If you choose to deploy to a server other than WebSphere Application Server, you cannot use the IBM JAX-RS library, and must install and configure your own JAX-RS libraries through the Project Facets > JAX-RS preferences page.
For detailed information on using JAX-RS web services on WebSphere Application Server, refer to: WebSphere Application Server information centre
Every web application must have a context root for the web application to deploy successfully. A context root for each Web module is defined in the application deployment descriptor during application assembly or during application deployment. The context root is combined with the defined servlet mapping from the WAR file to compose the full URL that users type to access the servlet. The context root for each deployed web application must be unique on the server. The context root can also be empty.
For instance, if a Web application used a context root of sample/application/, the web application request URL begins with http://<hostname>:<port>/sample/application/. The URL pattern of a servlet is appended to the context root of the Web application. For example, if the context root is sample/application/ and the servlet URL mapping is rest/api/*, the base URI for the JAX-RS web application is http://<hostname>:<port>/sample/application/rest/api.