one.world.io
Class NetworkIO.Client

java.lang.Object
  |
  +--one.world.util.AbstractHandler
        |
        +--one.world.io.NetworkIO.Client

All Implemented Interfaces:

EventHandler, Serializable

Enclosing class:

NetworkIO

protected class NetworkIO.Client

extends AbstractHandler

A reliable network I/O client. Implements structured I/O over a TCP client socket, providing reliable, in-order delivery. Handles SimpleInputRequests and SimpleOutputRequests.

Network I/O clients generally should be obtained via a binding request to the environment's request handler.

Note that any exception on the underlying object stream or socket will cause the resource to be revoked.

Internal fields and methods are protected so that a subclass can access or override any method, for instance to build an encrypted network I/O client.

See Also:

SioResource, BindingRequest, Environment, Serialized Form

Inner Class Summary

protected class	NetworkIO.Client.Listener Listens for data arriving from the network.
protected class	NetworkIO.Client.RevokationHandler The revokation handler.

Field Summary

protected ObjectInputStream	inputStream The object input stream for receiving tuples.
protected boolean	isRevoked Indicates whether the resource has been revoked.
protected EventHandler	leaseHandler The lease manager to use for requesting leases.
protected Object	lock The lock object.
protected ObjectOutputStream	outputStream The object output stream for sending tuples.
protected EventHandler	requester The original requester of the resource.
protected SioResource	sioResource The SioResource (for debugging only).
protected Socket	socket The socket.

Constructor Summary

protected

NetworkIO.Client(EventHandler requester, SioResource sioResource, Socket socket, EventHandler leaseHandler, NestedConcurrencyDomain cDomain) Create a new reliable network channel using the specified socket, in the specified environment.

Method Summary

boolean	handle1(Event event) Handles SimpleInputRequest and SimpleOutputRequest events.
protected void	put(SimpleOutputRequest request) Handles a put request by writing the tuple to the network channel.
protected void	requestTermination() Request that the nested concurrency domain be revoked.
protected void	revoke() Revokes the network I/O client resource.
protected void	revoke1() Revokes the network I/O client resource.
protected void	terminate() Terminates the nested concurrency domain.
String	toString() Returns a string representation of this network I/O client.

Methods inherited from class one.world.util.AbstractHandler

handle, isNotValid, respond, respond, respond, respond, respond, respond

Methods inherited from class java.lang.Object

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

Field Detail

requester

protected EventHandler requester

The original requester of the resource.

sioResource

protected final SioResource sioResource

The SioResource (for debugging only).

leaseHandler

protected EventHandler leaseHandler

The lease manager to use for requesting leases.

socket

protected Socket socket

The socket.

outputStream

protected ObjectOutputStream outputStream

The object output stream for sending tuples.

inputStream

protected volatile ObjectInputStream inputStream

The object input stream for receiving tuples. We do NOT wrap this stream in a lock because it is only read from in the NetworkIO.Client.Listener thread. Furthermore, we must be able to interrupt this thread by closing the socket.

lock

protected Object lock

The lock object.

isRevoked

protected volatile boolean isRevoked

Indicates whether the resource has been revoked. This should only be set by the revoke() method, but subclasses may need to read it to decide whether the resource is active.

Constructor Detail

NetworkIO.Client

protected NetworkIO.Client(EventHandler requester,
                           SioResource sioResource,
                           Socket socket,
                           EventHandler leaseHandler,
                           NestedConcurrencyDomain cDomain)
                    throws IOException

Create a new reliable network channel using the specified socket, in the specified environment. A thread is created to listen on the socket.

Parameters:

requester - The source of the original resource request.

sioResource - The SIO resource descriptor.

socket - The TCP socket to use for the channel.

leaseHandler - The lease manager used to acquire leases.

cDomain - The nested concurrency domain for the client.

Throws:

IOException - Signals an error in configuring the socket or obtaining the I/O streams.

Method Detail

handle1

public boolean handle1(Event event)

Handles SimpleInputRequest and SimpleOutputRequest events. A SimpleOutputRequest results in the tuple being sent over the network channel. SimpleInputRequests will wait for results until the timeout expires.

Also handles LeaseEvent.CANCELED events by revoking the resource.

Overrides:

handle1 in class AbstractHandler

Parameters:

event - The event to handle.

put

protected void put(SimpleOutputRequest request)

Handles a put request by writing the tuple to the network channel.

An I/O exception indicates that the output stream, outputStream, has been closed. This is an abnormal condition. An error is logged and the resource is revoked.

Parameters:

request - The output request.

revoke

protected void revoke()

Revokes the network I/O client resource. Thread safe.

If the system is shutting down, actually revokes the resource. Otherwise, queues a RevokeEvent in the nested concurrency domain.

revoke1

protected void revoke1()

Revokes the network I/O client resource. Not thread safe; writes to and closes the socket without a lock. This method must be executed either from the nested concurrency domain thread or during system shutdown

Clean-up includes interrupting and nullifying the listener thread, and closing and nullifying the streams and socket. May be called repeatedly without ill effects.

requestTermination

protected void requestTermination()

Request that the nested concurrency domain be revoked. We do this using an event because we are currently running from the nested concurrency domain, and the termination must happen within the environment's concurrency domain to avoid deadlock.

terminate

protected void terminate()

Terminates the nested concurrency domain. This should run in the main environment's concurrency domain; i.e., outside the nested concurrency domain.

toString

public String toString()

Returns a string representation of this network I/O client.

Overrides:

toString in class Object