Suman's PhD Candidacy Talk

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Ubiquitous Communication Model for Different Network Scenarios

Suman SrinivasanPhD Candidacy TalkFeb 23, 2009Advisor: Dr. Henning Schulzrinne

Introduction

Many different types of networks and connection scenarios exist

I will cover the following Traditional networking ←→ Sockets Remote execution ←→ RPC, RMI, CORBA Parallel computing ←→ MPI, PVM, Shared memory Grid computing ←→ Javaspaces, Linda Web services ←→ XML-RPC, SOAP, REST Overlay networks ←→ DHTs, Bittorrent, JXTA Opportunistic networks ←→ BonAHA, LightPeers, etc Active Networks ←→ ANTS, Janos, etc.

… mainly from the programmer’s perspective … and try to answer the following question Is there a common communication model, or

programming abstraction, for all of the above scenarios?

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Comparison metrics

API for programmers e.g., send/recv (or) find/get/set (or) remote

procedures Distribution of messages

1-to-1, 1-to-N Processing location

Where processed: node, network (router) Delay Destination known? Message functionality

Active (execution) or passive (data)

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Evaluation metricsAPI model

Dist Location Delay Dest IP known

Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N

Endpoints /Endpoints + routers

Network Yes Passive

Remote execution

RPC 1-to-1 Remote node

Network + processing

Yes Passive (func+args)

Parallel computing

Message; Process

1-to-N Endpoints (clustered)

Network/bus No Passive

Grid computing

Message (active obj.)

1-to-N Endpoints (distributed)


No Active

Web services

RPC; get/set 1-to-1 Remote node


Yes Passive (XML cmds)

Overlay find/get/set/rm

1-to-N (DHT)

Endpoints (overlay)

Setup time + query process + churn

No Passive

Opportunistic networks

find/get/set/rm

1-to-N Endpoints Delay on wire/wireless

No Passive

Active Networks

Routing 1-to-N (router)

Routers Processing time

No Active

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Stack diagram

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Sockets

Multicast DHTs (and) Overlay N/Ws

XML over HTTP

XML-RPC

Parallel computing

RESTSOAP

Shared mem.

PVMMPI RPC

Opportunistic N/Ws

Grid computing

JXTA/Jini

Type of API

Send/Recv (or) Read/Write Sockets, Parallel computing (MPI), Grid

computing (Javaspaces, Linda) Remote Procedures

Remote execution (RPC, RMI, CORBA), Web services (SOAP, XML-RPC)

Get/Set Web services (REST), Overlay networks (DHTs),

Opportunistic networks Process execution

Parallel computing (PVM)

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END-TO-END NETWORKING

Sockets: Simple, end-to-end communicationsocket()connect() / listen()send() / recv()close()

[RFC147] and [RFC2553]



Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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REMOTE EXECUTIONLocal function calls

Executed on remote machineResults returned to caller over

networkCommunication using sockets

TechnologiesRemote Procedure CallsRemote Method InvocationOMG CORBA

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http://msdn.microsoft.com/en-us/library/aa373935.aspx

RPC

Remote Procedure Call RFC 707 (1976): A High-Level

Framework for Network-Based Resource Sharing

“… outlines an alternative to the approach that ARPANET system builders have been taking...”

Argues that the "command/response discipline" remains "crude“

[rfc707]

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RPC

Early versions Xerox Courier (1981), Sun's ONC RPC

(1988, 1995) Microsoft provides RPC APIs

DCOM (1996) built on top of Microsoft RPC Other implementations for Windows

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RPC and RMI

Sun’s RPC Data serialized using IETF XDR format,

via TCP or UDP Port mapper

Maps RPC program numbers to port numbers on server

[RFC1057] and [RFC1831] Java RMI [javarmi]

Very similar to RPC, can work over CORBA

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OMG CORBA

Common Object Requesting Broker Architecture

Interface Definition Language (IDL) to specify interfaces Program communicates with ORB

