One of the advantages of RESTful applications is the ability
to return different representations of resources. With Representational
State Transfer (REST), clients and servers can exchange resources
of the same media type or use differing media types. Content negotiation
enables clients and servers to agree on the content format that is
used to exchange data.
About this task
Resources are represented by many different formats. XML, JavaScript Object Notation
(JSON), Atom, plain text, PNG, JPEG, GIF, and custom or proprietary
formats are used to represent resources. Representational State Transfer
(REST) provides the flexibility to represent a single resource in
multiple formats.
Depending on the requirements of your application,
resources can return representations in a single format or in different
formats, depending on the request. For example, resources accessed
using JavaScript clients
might prefer JSON representations because JSON is easy to consume.
However, other clients prefer XML.
Use content negotiation if
you want to serve multiple formats to clients. Content negotiation
is the method in which the client and server agree on the response
content type to use. There are three types of content negotiation
that affect the response. You can use content negotiation that is
based on the URL, based on a request parameter, or based on HTTP headers.
- Configure the development environment.
- Before you start developing JAX-RS applications, you
must set up your development environment by adding the JAX-RS libraries
on the classpath.
- 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 your application, you can make the service more useful
and easier to develop.
- Configure the JAX-RS application.
You can
configure JAX-RS applications in multiple ways depending on your needs.
To take advantage of the Java™ Platform,
Enterprise Edition (Java EE)
6 functionality, you can use the annotation scanning capabilities.
By using annotation scanning, you can omit a JAX-RS javax.ws.rs.core.Application
subclass or have a minimally defined javax.ws.rs.core.Application
subclass. Alternatively, you can specify the IBM® JAX-RS servlet or filter if you want to use
the functionality available in the IBM JAX-RS
servlet and filter.
Using one of the JAX-RS Version 1.1 configuration
methods, you can omit a javax.ws.rs.core.Application subclass in your
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 you do not want to have to 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, you
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
JavaServer Pages (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, if you want to specify security constraints
or roles, or you want to take advantage of other features enabled
using a web.xml file, you must specify the information in a web.xml
file.
Choose one of the following three methods to configure
your JAX-RS application:
- Configure
JAX-RS applications using JAX-RS 1.1 methods
Use this method
if you want to use the annotation scanning capabilities or to use
the JAX-RS 1.1 configuration methods. You can use the annotation
scanning capabilities to promote application portability, to minimize
the amount of configuration code, or to dynamically modify the application
without changes to the application code.
- Configure
the web.xml file for JAX-RS servlets
Use this method if you
want to specify features that are enabled using servlet initialization
parameters to change the behavior and ensure that you get the IBM JAX-RS servlet. When using
servlets, you can define a servlet path in the web.xml file that is
appended to the base URL.
- Configure
the web.xml file for JAX-RS filters
Use this method if you
want to use the filter when you have JSPs, other servlets and filters,
and JAX-RS resources with a mix of URL patterns. You can configure
the web.xml file to define filters that indicate the possible URLs
on which the filter can be invoked.
- Implement content negotiation to serve multiple content
types. Use content negotiation to determine the best resource
representation for the server to return to the client. You can implement
content negotiation based on URL patterns, request parameters, or
HTTP headers.
- Assemble JAX-RS web applications.
- After you develop the Java class
files for your JAX-RS web application and edit the web.xml file to
enable the JAX-RS servlet, you are ready to assemble the application.
Assemble the web application into a web application archive (WAR)
package. You can assemble the WAR package into an enterprise archive
(EAR) package if required.
- Deploy JAX-RS web applications.
- After you have assembled your JAX-RS web application,
you need to deploy your Web archive (WAR) package or the enterprise
archive (EAR) package onto the application server.