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{snippet:id=join|lang=java|url=http://svn.apache.org/repos/asf/incubator/servicemix/trunk/servicemix-beanflow/src/test/java/org/apache/servicemix/beanflow/CustomJoinConditionTest.java}

Building workflows

So we've been over the basics of activities and showed how we can perform joins along with compose them. Remember they are just Java bean so you can implement them however you wish.

However often folks think of workflows as a number of discrete steps; using a kind of state machine to move from step to step. One real simple approach to
writing workflows in this model is to use a specific method for each workflow step.

So we have a base class called Workflow which adds a new State object for the current step (which allows actvities to listen to the step changing) together with helper methods for moving to different steps, for suspending and so forth.

Moving steps

Inside a step you can call any Java methods on any objects. However to move from step to step in a declarative fashion you can call the goTo() method.
Another option is to use a method which returns a method to map to a workflow step.String; a non-null String is then interpreted as being the next step that is navigated to next.

Note that the movement to the next step always takes place outside of the step method to avoid deeply recursive methods.

Suspending workflows

Often in a workflow you have to wait for some external event such as

• a user enters some text
• a message is received

Once that happens you re-awaken the workflow and commence execution at some step. To implement this just call the goTo() method to cause the workflow to resume at the given step

Example

The following example is a fairly large one, but it shows a variety of different concepts

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