Working with Sequences via Tooling

You can create a sequence in your ESB Config project or in the registry and then add it right to that project's mediation workflow, or you can refer to it from a sequence mediator in the same ESB Config project or another project in this Eclipse workspace. 

This section describes how to create a new sequence or import an existing sequence from an XML file (such as a Synapse Configuration file), and how to use the sequence in your mediation flow.

About dynamic sequences

WSO2 EI tooling allows you to create a Registry Resource project, which can be used to store Resources and Collections you want to deploy to the registry of a Carbon Server through a Composite Application (C-App) project. When you create a sequence, you can save it as a dynamic sequence in the Registry Resource project and refer to that sequence from the mediation flow. At runtime, when you deploy the CAR file with both the Registry Resource project and mediation flow, WSO2 EI looks up and uses the sequence from the registry.

Creating a new sequence

Follow these steps to create a new, reusable sequence that you can add to your mediation workflow or refer to from a sequence mediator, or to create a sequence mediator and its underlying sequence all at once.

To create a reusable sequence:

1. In Eclipse, click the Developer Studio menu and then click Open Dashboard. This opens the Developer Studio Dashboard.
2. Click Sequence on the Developer Studio Dashboard.
3. Select Create New Sequence and click Next.

4. Specify a unique name for the sequence. 

   Creating a Main Sequence

   If you want to create the default main sequence that just sends messages without mediation, be sure to name it main, which automatically populates the sequence with the default in and out sequences.

5. Do one of the following:
   
   • To save the sequence in an existing ESB Config project in your workspace, click Browse and select that project.
   • To save the sequence in a new ESB Config project, click Create new Project and create the new project.
   • To save the sequence as a dynamic sequence in a Registry Resource project, click Make this as Dynamic Sequence, specify the registry space (Governance or Configuration), click the Browse button at the top of the dialog box next to Save Sequence in and select the registry resource project, and then type the sequence name in the Registry Path box.
6. Optionally, in the Advanced Configuration section, specify another sequence to run when there is an error and the endpoint where messages should be sent.
7. Click Finish. The sequence is created in the sequences folder under the ESB Config or Registry Resource project you specified, and the sequence is open in the editor.
8. Add the endpoints and other sequences you want in this sequence and then click File > Save.

The sequence is now available in the Defined Sequences section of the tool palette and ready for use.

To create a sequence when creating a sequence mediator:

1. With your proxy service open in the editor, click Sequence Mediator in the tool palette and then click the location in the mediation workflow where you want to add this sequence. 
   The sequence mediator is added to the workflow with a default name, which is highlighted and ready for you to change.
2. Type the name you want for this sequence mediator and press Enter.
3. Double-click the sequence mediator you just added. A sequence is created and opened in the editor using the same name you entered for the sequence mediator.
4. Add the endpoints and other sequences you want in this sequence, and then click Save.

The mediation workflow is updated with the endpoints you added to the sequence. The sequence is also now available in the Defined Sequences section of the tool palette and ready for use in other meditation workflows.

Importing a sequence

Follow these steps to import an existing sequence from an XML file (such as a Synapse configuration file) into an ESB Config project.

1. In Eclipse, click the Developer Studio menu and then click Open Dashboard. This opens the Developer Studio Dashboard.
2. Click Sequence on the Developer Studio Dashboard.
3. Select Import Sequence and click Next.
4. Specify the sequence file by typing its full path name or clicking Browse and navigating to the file.
5. In the Save Sequence In field, specify an existing ESB Config project in your workspace where you want to save the sequence, or click Create new Project to create a new ESB Config project and save the sequence there.  
6. In the Advanced Configuration section, select the sequences you want to import. 
7. Click Finish. The sequences you selected are created in the sequences folder under the ESB Config project you specified, and the first sequence is open in the editor.

Using a sequence

After you create a sequence, it appears in the Defined Sequences section of the tool palette. To use this sequence in a mediation flow, click the sequence in the tool palette and then click the spot on the canvas where you want the sequence to appear in the flow. The editor automatically adds any endpoints you used in your sequence.

If you want to use a sequence from a different project or from the registry, you need to create a sequence mediator and then refer to the sequence as follows:

1. Click Sequence Mediator on the tool palette, and then click the spot on the canvas where you want the sequence to appear in the mediation workflow.
2. Press Enter to accept the default name for now.
3. In the Properties pane at the bottom of the window, click Static Reference Key, and then click the browse [...] button on the right.
   
4. In the Resource Key Editor, click Registry if the sequence is stored in the registry or Workspace if it's in another ESB Config project in this Eclipse workspace.
5. If you are trying to select a sequence from the registry and no entries appear in the dialog box, click the add registry connection button (the first button in the upper right corner) and connect to the registry where the sequence resides.
6. Navigate to the sequence you want, select it and click OK, and then click OK again.

The sequence mediator name and static reference key are updated to point to the sequence you selected.