org.cometd.server
Class AbstractCometdServlet

java.lang.Object
  javax.servlet.GenericServlet
      org.cometd.server.AbstractCometdServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

ContinuationCometdServlet

public abstract class AbstractCometdServlet
extends javax.servlet.GenericServlet

Cometd Filter Servlet implementing the AbstractBayeux protocol. The Servlet can be initialized with a json file mapping channels to DataFilter definitions. The servlet init parameter "filters" should point to a webapplication resource containing a JSON array of filter definitions. For example:

  [
    {
      "channels": "/**",
      "class"   : "org.cometd.server.filter.NoMarkupFilter",
      "init"    : {}
    }
  ]
 

The following init parameters can be used to configure the servlet:

timeout

The server side poll timeout in milliseconds (default 250000). This is how long the server will hold a reconnect request before responding.

interval

The client side poll timeout in milliseconds (default 0). How long a client will wait between reconnects

maxInterval

The max client side poll timeout in milliseconds (default 10000). A client will be removed if a connection is not received in this time.

maxLazyLatency

The max time in ms(default 0) that a client with lazy messages will wait before sending a response. If 0, then the client will wait until the next timeout or non-lazy message.

multiFrameInterval

the client side poll timeout if multiple connections are detected from the same browser (default 1500).

JSONCommented

If "true" then the server will accept JSON wrapped in a comment and will generate JSON wrapped in a comment. This is a defence against Ajax Hijacking.

filters

the location of a JSON file describing DataFilter instances to be installed

requestAvailable

If true, the current request is made available via the AbstractBayeux.getCurrentRequest() method

logLevel

0=none, 1=info, 2=debug

jsonDebug

If true, JSON complete json input will be kept for debug.

channelIdCacheLimit

The limit of the ChannelId cache: -1 to disable caching, 0 for no limits, any positive value to clear the cache once the limit has been reached

refsThreshold

The number of message refs at which the a single message response will be cached instead of being generated for every client delivered to. Done to optimize a single message being sent to multiple clients.

Author:

gregw, aabeling: added JSONP transport

See Also:

AbstractBayeux}, ChannelId}, Serialized Form

Field Summary

protected AbstractBayeux	_bayeux
protected boolean	_jsonDebug
static String	BROWSER_ID
static String	CLIENT_ATTR
static String	HTTP_CLIENT_ID
static String	MESSAGE_PARAM
static String	TRANSPORT_ATTR
static String	TUNNEL_INIT_PARAM

Constructor Summary

AbstractCometdServlet()

Method Summary

protected String	findBrowserId(javax.servlet.http.HttpServletRequest request)
AbstractBayeux	getBayeux()
protected Message[]	getMessages(javax.servlet.http.HttpServletRequest request)
protected Message[]	handleJSONParseException(javax.servlet.http.HttpServletRequest request, String messageString, Exception x) Override to customize the handling of JSON parse exceptions.
void	init()
protected abstract AbstractBayeux	newBayeux()
protected abstract void	service(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp)
void	service(javax.servlet.ServletRequest req, javax.servlet.ServletResponse resp)
protected String	setBrowserId(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Field Detail

CLIENT_ATTR

public static final String CLIENT_ATTR

See Also:

Constant Field Values

TRANSPORT_ATTR

public static final String TRANSPORT_ATTR

See Also:

Constant Field Values

MESSAGE_PARAM

public static final String MESSAGE_PARAM

See Also:

Constant Field Values

TUNNEL_INIT_PARAM

public static final String TUNNEL_INIT_PARAM

See Also:

Constant Field Values

HTTP_CLIENT_ID

public static final String HTTP_CLIENT_ID

See Also:

Constant Field Values

BROWSER_ID

public static final String BROWSER_ID

See Also:

Constant Field Values

_bayeux

protected AbstractBayeux _bayeux

_jsonDebug

protected boolean _jsonDebug

Constructor Detail

AbstractCometdServlet

public AbstractCometdServlet()

Method Detail

getBayeux

public AbstractBayeux getBayeux()

newBayeux

protected abstract AbstractBayeux newBayeux()

init

public void init()
          throws javax.servlet.ServletException

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

service

protected abstract void service(javax.servlet.http.HttpServletRequest req,
                                javax.servlet.http.HttpServletResponse resp)
                         throws javax.servlet.ServletException,
                                IOException

Throws:

javax.servlet.ServletException

IOException

service

public void service(javax.servlet.ServletRequest req,
                    javax.servlet.ServletResponse resp)
             throws javax.servlet.ServletException,
                    IOException

Specified by:

service in interface javax.servlet.Servlet

Specified by:

service in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

IOException

findBrowserId

protected String findBrowserId(javax.servlet.http.HttpServletRequest request)

setBrowserId

protected String setBrowserId(javax.servlet.http.HttpServletRequest request,
                              javax.servlet.http.HttpServletResponse response)

getMessages

protected Message[] getMessages(javax.servlet.http.HttpServletRequest request)
                         throws IOException,
                                javax.servlet.ServletException

Throws:

IOException

javax.servlet.ServletException

handleJSONParseException

protected Message[] handleJSONParseException(javax.servlet.http.HttpServletRequest request,
                                             String messageString,
                                             Exception x)
                                      throws javax.servlet.ServletException

Override to customize the handling of JSON parse exceptions. Default behavior is to log at warn level on logger "org.cometd.json" and to throw a ServletException that wraps the original exception.

Parameters:

request - the request object

messageString - the JSON text, if available; can be null if the JSON is not buffered before being parsed.

x - the exception thrown during parsing

Returns:

a non-null array of messages, possibly empty, if the JSON parse exception is recoverable

Throws:

javax.servlet.ServletException - if the JSON parsing is not recoverable