diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMaxItems.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMaxItems.st
new file mode 100644
index 0000000..77f71af
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMaxItems.st
@@ -0,0 +1,12 @@
+tests
+testArrayWithMaxItems
+	| schema value |
+	schema := JSONSchema fromString: '{
+	"type": "array",
+   "items": {"type": "string"},
+   "maxItems": 2
+}'.
+	self 
+		shouldnt: [ value := schema validate: { 'bar' } ]
+		raise: Error.
+		
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMaxItemsFail.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMaxItemsFail.st
new file mode 100644
index 0000000..58d7537
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMaxItemsFail.st
@@ -0,0 +1,12 @@
+tests
+testArrayWithMaxItemsFail
+	| schema value |
+	schema := JSONSchema fromString: '{
+	"type": "array",
+   "items": {"type": "string"},
+   "maxItems": 2
+}'.
+	self 
+		should: [ value := schema validate: { 'bar'. 'foo' . 'baz' } ]
+		raise: Error.
+		
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMinItems.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMinItems.st
new file mode 100644
index 0000000..f2aea6e
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMinItems.st
@@ -0,0 +1,12 @@
+tests
+testArrayWithMinItems
+	| schema value |
+	schema := JSONSchema fromString: '{
+	"type": "array",
+   "items": {"type": "string"},
+   "minItems": 1
+}'.
+	self 
+		shouldnt: [ value := schema validate: { 'bar' } ]
+		raise: Error.
+		
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMinItemsFail.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMinItemsFail.st
new file mode 100644
index 0000000..5e071f4
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithMinItemsFail.st
@@ -0,0 +1,12 @@
+tests
+testArrayWithMinItemsFail
+	| schema value |
+	schema := JSONSchema fromString: '{
+	"type": "array",
+   "items": {"type": "string"},
+   "minItems": 2
+}'.
+	self 
+		should: [ value := schema validate: { 'foo' } ]
+		raise: Error.
+		
diff --git a/source/JSONSchema-Core-Tests.package/JSONTypeTests.class/instance/testReadArrayWithEmptyItems.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithNoItemsSpec.st
similarity index 92%
rename from source/JSONSchema-Core-Tests.package/JSONTypeTests.class/instance/testReadArrayWithEmptyItems.st
rename to source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithNoItemsSpec.st
index d981782..939c8f3 100644
--- a/source/JSONSchema-Core-Tests.package/JSONTypeTests.class/instance/testReadArrayWithEmptyItems.st
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testArrayWithNoItemsSpec.st
@@ -1,5 +1,5 @@
 tests
-testReadArrayWithEmptyItems
+testArrayWithNoItemsSpec
 	| schema value |
 	schema := JSONSchema fromString: '{"type": "array"}'.
 	self 
diff --git a/source/JSONSchema-Core-Tests.package/JSONTypeTests.class/instance/testReadNoTypeWithConstraints.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testNoTypeWithConstraints.st
similarity index 83%
rename from source/JSONSchema-Core-Tests.package/JSONTypeTests.class/instance/testReadNoTypeWithConstraints.st
rename to source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testNoTypeWithConstraints.st
index 44e0783..ce096a6 100644
--- a/source/JSONSchema-Core-Tests.package/JSONTypeTests.class/instance/testReadNoTypeWithConstraints.st
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testNoTypeWithConstraints.st
@@ -1,5 +1,5 @@
 tests
-testReadNoTypeWithConstraints
+testNoTypeWithConstraints
 	| schema |
 	schema := JSONSchema fromString: '{"exclusiveMaximum":10}'.
 
diff --git a/source/JSONSchema-Core.package/JSONFormatDate.class/class/validate..st b/source/JSONSchema-Core.package/JSONFormatDate.class/class/validate..st
new file mode 100644
index 0000000..afafa93
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONFormatDate.class/class/validate..st
@@ -0,0 +1,6 @@
+services
+validate: aDate
+	(aDate isKindOf: Date) ifFalse: [ 
+		JSONTypeError
+			signal: aDate printString , ' is not a date' ]
+	
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONFormatDateTime.class/class/validate..st b/source/JSONSchema-Core.package/JSONFormatDateTime.class/class/validate..st
new file mode 100644
index 0000000..b33204f
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONFormatDateTime.class/class/validate..st
@@ -0,0 +1,6 @@
+services
+validate: aDate
+	(aDate isKindOf: DateAndTime) ifFalse: [ 
+		JSONTypeError
+			signal: aDate printString , ' is not a date' ]
+	
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONFormatURI.class/class/validate..st b/source/JSONSchema-Core.package/JSONFormatURI.class/class/validate..st
new file mode 100644
index 0000000..9679039
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONFormatURI.class/class/validate..st
@@ -0,0 +1,6 @@
+services
+validate: aUrl
+	(aUrl isKindOf: ZnUrl) ifFalse: [ 
+		JSONTypeError
+			signal: aUrl printString , ' is not a URL' ]
+	
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONSchemaReference.class/instance/printOn..st b/source/JSONSchema-Core.package/JSONSchemaReference.class/instance/printOn..st
new file mode 100644
index 0000000..f89f30e
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONSchemaReference.class/instance/printOn..st
@@ -0,0 +1,3 @@
+printing
+printOn: aStream 
+	aStream << 'Reference: '<< path asString
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONStringFormat.class/class/validate..st b/source/JSONSchema-Core.package/JSONStringFormat.class/class/validate..st
new file mode 100644
index 0000000..bcdd2a5
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONStringFormat.class/class/validate..st
@@ -0,0 +1,6 @@
+services
+validate: aString 
+	aString isString ifFalse: [ 
+		JSONTypeError
+			signal: aString printString , ' is not a string' ]
+	
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONStringFormat.class/class/validateString..st b/source/JSONSchema-Core.package/JSONStringFormat.class/class/validateString..st
new file mode 100644
index 0000000..ecd35e6
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONStringFormat.class/class/validateString..st
@@ -0,0 +1,6 @@
+services
+validateString: aString 
+	aString isString ifFalse: [ 
+		JSONTypeError
+			signal: aString printString , ' is not a string' ]
+	
\ No newline at end of file