Internationalization context: Management policies
Internationalization policies prescribe how Java EE application components or their hosting containers manage internationalization context on component invocations. Two internationalization context management policies apply to all component types: Application-managed internationalization (AMI) and Container-managed internationalization (CMI).
These policies are represented in two parts:
- Internationalization type
- Container internationalization attribute
The service defines a default, or implicit, internationalization policy for every application component type. At development time, assemblers can override the default policy for server component types by explicitly configuring their internationalization type, and optional container internationalization attributes. Policies configured during assembly are preserved in the deployment descriptor for the application.
All components have an internationalization type that indicates whether it is AMI or CMI; that is, whether a component is to deploy under the application-managed or the container-managed internationalization policy. Application assemblers can set the internationalization type for servlets, session beans, and message-driven beans. Entity beans are implicitly CMI and EJB clients are implicitly AMI; neither can be configured otherwise.
For CMI servlets and enterprise beans, optional container internationalization attributes can be specified to indicate which invocation internationalization context the container is to scope to service or business methods. A CMI service or business method invocation can run under the context of the caller's process, under the default context of the server JVM, or under a custom context specified in the attribute. Assemblers can specify one container internationalization attribute per disjoint set of CMI servlets within a Web module, or one Attribute per disjoint set of business methods of CMI beans within an EJB module. A container internationalization attribute can be associated with more than one method, but a method cannot be associated with more than one attribute.
When an application server launches an application, the internationalization service collects policy information from the deployment descriptor, then uses this information to construct and associate an internationalization policy to every component invocation. A policy is denoted as:
- [<Internationalization Type>,<Container Internationalization Attribute>]
Several cases exist in which the deployment descriptor seems to lack policy information, for example: EJB client applications have no configurable internationalization policy settings; AMI components do not have container internationalization attributes; and you are not required to specify container internationalization attributes for CMI components. When the service cannot obtain the explicit internationalization type and container attribute settings from a well-formed deployment descriptor, it implicitly inserts the appropriate setting into the policy.
The service observes the following conventions when applying policies to invocations:
- Servlets (service) and EJB business methods lacking all internationalization
policy information in the deployment descriptor implicitly run under policy [CMI,RunAsCaller].
- CMI servlets and business methods lacking a container internationalization
attribute in the deployment descriptor implicitly run under policy [CMI,RunAsCaller].
- AMI servlets and business methods always lack container internationalization
attributes in the deployment descriptor, but implicitly run under the logical policy [AMI,RunAsServer].
- EJB clients always lack internationalization policy information in the deployment descriptor. By definition, EJB clients are implicitly AMI types and run under the invocation context of the JVM; they run under the logical policy [AMI,RunAsServer].
For conditions other than these cited examples, such as a malformed deployment descriptor, refer to Internationalization service errors.
Internationalization policies for EJB clients and HTTP clients cannot be configured; HTTP clients do, however, run under the language priority settings of the hosting Web browser. These settings are configurable under the options dialog of most Web browsers. Refer to the Web browser documentation for details.
Subtopics
- Internationalization type
Every server application component has an internationalization type setting that indicates whether the invocation internationalization context is managed by the component or by the hosting Java EE container. - Container internationalization attributes
The internationalization policy of every CMI servlet and EJB business method has a container internationalization attribute that specifies which internationalization context the container is to scope to its invocation.
Related tasks
Concept topic