The Struts Configuration file

 Struts Configuration file

Struts framework uses a centralized XML file based configuration. This allows us to configure most of the application properties like actions, formbeans, I18N, data sources etc in XML files rather than hard coding into java classes, which means that any changes to these configurations can be made without modifying or recompiling java code and the changes can be made by modifying a single file struts configuration file. This even benefits the Java developers to concentrate on implementing the business logic without needing to know about the overall system layout and concentrating on the infrastructure logic configurations. In this section, we will discuss the top level elements of struts configuration file like data sources form beans gloal-exception, global-forwards, action-mappings, controller, message-resources and plug-in. In this section, we will discussing the other topics in this struts post. The root element of struts configuration file is <struts-config> this element contains the following child elements.

Element Name	Description	Occurrence
Display-name	Contains short description of this module this is used in GUI tools	Optional
Description	Contains descriptive text of this module this is also for the use in GUI tools	Optional
Form-beans	Encapsulates all the form bean definitions of this module, where each of the form bean is defined using a formbean tag which is a child tag of this element	Optional
Global-exceptions	This element describes a set of excetion handler declarations that are in common for all the actions in this module. The <action> element can override a global exception handler by configuring a local exception handler for the same exception type.	Optional
Global-forwards	This element describes a set of forwards that are in common for all the actions in this module. The <action> element can override a global forward declaration by configuring a local forward declaration with the same forward name.	Optional
Action-mapping	This element holds all the action declarations of this module, where each of the action is configured using <action> tag	Optional
Controller	This element describes module runtie configuration details for this module like buffer-size it has to use while processing file uploads, Local scope, controller class etc	Optional
Message-resources	Describes the MessageResources object that defines the resource bundle that struts has to use while looking up for locale specific messages in this module	Optional and can appear for more than ones
Plug-in	This allows configuring additional plugins for this module.	Optional and can appear for more than ones

The above table describes the high – level elements of struts configuration file and the child tags of these high-level tags are describes in details in the next post.

Struts application has minimum one module and can be configured to handle multiple modules and in such a case we need to write a separate struts configuration file for each module with there respective configurations. As we have discussed an overview of struts configuration file and its top level elements we will continue our discussion on the other elements of struts architecture next post describes about the RequestProcessor.