er.extensions.appserver

Class ERXComponentActionRedirector

java.lang.Object

er.extensions.appserver.ERXComponentActionRedirector

public class ERXComponentActionRedirector
extends Object

Allows you to develop your app using component actions while still providing bookmarkable URLs. It should be considered highly experimental and it uses a few very dirty shortcuts, but no private API to work it's magic. The main problems may be garbage collection or space requirements. You might be better off to compress the responses.
The mode of operation is as follows; given a component action in a typical page:

  public WOComponent myAction() {
      WOComponent nextPage = pageWithName("Main");
      nextPage.takeValueForKey(Integer.valueOf(100), "someValue");
      return nextPage;
  }
 
  

then Main could be implemented something like this:

  public class Main extends WOComponent implements ERXComponentActionRedirector.Restorable {
      static Logger log = Logger.getLogger(Main.class);
 
      public Integer someValue = Integer.valueOf(10);
 
      public Main(WOContext aContext) {
          super(aContext);
      }
      
      // this page has a "Increment Some Value" link to itself which just doubles the current value
      public WOComponent addAction() {
          someValue = Integer.valueOf(someValue.intValue()*2);
          log.info(someValue);
          return this;
      }
 
      public String urlForCurrentState() {
          return context().directActionURLForActionNamed("Main$Restore", new NSDictionary(someValue, "someValue"));
      }
      public static class Restore extends WODirectAction {
          public Restore(WORequest aRequest) {
              super(aRequest);
          }
          public WOActionResults defaultAction() {
              WOComponent nextPage = pageWithName("Main");
              Number someValue = context().request().numericFormValueForKey("someValue", new NSNumberFormatter("#"));
              if(someValue != null) {
                  nextPage.takeValueForKey(someValue, "someValue");
              }
              return nextPage;
          }
      }
  }
  

But this is just one possibility. It only locates all the code in one place.
The actual workings are:

• You create a page with typical component action links
• URL in browser: /cgi-bin/WebObjects/myapp.woa/
• Links on page: /cgi-bin/WebObjects/myapp.woa/0.1.2.3

When you click on a link, the request-response loop gets executed, but instead of returning the response, we save it in a session-based cache and return a redirect instead. The current page is asked for the URL for the redirect when it implements the Restorable interface.
So the users browser receives redirection to a "reasonable" URL like "/article/1234/edit?wosid=..." or "../wa/EditArticle?__key=1234&wosid=...". This URL is intercepted and looked up in the cache. If found, the stored response is returned, else the request is handled normally.

The major thing about this class is that you can detach URLs from actions. For example, it is very hard to create a direct action that creates a page that uses a Tab panel or a collapsible component because you need to store a tremendous amount of state in the URL. With this class, you say: "OK, I won't be able to totally restore everything, but I'll show the first page with everything collapsed."
For all of this to work, your application should override the request-response loop like:

  public WOActionResults invokeAction(WORequest request, WOContext context) {
      WOActionResults results = super.invokeAction(request, context);
      ERXComponentActionRedirector.createRedirector(results);
      return results;
  }
 
  public void appendToResponse(WOResponse response, WOContext context) {
      super.appendToResponse(response, context);
      ERXComponentActionRedirector redirector = ERXComponentActionRedirector.currentRedirector();
      if(redirector != null) {
          redirector.setOriginalResponse(response);
      }
  }
 
  public WOResponse dispatchRequest(WORequest request) {
      ERXComponentActionRedirector redirector = ERXComponentActionRedirector.redirectorForRequest(request);
      WOResponse response = null;
      if(redirector == null) {
          response = super.dispatchRequest(request);
          redirector = ERXComponentActionRedirector.currentRedirector();
          if(redirector != null) {
              response = redirector.redirectionResponse();
          }
      } else {
          response = redirector.originalResponse();
      }
      return response;
  }
 

If you are using ERXApplication, you should set the er.extensions.ERXComponentActionRedirector.enabled=true property instead.

Author:

ak

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ERXComponentActionRedirector.Observer Observer class manages the responses cache by watching the session.
static interface	ERXComponentActionRedirector.Restorable implemented by the pages that want to be restorable

Field Summary

Fields

Modifier and Type	Field and Description
protected com.webobjects.appserver.WOResponse	originalResponse the original response
protected com.webobjects.appserver.WOResponse	redirectionResponse the redirection response
protected static NSMutableDictionary	responses static cache to hold the responses.
protected String	sessionID the session id for the request
protected String	url the url for the redirected request

Constructor Summary

Constructors

Constructor and Description
ERXComponentActionRedirector(ERXComponentActionRedirector.Restorable r) constructs the redirector from the Restorable.

Method Summary

Modifier and Type	Method and Description
static void	createRedirector(com.webobjects.appserver.WOActionResults results) Creates and stores a Redirector if the given results implement Restorable.
static ERXComponentActionRedirector	currentRedirector() Uses ERXThreadStorage with the key "redirector".
com.webobjects.appserver.WOResponse	originalResponse()
com.webobjects.appserver.WOResponse	redirectionResponse()
static ERXComponentActionRedirector	redirectorForRequest(com.webobjects.appserver.WORequest request)
String	sessionID()
void	setOriginalResponse(com.webobjects.appserver.WOResponse value) Sets the original response.
protected static void	storeRedirector(ERXComponentActionRedirector redirector) stores the redirector in the cache.
String	url()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

originalResponse

protected com.webobjects.appserver.WOResponse originalResponse

the original response

redirectionResponse

protected com.webobjects.appserver.WOResponse redirectionResponse

the redirection response

sessionID

protected String sessionID

the session id for the request

url

protected String url

the url for the redirected request

responses

protected static final NSMutableDictionary responses

static cache to hold the responses. They are stored on a by-session basis.

Constructor Detail

ERXComponentActionRedirector

public ERXComponentActionRedirector(ERXComponentActionRedirector.Restorable r)

constructs the redirector from the Restorable.

Parameters:

r - - Restorable component used to construct a redirector

Method Detail

storeRedirector

protected static void storeRedirector(ERXComponentActionRedirector redirector)

stores the redirector in the cache.

Parameters:

redirector - The redirector to store.

redirectorForRequest

public static ERXComponentActionRedirector redirectorForRequest(com.webobjects.appserver.WORequest request)

Parameters:

request - The request

Returns:

the previously stored redirector for the given request

createRedirector

public static void createRedirector(com.webobjects.appserver.WOActionResults results)

Creates and stores a Redirector if the given results implement Restorable.

Parameters:

results -

currentRedirector

public static ERXComponentActionRedirector currentRedirector()

Uses ERXThreadStorage with the key "redirector".

Returns:

the currently active Redirector in the request-response loop.

redirectionResponse

public com.webobjects.appserver.WOResponse redirectionResponse()

Returns:

the redirection response.

url

public String url()

Returns:

the URL with which the component can be restored.

sessionID

public String sessionID()

Returns:

the session ID for the Redirector.

originalResponse

public com.webobjects.appserver.WOResponse originalResponse()

Returns:

the original response.

setOriginalResponse

public void setOriginalResponse(com.webobjects.appserver.WOResponse value)

Sets the original response.

Parameters:

value - the original response.