Package com.vaadin.client.communication

Class MessageHandler

java.lang.Object
com.vaadin.client.communication.MessageHandler
public class MessageHandler extends Object
A MessageHandler is responsible for handling all incoming messages (JSON) from the server (state changes, RPCs and other updates) and ensuring that the connectors are updated accordingly.
Since:
1.0
Author:
Vaadin Ltd

  • Field Details

    • JSON_COMMUNICATION_PREFIX

      public static final String JSON_COMMUNICATION_PREFIX
      See Also:

    • JSON_COMMUNICATION_SUFFIX

      public static final String JSON_COMMUNICATION_SUFFIX
      See Also:

    • lastProcessingTime

      protected int lastProcessingTime
      Holds the time spent rendering the last request.

    • totalProcessingTime

      protected int totalProcessingTime
      Holds the total time spent rendering requests during the lifetime of the session.

  • Constructor Details

    • MessageHandler

      public MessageHandler(Registry registry)
      Creates a new instance connected to the given registry.
      Parameters:
      registry - the global registry

  • Method Details

    • handleMessage

      public void handleMessage(ValueMap json)
      Handles a received UIDL JSON text, parsing it, and passing it on to the appropriate handlers, while logging timing information.
      Parameters:
      json - The JSON to handle

    • handleJSON

      protected void handleJSON(ValueMap valueMap)

    • suspendReponseHandling

      public void suspendReponseHandling(Object lock)
      This method can be used to postpone rendering of a response for a short period of time (e.g. to avoid the rendering process during animation).
      Parameters:
      lock - the lock

    • resumeResponseHandling

      public void resumeResponseHandling(Object lock)
      Resumes the rendering process once all locks have been removed.
      Parameters:
      lock - the lock

    • getLastSeenServerSyncId

      public int getLastSeenServerSyncId()
      Gets the server id included in the last received response.

      This id can be used by connectors to determine whether new data has been received from the server to avoid doing the same calculations multiple times.

      No guarantees are made for the structure of the id other than that there will be a new unique value every time a new response with data from the server is received.

      The initial id when no request has yet been processed is -1.

      Returns:
      an id identifying the response

    • getCsrfToken

      public String getCsrfToken()
      Gets the token (synchronizer token pattern) that the server uses to protect against CSRF (Cross Site Request Forgery) attacks.
      Returns:
      the CSRF token string

    • getPushId

      public String getPushId()
      Gets the push connection identifier for this session. Used when establishing a push connection with the client.
      Returns:
      the push connection identifier string

    • isInitialUidlHandled

      public boolean isInitialUidlHandled()
      Checks if the first UIDL has been handled.
      Returns:
      true if the initial UIDL has already been processed, false otherwise

    • stripJSONWrapping

      public static String stripJSONWrapping(String jsonWithWrapping)
      Strips the JSON wrapping from the given json string with wrapping. If the given string is not wrapped as expected, returns null
      Parameters:
      jsonWithWrapping - the JSON received from the server
      Returns:
      an unwrapped JSON string or null if the given string was not wrapped

    • parseJson

      public static ValueMap parseJson(String jsonText)
      Unwraps and parses the given JSON, originating from the server.
      Parameters:
      jsonText - the json from the server
      Returns:
      A parsed ValueMap or null if the input could not be parsed (or was null)

    • parseWrappedJson

      public static ValueMap parseWrappedJson(String wrappedJsonText)
      Parse the given wrapped JSON, received from the server, to a ValueMap.
      Parameters:
      wrappedJsonText - the json, wrapped as done by the server
      Returns:
      a ValueMap, or null if the wrapping was incorrect or json could not be parsed

    • setNextResponseSessionExpiredHandler

      public void setNextResponseSessionExpiredHandler(Command nextResponseSessionExpiredHandler)
      Sets a temporary handler for session expiration. This handler will be triggered if and only if the next server message tells that the session has expired.
      Parameters:
      nextResponseSessionExpiredHandler - the handler to use or null to remove a previously set handler