org.w3c.www.protocol.http.micp
Class MICPFilter

java.lang.Object
  java.lang.Thread
      org.w3c.www.protocol.http.micp.MICPFilter

All Implemented Interfaces:

java.lang.Runnable, PropertyMonitoring, MICP, PropRequestFilter, RequestFilter

public class MICPFilter
extends java.lang.Thread
implements PropRequestFilter, PropertyMonitoring, MICP

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

protected java.net.InetAddress	addr Our multicast group address.
static java.lang.String	ADDRESS_P Properties - Our multicast group address.
protected CacheFilter	cache The CacheFilter we are working for.
protected boolean	debug Our we in debug mode ?
static java.lang.String	DEBUG_P Properties - Our debug flag.
static java.lang.String	DISABLE_CACHE_P Properties - disable caching when fetching from a neighbour proxy.
protected boolean	disableCache Should we disablecaching when fetching through a proxy ?
protected byte[]	localaddr Our local internet address as a byte array.
protected byte[]	localproxy Our local proxy address, in a byte array.
protected long	localsrc Our local internet address, as a long.
static java.lang.String	PORT_P Properties - Our own UDP port number.
protected ObservableProperties	props The properties we are initialized from.
static java.lang.String	PROXY_P Properties - location of proxy to redirect to (if success)
protected java.net.MulticastSocket	socket Our socket to the group.
static java.lang.String	STATE_HOW State - To mark requests that have been redirected.
static java.lang.String	TIMEOUT_P Properties - Our default timeout value.
protected long	timeoutValue Our default timeout value for waiting for replies (in ms).
protected int	ttl Our TTL for writing packets.
protected java.util.Vector	waiters Queue of threads waiting for some replies.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Fields inherited from interface org.w3c.www.protocol.http.micp.MICP

MICP_OP_QUERY, MICP_OP_REPLY, MICP_VERSION

Constructor Summary

MICPFilter()

Method Summary

protected org.w3c.www.protocol.http.micp.ReplyWaiter	addWaiter(int id)
boolean	exceptionFilter(Request request, HttpException ex) This filter doesn't handle exceptions.
protected void	handle(byte[] buf, int len) Parse and handle the given MICP packet.
Reply	ingoingFilter(Request request) Our ingoingFilter method.
void	initialize(HttpManager manager) Initialize the ICP filter.
protected int	locateProxy(java.net.URL u) Locate some proxy for the given URL.
protected org.w3c.www.protocol.http.micp.ReplyWaiter	lookupWaiter(int id)
Reply	outgoingFilter(Request request, Reply reply) Our outgoingFilter does nothing (at all).
boolean	propertyChanged(java.lang.String name) The callback method, invoked when any property change occurs.
protected void	removeWaiter(org.w3c.www.protocol.http.micp.ReplyWaiter w)
void	run()
void	sync() This filter doesn't maintain dynamic state.
java.net.URL	waitOn(int id) Wait for the reply on this reqiest identifier.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

STATE_HOW

public static final java.lang.String STATE_HOW

State - To mark requests that have been redirected. This state is set to the URL of the proxy that has been used to run the request, if any.

See Also:

Constant Field Values

DEBUG_P

public static final java.lang.String DEBUG_P

Properties - Our debug flag.

See Also:

Constant Field Values

ADDRESS_P

public static final java.lang.String ADDRESS_P

Properties - Our multicast group address.

See Also:

Constant Field Values

PORT_P

public static final java.lang.String PORT_P

Properties - Our own UDP port number.

See Also:

Constant Field Values

TIMEOUT_P

public static final java.lang.String TIMEOUT_P

Properties - Our default timeout value.

See Also:

Constant Field Values

DISABLE_CACHE_P

public static final java.lang.String DISABLE_CACHE_P

Properties - disable caching when fetching from a neighbour proxy.

