org.xmlBlaster.protocol.http
Class HttpPushHandler

java.lang.Object
  org.xmlBlaster.protocol.http.HttpPushHandler

All Implemented Interfaces:

I_Callback

public class HttpPushHandler
extends java.lang.Object
implements I_Callback

This handles and hides the different http push modes when sending data back to the browser through method update().
Push mode works with keeping a permanent http connection

TODO: HTTP 1.1 specifies rfc2616 that the connection stays open as the default case. How must this code be changed?

See Java Servlet Programming from Jason Hunter

Author:

Marcel Ruff xmlBlaster@marcelruff.info

Nested Class Summary

private class

HttpPushHandler.HttpPingThread Ping the browser, to avoid that the web server or the browser closes the http connection after a vendor specific timeout.

Field Summary

private boolean	browserIsReady Check it the browser is ready to accept more messages
private I_Callback	callbackInterceptor
private boolean	closed Current http connection state
private boolean	firstPush
private boolean	handlesMultipart handlesMultipart is true for netscape browser
private java.lang.String	head The header of the HTML page
private static java.util.logging.Logger	log
private java.lang.String	ME
private javax.servlet.ServletOutputStream	outMulti
private java.io.PrintWriter	outPlain
private long	PING_INTERVAL Ping the browser every 10 seconds.
private HttpPushHandler.HttpPingThread	pingThread Check browser and holds the http connection
private java.util.Vector	pushQueue Queue to hold messages (class PushDataItem) until the browser is ready for them
private javax.servlet.http.HttpServletRequest	req
private javax.servlet.http.HttpServletResponse	res
private java.lang.String	sessionId
private java.lang.String	tail The tail of the HTML page
private I_XmlBlasterAccess	xmlBlasterAccess

Constructor Summary

HttpPushHandler(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res, java.lang.String sessionId, java.lang.String loginName, I_XmlBlasterAccess xmlBlasterAccess)
Use this constructor if you are too lazy to pass a HTML header, a default will be used.

Method Summary

static java.lang.String	alert(java.lang.String text) Display a popup alert message containing the error text.
void	cleanup() Delegates the cleanup call to HttpPushHandler
boolean	closed() check's whether the HTTP connection is closed or not
private boolean	doesHandleMultipart() Determine if the browser can handle multipart pushs.
I_XmlBlasterAccess	getXmlBlasterAccess()
private void	initialize(java.lang.String head, java.lang.String tail)
boolean	isBrowserReady() check's whether the browser is ready to accept more messages or not [if (parent.browserReady != null) parent.browserReady();].
void	message(java.lang.String text) Calls the message method in the parentframe of the callback frame.
void	ping(java.lang.String state) calls the ping method in the parentframe of the callback frame The data must be Javascript code
void	pong() This is the browser response for our previous ping.
void	push(PushDataItem item) Updating data to the browser (callback/push mode).
private void	pushToBrowser() Pushing messages in the queue to the browser
void	setBrowserIsReady(boolean ready)
void	setClosed(boolean closed)
void	setProxyInterceptor(I_Callback interceptor) If you implement I_ProxyInterceptor and register it here, your update() implementation is called and may manipulate the received message from xmlBlaster before it is sent to the browser.
void	shutdownBrowserConnection() Don't forget to call this method when you want to close the connection.
void	startPing()
java.lang.String	update(java.lang.String sessionId, UpdateKey updateKey, byte[] content, UpdateQos updateQos) Pushes received message back to browser or applet.

Methods inherited from class java.lang.Object

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

Field Detail

ME

private java.lang.String ME

log

private static java.util.logging.Logger log

PING_INTERVAL

private final long PING_INTERVAL

Ping the browser every 10 seconds.
You need to adjust ping() in persistenWindow/index.html as well, if you change the value here.

See Also:

Constant Field Values

xmlBlasterAccess

private I_XmlBlasterAccess xmlBlasterAccess

callbackInterceptor

private I_Callback callbackInterceptor

req

private javax.servlet.http.HttpServletRequest req

res

private javax.servlet.http.HttpServletResponse res

sessionId

private java.lang.String sessionId

closed

private boolean closed

Current http connection state

outMulti

private javax.servlet.ServletOutputStream outMulti

outPlain

private java.io.PrintWriter outPlain

head

private java.lang.String head

The header of the HTML page

tail

private java.lang.String tail

The tail of the HTML page

browserIsReady

private boolean browserIsReady

Check it the browser is ready to accept more messages

handlesMultipart

private boolean handlesMultipart

handlesMultipart is true for netscape browser

pingThread

private HttpPushHandler.HttpPingThread pingThread

Check browser and holds the http connection

pushQueue

private java.util.Vector pushQueue

Queue to hold messages (class PushDataItem) until the browser is ready for them

firstPush

private boolean firstPush

Constructor Detail

HttpPushHandler

public HttpPushHandler(javax.servlet.http.HttpServletRequest req,
                       javax.servlet.http.HttpServletResponse res,
                       java.lang.String sessionId,
                       java.lang.String loginName,
                       I_XmlBlasterAccess xmlBlasterAccess)
                throws javax.servlet.ServletException,
                       java.io.IOException

