Package de.xima.fc.gui.bean.designer.conversation

Class DesignerConversationBean

java.lang.Object
de.xima.fc.gui.bean.designer.conversation.DesignerConversationBean
All Implemented Interfaces:
Serializable
@Named @SessionScoped public class DesignerConversationBean extends Object implements Serializable
Bean for handling the designer conversation context. A designer session consists of multiple pages within iframes that need to communicate with each other. They do so by by sharing a conversation ID that identifies the designer session. The ID is created when the designer is first opened and propagated to all child iframes and pages. All individual beans in the pages are scoped to the view. When the view who initiated the designer session is destroyed, the entire designer session is destroyed. This bean itself is scoped to the session and keeps a map of all active designer sessions.

This is similar to the CDI ConversationScoped annotation via the cid parameter, but does not require a lock on the entire request, which can quickly result in a BusyConversationException. Instead, locking is performed via a reentrant synchronized on the designer session state (see withDesignerConversationModel) only when it is needed. This allows for more parallelity between requests of different designer pages and prevents BusyConversationException. Make sure you only access the conversation model directly within the handler passed to withDesignerConversationModel!

This bean also lets you send events to other designer views via post. When you need to access data from a different view, you can use request.

Since:
7.0.0
Author:
XIMA MEDIA GmbH
See Also:

  • Constructor Details

    • DesignerConversationBean

      public DesignerConversationBean()

  • Method Details

    • getConversationId

      public String getConversationId()
      Returns:
      The current conversation ID, if it exists.

    • handleConversationRequest

      public void handleConversationRequest()
      Remote command callback for CmnConst.Designer.RemoteCommand.HANDLE_CONVERSATION_REQUEST. This remote command is invoked by the client in the view scope of the request target. We can now invoke the supplier that can provide the requested data.

    • handleConversationResponse

      public void handleConversationResponse()
      Remote command callback for CmnConst.Designer.RemoteCommand.HANDLE_CONVERSATION_RESPONSE. This remote command is invoked by the client in the view scope of the original request source. We can now invoke the consumer that originally requested the data.

    • post

      public void post(ISessionConversationEvent event)
      Posts the given designer conversation event and informs all event handlers that have subscribed to that event. When no designer conversation is active, this is a no-op.
      Parameters:
      event - Event to post.

    • registerEventHandler

      public void registerEventHandler(ISessionConversationEventHandler eventHandler)
      Registers the given conversation event handler for the active designer conversation. When no designer conversation is active, this is a no-op.
      Parameters:
      eventHandler - Designer conversation event handler to register. All subscriber methods of the event handler will be noticed when the corresponding designer conversation event occurs.

    • registerRequestHandler

      public <T extends Serializable, R extends ICrossViewScopeRequest<T>> void registerRequestHandler(Class<R> requestType, ICrossViewScopeRequestHandler<T,R> requestHandler)
      Registers the given conversation request handler for the active designer conversation. When no designer conversation is active, this is a no-op.
      Type Parameters:
      T - Type of the requested data.
      R - Type of the request.
      Parameters:
      requestType - Request type to listen to.
      requestHandler - Designer conversation request handler to register. The handler is called when a request is made.

    • request

      public <T extends Serializable, R extends ICrossViewScopeRequest<T>> boolean request(R request, Duration timeout, ICrossViewScopeResponseConsumer<? super T> consumer, BackendViewPushContext viewPushContext)
      Allows to retrieve a piece of data from another view scope that participates in the same conversation.

      Assume there are two view scopes A and B. A method running in the scope of A wishes to obtain some data form B. It needs to send a message (such as via an event bus) to B. However, when the message handler of B is invoked synchronously, it will still be within the scope of A and will not have access to the state of B.

      To solve this, A can first store the request data within the shared conversation state. A can send a push message via a web socket to the client (web browser) of B, which can then initiate an AJAX call to the view scope of B. Now B can access the request data from the shared conversation state, create the requested data and store the requested data in the conversation state. Afterwards, B sends a push message to the client (browser) of A, which initiates another AJAX call to the view scope of A. Finally, A can access the response from the conversation state and proceed to process that response.

      Type Parameters:
      T - Type of the requested data.
      R - Type of the request.
      Parameters:
      request - Request to send.
      timeout - Timeout to set on the request. When no response is received within this time frame, the handler is invoked with an error.
      consumer - Handler to invoke when the request completes either successfully or erroneously.
      viewPushContext - The current view push context of the caller.
      Returns:
      true if there are any pending responses, false if all requests have been processed, such as when no handlers did respond to the request.

    • requestBuilder

      public IRequestHandlerBuilder requestBuilder(BackendViewPushContext viewPushContext)
      Parameters:
      viewPushContext - The current view push context of the caller.
      Returns:
      A new builder for sending multiple requests and performing some logic when all have finished.

    • unregisterEventHandler

      public void unregisterEventHandler(ISessionConversationEventHandler eventHandler, String conversationId)
      Unregisters the given conversation event handler from the active designer conversation. When no designer conversation is active, this is a no-op.
      Parameters:
      eventHandler - Designer conversation event handler to remove.
      conversationId - ID of the conversation from which to unregister the handlers. This is required because a bean may be destroyed e.g. during a different view scope (when the number of allowed views per session has been exceeded). In that case, it is impossible to determined the correct conversation ID.

    • unregisterRequestHandler

      public <T extends Serializable, R extends ICrossViewScopeRequest<T>> void unregisterRequestHandler(Class<R> requestType, ICrossViewScopeRequestHandler<T,R> requestHandler, String conversationId)
      Unregisters the given conversation request handler for the active designer conversation. When no designer conversation is active, this is a no-op.
      Type Parameters:
      T - Type of the requested data.
      R - Type of the request.
      Parameters:
      requestType - Request type to listen to.
      requestHandler - Designer conversation request handler to unregister.
      conversationId - ID of the conversation from which to unregister the handlers. This is required because a bean may be destroyed e.g. during a different view scope (when the number of allowed views per session has been exceeded). In that case, it is impossible to determined the correct conversation ID.

    • withDesignerConversationModel

      public <R> R withDesignerConversationModel(Function<DesignerConversationModel,R> fn)
      The designer conversation model is shared between different views and may thus be accessed in simultaneously by different threads handling different requests. This method acquires a lock to ensure only on thread processed a conversation model at a given time. The lock is held for as long as the given handler fn is invoked. Make sure you do not use the model outside the handler fn.
      Parameters:
      fn - It is given the model for the designer session. This is used to share data between the different views in each iframe. This model is scoped to the designer Conversation.
      Returns:
      The value return by the given handler fn