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The following page has been changed by MichaelJouravlev: http://wiki.apache.org/struts/ModelingNotes The comment on the change is: Orphaned; Not really a wiki page, just a scratchpad. ------------------------------------------------------------------------------ - Modeling Notes + deleted - This is a scatchpad page that tries to describe the Struts workflow in generic form, and then reconstruct a generic configuration file to match the description. This is a brainstorming document only. - - ---- - - On startup, controller parses configuration and deploys the decorator objects, including the handlers, as its ControllerConfig object. - - The configuration elements are decorators that are used to create and manage other objects. At runtime, the target objects may be passed a reference to its decorator. The object can then alter its behavior according to the properties of its decorator. If the target object is a singleton, the decorator lets us reuse the object without changing its member properties. - - A reference to the servlet's ControllerConfig is placed in application scope, using upper-case versions of the servlet-name and config-name properties as the attribute name {$SERVLET-NAME.$CONFIG-NAME}. - If an attribute by this name already exists, a servlet exception must be thrown. - At runtime, container passes request to controller (servlet). Controller passes both get and post requests to its processor object. - - Processor matches URI with handler's matchPath property. (This is the handler decorator, not its target object.) - If no path matches, processor checks for the default-handler before surrendering request back to container. - Processor checks for secure attribute and the security role and throws an exception if user is not authorized to access this handler. - - Processor obtains a copy of the handler (decorator) and passes it the details of this request event. A reference to the handler is placed in the request (under the default token: HANDLER). If so configured by the controller, the processor also obtains a reference to the standard locale object in the user's session. - - If a handler already exists in the request, it is set to to the new handler's previous property. The new object then replaces the old in the request. - - {A reference collection of the handlers (decorators) is deployed at startup. The processor refers to this collection when creating a new copy of the handler for a request. When a handler (later) refers to other handler, a reference from the collection may be returned to avoid unnecessary object creates. The handlers have a locked property which indicate whether they are global singletons (locked) or local to this request (not locked).} - - By default, the controller will maintain a standard locale object in the user's session (LOCALE). - The processor may be configured to place additional helper beans in every request. The helper beans must have a zero-arguments constructor and a handler property. - - If the handler specifies an input decorator, the processor obtains the input-object and, if appropriate, calls the input bean's reset, populate, and validate methods, passing each method a reference to the handler for this request. - The handler encapsulates details such as a reference to the pending request (which includes the handler instance.) - To obtain the input-object, processor first checks to see if there is already an object under the name and scope specified by the input decorator. Otherwise, a new input-object is instantiated. - - If the input-object's locked property is true, processor will not call reset or populate (but may still call validate). - If the handler's validateInput property is false, validate on the input bean is not called. - - The validate method can examine the input-object's properties (populated from the request). If messages are generated, the method can pass a queue of errors to the handler. - If validate returns false, the processor uses the specified input-location to complete this cycle. If the input-location is non-null, the processor uses its path (or handler-name) to return a URI to the controller. If null is returned, the response is considered complete. - - Processor obtains the handler-object and any helper bean. When a handler-object is specified, the processor calls the object's dispatch method, passing it the handler for this request. The dispatch method returns a location or null. - If the handler (decorator) specifies a forward-path property or redirect-path property instead of a handler-object, a servlet-forward or servlet-redirect is performed instead of calling the handler-object. One of these three must be specified. - - When a non-null location is return, the processor uses its match-path to return a URI to the controller. If null is returned, the response is considered complete. - - Other components in the application (servlet or presentation-layer) may access the handler from the request (and any helper beans) to obtain whatever implementation details may be needed. The controller configuration may also be accessed by other components. - - On the presentation layer, handlers may be used to create hyperlinks. The link-param property is provided to help create hyperlinks that use a query string. The hyperlink may be to a handler or any other resource. If the hyperlink is to a resource handled by another component or service (JSPs, HTMLs, VMs,), the handler-object property may be omitted (null). In this case, the match-path will not correspond to the pattern registered for our controller servlet. (But it other cases it may.) - - A handler is recommended to create links to local resources, but locations may also be used to create hyperlinks, expecially when the location is outside the application context. - - The controller may be passed a module name and template by the web deployment descriptor (web.xml). By default, the module name and template will be applied when matching URIs or rendering the match-path as a hyperlink. When modules are used, non-virtual resources (JSPs, HTMLs) must be placed in a subdirectory corresponding to the module name and template. For a reference outside the module, but within the same application, set the <context> property on the handler to "application". For a reference in the same domain, but in another application, set the <content> property to "server" or "domain". For a reference to another domain, set the <context> property to "absolute". Including the scheme ("http://";) in the property value forces the context to be absolute. - - Note that all handlers, whether to internal or external resources, share a common name space. All components refer to the handler by its logical name. The match-path is used when the URI first enters the controller, but does not need to be referenced by other components - - ---- - - These are some scratchpad elements to illustrate the workflow. Note that it tries to distinguish between the "decorator" objects (like Struts FormBeans) and the "worker" objects (like Struts ActionForms). - - <controller-config> - <name/> - <module-name/> - <module-template/> - <default-handler/> - <decorators> - - <input["classname"]> - <name/> - <input-object-classname/> - <dyna-property/>+ - <init-param/>+ - <scope/> - </input> - - <!-- input-object interface - boolean isLocked(); - void setLocked(boolean locked); - void reset(Handler handler); - void populate(Handler handler); - boolean validate(Handler handler); - --> - - ---- - - <helper["classname"]> - <name/> - <helper-object-classname/> - <dyna-property///>+ - <init-param/>+ - <scope/> - </helper> - - ---- - - <location["classname"]> - <name/> - <path/> - </location> - or - <location["classname"]> - <name/> - <handler-name/> - </location> - - ---- - - <handler["classname"]> - <name/> - <handler-object-classname/> - <dyna-property/>+ - <init-param>+ - <scope/> - <match-path/> - <scheme/> - <secure/> - <context["module"]]/> - <roles/> - <validate-input/> - <input-location-name/> - <error-location-name/> - <helper-name/> - <exception-location-name/>+ - <exit-location-name/>+ - </handler> - - <!-- handler interface - handler-object-instance - previous-handler - locked - locale - void setMessages(Messages messages, String bundleName); - Messages getMessages(referenceName); - --> - - <!-- handler-object interface - Location dispatch(Handler handler); - ControllerConfig getConfig(); - ServletRequest getRequest(); - --> - - <!-- http-handler-object interface - HttpLocation HttpDispatch(HttpHandler HttpHandler); - HttpServletRequest getHttpRequest(); - HttpServletResponse getHttpResponse(); - String getHref(); - --> - - {alternate forms: servlet forward, servlet redirect, hyperlink} - <handler> - <name/> - <match-path/> - <forward-path/> - </handler> - - <handler> - <name/> - <match-path/> - <redirect-path/> - </handler> - <handler> - <name/> - <match-path> - <link-param/>+ - </handler> - - ---- - - <event["classname"]> - <name/> - <classname/> - <init-param/>+ - <handler-name/> - </event> - - ---- - - <processor/> - - ---- - - <session/> - - ---- - - <exception/> - ---- - - <properties/> - - ---- - - <resourceBundle/> - {first = default bundle} - - ---- - - <resource/> <!-- including DataSources --> - - ---- - - </decorators> - </controller-config> - - ----- - --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
