WAS v8.5 > WebSphere applications > Work area

Overview of work area service

The work area service passes information explicitly as an argument or implicitly to remote methods.

One of the foundations of distributed computing is the ability to pass information, typically in the form of arguments to remote methods, from one process to another. When application-level software is written over middleware services, many of the services rely on information beyond that passed in the application's remote calls. Such services often make use of the implicit propagation of private information in addition to the arguments passed in remote requests; two typical users of such a feature are security and transaction services. Security certificates or transaction contexts are passed without the knowledge or intervention of the user or application developer. The implicit propagation of such information means that application developers do not have to manually pass the information in method invocations, which makes development less error-prone, and the services requiring the information do not have to expose it to application developers. Information such as security credentials can remain secret.

The work area service gives application developers a similar facility. Applications can create a work area, insert information into it, and make remote invocations. The work area is propagated with each remote method invocation, eliminating the need to explicitly include an appropriate argument in the definition of every method. The methods on the server side can use or ignore the information in the work area as appropriate. If methods in a server receive a work area from a client and subsequently invoke other remote methods, the work area is transparently propagated with the remote requests. When the creating application is done with the work area, it terminates it.

There are two prime considerations in deciding whether to pass information explicitly as an argument or implicitly using a work area. These considerations are:

• Pervasiveness: Is the information used in a majority of the methods in an application?
• Size: Is it reasonable to send the information even when it is not used?

When information is sufficiently pervasive that it is easiest and most efficient to make it available everywhere, application programmers can use the work area service to simplify programming and maintenance of code. The argument does not need to go onto every argument list. It is much easier to put the value into a work area and propagate it automatically. This is especially true for methods that simply pass the value on but do nothing with it. Methods that make no use of the propagated information simply ignore it.

Work areas can hold any kind of information, and they can hold an arbitrary number of individual pieces of data, each stored as a property.

Use the work area service in the dmgr console to configure the UserWorkArea partition. The UserWorkArea partition is the partition that is available in JNDI naming under the name "java:comp/websphere/UserWorkArea", as demonstrated in the Accessing the UserWorkArea partition article. The UserWorkArea partition is the default work area partition created automatically, if it has not been disabled, and is available through JNDI naming to all users. Any configuration option made to the UserWorkArea partition under the work area service panel in the dmgr console does not affect the work area partition service or any partitions defined in it, and conversely. For example, if you select the enable or disable option in the work area service panel, this does not affect the work area partition service or any partition within it.

Subtopics

• Work area property modes
  The information in a work area consists of a set of properties; a property consists of a key-value-mode triple. The key-value pair represents the information contained in the property; the key is a name by which the associated value is retrieved. The mode determines whether we can modify or remove the property.
• Nested work areas
  Applications can nest work areas to define and scope properties for specific tasks without having to make the work areas available to all parts of the application.
• Distributed work areas
  Work area context propagates to a target object on a remote invocation on both bidirectional and non-bidirectional defined work area partitions. The propagation of work area context operates differently depending on whether a work area partition is defined as bidirectional. If the partition is defined as bidirectional, the context propagates from a target object back to the originator.
• WorkArea service: Special considerations
  Developers who use work areas should consider the following issues that could potentially cause problems: interoperability between the EJB and CORBA programming models; and the use of work areas with Java's Abstract Windowing Toolkit.
• Work area service performance considerations
  
• Work area property modes
  The information in a work area consists of a set of properties; a property consists of a key-value-mode triple. The key-value pair represents the information contained in the property; the key is a name by which the associated value is retrieved. The mode determines whether we can modify or remove the property.
• Nested work areas
  Applications can nest work areas to define and scope properties for specific tasks without having to make the work areas available to all parts of the application.
• Distributed work areas
  Work area context propagates to a target object on a remote invocation on both bidirectional and non-bidirectional defined work area partitions. The propagation of work area context operates differently depending on whether a work area partition is defined as bidirectional. If the partition is defined as bidirectional, the context propagates from a target object back to the originator.
• WorkArea service: Special considerations
  Developers who use work areas should consider the following issues that could potentially cause problems: interoperability between the EJB and CORBA programming models; and the use of work areas with Java's Abstract Windowing Toolkit.

Related concepts:

Work area partition service

Related

Develop applications that use work areas
Manage the UserWorkArea partition
Access the UserWorkArea partition

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