The REST API uses RESTEasy and other libraries, and shares some components with the Maven Plugin and Command-Line Client.
Each REST endpoint is mapped to one or more methods in a Java class. This page will use the project endpoint as an example.
Each endpoint usually has an interface that describes the REST methods that are available at that endpoint, but some interfaces describe methods for multiple related endpoints. These interfaces are located in repository zanata-api, project zanata-common-api under /src/main/java/org/zanata/rest/service and are named *Resource (e.g. ProjectResource)
Interface methods are annotated with a HTTP method type (e.g. @HEAD, @GET, @PUT). These annotations are found in the javax.ws.rs package.
Enunciate is a tool to generate REST API documentation. Enunciate needs the @Path annotation to determine the API endpoints, but there are some practical reasons not to add these to the interfaces directly. To hold the @Path annotation for each service interface, an additional interface is present in package /src/main/java/org/zanata/rest/enunciate. Each interface in the enunciate package has the same simple name as the interface from the service package it extends.
The generated enunciate documentation can be seen at https://zanata.ci.cloudbees.com/job/zanata-api-site/site/zanata-common-api/rest-api-docs/index.html
Each Resource Interface has a concrete implementation in the server, responsible for handling the actual REST method calls. Implementations are found in repository zanata, project zanata-war under /src/main/java/org/zanata/rest/service and are named *Service (e.g. ProjectService).
The URI path for each method (or the entire implementation class) is specified with @Path annotations in the implementation. For example, ProjectService class is annotated with @Path(ProjectService.SERVICE_PATH), SERVICE_PATH is a string which describes a path of /projects/p/<projectSlug> from the base server rest path.
Each Resource Interface is extended to make a client-side interface used by RESTEasy to create proxy methods. Client-side interfaces are found in repository zanata-api, project zanata-common-api under /src/main/java/org/zanata/rest/client, and are usually named I*Resource (e.g. IProjectResource).
Client-side interfaces are used by ZanataProxyFactory to create proxy methods used by Zanata clients, e.g. org.zanata.rest.client.ZanataProxyFactory.getProject(String proj). ZanataProxyFactory is in repository zanata-client, project zanata-rest-client under /src/main/java/org/zanata/rest/client.