See Also:

Constant Field Values

PROXY_P

public static final java.lang.String PROXY_P

Properties - location of proxy to redirect to (if success)

See Also:

Constant Field Values

props

protected ObservableProperties props

The properties we are initialized from.

cache

protected CacheFilter cache

The CacheFilter we are working for.

timeoutValue

protected long timeoutValue

Our default timeout value for waiting for replies (in ms).

debug

protected boolean debug

Our we in debug mode ?

disableCache

protected boolean disableCache

Should we disablecaching when fetching through a proxy ?

waiters

protected java.util.Vector waiters

Queue of threads waiting for some replies.

addr

protected java.net.InetAddress addr

Our multicast group address.

localproxy

protected byte[] localproxy

Our local proxy address, in a byte array.

localsrc

protected long localsrc

Our local internet address, as a long.

localaddr

protected byte[] localaddr

Our local internet address as a byte array.

socket

protected java.net.MulticastSocket socket

Our socket to the group.

ttl

protected int ttl

Our TTL for writing packets.

Constructor Detail

MICPFilter

public MICPFilter()

Method Detail

lookupWaiter

protected final org.w3c.www.protocol.http.micp.ReplyWaiter lookupWaiter(int id)

removeWaiter

protected final void removeWaiter(org.w3c.www.protocol.http.micp.ReplyWaiter w)

addWaiter

protected final org.w3c.www.protocol.http.micp.ReplyWaiter addWaiter(int id)

waitOn

public java.net.URL waitOn(int id)

Wait for the reply on this reqiest identifier. Don't wait for more than the timeout value.

Returns:

The replied URL if any, or null.

handle

protected void handle(byte[] buf,
                      int len)
               throws java.io.IOException

Parse and handle the given MICP packet. This method does not use (currently) the reader/writer. The point is that on queries, it tries to reuse the receive buffer for output (which allows to handle queries without nearly zero allocations).

Parameters:

buf - The packet.

len - Total length of packet.

Throws:

java.io.IOException

locateProxy

protected int locateProxy(java.net.URL u)
                   throws java.io.IOException

Locate some proxy for the given URL. Synchronizing this method allows to reuse the emit buffer (kind of nice), and anyway, there will be a synchronized point when writting to the network (see, I am not convinced)

Parameters:

u - The URL to locate.

Returns:

An integer reply identifier to wait on for the reply.

Throws:

java.io.IOException - If the multicast group wasn't available.

propertyChanged

public boolean propertyChanged(java.lang.String name)

Description copied from interface: PropertyMonitoring

The callback method, invoked when any property change occurs.

Specified by:

propertyChanged in interface PropertyMonitoring

Parameters:

name - The name of the property that changed.

Returns:

A boolean, if true, accept the new property value, otherwise, reject it and reset the property to its old value.

exceptionFilter

public boolean exceptionFilter(Request request,
                               HttpException ex)

This filter doesn't handle exceptions.

Specified by:

exceptionFilter in interface RequestFilter

Parameters:

request - The request that triggered the exception.

ex - The triggered exception.

Returns:

Always false.

ingoingFilter

public Reply ingoingFilter(Request request)

Our ingoingFilter method. This method emits (only for GET requestst currently) an ICP query to all our neighbors, and wait for either one of them to reply with a hit, or, our timeout value to expire.

If a hit reply is received, we then use the corresponding proxy to fullfill the request.

Specified by:

ingoingFilter in interface RequestFilter

Parameters:

request - The request that is about to be emitted.

Returns:

Always null.

outgoingFilter

public Reply outgoingFilter(Request request,
                            Reply reply)

Our outgoingFilter does nothing (at all).

Specified by:

outgoingFilter in interface RequestFilter

Parameters:

request - The request that has been processed.

reply - The original reply (from origin server)

Returns:

Always null.

sync

public void sync()

This filter doesn't maintain dynamic state.

Specified by:

sync in interface RequestFilter

run

public void run()

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

initialize

public void initialize(HttpManager manager)
                throws PropRequestFilterException

Initialize the ICP filter. This is where we parse the configuration file in order to know about our neighbors. We then register ourself to the HTTP manager.

Specified by:

initialize in interface PropRequestFilter

Parameters:

manager - The HTTP manager.

Throws:

PropRequestFilterException - If the filter cannot launch its server part (listening for incomming ICP requests)