResponse().apply {
         ByteArrayOutputStream()
             .also { request.write(it) }
             .toByteArray()
-            .run { log.info { "post $size request bytes to $httpUri, ${rawResponse.size} response bytes" } }
+            .run { logger.info { "post $size request bytes to $httpUri, ${rawResponse.size} response bytes" } }
         decode(rawResponse)
     }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/de/gmuth/ipp/client/IppExchangeExceptionTests.kt b/src/test/kotlin/de/gmuth/ipp/client/IppExchangeExceptionTests.kt
index 96b9677c..1a78fd9e 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/IppExchangeExceptionTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/IppExchangeExceptionTests.kt
@@ -12,7 +12,7 @@ import kotlin.test.assertEquals
 
 class IppExchangeExceptionTests {
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     @Test
     fun constructor() {
@@ -22,7 +22,7 @@ class IppExchangeExceptionTests {
                 null, 400
         )
         ) {
-            log(log)
+            log(logger)
             assertEquals(11, request.code)
             assertEquals(400, httpStatus)
             assertEquals(message, "Get-Printer-Attributes failed")
diff --git a/src/test/kotlin/de/gmuth/ipp/client/IppJobTests.kt b/src/test/kotlin/de/gmuth/ipp/client/IppJobTests.kt
index 22c55168..e14aad68 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/IppJobTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/IppJobTests.kt
@@ -22,7 +22,7 @@ import kotlin.test.assertTrue
 
 class IppJobTests {
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     val blankPdf = File("tool/A4-blank.pdf")
 
     val ippClientMock = IppClientMock("printers/CUPS_HP_LaserJet_100_color_MFP_M175")
@@ -42,8 +42,8 @@ class IppJobTests {
     @Test
     fun jobAttributes() {
         job.apply {
-            log.info { toString() }
-            log(log)
+            logger.info { toString() }
+            log(logger)
             assertEquals("ipp://localhost:631/jobs/2366", uri.toString())
             assertEquals(0, mediaSheetsCompleted)
             assertEquals(2, kOctets)
@@ -66,7 +66,7 @@ class IppJobTests {
         job.apply {
             attributes.onReplaceWarn = true
             updateAttributes()
-            log(log)
+            log(logger)
             assertEquals(32, attributes.size)
         }
     }
@@ -172,8 +172,8 @@ class IppJobTests {
     fun cupsGetDocument1() {
         ippClientMock.mockResponse(cupsDocumentResponse("application/pdf"))
         job.cupsGetDocument().apply {
-            log.info { toString() }
-            log(log)
+            logger.info { toString() }
+            log(logger)
             save().delete()
             assertEquals("job-2366-gmuth-A4-blank.pdf", filename())
         }
@@ -194,10 +194,10 @@ class IppJobTests {
             jobGroup.remove("document-name")
         })
         job.cupsGetDocument(2).apply {
-            log.info { toString() }
-            log.info { "${filename()} (${readBytes().size} bytes)" }
+            logger.info { toString() }
+            logger.info { "${filename()} (${readBytes().size} bytes)" }
             job.attributes.remove("document-name-supplied")
-            log.info { filename() }
+            logger.info { filename() }
             assertEquals("bin", filenameSuffix())
         }
     }
diff --git a/src/test/kotlin/de/gmuth/ipp/client/IppPrinterTests.kt b/src/test/kotlin/de/gmuth/ipp/client/IppPrinterTests.kt
index 7f9d7a1e..8b885e27 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/IppPrinterTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/IppPrinterTests.kt
@@ -31,7 +31,7 @@ import kotlin.test.assertTrue
 
