SwitchYard Milestone 1 Notes

Using this page to document/track our thoughts on Milestone 1 functionality.  The related forum discussion can be found here.

 

The goal for M1 is a basic end-to-end service implementation and composition scenario:

 

  1. Create service "A" using the Bean component
  2. Unit test service "A"
  3. Add an invocation of service "B" from service "A"
  4. Create service "B" using the Bean component
  5. Test service "A" including dependency on "B"
  6. Bind service "A" to SOAP for external consumption
  7. Deploy packaged application

 

Notes on each step in the scenario:

 

 

Step 1 : Create service "A" using the Bean component
  • I probably should have included a step '0' for creating the actual SwitchYard project.  Before we can create any services, we will need a project structure with the appropriate dependencies setup, etc.  Need to create a maven archetype for a SwitchYard project (SWITCHYARD-6) and add dependencies for core-api at compile scope and core-runtime at test scope (alternatively, test-util can pull in the core-runtime dependency transitively).
  • For M1 we will need a dependency on Bean component annotations and runtime for testing.  I consider this to be a temporary hack as I'm hoping tooling will ultimately generate the dependencies for us as we choose to include certain components in our project (e.g. add a bean service, appropriate dependencies are generated in the pom).
  • Need to publish SwitchYard artifacts for M1 so that people can try it out without a source checkout and local build (SWITCHYARD-35).
  • Once the project is created, user creates a new Java interface representing the service contract.
  • User then creates a new Java class implementing the service interface.  The implementation class is annotated with @Service.
  • Build the project - user now has a service which can be hosted in SwitchYard.

 

 

Step 2 : Unit test service "A"
  • Need a base test class which makes it easy to create, send, and receive messages (SWITCHYARD-36) without having to get into the nitty gritty core API details (create domain, register service, create and handle exchanges, etc.).  This will likely be more than just a single base class, but we can start there.
  • The scope of the unit test should be testing a service provided by a single component.
  • For M1, we need a way to bootstrap the CDI runtime for each test as is currenty done in AbstractCDITest.  It would be nice to have a uniform pattern for creating component-specific tests without reimplementing the basic send/receive logic in each component test.  For example, AbstractCDITest could extend SwitchYardTest, which would have the utility logic described above.
  • For testing multiple components together, I think we will want to test "in-container", which means Arquillian.

 

 

Step 3 : Add an invocation of service "B" from service "A"
  • I debated the order of this and step 4 - i.e. should we implement the service or declare a reference to it first?  I decided to put the reference first because it highlights some cool things about how CDI integration works.
  • First thing to do is create a Java interface representing our contract with service B.
    • Note that the interface used for the reference could come from anywhere.  We might have pulled it from a service repository, generated it off of a WSDL in our workspace, etc.
    • Also worth noting is that the Java interface does not have to be the same interface (as in class) used by the service provider.  The interface is actually just a proxy to an exchange and the method name and parameter are mapped to an exchange.
  • Now we add an @Inject and @Reference to the our bean service.  The SwitchYard CDI extension takes care of injecting the service proxy as part of the CDI lifecycle.
  • It would be nice if our testing framework could create "mock" responses for references, which would allow us to unit test a service without requiring the services identified by @Reference to be loaded.  Behind the scenes, the test would register for each service with @Reference and return the mock payload identified in the test.

 

Step 4 : Create service "B" using the Bean component
  • Same as step 1, but we don't need to create the project (created in step 1) or the Java interface (created in step 3).
  • Probably a good idea to add another unit test for service B.

 

Step 5 : Test service "A" including dependency on "B"
  • This is an integration test for our SwitchYard application, testing the wiring between the consuming and providing components.
  • Technically, we could do this with AbstractCDITest today, but I would like to explore the use of Arquillian(SWITCHYARD-7) to handle this with embedded AS7.

 

Step 6 : Bind service "A" to SOAP for external consumption
  • We should be able to take an existing service and expose it to the outside world using any gateway.  In this case, it will be SOAP.
  • Add necessary SOAP binding configuration to the SwitchYard config file (SWITCHYARD-10).

 

Step 7 : Deploy packaged application
  • Build the project and produce a deployable SwitchYard archive (SWITCHYARD-5).
  • Need a deployer implementation to handle the deployment for each target container (SWITCHYARD-38).