Session

The Session is a storage attached to each "virtual user".

Using saveAs("key" actually stores the data into the Session, under the given key.

Using a ${...} EL in a String retrieves the data stored in the Session under the given key.

Expression Language #

Gatling supports very basic Expression Language that can be used for making String parameters dynamic, such as URLs, HTTP parameters, HTTP basic auth credentials, etc.

"${myKey}" returns the Session attribute stored as myKey

"${myKey(i)}" where i is an Integer returns the value in the multivalued Session attribute stored as myKey with the rank i

"${myKey.size()}" returns the size of the multivalued Session attribute stored as myKey

"${myKey(myRank)}" where myRank is a String returns the value in the multivalued Session attribute stored as myKey with the rank that is the value of the Session attribute myRank

For example, if a given Session contains ("myValue" -> "foo"), ("myList" -> List("bar", baz)) and ("myInteger" -> 1):

• "AAA${myValue}BBB" will be resolved as "AAAfooBBB"
• "AAA${myList(0)}BBB" will be resolved as "AAAbarBBB"
• "AAA${myList(myInteger)}BBB" will be resolved as "AAAbazBBB"
• "AAA${myList.size()}" will be resolved as 2

Immutability #

The most important characteristic of Sessions is that they are immutable.

As Gatling engine is completely asynchronous, immutability garanties that state desynchronization can't happen when moving from one core to another.

As a consequence, editing the Session actually generates a new Session instance and leaves the original instance untouched.

Session members #

• getAttribute(key: String): Any = getTypedAttribute[Any](key)
• getTypedAttribute[X](key: String)
• getAttributeAsOption[T](key: String): Option[T]
• setAttributes(attributes: Map[String, Any])
• setAttribute(attributeKey: String, attributeValue: Any)
• removeAttribute(attributeKey: String)
• isAttributeDefined(attributeKey: String)
• getCounterValue(counterName: String)
• getTimerValue(timerName: String)

Building Session functions #

Sometimes, one might want to manipulate the Session is a way that is not built in Gatling, like printing for debugging or adding custom attributes.

In this case, Gatling provides a hack for editing the Session programmatically.

Notice: As Session is immutable, so when writing a Session function, one has to ensure that it returns the new Session.

.exec(session => {
  // print the Session for debugging, don't do that on real Simulations
  println(session)
  session
})
.exec(session =>
  // session.setAttribute returns the new Session, and Scala automatically returns the last assignment
  // braces are omitted as there's only one instruction
  session.setAttribute("foo", "bar")
)