WAS v8.5 > End-to-end paths > Web services - RESTful services

Use JSON content in JAX-RS application requests and responses

JSON is a common media format that RESTful services consume and produce. We can use this lightweight data-interchange format based on the object-literal notation of JavaScript to exchange data.

JSON is a popular data format that is programming-language neutral. Multiple web browsers and JavaScript libraries such as Dojo provide support for JSON. WebSphere supports the Jackson and JavaScript Object Notation (JSON4J) libraries.

The Jackson library is a JSON processor (both parser and generator) based on streaming API for XML (StAX) pull parser technology. It provides basic JSON reading and writing (parsing and generating), a full node-based tree model, as well as object-to-JSON data binding.

We can use the Jackson library to unmarshal and marshal JSON data to and from Plain Old Java Objects (POJOs) and JAXB objects. To use Jackson to process JSON data, you must include the Jackson libraries in the class path. After adding Jackson to the class path, we use POJOs and JAXB objects to represent request and response message bodies. Jackson is included in the server-side run time WAS v8.5.

The JSON4J library is an implementation of a set of JSON handling classes for use within Java environments. The JSON4J library provides a simple Java model for constructing and manipulating data to be rendered as JSON data.

We can use the JSON4J library to output JSON data. To use JSON4J types as supported entity types, you must include the JSON4J library in the class path. After adding JSON4J to the class path, we can use the JSONObject, and the JSONArray classes from the JSON4J library as types to represent request and response message bodies. JSON4J is included in the server-side runtime environment of WAS v8.5.


Procedure

  1. Configure the development environment

    Before you start developing JAX-RS applications, set up your development environment by adding the JAX-RS libraries on the class path.

  2. Define the resources in JAX-RS web applications

    Resources are the basic building block of a RESTful service. Resources can contain static or dynamically updated data. Examples of resources from an online book store application include a book, an order from a store, and a collection of users. By identifying the resources in the application, we can make the service more useful and easier to develop.

  3. Configure the JAX-RS application

    We can configure JAX-RS applications in multiple ways depending on your needs. To take advantage of the Java EE 6 functionality, we can use the annotation scanning capabilities. By using annotation scanning, we can omit a JAX-RS javax.ws.rs.core.Application subclass or have a minimally defined javax.ws.rs.core.Application subclass. Alternatively, we can specify the IBM JAX-RS servlet or filter to use the functionality available in the IBM JAX-RS servlet and filter.

    Using one of the JAX-RS v1.1 configuration methods, we can omit a javax.ws.rs.core.Application subclass in the application or have a javax.ws.rs.core.Application subclass that returns an empty set of classes to inform the JAX-RS runtime environment to find and use all the JAX-RS classes in the application. You might want to use this method when we do not want to must manually add every relevant JAX-RS class to a javax.ws.rs.core.Application subclass as you develop the application.

    By specifying the specific IBM JAX-RS servlet and filter, we can take advantage of and ensure specific IBM JAX-RS behavior. For example, using the IBM JAX-RS filter can be helpful in developing a web application with a mix of JAX-RS resources and JSP files with the same URL patterns.

    Even though there is a JAX-RS V1.1 configuration method that supports the use of an optional web.xml file, to specify security constraints or roles, or to take advantage of other features enabled with a web.xml file, specify the information in a web.xml file.

    Choose one of the following three methods to configure your JAX-RS application:

  4. Implement a resource method using JSON content for a request and response entity

    RESTful services can consume and produce content using the JSON format.

    1. Use Jackson with plain old Java objects (POJOs)
    2. Implement a JSON representation of a resource with Jackson and JAXB annotated objects
    3. Implement a resource method using IBM JSON4J
    4. Implement a JSON resource method using JAXB annotated objects with IBM JSON4J

  5. Assemble JAX-RS web applications

    After you develop the Java class files for the JAX-RS web application and edit web.xml to enable the JAX-RS servlet, you are ready to assemble the application. Assemble the web application into a WAR package. We can assemble the WAR package into an EAR package, if required.

  6. Deploy JAX-RS web applicationsDeploy JAX-RS web applications

    After we have assembled your JAX-RS web application, you must deploy the web archive (WAR) package or the EAR package onto the application server.


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Deploy JAX-RS web applications


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