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Tutorial: JaxRS Remote Services on Karaf

Introduction

Jersey can be run on Karaf as an ECF distribution provider for remote services that use standard JaxRS annotations.

This tutorial describes installing and running an example JaxRS remote service on Karaf. Developers can create and deploy arbitrary remote services by reusing the ECF RSA impl and the Jersey (or CXF) distribution provider.

For more recent versions of the Jersey and CXF distribution provider components see this github repo and the karaf-features.xml in the build directory.

Requirements: Karaf 4.3.1+ running on Java 11+

Install Jersey Distribution Provider via Karaf Console

Add the ECF JaxRS Provider features repo: 

karaf@root()>feature:repo-add https://raw.githubusercontent.com/ECF/JaxRSProviders/master/build/karaf-features.xml

Install the Jersey Distribution Provider and dependencies 

karaf@root()>feature:install -v ecf-rs-distribution-jersey

The -v option (verbose) will produce a lot of output describing the bundles downloaded and installed.

To properly run in Karaf the org.osgi.service.http.port system property must be set to the desired port: 

karaf@root()> system:property -p org.osgi.service.http.port 8181

and since Karaf typically uses the root path (/) of the HttpService, it's necessary to set an explicit pathPrefix to something other than the default of '/' 

karaf@root()> system:property -p ecf.jaxrs.server.pathPrefix /rservices

NOTE: These and other parts of the dynamically-constructed remote service URL can be set via system properties OR service-instance-specific service properties. For the [JaxRSProviders the system or service properties are described here.

Shutdown and restart Karaf so that the org.osgi.service.http.port system property set can take effect on startup.

JaxRS Student Example

In this tutorial an example REST service is presented. The completed example bundles with source are available in the ECF JaxRSProviders repository. To run this example you may wish to clone this repo, and import into Eclipse these three projects: examples/com.mycorp.examples.student, examples/com.mycorp.examples.remoteservice.host, and examples/com.mycorp.examples.client.

Install JaxRS Student Example Service Client and Host

karaf@root()> feature:install ecf-rs-examples-jaxrs-student-client
karaf@root()> feature:install ecf-rs-examples-jaxrs-student-host

