Call-triggered flow

The Server Access is an API that allows an external process to request execution of a collaboration inside IBM WebSphere Business Integration Server Express and Express Plus. A collaboration represents a business process that can involve several applications. By using Server Access, this external process, called an access client, can obtain data from applications that IBM WebSphere Business Integration Server Express and Express Plus handles through executing a collaboration.

The Server Access facility makes it possible for IBM WebSphere Business Integration Server Express and Express Plus to receive requests for execution of a collaboration directly, without receiving a triggering event from a connector. The requests that the access client sends are called access requests. To send an access request, an access client issues a call to a method in the Server Access instead of actually sending an event. Therefore, the flow trigger that an access client initiates is called a call-triggered flow, instead of the event-triggered flow that a connector initiates (see Figure 1).

The call-triggered flow is handled with the economy and transparency of an event-triggered flow. The main operational distinction is that call-triggered flows are processed synchronously and are therefore not persistent within the IBM WebSphere Business Integration Server Express and Express Plus system. By contrast, the event-triggered flows are processed asynchronously and are persistent. For more on how these flows are processed in the system, see the System Implementation Guide.

Figure 1. Call-triggered flow


As Figure 1 shows, an access request that an access client initiates involves the following steps:

  1. The access client creates the triggering access data, which it sends to IBM WebSphere Business Integration Server Express and Express Plus during the access request. This data is what triggers the specified collaboration; that is, the collaboration requires this data to begin execution.
  2. The access client calls a method of the Server Access API to send a triggering access call to the Server Access within IBM WebSphere Business Integration Server Express and Express Plus. The triggering access call includes the triggering access data and the name of the collaboration to execute. Through this method call, the access client performs an access request, which initiates the call-triggered flow.
  3. The Server Access within IBM WebSphere Business Integration Server Express and Express Plus receives the triggering access call, performing any needed conversion of its triggering access data to a system business object. For more information on this data conversion, see "The role of IBM WebSphere Business Integration Server Express and Express Plus data handlers".
  4. The Server Access within IBM WebSphere Business Integration Server Express and Express Plus sends the triggering access data to the specified collaboration to trigger its execution.
  5. Once the collaboration completes, it sends the resulting business object to the Server Access.
  6. The Server Access performs any needed conversion from the resulting business object to the triggering access data's original format then performs the access response to send the access-response data back to the access client. For more information on this data conversion, see "The role of IBM WebSphere Business Integration Server Express and Express Plus data handlers".

This section provides the following additional information about call-triggered flow:

Copyright IBM Corp. 2004