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 Summary

Fields

Modifier and Type	Field and Description
static String	JSON_COMMUNICATION_PREFIX
static String	JSON_COMMUNICATION_SUFFIX
protected int	lastProcessingTime Holds the time spent rendering the last request.
protected int	totalProcessingTime Holds the total time spent rendering requests during the lifetime of the session.

Constructor Summary

Constructors

Constructor and Description
MessageHandler(Registry registry) Creates a new instance connected to the given registry.

Method Summary

Modifier and Type	Method and Description
String	getCsrfToken() Gets the token (aka double submit cookie) that the server uses to protect against Cross Site Request Forgery attacks.
int	getLastSeenServerSyncId() Gets the server id included in the last received response.
String	getPushId() Gets the push connection identifier for this session.
protected void	handleJSON(ValueMap valueMap)
void	handleMessage(ValueMap json) Handles a received UIDL JSON text, parsing it, and passing it on to the appropriate handlers, while logging timing information.
boolean	isInitialUidlHandled() Checks if the first UIDL has been handled.
static ValueMap	parseJson(String jsonText) Unwraps and parses the given JSON, originating from the server.
static ValueMap	parseWrappedJson(String wrappedJsonText) Parse the given wrapped JSON, received from the server, to a ValueMap.
void	resumeResponseHandling(Object lock) Resumes the rendering process once all locks have been removed.
void	setNextResponseSessionExpiredHandler(Command nextResponseSessionExpiredHandler) Sets a temporary handler for session expiration.
static String	stripJSONWrapping(String jsonWithWrapping) Strips the JSON wrapping from the given json string with wrapping.
void	suspendReponseHandling(Object lock) This method can be used to postpone rendering of a response for a short period of time (e.g.

Methods inherited from class java.lang.Object

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

Field Detail

JSON_COMMUNICATION_PREFIX

public static final String JSON_COMMUNICATION_PREFIX

See Also:

Constant Field Values

JSON_COMMUNICATION_SUFFIX

public static final String JSON_COMMUNICATION_SUFFIX

See Also:

Constant Field Values

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 Detail

MessageHandler

public MessageHandler(Registry registry)

Creates a new instance connected to the given registry.

Parameters:

registry - the global registry

Method Detail

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 (aka double submit cookie) that the server uses to protect against 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