 class IppPrinterTests {
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     val blankPdf = File("tool/A4-blank.pdf")
     val ippClientMock = IppClientMock("printers/Simulated_Laser_Printer")
     val printer = IppPrinter(
@@ -42,7 +42,7 @@ class IppPrinterTests {
     @Test
     fun printerAttributes() {
         printer.run {
-            log.info { toString() }
+            logger.info { toString() }
             assertTrue(isAcceptingJobs)
             assertTrue(documentFormatSupported.contains("application/pdf"))
             assertTrue(supportsOperations(GetPrinterAttributes))
@@ -64,7 +64,7 @@ class IppPrinterTests {
                 assertEquals(80, levelPercent())
                 assertEquals("#000000", colorCode)
                 assertFalse(levelIsLow())
-                log.info { this.toString() }
+                logger.info { this.toString() }
             }
             assertTrue(isIdle())
             assertFalse(isProcessing())
@@ -72,13 +72,13 @@ class IppPrinterTests {
             assertFalse(isMediaNeeded())
             assertFalse(isCups())
             printerType.apply {
-                log.info { toString() }
-                log(log)
+                logger.info { toString() }
+                log(logger)
             }
             communicationChannelsSupported.forEach {
-                log.info { "${it.uri}, ${it.security}, ${it.authentication}, $it" }
+                logger.info { "${it.uri}, ${it.security}, ${it.authentication}, $it" }
             }
-            ippConfig.log(log)
+            ippConfig.log(logger)
         }
     }
 
@@ -93,7 +93,7 @@ class IppPrinterTests {
         ippClientMock.mockResponse("Get-Printer-Attributes.ipp")
         printer.run {
             updateAttributes()
-            log(log)
+            log(logger)
             assertEquals(122, attributes.size)
         }
     }
@@ -142,7 +142,7 @@ class IppPrinterTests {
     fun printJobInputStream() {
         ippClientMock.mockResponse("Print-Job.ipp")
         printer.printJob(FileInputStream(blankPdf)).run {
-            log(log)
+            log(logger)
             assertEquals(461881017, id)
             assertEquals(JobState.Pending, state)
             assertEquals(listOf("none"), stateReasons)
diff --git a/src/test/kotlin/de/gmuth/ipp/client/issueNo11.kt b/src/test/kotlin/de/gmuth/ipp/client/issueNo11.kt
index bf2001f3..d6387fe9 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/issueNo11.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/issueNo11.kt
@@ -5,17 +5,13 @@ import java.util.logging.Level.SEVERE
 import java.util.logging.Logger.getLogger
 
 fun main() {
-    //Logging.defaultLogLevel = Logging.LogLevel.DEBUG
-    //HttpURLConnectionClient.log.logLevel = Logging.LogLevel.TRACE
-    //IppClient.log.logLevel = Logging.LogLevel.DEBUG
-
-    val log = getLogger("issueNo11")
+    val logger = getLogger("issueNo11")
 
     //val printerUri = URI.create("ipp://192.168.31.244:631/ipp/print")
     val printerUri = URI.create("ipp://xero.local/ipp/print")
 
     try {
-        log.info { "open ipp connection to $printerUri" }
+        logger.info { "open ipp connection to $printerUri" }
         with(
             IppPrinter(
                 printerUri,
@@ -23,11 +19,11 @@ fun main() {
                 //getPrinterAttributesOnInit = false
             )
         ) {
-            log.info { "successfully connected $printerUri" }
-            log.info { toString() }
-            markers.forEach { log.info { it.toString() } }
+            logger.info { "successfully connected $printerUri" }
+            logger.info { toString() }
+            markers.forEach { logger.info { it.toString() } }
         }
     } catch (exception: Exception) {
-        log.log(SEVERE, exception, { "failed to connect to $printerUri" })
+        logger.log(SEVERE, exception, { "failed to connect to $printerUri" })
     }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/de/gmuth/ipp/client/issueNo3.kt b/src/test/kotlin/de/gmuth/ipp/client/issueNo3.kt
index 043f1d5e..b97ffdc0 100644
--- a/src/test/kotlin/de/gmuth/ipp/client/issueNo3.kt
+++ b/src/test/kotlin/de/gmuth/ipp/client/issueNo3.kt
@@ -11,7 +11,7 @@ fun main() {
 
     //ConsoleLogger.defaultLogLevel = Logging.LogLevel.DEBUG
     //HttpURLConnectionClient.log.logLevel = Logging.LogLevel.TRACE
-    val log = getLogger("issueNo3")
+    val logger = getLogger("issueNo3")
     var ippPrinter: IppPrinter? = null
 
