Developing in WebSphere Message Broker Best practices guide Part 1

In this post I will provide with some guidelines you need to keep in mind when developing message flows in WMB (WebSphere Message Broker).

WMB is a good integration software but you need to know some internals for developing suit solution.

1. Avoid using hard wired looping in the message flows, Use PROPAGATE statement instead.

When using hard wired looping in message flow All the resources of the loop participant are stored on the stack storage. Nodes , message trees, variables copied and held in memory.
Therefore while message processing the stack storage of the Execution Group (process) can ran out.
You also probably will get abends and core dumps.

By using the PROPAGATE statement the data won't be copied and stored during the loop iterations. After each iteration all the iteration data will be freed and re-used.

2. Work with reference variable and don't navigate through message tree directly.

SET OutputRoot.XML.Root.Child.Field1 = 1;
SET OutputRoot.XML.Root.Child.Field2 = 2;


For those simple assigning statements about 20 navigation action will be made. And it's only if the OutputRoot element is empty.
If not it can be much more.


If you have complex message transformation and performance is your concern work with Reference variable and Create statement.

DECLARE ref REFERENCE TO OutputRoot;
CREATE LASTCHILD OF ref as ref DOMAIN('XML') NAME 'XML';
CREATE LASTCHILD OF ref as ref NAME 'Root';
CREATE LASTCHILD OF ref as ref NAME 'Child';
CREATE LASTCHILD OF ref NAME 'Field1' VALUE '1';
CREATE LASTCHILD OF ref NAME 'Field2' VALUE '2';


We no using SET statement and since all CREATES specify relative keywords no navigation are required. But we got more code :-(.
You can use the ROW statement to get more code visibility and simplicity combined with SET statement.

remember to work with REFERENCE.

3. Avoid using Environment tree to handle local variables.

All data which stored in the Environment tree are stored in Memory during the whole message flow and not freed after it's out of scope.
so if you need space to store local data for node work with the LocalEnvironment tree. Thus avoiding high memory consumption.
Even if you delete the fields from the Environment tree it still won't free the memory till message flow end processing the message. The broker use pool allocation and reuse an pointed resources of the Environment Tree.

more will come soon.