(Object Request Broker), which interacts with other apps on network

Transport protocol: General Inter-ORB protocol (GIOP): IIOP, SSLIOP, HTIOP

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OMG CORBA

http://en.wikipedia.org/wiki/CORBA 14



Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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PARALLEL COMPUTING

Deals with execution or sharing of data across multiple processors

Tightly coupled, physically close nodesMessage Passing Interface (MPI)Parallel Virtual Machine (PVM)Shared memory

https://computing.llnl.gov/tutorials/parallel_comp/

MPI and PVM

Message Passing Interface [mpi96] Language independent communications

protocol Communicators connect groups of processes mpi_send() and mpi_recv() Parallel Virtual Machine [pvm90] Software library: allows network of

computers to work as though it were one distributed parallel processor

pvm_spawn() and pvm_notify()

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Shared Memory Model

Memory that can be accessed by multiple programs On same processor or multiple

processors OpenMP: API using preprocessor

directives1. #pragma omp parallel for

2. for (i=0;i<N;i++)

3. a[i]= 2*I;

[sharedmem07]

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Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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GRID COMPUTINGSeveral nodes working on the same

problem at the same timeProgram divided into portionsDistributed for processingMore loosely coupled, heterogeneous

and dispersed than parallel computingE.g.: Berkley’s BOINC, SETI@home,

Folding@homeJavaspaces

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Tuple Spaces

Stores distributed system state Javaspaces: Use Javaspace.write()

and Javaspace.read() to put and get objects and results Javaspaces modeled

after Linda (1985) Master-worker

pattern Tuple space

http://java.sun.com/developer/technicalArticles/tools/JavaSpaces/

[linda85] + [javaspaces]

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Javaspaces code

1. public static void main(String argv[]) {2. try {3. MessageEntry msg = new MessageEntry();4. msg.content = "Hello there";5. System.out.println("Searching for a JavaSpace...");6. Lookup finder = new Lookup(JavaSpace.class);7. JavaSpace space = (JavaSpace) finder.getService();8. 9. space.write(msg, null, 60*60*1000);10. MessageEntry template = new MessageEntry();11. 12. MessageEntry result = (MessageEntry) space.read(template, null,

Long.MAX_VALUE);13. System.out.println("The message read is: "+result.content);14. } catch(Exception e) {15. }16. }

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Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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WEB SERVICESRemote procedure callsBut using text, not binary

objectsOften using XML over

HTTPTo build distributed systems

over traditional web protocols (XML/HTTP) Web-based consumer apps Enterprise apps

XML-RPCSOAPREST

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http://developer.garmin.com/wp-content/uploads/2007/05/picture-5.png

Web Services

XML-RPC Simple protocol, created in 1998 Data types, commands

Example from: http://www.tutorialspoint.com/xml-rpc/xml_rpc_examples.htm Function call

<?xml version="1.0" encoding="ISO-8859-1"?> <methodCall> <methodName>sample.sum</methodName> <params> <param> <value><int>17</int></value> </param> <param> <value><int>13</int></value> </param> </params> </methodCall>

Response <?xml version="1.0" encoding="ISO-8859-1"?> <methodResponse> <params><param> <value><int>30</int></value> </param></params> </methodResponse>

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SOAP

Simple Object Access Protocol W3C standard

Uses XML for messages HTTP and HTTPS used for message

negotiation and transmission Can use SMTP as well But HTTP/HTTPS more preferred

SOAP slower than competing RPC technologies because of XML

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SOAP

<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Header> <n:alertcontrol xmlns:n="http://example.org/alertcontrol"> <n:priority>1</n:priority> <n:expires>2001-06-22T14:00:00-05:00</n:expires> </n:alertcontrol> </env:Header> <env:Body> <m:alert xmlns:m="http://example.org/alert"> <m:msg>Pick up Mary at school at 2pm</m:msg> </m:alert> </env:Body> </env:Envelope>

