Correlation is a technique that helps to correlate messages between a producer and consumer of the messages in an asynchronous transaction. Correlation helps in scenarios where the interactions are complex. Mid-process receive uses correlation sets to correlate messages between incoming message and running instances that are waiting for a message to continue its operations. To understand correlation sets, it is necessary to know about property and property sets. Property and property set information are defined in WSDL.
A property is like a variable that stores information which will be used to match the running process instance to a new message arrival.
A property alias is used in two situations — as an assign operation to define what information needs to be stored in the property and also as a query to match the information received in a message with the information stored in the property.
Listing 6.5: Property and property alias are...