     // httpConnect(printerUri)
@@ -19,30 +19,30 @@ fun main() {
 
     val ippConfig = IppConfig().apply {
         ippVersion = "1.1"
-        log(log)
+        log(logger)
     }
     try {
-        log.info { "open ipp connection to $printerUri" }
+        logger.info { "open ipp connection to $printerUri" }
         ippPrinter = IppPrinter(printerUri, ippConfig = ippConfig, getPrinterAttributesOnInit = true)
-        log.info { "successfully connected $printerUri" }
+        logger.info { "successfully connected $printerUri" }
     } catch (exception: Exception) {
-        log.log(SEVERE, exception, { "failed to connect to $printerUri" })
+        logger.log(SEVERE, exception, { "failed to connect to $printerUri" })
     }
 
     if (ippPrinter != null) ippPrinter.run {
         if (saveAttributes) {
             try {
                 savePrinterAttributes()
-                log.info { "saved printer attributes" }
+                logger.info { "saved printer attributes" }
             } catch (exception: Exception) {
-                log.log(SEVERE, exception, { "failed to save printer attributes" })
+                logger.log(SEVERE, exception, { "failed to save printer attributes" })
             }
         }
         try {
-            log.info { "documentFormatSupported:" }
-            documentFormatSupported.forEach { log.info { " $it" } }
+            logger.info { "documentFormatSupported:" }
+            documentFormatSupported.forEach { logger.info { " $it" } }
         } catch (exception: Exception) {
-            log.log(SEVERE, exception, { "failed to read documentFormatSupported" })
+            logger.log(SEVERE, exception, { "failed to read documentFormatSupported" })
         }
     }
 }
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppAttributeTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppAttributeTests.kt
index 31e316a4..d845a794 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppAttributeTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppAttributeTests.kt
@@ -16,7 +16,7 @@ class IppAttributeTests {
         Logging.configure()
     }
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     private val attribute = IppAttribute("printer-state-reasons", Keyword, "none")
 
     @Test
@@ -98,7 +98,7 @@ class IppAttributeTests {
     @Test
     fun log() {
         // cover an output with more than 160 characters and a collection value
-        IppAttribute("media-col".padEnd(160, '-'), BegCollection, IppCollection()).log(log)
+        IppAttribute("media-col".padEnd(160, '-'), BegCollection, IppCollection()).log(logger)
     }
 
     @Test
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppAttributesGroupTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppAttributesGroupTests.kt
index de725e93..7087d0ab 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppAttributesGroupTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppAttributesGroupTests.kt
@@ -14,7 +14,7 @@ import kotlin.test.assertTrue
 
 class IppAttributesGroupTests {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     private val group = IppAttributesGroup(Operation)
 
     @Test
@@ -121,7 +121,7 @@ class IppAttributesGroupTests {
     @Test
     fun log() {
         group.attribute("Commodore PET", Integer, 2001)
-        group.log(log, prefix = "|", title = "title")
+        group.log(logger, prefix = "|", title = "title")
     }
 
     @Test
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppCollectionTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppCollectionTests.kt
index d4d8f14c..a1c8c2f2 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppCollectionTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppCollectionTests.kt
@@ -12,7 +12,7 @@ import kotlin.test.assertFailsWith
 
 class IppCollectionTests {
 
-    private val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     private val collection = IppCollection(IppAttribute("foo", IppTag.Keyword, "a", "b"))
 
     @Test
@@ -41,13 +41,13 @@ class IppCollectionTests {
 
     @Test
     fun logNarrow() {
-        collection.log(log)
+        collection.log(logger)
     }
 
     @Test
     fun logWide() {
         collection.addAll(listOf(IppAttribute("bar", IppTag.Keyword, "c".repeat(160))))
-        collection.log(log)
+        collection.log(logger)
     }
 
 }
\ No newline at end of file
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppInputStreamTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppInputStreamTests.kt
index 79e1b89d..efa00c76 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppInputStreamTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppInputStreamTests.kt
@@ -185,7 +185,7 @@ class IppInputStreamTest {
             "01 01 00 0B 00 00 00 08 01 47 00 01 61 00 01 66 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF AA"
         assertFailsWith<IppException> {
             encoded.toIppInputStream().run {
-                log.level = ALL
+                logger.level = ALL
                 readMessage(message)
             }
         }
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppMessageTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppMessageTests.kt
index 5fe106f8..ab64b456 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppMessageTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppMessageTests.kt
@@ -12,7 +12,7 @@ import kotlin.test.*
 
 class IppMessageTests {
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     private val message = object : IppMessage() {
         override val codeDescription: String
@@ -57,7 +57,7 @@ class IppMessageTests {
             assertEquals(38, rawBytes!!.size)
             write(ByteArrayOutputStream()) // cover warning
             toString() // cover toString
-            log(log) // cover log
+            log(logger) // cover log
         }
     }
 
