group communication service
Download
Skip this Video
Download Presentation
Group Communication Service

Loading in 2 Seconds...

play fullscreen
1 / 41

Group Communication Service - PowerPoint PPT Presentation


  • 250 Views
  • Uploaded on

Group Communication Service. by Abhijeet Dharmapurikar Jesse Greenwald Sapna Gumidyala Shashidhar Rampally Varsha Mahadevan. Introduction. What is a Group Communication Service? Why do we need a Group Communication Service? Sample Applications Data Replication Process Groups.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Group Communication Service' - Gideon


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
group communication service

Group Communication Service

by

Abhijeet Dharmapurikar

Jesse Greenwald

Sapna Gumidyala

Shashidhar Rampally

Varsha Mahadevan

introduction
Introduction
  • What is a Group Communication Service?
  • Why do we need a Group Communication Service?
  • Sample Applications
    • Data Replication
    • Process Groups
introduction contd
Introduction (contd)
  • Existing Group Communication Services
    • Java Groups
    • Spread
  • Configurable protocol stack used by Java Groups
  • Scope for utilization of application specific information
our group communication service
Our Group Communication Service
  • Using application specific information
    • Message Types
    • Message Patterns
  • Finding best-fit protocol stack for the above application
  • Optimization of number of messages
illustrative examples
Illustrative Examples
  • Tele-teaching Application
  • Card Game Application
tele teaching application
Tele-Teaching Application

<protocol>

<roles>

<role name="Student" min="1" max="n"/>

<role name="Teacher" min="1" max="1"/>

</roles>

<message-types>

<message-type name="Question"/>

<message-type name="Answer"/>

<message-type name="Formula"/>

<message-type name="Doubt"/>

<message-type name="TeacherAnswer"/>

</message-types>

. . .

</protocol>

tele teaching application contd
Tele-Teaching Application (contd)

<message-patterns>

<pattern>

<query type="Question" role="Teacher" receiver="Student"

min="1" max="1"/>

<response type="Answer" role="Student” receiver="Teacher"

min="0" max="#Student" timeout="60s"/>

</pattern>

<pattern>

<query type="Formula” min="1" max="1"/>

<response type="Doubt" min="0" max="#Student"

timeout="120s"/>

</pattern>

</message-patterns>

card game application
Card Game Application

<protocol>

<roles>

<role name="Player1" min="1" max="1"/>

<role name="Player2" min="1" max="1"/>

<role name="Player3" min="1" max="1"/>

<role name="Player4" min="1" max="1"/>

</roles>

<message-types>

<message-type name="Play"/>

</message-types>

. . .

</protocol>

card game application contd
Card Game Application (contd)

<message-patterns>

<pattern>

<message type="Play" role="Player1" min="1" max="1” receiver="Player1,Player2,Player3,Player4"/>

<message type="Play" role="Player2" min="1" max="1” receiver="Player1,Player2,Player3,Player4"/>

<message type="Play" role="Player3" min="1" max="1” receiver="Player1,Player2,Player3,Player4"/>

<message type="Play" role="Player4" min="1" max="1” receiver="Player1,Player2,Player3,Player4"/>

</pattern>

</message-patterns>

related concepts
Related Concepts
  • Proactive Messages
  • Reactive Messages
system design
System Design

Application Protocol

Group Membership Protocol

Correlation Protocol

Ordering Protocol

Filtering Protocol

Event Service

system design14
System Design

Application Protocol

Group Membership Protocol

Correlation Protocol

Ordering Protocol

Filtering Protocol

Event Service

corba
CORBA
  • Common Object Request Broker Arch.
  • Object Management Group (OMG)
  • Defines IDL Language
  • Defines the API for ORB
object services
Object Services
  • Name Service
  • Event Service
  • Notification Service
  • Time Service
  • Transaction Service
  • Persistent State Service
event service
Event Service