Use this constructor if you are too lazy to pass a HTML header, a default will be used.

Parameters:

req - The request object

res - The response object

sessionId - The browser id

loginName - For loggin only

xmlBlasterAccess - Not yet logged in

Throws:

javax.servlet.ServletException

java.io.IOException

Method Detail

getXmlBlasterAccess

public I_XmlBlasterAccess getXmlBlasterAccess()

initialize

private void initialize(java.lang.String head,
                        java.lang.String tail)
                 throws java.io.IOException

Throws:

java.io.IOException

shutdownBrowserConnection

public void shutdownBrowserConnection()

Don't forget to call this method when you want to close the connection.

setProxyInterceptor

public void setProxyInterceptor(I_Callback interceptor)

If you implement I_ProxyInterceptor and register it here, your update() implementation is called and may manipulate the received message from xmlBlaster before it is sent to the browser.

Parameters:

interceptor - Your optional implementation

cleanup

public void cleanup()

Delegates the cleanup call to HttpPushHandler

startPing

public void startPing()
               throws javax.servlet.ServletException,
                      java.io.IOException

Throws:

javax.servlet.ServletException

java.io.IOException

closed

public boolean closed()

check's whether the HTTP connection is closed or not

setClosed

public void setClosed(boolean closed)

isBrowserReady

public final boolean isBrowserReady()

check's whether the browser is ready to accept more messages or not [if (parent.browserReady != null) parent.browserReady();]. This shows, that the browser had processed the whole message. If the Browser implements this javascript function, it could send a browserReady signal back to the BlasterHttpProxyServlet. This feature solves the problem, that the browser got messages too fast and could not process all content of the message.

setBrowserIsReady

public void setBrowserIsReady(boolean ready)

doesHandleMultipart

private boolean doesHandleMultipart()
                             throws java.io.IOException

Determine if the browser can handle multipart pushs. Only Netscape returns true.

Throws:

java.io.IOException

push

public void push(PushDataItem item)
          throws javax.servlet.ServletException,
                 java.io.IOException

Updating data to the browser (callback/push mode). The data must be Javascript code

Parameters:

str -

Throws:

javax.servlet.ServletException

java.io.IOException

pushToBrowser

private void pushToBrowser()
                    throws javax.servlet.ServletException,
                           java.io.IOException

Pushing messages in the queue to the browser

Throws:

javax.servlet.ServletException

java.io.IOException

update

public java.lang.String update(java.lang.String sessionId,
                               UpdateKey updateKey,
                               byte[] content,
                               UpdateQos updateQos)

Pushes received message back to browser or applet.

Browser: Calls the update method in the parentframe of the callback frame The data must be Javascript code

Applet: The callbacks are java-serialized Map for key/qos etc.

Specified by:

update in interface I_Callback

Parameters:

sessionId - The session ID specified by the client which registered the callback. You can specify a cbSessionId during connection (with ConnectQos) and this is bounced back here so you can authenticate the message.

updateKey - The arrived key containing the topic name

content - The arrived message content. This is your payload.

See Also:

I_XmlBlasterAccess

alert

public static final java.lang.String alert(java.lang.String text)

Display a popup alert message containing the error text.

This method wraps your text into javascript/alert code and escapes "\n" and "'" characters

Parameters:

text - The error text

message

public void message(java.lang.String text)

Calls the message method in the parentframe of the callback frame.

See callback.js message() method. Can be used by applications to send a message to the browser.

Parameters:

text - This must be Javascript code (usually a message string)

ping

public void ping(java.lang.String state)
          throws javax.servlet.ServletException,
                 java.io.IOException

calls the ping method in the parentframe of the callback frame The data must be Javascript code

Parameters:

state - The string "refresh"
When login is done successfully, state="loginSucceeded" is sent one time

Throws:

javax.servlet.ServletException

java.io.IOException

pong

public void pong()

This is the browser response for our previous ping.