Private:psim

This page documents the development of a discrete event simulator for P2P video streaming applications. This simulator captures important features of data-driven video streaming systems. In particular, it is designed to evaluate: (i) the performance of various segment scheduling algorithms; (ii) the potential of network coding in multi-layer P2P video streaming systems.

Class Diagrams

• use long for time/offset in msec, which has a rollover time 24.85 days

class Layer { // video layer, we divide each layer into fixed size blocks, we keep track of
                    // block size and no blocks here
    int layer; // layer number it belongs to, set to zero for nonscalable frame
    int blockSize; // blocks are fixed size, in bytes
    int noBlocks; // how many block here
    int dataSize; // aggregate size of all blocks
}

class Frame { // video frame, read from trace file
    int no; // serial number
    long deadlineOffset; // deadline offset compared to the start of the video, in msec
    int totalSize; // total frame size in bytes, including all layers
}

class Segment { // packetized frames
    int no; // serial number
    Vector<Frame> frames; // reference to included frame
    int totalSize; // aggregate size in bytes
    Hashtable<Integer, Layer> layers; // reference to layers of this frame, key is the layer id
    long getDeadline(); // returns the worst case deadline of this segment (first frame?)
}

class Video { // a media file, shared by a group of peers
    String filename; // video trace file path and name
    Hashtable<int, Frame> frameTrace; // frames read from the trace file
    Hashtable<int, Segment> segmentTrace; // segments generated by the prepareSegments(...)
    void prepareSegments(int noFrame); // packetize frames into segment, 
        // noFrame indicates how many frames should we put in one segment; 
        // we might implement other packtization schemes later.
}

Interface Node { // a network node, currently can be either a tracker or a peer
}
                        
class Tracker implement Node { // holds a set of groups/videos
    Vector<Group> groups; // all the video groups
    void addPeer(Group group, Peer peer); // insert a peer into a video group
}

class Peer implements Node { // represent a running peer
    int id; // sequential peer id
    int ingressBW; // incoming bandwidth in bps
    int egressBW; // outgoing bandwidth in bps
    Hashtable<Video, Vector<Connection>> senders; // peers that we may send requests to 
    Hashtable<Video, Vector<Connection>> receivers; // peers that we may send data to 
    Connection tracker; // control connection to the tracker
    Hashtable<Video, VideoBufMap> vBufMaps; // points to the video-level buffer map
    void join(Video vide); // the peer joins a group
    void leave(Video video); //the peer leaves the group
    //here we should call a scheduling algorithm to do the scheduling
    void start(Video video); // start downloading a video 
    void stop(Video video); // stop downloading
}

class Group { // peers that have downloaded or want to download a Video
    Video video; // media shared among peers
    Vector<Peer> peers; // peers in this group
    Vector<Peer> join(Peer peer); // adding a new peer into this group, and return a list of senders
    void leave(Peer peer); // removing a peer from this group
}

class Connection { // end to end network link between two peers
    Peer peer1; // one end
    Peer peer2; // the other
    long delay; // transmission delay in msec
    int e2eBW; // end-to-end bandwidth in bps
    int estimateRate; // estimated rate (maybe historical)
}

class VideoBufMap {
    Hashtable<Integer, SegBufMap> sBufMaps; // points to segment bufmap
}

class SegBufMap {
    Hashtable<Integer, LayerBufMap> lBufMaps; // points to layer bufmap
}

class LayerBufMap {
    boolean avail; // availability bit for this (video, segment, layer) tuple
    NCBuf ncBuf; // network coding structure
}

class NCBuf {
    boolean servCapibility; // Serving capability of each segment
                                      // show whether this segment is capable of serving other peers(applicable in NC)
    int noCodedBl; //  No. of encoded blocks for this (video,segment,layer)
    BufferedMatrix matrix; // coefficients and their corresponding encoded blocks up to now
}

class BufferedMatrix{ // save coefficients and their corresponding encoded blocks up to now
    Vector<Vector<Integer>> coef; // coefficients of the corresponding encoded blocks
    Vector <Integer>encodedValue; // encoded blocks
    Vector<Integer> decode(); // perform decoding process and return the original blocks of a segment
    void encode(); // perform encoding process on blocks of a segment
    
}

class SysParam{ // system parameters that can be changed in each iteration of the simulation
    float portionServ; // after receiving this portion of coded blocks out of total number of blocks, the segment is capable  
                                  of serving to others [in case of network coding]
    long skipSec; // time duration which is skipped from the current playback point for a new joined peer [in case of 
                            network coding]
    float portionEncoding; // a given peer peform encoding among this portion of encoded blocks out of the total coded
                                        blocks that has been received so far
                                    // blocks for encoding will be chosen randomly out of all received encoded blocks [in case of  
                                        network coding]
}
    
