Package org.jcsp.net2

Class Link

  • All Implemented Interfaces:
    CSProcess
    Direct Known Subclasses:
    TCPIPLink
    public abstract class Link
extends Object
implements CSProcess
    Abstract class representing a Link. This class defines the two processes (Link TX, Link RX) where the network protocol is of key importance. Specific technology protocols (e.g. TCP/IP) must extend this class, providing the necessary streams for operation, and also overriding the methods connect, createResources and destroyResources, which will have specific implementations dependent on the underlying technology. Everything else should operate as defined in this class.
    Author:
    Kevin Chalmers
    See Also:
    NetworkProtocol

    • Field Detail

      • connected

        protected boolean connected
        A flag used to indicate whether the Link is connected or not. This flag is set normally during the connect operation, but may be done within the constructor. If not set during the constructor, and if connect is not called to set the flag to true, then when the process is run connect will be called.

      • rxStream

        protected DataInputStream rxStream
        The incoming stream for the connection. This must be created by the specific protocol implementation.

      • txStream

        protected DataOutputStream txStream
        The outgoing stream for the connection. This must be created by the specific protocol implementation.

      • remoteID

        protected NodeID remoteID
        The NodeID of the opposite end of the connection. This should be set either during construction, or during the connect method of a child class.

      • LINK_PRIORITY

        public static int LINK_PRIORITY
        Link priority in the system. This is a publicly accessible value that can be set by a user.

      • priority

        protected int priority
        Link priority for this Link. This is exposed to child classes to allow specific Link priorities for different Link types.

    • Constructor Detail

      • Link

        public Link()

    • Method Detail

      • getRemoteNodeID

        public final NodeID getRemoteNodeID()
        Returns the NodeID of the connected Link.
        Returns:
        NodeID of the connected Link.

      • getTxChannel

        protected final ChannelOutput getTxChannel()
        Gets the channel that is connected to the Link Tx process.
        Returns:
        The ChannelOutput used to communicate with the Link Tx.

      • connect

        public abstract boolean connect()
                         throws JCSPNetworkException
        Connects to the remote Node. This must be overridden by a child class implementation.
        Returns:
        True if the connection succeeds, false otherwise.
        Throws:
        JCSPNetworkException - Thrown if the connection fails.

      • createResources

        protected abstract boolean createResources()
                                    throws JCSPNetworkException
        Creates the resources (if any) required for the Node. These could be set up during construction, but if not, this method is called immediately after connect within the run method. Child implementations should override this method.
        Returns:
        True if resources were created OK, false otherwise.
        Throws:
        JCSPNetworkException - Thrown if a problem occurs creating the resources.

      • destroyResources

        protected abstract void destroyResources()
        Destroys any used resources. This is called whenever a Node fails. Particular implementations must overwrite this method.

      • registerLink

        public final boolean registerLink()
        Registers the Link with the LinkManager
        Returns:
        True if Link was registered, false otherwise.

      • lostLink

        protected final void lostLink()
        Marks the Link as lost within the LinkManager.

      • run

        public final void run()
        The run method for the process. This will connect the Link (if necessary) and then start the Tx and Rx Loops.
        Specified by:
        run in interface CSProcess