@@ -89,7 +89,7 @@ class IppMessageTests {
     @Test
     fun withoutRawBytes() {
         assertEquals("codeDescription []", message.toString())
-        message.log(log)
+        message.log(logger)
         assertFailsWith<IppException> { // missing raw bytes
             message.saveBytes(createTempFile("test", null))
         }
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppOutputStreamTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppOutputStreamTests.kt
index 753246d6..41d54f6c 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppOutputStreamTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppOutputStreamTests.kt
@@ -18,7 +18,6 @@ import kotlin.test.assertFailsWith
 
 class IppOutputStreamTest {
 
-    private val log = Logger.getLogger(javaClass.name)
     private val byteArrayOutputStream = ByteArrayOutputStream()
     private val ippOutputStream = IppOutputStream(byteArrayOutputStream).apply { attributesCharset = Charsets.US_ASCII }
 
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppRequestTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppRequestTests.kt
index da9350eb..7c4905aa 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppRequestTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppRequestTests.kt
@@ -15,14 +15,14 @@ import kotlin.test.assertNotNull
 
 class IppRequestTests {
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
 
     @Test
     fun requestConstructor1() {
         IppRequest().run {
             code = 5
-            log.info { toString() }
-            log(log)
+            logger.info { toString() }
+            log(logger)
             assertEquals(null, version)
             assertEquals(IppOperation.CreateJob, operation)
             createAttributesGroup(IppTag.Operation)
@@ -51,10 +51,10 @@ class IppRequestTests {
             listOf("one", "two"), "user"
         )
         request.documentInputStream = "pdl-content".byteInputStream()
-        log.info { request.toString() }
-        request.log(log)
+        logger.info { request.toString() }
+        request.log(logger)
         val requestEncoded = request.encode()
-        log.info { "encoded ${requestEncoded.size} bytes" }
+        logger.info { "encoded ${requestEncoded.size} bytes" }
         val requestDecoded = IppRequest()
         requestDecoded.decode(requestEncoded)
         assertEquals("2.0", requestDecoded.version)
diff --git a/src/test/kotlin/de/gmuth/ipp/core/IppResponseTests.kt b/src/test/kotlin/de/gmuth/ipp/core/IppResponseTests.kt
index e1735f14..b770c918 100644
--- a/src/test/kotlin/de/gmuth/ipp/core/IppResponseTests.kt
+++ b/src/test/kotlin/de/gmuth/ipp/core/IppResponseTests.kt
@@ -18,7 +18,7 @@ class IppResponseTests {
         Logging.configure()
     }
 
-    val log = getLogger(javaClass.name)
+    private val logger = getLogger(javaClass.name)
     private val ippResponse = IppResponse()
 
     @Test
@@ -43,7 +43,7 @@ class IppResponseTests {
     @Test
     fun invalidXeroxMediaColResponse() = ippResponse.run {
         read(File("src/test/resources/invalidXeroxMediaCol.response"))
-        log(log)
+        log(logger)
         jobGroup.run {
             assertEquals(598, getValue("job-id"))
             assertEquals(4, getValue("job-state")) // pending-held
@@ -60,7 +60,7 @@ class IppResponseTests {
         // IppInputStream solution: first mark(2) then NameWithLanguage -> readShort().let { if (markSupported() && it < 6) reset() }
         // requestNaturalLanguage = "de" // triggers HP name with language bug
         ippResponse.read(File("src/test/resources/invalidHpNameWithLanguage.response"))
-        ippResponse.log(log)
+        ippResponse.log(logger)
         ippResponse.jobGroup.run {
             assertEquals(IppString("A4-blank.pdf", "de"), getValue("job-name"))
             assertEquals(993, getValue("job-id"))