Compound Module OverlayChord

File: Overlay/Chord/OverlayChord.ned

Implementation of the Chord KBR overlay as described in "Chord: A Scalable Peer-to-Peer Lookup Protocol for Inetnet Applications" by I. Stoica et al. published in Transactions on Networking.

Author: Ingmar Baumgart, Markus Mauch

chord: Chord fingerTable: ChordFingerTable successorList: ChordSuccessorList

Usage diagram:

The following diagram shows usage relationships between modules, networks and channels. Unresolved module (and channel) types are missing from the diagram. Click here to see the full picture.

Contains the following modules:

If a module type shows up more than once, that means it has been defined in more than one NED file.

Chord

The main module of the Chord implementation

ChordFingerTable

This modul contains the finger table of the Chord implementation.

ChordSuccessorList

This modul contains the successor list of the Chord implementation.

Parameters:

Name Type Description
localPort numeric

UDP port for Chord messages

debugOutput bool

enable debug output

keyLength numeric

overlay key length in bits

measureNetwInitPhase bool

gather statistics when bootstrapping

drawOverlayTopology bool

draw arrow to successor node?

hopCountMax numeric

maximum number of overlay hops

lookupNumberNextHops numeric

number of next hops in each step

lookupParallelPaths numeric

number of parallel paths

lookupParallelRpcs numeric

number of nodes to ask in parallel

lookupSecure bool

true, if all nodes should be identified with a ping

lookupMerge bool

true, if parallel Rpc results should be merged

Gates:

Name Direction Description
from_udp input

gate from the UDP layer

to_udp output

gate to the UDP layer

from_app input

gate from the application

to_app output

gate to the application

Unassigned submodule parameters:

Name Type Description
chord.useCommonAPIforward bool

enable CommonAPI forward() calls

chord.useBaseLookup bool

use the base lookup class

chord.iterativeLookup bool

do iterative instead of recursive lookups

chord.successorListSize numeric

max number of successors in the SuccessorList

chord.joinRetry numeric

after joinRetry unsuccessful join requests, we fetch a need bootstrap node from the BootstrapOracle

chord.stabilizeRetry numeric

retries before a successor is considered failed

chord.joinDelay numeric

delay between join retries (sec)

chord.stabilizeDelay numeric

stabilize interval (sec)

chord.fixfingersDelay numeric

fix_fingers interval (sec)

chord.aggressiveJoinMode bool

use modified (faster) JOIN protocol

Source code:

module OverlayChord

    parameters:
        localPort : numeric,         // UDP port for Chord messages
        debugOutput : bool,          // enable debug output
        keyLength : numeric,         // overlay key length in bits
        measureNetwInitPhase: bool,  // gather statistics when bootstrapping
        drawOverlayTopology : bool,  // draw arrow to successor node?
        hopCountMax : numeric,       // maximum number of overlay hops

	lookupNumberNextHops : numeric, // number of next hops in each step
	lookupParallelPaths : numeric,  // number of parallel paths
	lookupParallelRpcs : numeric,   // number of nodes to ask in parallel
	lookupSecure : bool, // true, if all nodes should be identified with a ping
	lookupMerge : bool; // true, if parallel Rpc results should be merged

    gates:
        in: from_udp;	// gate from the UDP layer
        out: to_udp;    // gate to the UDP layer
	in: from_app;   // gate from the application
	out: to_app;	// gate to the application

    submodules:
        chord: Chord;
            parameters: 
                localPort = localPort,
    		debugOutput = debugOutput,
                keyLength = keyLength,
                measureNetwInitPhase = measureNetwInitPhase,
                drawOverlayTopology = drawOverlayTopology,
		hopCountMax = hopCountMax,
		lookupNumberNextHops = lookupNumberNextHops,
		lookupParallelPaths = lookupParallelPaths,
		lookupParallelRpcs = lookupParallelRpcs,
		lookupSecure = lookupSecure,
		lookupMerge = lookupMerge;
            display: "p=60,60;i=block/circle";

        fingerTable: ChordFingerTable;
            display: "p=150,60;i=block/table";
        successorList: ChordSuccessorList;
            display: "p=240,60;i=block/table";

        connections:
                from_udp --> chord.from_udp++;
                to_udp <-- chord.to_udp++;
                from_app --> chord.from_app;
                to_app <-- chord.to_app;
endmodule