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Class w3c.www.protocol.http.icp.ICPFilter 

java.lang.Object
   |
   +----w3c.www.protocol.http.icp.ICPFilter
public class ICPFilter
extends Object
implements PropRequestFilter, PropertyMonitoring

Variable Index

o CONFIG_P
Properties - Our configuration file.
o debug
Our we in debug mode ?
o DEBUG_P
Properties - Our debug flag.
o DISABLE_CACHE_P
Properties - disable caching when fetching from a neighbour proxy.
o disableCache
Should we disablecaching when fetching through a proxy ?
o friends
Our senders, indexed by InetAddress.
o icp
Our ICP engine.
o PORT_P
Properties - Our own UDP port number.
o props
The properties we are initialized from.
o TIMEOUT_P
Properties - Our default timeout value.
o timeoutValue
Our default timeout value for waiting for replies (in ms).

Constructor Index

o ICPFilter()

Method Index

o createICPSender(String, int, String)
o exceptionFilter(Request, HttpException)
This filter doesn't handle exceptions.
o getSender(InetAddress, int)
Get the sender object for the given InetAddress instance.
o getSocket()
o ingoingFilter(Request)
Our ingoingFilter method.
o initialize(HttpManager)
Initialize the ICP filter.
o locateProxy(ICPReply)
Locate the HTTP service of the proxy that has emitted that reply.
o outgoingFilter(Request, Reply)
Our outgoingFilter does nothing (at all).
o parseConfiguration()
Parse the configuration file.
o propertyChanged(String)
o runQuery(ICPQuery)
Run the ICP query, and return the proxy we should go to.
o sendQuery(ICPQuery)
Send the given query to all our neighbors.
o sync()
This filter doesn't maintain dynamic state.

Variables

o DEBUG_P 
 public static final String DEBUG_P
Properties - Our debug flag.

o CONFIG_P 
 public static final String CONFIG_P
Properties - Our configuration file.

o PORT_P 
 public static final String PORT_P
Properties - Our own UDP port number.

o TIMEOUT_P 
 public static final String TIMEOUT_P
Properties - Our default timeout value.

o DISABLE_CACHE_P 
 public static final String DISABLE_CACHE_P
Properties - disable caching when fetching from a neighbour proxy.

o props 
 protected ObservableProperties props
The properties we are initialized from.

o icp 
 protected ICPReceiver icp
Our ICP engine.

o friends 
 protected Hashtable friends
Our senders, indexed by InetAddress.

o timeoutValue 
 protected long timeoutValue
Our default timeout value for waiting for replies (in ms).

o debug 
 protected boolean debug
Our we in debug mode ?

o disableCache 
 protected boolean disableCache
Should we disablecaching when fetching through a proxy ?

Constructors

o ICPFilter 
 public ICPFilter()

Methods

o propertyChanged 
 public boolean propertyChanged(String name)
o getSocket 
 protected DatagramSocket getSocket()
o createICPSender 
 protected void createICPSender(String host,
                                int dstport,
                                String http) throws UnknownHostException, MalformedURLException, SocketException
o parseConfiguration 
 protected void parseConfiguration()
Parse the configuration file.

o getSender 
 public ICPSender getSender(InetAddress addr,
                            int port)
Get the sender object for the given InetAddress instance.

Parameters:
addr - The InetAddress of the sender.
Returns:
An ICPSender instance, if available, null otherwise.
o locateProxy 
 protected URL locateProxy(ICPReply reply)
Locate the HTTP service of the proxy that has emitted that reply.

Parameters:
reply - The reply emitted by the host that alos host the HTTP service we are looking for.
Returns:
The URL of the proxy, or null if no matching proxy was found.
o sendQuery 
 protected int sendQuery(ICPQuery query)
Send the given query to all our neighbors.

Returns:
The number of times we emitted the query.
o runQuery 
 protected URL runQuery(ICPQuery query)
Run the ICP query, and return the proxy we should go to.

Parameters:
url - The URL we are looking for.
Returns:
The URL of the proxy we should go to for that URL, or null if none was found.
o exceptionFilter 
 public boolean exceptionFilter(Request request,
                                HttpException ex)
This filter doesn't handle exceptions.

Parameters:
request - The request that triggered the exception.
ex - The triggered exception.
Returns:
Always false.
o 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.

Parameters:
request - The request that is about to be emitted.
Returns:
Always null.
o outgoingFilter 
 public Reply outgoingFilter(Request request,
                             Reply reply)
Our outgoingFilter does nothing (at all).

Parameters:
request - The request that has been processed.
reply - The original reply (from origin server)
Returns:
Always null.
o sync 
 public void sync()
This filter doesn't maintain dynamic state.

o 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.

Parameters:
manager - The HTTP manager.
Throws: FilterInitException
If the filter cannot launch its server part (listening for incomming ICP requests) 
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