Message correlation key. Correlation keys are used to match up incoming messages with a particular process instance. The basic procedure is to generate and save a correlation key when a receive or pick activity is activated, and then to match incoming messages against all correlation keys so saved, finally associating the message with the process instance that had the matching correlation key. In reality this process is somewhat more complicated as pains must be taken to avoid race conditions and to make the matching efficient.
The correlation keys used in the above process consists of a collection of name-value pairs, with the name corresponding to a property name (as defined using the <property> element of the BPEL process document) and with the value corresponding to the value of said property as obtained from a message by means of a property alias (as defined using the <propertyAlias;> BPEL process document element).
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