/* * ** Network and Service Differentiation Extensions to GridSim 3.0 ** * * Gokul Poduval & Chen-Khong Tham * Computer Communication Networks (CCN) Lab * Dept of Electrical & Computer Engineering * National University of Singapore * August 2004 * * Licence: GPL - http://www.gnu.org/copyleft/gpl.html * * Router.java - Simulates a network router * */package gridsim.net;import eduni.simjava.*;import gridsim.*;import gridsim.util.SimReport;import java.util.*;/** * This class implements a Router which forwards data from one entity to * another. * <p> * This abstract class only contains abstract methods to connect other * routers and hosts. In addition, common functionalities are available * in this class for its children classes to use. * However, this class does not provide methods on how to setup forwarding * tables, so the design of that is left to the user if he/she wants to * create a Router with some specific routing algorithm. * <p> * Few important notes to consider when extending from this class: * <ul> * <li>do not override {@link #body()} method as *     it contains code/functionality to register this entity to *     {@link gridsim.GridInformationService} entity, and finalizing *     logging information before exiting the simulation. * <li>must overridden {@link #advertiseHosts()} method. It is *     needed for advertising all hosts or *     entities connected to this entity to adjacent routers. * <li>{@link #registerOtherEntity()} method : for registering other *     event type/tag to {@link gridsim.GridInformationService}. *     This is optional. * <li>must overridden {@link #processEvent(Sim_event)} method. *     It is needed for processing incoming events. * <li>do not forget to implement logging or recording functionalities *     for incoming and outgoing packets. <br> *     {@link gridsim.util.SimReport} object is created in this class, *     hence, you only need to use {@link #write(String)} method. * </ul> * * @invariant $none * @since GridSim Toolkit 3.1 * @author Gokul Poduval & Chen-Khong Tham, National University of Singapore */public abstract class Router extends Sim_entity{    /** An attribute that logs incoming and outgoing packets into a file.     * Use {@link #write(String)} to log or record the information.     */    protected SimReport reportWriter_;    /** Denotes a time delay (in second) for sending events in the future. */    protected static int DELAY = 2;  // in seconds    /**     *Creates a new RIPRouter object. By default, <b>no recording or logging</b>     * is done for packets' activities. If you want to log operations of this     * entity, please use {@link #Router(String, boolean)}.     *     * @param name Name of this router     * @throws NullPointerException This happens when name is empty or null     * @see #Router(String, boolean)     * @pre name != null     * @post $none     */    public Router(String name) throws NullPointerException    {        super(name);        reportWriter_ = null;    }    /**     * Creates a new Router object with logging facility if it is turned on.     * <br>     * NOTE: If logging facility is turned on, there are some overheads     * in terms of performance and memory consumption.     *     * @param name      Name of this router     * @param trace     <tt>true</tt> if you want to record this router's     *                  activity, <tt>false</tt> otherwise     * @throws NullPointerException This happens when name is empty or null     * @pre name != null     * @post $none     */    public Router(String name, boolean trace) throws NullPointerException    {        super(name);        try        {            if (trace == true) {                reportWriter_ = new SimReport(name + "_report");            }            else {                reportWriter_ = null;            }        }        catch (Exception e)        {            System.out.println(name + "(): Exception error.");            System.out.println( e.getMessage() );            reportWriter_ = null;        }    }    /**     * Joins two routers with a Link.     *     * @param router    The router on the other side to which this one will     *                  be attached.     * @param link      This is the link that will be used to connect the two     *                  routers.     * @param thisSched The scheduling policy used on this routers egress port     *                  when sending data through it.     * @param otherSched    The scheduling policy that will be used on the     *                      egress port of the router being connected to when     *                      sending data to this router.     * @pre router != null     * @pre link != null     * @pre thisSched != null     * @pre otherSched != null     * @post $none     */    public abstract void attachRouter(Router router, Link link,                PacketScheduler thisSched, PacketScheduler otherSched);    /**     * Joins two routers together. This is called by the routers themselves     * and should not be called by other entities.     *     * @param router    The Router to which this router will be connected.     * @param link      The Link that will be used to join these routers.     * @param sched     The scheduling policy used on the egress port of the     *                  router when sending data through this route.     * @pre router != null     * @pre link != null     * @pre sched != null     * @post $none     */    public abstract void attachRouter(Router router, Link link,                PacketScheduler sched);    /**     * Attaches an entity to this router. The link between the router and the     * entity being attached is taken from     * {@link gridsim.GridSimCore#getLink()}.     *     * @param entity    The entity to be attached.     * @param sched     The scheduling policy that will be used on the egress     *                  port when the router sends data to the entity being     *                  joined.     * @see gridsim.GridSimCore#getLink()     * @pre entity != null     * @pre sched != null     * @post $none     */    public abstract void attachHost(GridSimCore entity, PacketScheduler sched);    /**     * Returns the Scheduler associated with a packet. Each packet has a     * destination. The router returns the scheduler that it would use to     * scheduler this packet if it were traversing this router. Once a     * reference to the scheduler is obtained, different parameters     * (like priorities, weights etc.) could be modified.     *     * @param np    NetPacket for which the associated scheduler is to be     *              returned. This can be used to set weigths, priorities, etc.     *              as the case may be on the Scheduler.     * @return the packet's scheduler     * @pre np != null     * @post $none     */    public abstract PacketScheduler getScheduler(Packet np);    /**     * Returns the Scheduler that the router would use to reach a particular     * destination. Once a reference to the scheduler is obtained, different     * parameters (like priorities, weights etc.) could be modified.     *     * @param dest  id of the destination for which the Scheduler is required.     * @return the packet's scheduler     * @pre dest > 0     * @post $none     */    public abstract PacketScheduler getScheduler(int dest);    /**     * Returns the Scheduler that the router would use to reach a particular     * destination. This can be used to set weigths, priorities etc. as the     * case may be on the Scheduler     *     * @param dest Name of the destination for which the Scheduler is required.     * @return the packet's scheduler     * @pre dest != null     * @post $none     */    public abstract PacketScheduler getScheduler(String dest);    /**     * This method prints out the forwarding table of the router in a human     * readable form.     * @pre $none     * @post $none     */    public abstract void printRoutingTable();    /**     * Handles incoming requests. <b>DO NOT</b> overrides this method as     * it contains code/functionality to register this entity to     * {@link gridsim.GridInformationService} entity, and finalizing     * logging information before exiting the simulation.     * <p>     * This method also calls these methods in the following order:     * <ol>     * <li>must overridden {@link #advertiseHosts()} method. It is     *     needed for advertising all hosts or     *     entities connected to this entity to adjacent routers.     * <li> {@link #registerOtherEntity()} method : for registering other     *      event type/tag to {@link gridsim.GridInformationService}.     *      This is optional.     * <li>must overridden {@link #processEvent(Sim_event)} method.     *     It is needed for processing incoming events.     * </ol>     *     * @pre $none     * @post $none     */    public void body()    {        //register oneself        write("register this entity to GridInformationService entity.");        super.sim_schedule(GridSim.getGridInfoServiceEntityId(),                GridSimTags.SCHEDULE_NOW, GridSimTags.REGISTER_ROUTER,                new Integer(super.get_id()) );        // methods to be overriden by children classes        advertiseHosts();        registerOtherEntity();        // Process incoming events        Sim_event ev = new Sim_event();        while ( Sim_system.running() )        {            //Sim_event ev = new Sim_event();            super.sim_get_next(ev);            // if the simulation finishes then exit the loop            if (ev.get_tag() == GridSimTags.END_OF_SIMULATION)            {                write("receives, END_OF_SIMULATION, signal, from, " +                      GridSim.getEntityName(ev.get_src()) );                processEndSimulation();                break;            }            // process the received event            processEvent(ev);        }        // finalize logging before exiting        if (reportWriter_ != null) {            reportWriter_.finalWrite();        }    }    /**     * All hosts connected to this router are advertised to adjacent routers     * @pre $none     * @post $none     */    protected abstract void advertiseHosts();    /**     * Overrides this method when creating a new type of router.     * This method is called by {@link #body()} for incoming unknown tags.     * <p>     * The services or tags available for this resource are:     * <ul>     * <li> {@link gridsim.GridSimTags#PKT_FORWARD}     * <li> {@link gridsim.GridSimTags#JUNK_PKT}     * <li> {@link gridsim.GridSimTags#ROUTER_AD}     * </ul>     *     * @param ev   a Sim_event object     * @pre ev != null     * @post $none     */    protected abstract void processEvent(Sim_event ev);    /**     * Overrides this method when making a type of router.     * This method is called by {@link #body()} to register other type to     * {@link gridsim.GridInformationService} entity. In doing so, you     * need to create a new child class extending from     * {@link gridsim.GridInformationService}.     * <br>     * <b>NOTE:</b> You do not need to override {@link #body()} method, if     * you use this method.     *     * @pre $none     * @post $none     * @see gridsim.GridInformationService     */    protected void registerOtherEntity() {        // ... empty    }    /**     * Writes a debug information to a file.     * The format of information is left to the coder.     *     * @param str  a string message     * @pre str != null     * @post $none     */    protected void write(String str)    {        if (reportWriter_ != null) {            reportWriter_.write(str);        }    }    /**     * Informs the registered entities regarding to the end of a simulation.     * @pre $none     * @post $none     */    protected abstract void processEndSimulation();} // end class