By Saurabh Sahai
An incoming message may encapsulate one or more submessages. It is often desired to process submessages independently as separate messages. For example, an order message may consist of multiple order line items, each of which corresponds to a unique item type and may be fulfilled by a separate inventory store.
A splitter solves the problem of processing a composite message comprising multiple submessages, each of which may be processed differently by breaking up the message into individual messages and sending each separate message for further processing by a downstream component.
A splitter can be implemented in Java CAPS in multiple ways. Java Collaborations can be used to receive the composite message, iterate over the individual submessages, and, on the basis of the message content, send each of them to a unique destination that is responsible for processing a specific type of message.
The collaboration shown in Figure 6-11 is an example of processing an incoming message consisting of multiple order items. The collaboration iterates over each order item and creates a new message, enriched with the original order item information, and sends it for processing by a specific system. The item number contained in each order item is used to determine the destination address where the enriched order item message is to be sent. Exception processing has been omitted in the example to focus on the essentials of the example.
Figure 6-11 Dynamic content-based routing
Splitter is a component that, as the name suggests, breaks messages into component parts. How easy or difficult it is to split original messages and create component messages largely depends on the size and complexity of the message structures involved. As a general rule, it is easier to handle a composite message with more than one level of components using a Java Collaboration than to do so using an eInsight Business Process. Implementing nested loops in a Java Collaboration is easier and more compact than doing the same in Business Process Execution Language (BPEL) using the graphical environment. While loops, whether single-level or nested, are clearly visible in an eInsight Business Process graphic, making it obvious that splitting is taking place, it is necessary to reset the target OTD structure prior to its being populated in each iteration, which is neither obvious nor easily discovered by the casual observer.