A fetch client exchange step defines how information about the target collection is processed by the Agentry Server. This definition references a step definition within the same module. This step has access to information about the target collection, as well as to any data captured in fetch properties. A client exchange step can be defined to execute once or iteratively, and can return data for an object collection. A fetch can contain multiple client exchange step definitions, which are processed by the Server in a defined order.
Though a client exchange step can return data to create and populate object instances, its intended purpose is to provide information about the current objects stored in the collection property targeted by the parent fetch (target collection) definition. A Client exchange step has access to the key property and last update value for each object instance in the target collection. This information is provided in support of the exchange data model. The intent is that the client exchange steps update this information to an exchange data object in the back end for later comparison to determine which data may need to be retrieved to update the Client.