WORKSHOP-INSTRUCTIONS-PART-3.md

Part 3 Instructions

Turn the OSGi service into a web service

Does the GreeterImpl correctly provide the Greeter service? Who knows? Let's connect the Greeter service to a web server to create an endpoint that allows HTTP requests to invoke the service.

Catch up on your reading

• Read the REAMDE. It is chock-full of goodness.

Use annotations to create the web service

Add the JAX-RS annotations to hello method to make it a web service. (You will also need to add new dependencies to the POM file so that the annotations are recognized)

1. @GET
2. @Path("/hello/{name}")
3. @Produces(MediaType.TEXT_PLAIN)

Exercise

• Turn to a neighbor and explain what each of the three JAX-RX annotations is supposed to do.

Update the blueprint specification

Add Blueprint instructions to blueprint.xml that create the web server

• Update the <blueprint> element's attributes to include some new XML namespaces. The new namespaces are cxf (the application server) and jaxrs the annotations. The blueprint tag should look like:

 <blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
            xmlns:cxf="http://cxf.apache.org/blueprint/core"
            xmlns:jaxrs="http://cxf.apache.org/schemas/jaxrs.xsd">

• Add an element to create the something called the bus". I think this is the transport layer that all of your CXF applications (servers) will use to communicate using HTTP.

    <cxf:bus id="greetingServiceBus">
        <cxf:features>
            <cxf:logging/>
        </cxf:features>
    </cxf:bus>

• Register the bean that provides the service with the application:

<jaxrs:server address="/greeting" id="greetingRest">
        <jaxrs:serviceBeans>
            <ref component-id="greetingImpl"/>
        </jaxrs:serviceBeans>
    </jaxrs:server> 

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NOTE TO SELF: I don't think we need the directive at this point. We aren't really using an OSGi service lookup anywhere. We needed it in the original Karaf tutorial because we created a class called `GreetingRest` that needed the service. We injected the service provider into `GreetingRest` with Blueprint, in the directive ``. Mabye change up the tutorial to first create and use multiple providers **then** expose all that as a webservice?

Exercise

• What do you think would happen if you built the bundle and installed in Karaf?
• Try it and find out.