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Splitters are preparsers that break up large input messages into smaller messages that are processed piece by piece. Each piece flows through the work flow independently, as if it were a complete document. At the end of the stream, a special End of Stream (EOS) message is sent, enabling the subsequent exits in the flow to take any end-of-stream actions such as emitting aggregation documents, issuing commits, and so on.

Generally, exits downstream from a splitting preparser need not be concerned with the splitting of the message or with the end of stream signal. The exit processes the split portion exactly as it would a complete message. The exit can expose the

boolean wantEOS()

method to signal to the engine that the exit is to be called on EOS. False is the default value, so that if this method is not implemented by the exit, the exit is not invoked on EOS. To receive EOS signals, implement:

boolean wantEOS()
{
  return true;
}

Note: The Development Wizards set this as required.

In an execution method, such as a process of execute method in a business agent, the method can call:

int getStreamState()

to determine the state of the stream. Possible return values are:

Return Value	Description
STREAM_NONE	Exit is not operating in a streaming/splitting mode. This is the normal mode of a workflow.
STREAM_ACTIVE	Exit was invoked for a split portion of a streamed document.
STREAM_EOS	Exit was invoked to handle the EOS signal. No other data is available. In addition, special register EOS is defined with the value 1.

Splitting is performed by preparsers. A splitting preparser must be the first user-configured preparser. Pre-built splitting preparsers are provided for XML, non-XML, and EDI messages.

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Example: Stream Handling Agent

This example shows two methods from a stream handling agent and illustrates the handling of EOS and non-EOS tasks. The agent emits an accumulated document when all parts have arrived, but avoids any output at non-EOS. The execute method adds each arriving part as a child of a root, and at EOS emits the new tree based on root.

List reps;     // place to save replyTo list
List errs;     // place to save errorTo list
XDNode accumroot=null;  // build accumulation document here
public String execute(XDDocument docIn, XDDocument docOut)
       throws XDException
{
   int streamState = getStreamState();  // ask what state we are in
   XDNode passRoot;
   if (streamState != XDAgent.STREAM_EOS)
   {
       if (accumroot == null)  // is this new document (new stream)?
       {
           accumroot=new XDNode("root"); // make root for accum document
           reps = docIn.getReplyTo();  // save the replyTo list
           errs = docIn.getErrorTo();  // save the errorTo list
       }
       passRoot = XDNode.cloneTree(docIn.getRoot()); // add to accum
       docOut.setRoot(null);                        // we want NO doc out
       docOut.setReplyTo(null);                // clean out any replyto's
       docOut.addReplyTo(XD.PROTOCOL_NULL, null);    // avoid ANY emit
       accumroot.setLastChild(passRoot);          // add to accumulation
   }
   else   // this is EOS, so emit accumulated document
   {
       docOut.setRoot(accumroot);    // set last copy to output
       docOut.setReplyTo(reps);      // restore replyTo
       docOut.setErrorTo(errs);      // restore errorTo
       accumroot=null;               // for next pass
   }
   return "success";
}
 protected boolean wantEOS()  // added by development wizard
 {
     return true; // tell engine we want to receive the EOS signal
 }