From http://www.w3.org/TR/soap12-part1/

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REST

Representational State Transfer 2000 PhD Thesis by Roy Fielding

Resources with a identifier Exchange representations of resources Connectors (clients, servers, caches,

tunnels) Instead of calling getData(1), you

would get content from a URN: http://somesite.com/data/1

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REST

From http://developer.yahoo.com/maps/rest/V1/geocode.html Call a “REST-like” service:

http://local.yahooapis.com/MapsService/V1/geocode?appid=YD-9G7bey8_JXxQP6rxl.fBFGgCdNjoDMACQA--&street=701+First+Ave&city=Sunnyvale&state=CA

Response from Yahoo: <?xml version="1.0" encoding="UTF-8"?> <ResultSet xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:yahoo:maps" xsi:schemaLocation="urn:yahoo:maps

http://local.yahooapis.com/MapsService/V1/GeocodeResponse.xsd"> <Result precision="address"> <Latitude>37.416384</Latitude>

<Longitude>-122.024853</Longitude> <Address>701 FIRST AVE</Address> <City>SUNNYVALE</City> <State>CA</State>

<Zip>94089-1019</Zip> <Country>US</Country> </Result> </ResultSet>

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Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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OVERLAY NETWORKSBuilt on top of always-connected

networks (and others) Form a sub-network with specific

functionality With routing protocol Distributed key-value pairs

Structured overlays Tapestry, CAN, Chord Constrained, structured graph topology Exact-match queries

Unstructured overlays Organized in random graph topology Keyword queries E.g.: Gnutella

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http://www.dynamicobjects.com/papers/w4spot.pdf

DHT service model

API Example: [OpenDHT] get(), put(), rm() Behind the scenes – [BambooDHT] Running on PlanetLab

Other DHTs use similar APIs Can be extended to usage outside of

DHTs as well

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DHTs

Well-known DHTs Chord [Chord01] CAN [Can01] Kademilia [Kademilia02] Pastry [Pastry01]

Partitioned keyspace Distributed amongst nodes Deals with churn

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Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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OPPORTUNISTIC NETWORKS

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Mobile nodes; highly mobile networksNo infrastructure

OLPC; mesh networksCan be used for ad-hoc, community

applicationsTraditional network apps have to be

adapted for oppnets[Opp06]

BonAHA

Framework for applications running on opportunistic networks

Updates on network serviceUpdated() serviceExited()

Node properties node.get() node.set() Node 2

Node 1

key21 = value21key22 = value22key23 = value23key24 = value24

key11 = value11key12 = value12key13 = value13key14 = value14

[2] node1.get(key13)

[1] node1.register()

[3] data = node1.fileGet( value13);

[bonaha09]

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Other OppNet Frameworks

For opportunistic and mobile networks Proem (2001) Peer2Me (2004)

File sharing on BlueTooth Market Contact Protocol (MCP) (2008)

Oppnet commerce LightPeers (2007)

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LightPeers

Similar model to BonAHA “Application”: Each application has its own GUID that

identifies it “Session”: A group of nodes registered as running the

application

Code1. Application app = new Application(appid);

2. lpconn = new Connection(app);

3. ses = lpconn.CreateSession();

4. List<Session> sessions = lpconn.GetSessionList();

[Lightpeers07]

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Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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ACTIVE NETWORKSAllows “injection” of customized active code

into network coreANTS, JanOS, Open Multi-Service Router,

Netscript, SwitchwareAll circa 1996-2001Why important?

