Working with Mediators via WSO2 ESB Tooling

If you need to create a custom mediator that performs some logic on a message, you can either create a new mediator project, or import an existing mediator project using WSO2 ESB tooling.

You need to have WSO2 ESB tooling installed to create a new message store or to import an existing message store via ESB tooling. For instructions on installing WSO2 ESB tooling, see Installing WSO2 ESB Tooling.

Once a mediator project is finalised, you can export it as a deployable artifact by right-clicking on the project and selecting Export Project as Deployable Archive. This creates a JAR file that you can deploy to the ESB. Alternatively, you can group the mediator project as a Composite Application Project, create a Composite Application Archive (CAR), and deploy it to the ESB.

A URL classloader is used to load classes in the mediator (class mediators are not deployed as OSGi bundles). Therefore, it is only possible to refer to the class mediator from artifacts packed in the same CAR file in which the class mediator is packed. Accessing the class mediator from an artifact packed in another CAR file is not possible. However, it is possible to refer to the class mediator from a sequence packed in the same CAR file and call that sequence from any other artifact packed in other CAR files.

Creating a mediator project

Follow these steps to create a new mediator. Alternatively, you can import a mediator project.

Open the Developer Studio Dashboard (click Developer Studio > Open Dashboard) and click Mediator Project in the Enterprise Service Bus area.
Leave the first option selected and click Next. The New Mediator Creation Wizard appears.
Do the following:
1. Type a unique name for the project.
2. Specify the package and class names you are creating.
3. Optionally specify the location where you want to save the project (or leave the default location specified).
4. Optionally specify the working set, if any, that you want to include in this project.
A Maven POM file will be generated automatically for this project. If you want to include parent POM information in the file from another project in this workspace, click Next, click the Specify Parent from Workspace check box, and then select the parent project.
Click Finish.

The mediator project is created in the workspace location you specified with a new mediator class that extends org.apache.synapse.mediators.AbstractMediator.

Importing a Java Mediator Project

Follow the steps below to import a Java mediator project (that includes a Java class, which extends the org.apache.synapse.mediators.AbstractMediator class) to WSO2 Developer Studio.

Open the Developer Studio Dashboard (click Developer Studio > Open Dashboard) and click Mediator Project in the Enterprise Service Bus area.
Select Import From Workspace and click Next.
Specify the mediator project in this workspace that you want to import. Only projects with source files that extend org.apache.synapse.mediators.AbstractMediator are listed. Optionally, you can change the location where the mediator project will be created and add it to working sets.
Click Finish.

The mediator project you selected is created in the location you specified.

The mediator projects you create using WOS2 Developer Studio are of the org.wso2.developerstudio.eclipse.artifact.mediator.project.nature nature by default. Follow the steps below to view this nature added to the <PROJECT_NAME>/target/.project file of the Java mediator project you imported.

Click the View Menu icon, and click Customize View.
Deselect .*resources, and click OK.

For information on importing a mediator project, which you created using WSO2 Developer Studio, see Importing Existing Projects into Workspace.