Supplier

Supplier

Supplier

Event Channel

Consumer

Consumer

push communication model
Push Communication Model

Push Supplier

Push Consumer

Initiative

I wish to decide when

the data is to be sent

Just call my method

whenever you have

data for me

DATA

pull communication model
Pull Communication Model

Pull Supplier

Pull Supplier

Initiative

I wish to decide when

to go for data

Just call my method

whenever you want data

DATA

system design20
System Design

Application Protocol

Group Membership Protocol

Correlation Protocol

Ordering Protocol

Filtering Protocol

Event Service

filtering protocol
Filtering Protocol
  • Filters based on
    • Message Type
    • Destination
  • Operates in two modes
    • JOIN_MODE
    • ONLINE_MODE
filtering protocol cond
Filtering Protocol cond..

JOIN_MODE:

 Allows only JOIN_GROUP messages

 Allows only UpdatedView messages

ONLINE_MODE:

 Allows all the messages

 Allows all messages except the

messages to which its not a destination.

system design23
System Design

Application Protocol

Group Membership Protocol

Correlation Protocol

Ordering Protocol

Filtering Protocol

Event Service

message format
struct Message

{

long messageId;

long source;

long destination;

string message;

char messageType;

boolean isProactive;

};

struct SequenceMessage

{

long messageId;

long source;

long destination;

long sequenceId;

};

Message Format
ordering protocol
Ordering Protocol
  • Sequencer based algorithm
    • Send broadcast message to all the members in the group and the sequencer
    • Sequencer assigns ids to these broadcast messages in a strictly increasing order
    • Member delivers the broadcast messages in the increasing order of sequencer ids
system design26
System Design

Application Protocol

Group Membership Protocol

Correlation Protocol

Ordering Protocol

Filtering Protocol

Event Service

correlation protocol
Correlation Protocol
  • Buffered ordering of reactive messages with respect to proactive messages
  • Tele-Teaching Example
    • Question (proactive message)
    • Answer (reactive message)
correlator
Correlator
  • Handles relationship between messages
  • Could be imagined as a smart tree-structured buffer
  • Patterns

X –Y5 - Z2

slide29

z

Y

z

z

Y

z

z

Y

X

z

z

Y

z

z

Y

z

system design30
System Design

Application Protocol

Group Membership Protocol

Correlation Protocol

Ordering Protocol

Filtering Protocol

Event Service

group membership roles
Group Membership Roles
  • Roles for the membership protocol
    • Groups Administrator
    • Group Manager
    • Member
  • Related Concept
    • View
membership message formats
struct JoinGroup

{

long member;

};

struct LeaveGroup

{

long member;

};

struct UpdateView

{

long messageId;

long source;

viewSeq view;

};

Membership Message Formats
group membership protocol
Group Membership Protocol

NM

M1

M2

M3

GManager

GM

GM

GM

GM

JoinGroup

UpdateView

UpdateView

UpdateView

Event Channel

configurable protocol stack 1
Configurable Protocol Stack (1)

DownQueue

UpHandler

DownHandler

Protocol 1

UpQueue

DownQueue

UpHandler

DownHandler

Protocol 2

UpQueue

optimizations
Optimizations
  • Save round trip to sequencer for reactive messages
    • Tele-Teaching example
    • Card Game example
  • Selective build of required layers in the protocol stack
group communication issues
Group Communication Issues
  • One channel per group concept
  • Atomicity of broadcast messages
  • Ordering of membership messages with respect to broadcast messages
    • Implicit notion of proactive membership messages
  • Support for uni-cast communication
conclusion
Conclusion
  • Possible extensions
    • Cross Group Communication
    • Fault-Tolerance issues
    • Group State Management
references
References
  • Lecture Notes
    • http://www.cis.ksu.edu/~singh/CIS825/F02/cis825.html
  • Java Groups
    • http://www.cs.cornell.edu/Info/Projects/JavaGroupsNew/
  • Event Service Specification
    • http://cgi.omg.org/docs/formal/01-03-01.pdf
ad