Example of frameworks for executable/active code that change network operations

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ANTS (Active Node Transfer Sys)

New network protocolsautomatically deployedusing mobile code Packets are replaced by

capsules Capsules contain instructions with

executable code Routers (active nodes) execute code

[Ants98]

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Janos

Janos is a NodeOS (Moab) with: Execution Environment (EE) : similar to

virtual machine Active Applications (AA), which are

injected into the network Written to run on ANTSR runtime Which runs on

top of Janosvirtual machine

[Janos01]

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Switchware

Active packets, active extensions, active router infrastructure CAML-based Packets contain PLAN

(Programming Language for Active Networks) code

SANE (Secure Active Network Environment)

[Switchware98]

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Message function

End-to-end sockets

Message (send/recv)

1-to-1 / 1-to-N


Network Yes Passive

Remote execution




Parallel computing

Message; Process



Grid computing




No Active

Web services





1-to-N (DHT)

Endpoints (overlay)


No Passive


find/get/set/rm


No Passive

Active Networks



No Active

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Conclusion

Covered the following network topologies, and the associated programming models:

Traditional networking ←→ Sockets Remote execution ←→ RPC, RMI, CORBA Parallel computing ←→ MPI, PVM, Shared memory Grid computing ←→ Javaspaces, Linda Web services ←→ XML-RPC, SOAP, REST Overlay networks ←→ DHTs, Bittorrent, JXTA Opportunistic networks ←→ BonAHA, LightPeers, etc Active Networks ←→ ANTS, Janos, etc.

Question: Is there a common communication model, or abstraction for all of these scenarios?

Answer: Hard to see common ground Perhaps among some sub-groups, e.g., grid and

parallel computing, overlay and opportunistic networks

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Backup Slides

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RPC

http://msdn.microsoft.com/en-us/library/aa373937%28VS.85%29.aspx47

Java RMI command

java -cp /home/ann/src:/home/ann/public_html/classes/compute.jar -Djava.rmi.server.codebase=http://zaphod/~ann/classes/compute.jar -Djava.rmi.server.hostname=zaphod.east.sun.com -Djava.security.policy=server.policy engine.ComputeEngine

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MPI Sample code

1. int main(int argc, char *argv[])2. {3. MPI_Status stat; 4. 5. // Init6. MPI_Init(&argc,&argv); /* all MPI programs start with MPI_Init; all 'N' processes exist

thereafter */7. MPI_Comm_size(MPI_COMM_WORLD,&numprocs); /* find out how big the SPMD world is

*/8. MPI_Comm_rank(MPI_COMM_WORLD,&myid); /* and this processes' rank is */

9. // Send any number of processses 10. MPI_Send(buff, BUFSIZE, MPI_CHAR, i, TAG, MPI_COMM_WORLD);

11. // Receive data12. MPI_Recv(buff, BUFSIZE, MPI_CHAR, i, TAG, MPI_COMM_WORLD, &stat);13. 14. // Weak synchronization15. MPI_Finalize(); 16. }

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PVM sample code

1. int main(int argc, char* argv[])2. {3. mytid = pvm_mytid(); /* find out my task id number */4. /* find my parent's task id number */5. myparent = pvm_parent();6. /* if i don't have a parent then i am the parent */7. if (myparent == PvmNoParent) {8. info = pvm_spawn(argv[0], (char**)0, PvmTaskDebug, (char*)0,9. ntask, child);10. /* wait for the notification */11. info = pvm_recv(-1, TASKDIED);12. pvm_exit();13. return 0;14. }15. /* i'm a child */16. pvm_exit();17. return 0;18. }

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ANTS example

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Netscript

Agents dispatched to remote systems Uses SOS to manage

delegation agents Virtual Network

Engines (VNE) interconnected by Virtual Links (VL) Packet arrives at VNE; headers used to

pass it on executing agent [Netscript96]

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JXTA

Framework for building P2P apps Peers create a overlay network

Nodes identified by 160-bit SHA-1 URN Different protocols

Peer Resolver, Peer Information, Rendezvous, Peer Membership, Pipe Binding, Endpoint Routing

Peer types: Edge, Super, Rendezvous, Relay

[jxta]

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Technology

Suman's PhD Candidacy Talk