// XXX TODO XXX

class SlidingWindow{ // the sliding window which contains all the segments that the receiver is interested currently
                                  // set it to a fixed size, for example 1 minute of videos
                                    // the receiver first inform all its neighbors which part of the video it is interested currently,
                                    // then its neighbors will send their bitmap of that part to the receiver for scheduling
  int startOffset;         //the offset of the starting segment compared with the start of the video
  int endOffset;           // the offset of the ending segment compared with the start of the video
  double slidingWindowSize(); //get the size of the sliding window
}

class exchangeWindow{ // the exchange window is the front part of the sliding window. 
                                       //The unavailable segments in exchange window will be requested by the peer
                                       //usually we set it to a fixed size, for example, 10 seconds of video
                                       // the field of this class is similar to that of the SlidingWindow class
  int startOffset;
  int endOffset;
  void move();           // move the exchange window forward afte a scheduling period and do a next scheduling 
  double getSlidingWindowSize()
}

interface Scheduler{ // any class wants to do scheduling should implement this interface
  void schedule() throws simException; // the scheduling period is specified in the specific scheduling algorithm class
}

class resultItem{ //this class records a scheduling item
   int peerID;
   int segID;
   long startTime; //start time of the peer to transmit this segment
}

class SchedulingResult{                // this class is used to record scheduling results and do some statistics, 
                                                      // for example, calculate the average delivery rate
  Vector<resultItem> item;    // result item: <peerID, segID, startTime> (we may write this vector to a log file later)
  long runningTime;                  //running time of the algorithm
  long deliveryRatio;                 //Average delivery ratio

  double getDeliveryRatio();  //get the actual  average delivery ratio
  double getRunningTime(); //get the running time 
}

class SEFF implements Scheduler{ // the Serial Earliest Finish-time First scheduling algorithm
  SchedulingResult result;                 // create a schedulingResult object to store the result
  
  void schedule();                                   //implement the Scheduler interface
  void writeResult();  //write scheduling result to the result object of one scheduling period
                                                              //including calculating the average delivery ratio and running time
}

class LRF implements Scheduler{ // the Local Rarest First algorithm
  SchedulingResult result;                 // create a schedulingResult object to store the result
  
  void schedule();                                   //implement the Scheduler interface
  void writeResult();  //write scheduling result to the result object of one scheduling period
                                                              //including calculating the average delivery ratio and running time
}



class RndGen { // common random number/event generators, to deal with
                       // 1. event: add new receiver for a group/video
                       // 2. event: remove a receiver from a group/video
                       // 3. number: peer's bandwidth
}

class SimException {

}

Interface EventHandler {
    void handle() throws SimException; // callback function
}

class Event {
    long time; // when this event happens
    Node src; // which peer generates this event
    Node dst; // whom is destinate of this event 
    Vector<EventHandler> handlers; //process an event and update states accordingly
    int type; // enum, see below
    // 1. connectSent: peer 1 makes a connection to peer 2, and add each other into neighbors
    // 2. connectArrived: the connect message is received by the peer 2
    // 3. acceptSent: the potential sender reply with an accept message
    // 4. acceptArrived: the accept message arrives at the connection originator
    // 5. requestSent: a receiver sends a high-priority request message to a sender
    // 6. requestArrived: a request message gets to a sender
    // 7. dataSent: a sender sends a data segment
    // 8. dataArrived: a data segment arrives to a receiver
    // 9. joinSent: a join message to the tracker
    // 10. joinArrived: a join message reaches the tracker
    // 11. responseSent: a response message sent by the tracker
    // 12. responseArrived: a response message reaches the receiver
   
    // 13. scheduleStarted: a scheduling period started.
     //14. bimapSyncSent: the receiver inform all its neighbors what part of the video it is interested currently
                                           in order to get a small bitmap from them to do scheduleing, this message is sent
                                            when the receiver: jumps to view another part of the video or a new neighbor joins. 
     //15. bitmapSyncArrived: the sender receives the bitmap Synchronization information

    //commet: how should we do when a scheduling period expires? 
    //There are two situations: 1. all scheduled segments arrived; 2. some segments are still in transmission.

    void addHandler(Interface EventHandler); // add an additional event handler
    void rmvHandler(Interface EventHandler); // remove an additional event handler
}

class EventQueue {
    SortedMap<Long, Event> queue; // events sorted on its time
    void dispatch(Event event); // sequentially invoke even handlers 
}

class Simulator {
    long simTime; // elapsed simulation time in msec
    EventQueue events; // pending events that will be processed
    void dispatchEvent(); // forever loop to process the next event
}



Some comments:
*
  

Performance metrics for scheduling

Here are some performance metrics:

1. Average delivery ratio: number of on-time scheduled segments over total number of segments to be scheduled
2. Load balance among senders
3. Initial buffering time
4. Time and space complexity of the scheduling algorithm

How to install uml and svn tools in eclipse3.2.x

*. Install emul2
1. Go to http://www.soyatec.com/euml2/installation/, download its free edition. (Select the right version according to your eclipse)
2. Unpack the zip file
3. Open your eclipse, and go to Help -> Software Updates -> Find and install ... -> Search for new features to install -> New local site
     then find the unpakced file to install it.
4. How to use: after you create a new java project, go to File -> New -> Other, select the "UML2 Class Diagram" under the eUML directory,
    then you can create a class diagram for your project .


*. Install subclipse
1. Open your eclipse, and go to Help -> Software Updates -> Find and install ... -> Search for new features to install -> New  Remote Site
2. Add http://subclipse.tigris.org/update_1.4.x to the URL field and add an arbitrary name to the Name field
3. Follow the instruction to install it.
4. If you encounter an error like "Subclipse Integration for Mylyn 3.x (Optional) (3.0.0) requires plug-in "org.eclipse.mylyn.tasks.core (3.0.0)"
    don't worry, just deselect the "Integrations" item and continue to install.
5. Go to Window -> Preferences -> Team. If you can see SVN under the Team tab, congratulations, your installation is done. 
6. How to use: right click the project you want to commit, select Tean -> Share project -> SVN, input the URL of 
    your svn server, then you can import your project to it.