This should produce output indicating the StudentService was exported 

karaf@root()> feature:install ecf-rs-examples-jaxrs-student-host
20:44:37.637;EXPORT_REGISTRATION;exportedSR=[com.mycorp.examples.student.StudentService];cID=URIID [uri=http://localhost:8181/rservices/rs1];rsId=1
--Endpoint Description---
<endpoint-descriptions xmlns="http://www.osgi.org/xmlns/rsa/v1.0.0">
  <endpoint-description>
    <property name="ecf.endpoint.id" value-type="String" value="http://localhost:8181/rservices/rs1"/>
    <property name="ecf.endpoint.id.ns" value-type="String" value="ecf.namespace.jaxrs"/>
    <property name="ecf.endpoint.ts" value-type="Long" value="1573015476480"/>
    <property name="ecf.jaxrs.server.pathPrefix" value-type="String" value="/rs1"/>
    <property name="ecf.rsvc.id" value-type="Long" value="1"/>
    <property name="endpoint.framework.uuid" value-type="String" value="a77850ca-06b5-48f8-803b-467bb441e47c"/>
    <property name="endpoint.id" value-type="String" value="7cb088e9-76ec-49a3-96e6-f68ba62d20bd"/>
    <property name="endpoint.package.version.com.mycorp.examples.student" value-type="String" value="1.0.0"/>
    <property name="endpoint.service.id" value-type="Long" value="155"/>
    <property name="objectClass" value-type="String">
      <array>
        <value>com.mycorp.examples.student.StudentService</value>
      </array>
    </property>
    <property name="osgi.basic.timeout" value-type="String" value="5000000"/>
    <property name="remote.configs.supported" value-type="String">
      <array>
        <value>ecf.jaxrs.jersey.server</value>
      </array>
    </property>
    <property name="remote.intents.supported" value-type="String">
      <array>
        <value>passByValue</value>
        <value>exactlyOnce</value>
        <value>ordered</value>
        <value>osgi.async</value>
        <value>osgi.private</value>
        <value>osgi.confidential</value>
        <value>jaxrs</value>
      </array>
    </property>
    <property name="service.imported" value-type="String" value="true"/>
    <property name="service.imported.configs" value-type="String">
      <array>
        <value>ecf.jaxrs.jersey.server</value>
      </array>
    </property>
    <property name="service.intents" value-type="String">
      <array>
        <value>osgi.async</value>
        <value>jaxrs</value>
      </array>
    </property>
  </endpoint-description>
</endpoint-descriptions>
---End Endpoint Description
Discovered student service=com.mycorp.examples.student.remoteservice.host.StudentServiceImpl@8bb24f7
Student0=Student [id=6871a134-554b-4096-a56d-6f8c213f390d, name=Joe Senior, grade=First, address=Address [street=111 Park Ave, city=New York, state=NY, postalCode=11111]]
Updated Student0=Student [id=6871a134-554b-4096-a56d-6f8c213f390d, name=Joe Senior, grade=Eighth, address=Address [street=111 Park Ave, city=New York, state=NY, postalCode=11111]]
getStudentCF().Student0=Student [id=6871a134-554b-4096-a56d-6f8c213f390d, name=Joe Senior, grade=Eighth, address=Address [street=111 Park Ave, city=New York, state=NY, postalCode=11111]]
Created student=Student [id=09b63a9b-338e-450a-99b3-cf2c3261cab3, name=April Snow, grade=null, address=null]
Updated student=Student [id=09b63a9b-338e-450a-99b3-cf2c3261cab3, name=April Snow, grade=First, address=Address [street=111 NE 1st, city=Austin, state=Oregon, postalCode=97200]]
Deleted student=Student [id=09b63a9b-338e-450a-99b3-cf2c3261cab3, name=April Snow, grade=First, address=Address [street=111 NE 1st, city=Austin, state=Oregon, postalCode=97200]]
20:44:40.321;EXPORT_REGISTRATION;exportedSR=[com.mycorp.examples.student.StudentService];cID=URIID [uri=http://localhost:8181/rservices/rs2];rsId=2
--Endpoint Description---
<endpoint-descriptions xmlns="http://www.osgi.org/xmlns/rsa/v1.0.0">
  <endpoint-description>
    <property name="ecf.endpoint.id" value-type="String" value="http://localhost:8181/rservices/rs2"/>
    <property name="ecf.endpoint.id.ns" value-type="String" value="ecf.namespace.jaxrs"/>
    <property name="ecf.endpoint.ts" value-type="Long" value="1573015480268"/>
    <property name="ecf.jaxrs.server.pathPrefix" value-type="String" value="/rs2"/>
    <property name="ecf.rsvc.id" value-type="Long" value="2"/>
    <property name="endpoint.framework.uuid" value-type="String" value="a77850ca-06b5-48f8-803b-467bb441e47c"/>
    <property name="endpoint.id" value-type="String" value="0441de73-e6fd-4ef3-8436-6ea526f71ce4"/>
    <property name="endpoint.package.version.com.mycorp.examples.student" value-type="String" value="1.0.0"/>
    <property name="endpoint.service.id" value-type="Long" value="158"/>
    <property name="objectClass" value-type="String">
      <array>
        <value>com.mycorp.examples.student.StudentService</value>
      </array>
    </property>
    <property name="osgi.basic.timeout" value-type="String" value="50000"/>
    <property name="remote.configs.supported" value-type="String">
      <array>
        <value>ecf.jaxrs.jersey.server</value>
      </array>
    </property>
    <property name="remote.intents.supported" value-type="String">
      <array>
        <value>passByValue</value>
        <value>exactlyOnce</value>
        <value>ordered</value>
        <value>osgi.async</value>
        <value>osgi.private</value>
        <value>osgi.confidential</value>
        <value>jaxrs</value>
      </array>
    </property>
    <property name="service.imported" value-type="String" value="true"/>
    <property name="service.imported.configs" value-type="String">
      <array>
        <value>ecf.jaxrs.jersey.server</value>
      </array>
    </property>
    <property name="service.intents" value-type="String">
      <array>
        <value>osgi.async</value>
        <value>jaxrs</value>
      </array>
    </property>
  </endpoint-description>
</endpoint-descriptions>
---End Endpoint Description

The output in between the first --Start Endpoint Description-- and ---End Endpoint Description--- is debug output from the ECF RSA Console for the remote service export of the first remote service.

The output that begins Discovered student service... is output from the StudentService consumer when the remote service is discovered and injected into the client component so that it can be called. This output shows the invocation of the JaxRS remote service methods by the client component.

The output in between the second --Start Endpoint Description-- and ---End Endpoint Description--- is debug output from the second exported remote service.

Note that once exported, the getStudents() service methods on the two remote services can be accessed directly via an http get call via the following url:

First exported remote service

http://localhost:8181/rservices/rs1/studentservice/students

Second exported remote service

http://localhost:8181/rservices/rs2/studentservice/students

The URL path of these remote services breaks down into the following components:

/rservices - Set by the value of system property: -Decf.jaxrs.server.pathPrefix=/rservices /rs1 or /rs2 - Set by the value of the service property: ecf.jaxrs.server.pathPrefix=/rs1 on line 22 of the StudentServiceImpl class (first remote service) and the value of the same service property on line 22 of StudentServiceImpl2 class (second remote service). /studentservice - Set by the value given to the @Path jaxrs annotation the the remote service class declaration. /students - Set by the @Path jaxrs annotation on the abstract superclass used by both the StudentServiceImpl and the StudentServiceImpl2 class.

For example: 

$ curl http://localhost:8181/rservices/rs1/studentservice/students
{"students":[{"id":"24e7dfdb-b9e1-4540-a450-b0c19bf43ec9","name":"Joe Senior","grade":"Eighth","address":{"street":"111 Park Ave","city":"New York","state":"NY","postalCode":"11111"}}]}

and 

$ curl http://localhost:8181/rservices/rs2/studentservice/students
{"students":[{"id":"24e7dfdb-b9e1-4540-a450-b0c19bf43ec9","name":"Joe Senior","grade":"Eighth","address":{"street":"111 Park Ave","city":"New York","state":"NY","postalCode":"11111"}}]}

The client/remote service consumer source code is here.


See Also

Extending the JaxRS Distribution Providers

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This page was last modified 23:38, 8 February 2022 by Eclipsepedia anonymous user Unnamed Poltroon.

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