1 / 17

The Jgroup Project Alberto Montresor Ozalp Babaoglu

The Jgroup Project Alberto Montresor Ozalp Babaoglu University of Bologna - Italy Department of Computer Science. Introduction. What is Jgroup? A group communication toolkit developed at the University of Bologna Main characteristics: Partition-aware group membership Written in Java

brady-fry
Download Presentation

The Jgroup Project Alberto Montresor Ozalp Babaoglu

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Jgroup Project Alberto MontresorOzalp Babaoglu University of Bologna - ItalyDepartment of Computer Science

  2. Introduction • What is Jgroup? • A group communication toolkit developed at the University of Bologna • Main characteristics: • Partition-aware group membership • Written in Java • Tightly integrated with Java RMI • Partially integrated with Jini • Can be integrated with J2EE! • Please note: • Still a prototype: never reached the stability of other toolkits

  3. Brief History • 1997-1999 • Specification and implementation of the main Jgroup core Group Membership, View Synchrony, Merging Support • 2000 • Integration with Java RMI started • First contacts with Sun RMI group • 2001-2002 • Collaboration with Sun on a new RMI API and framework • (Partially) integrated in JDK 1.4 • Downloadble as separate module(Jeri project in Jini)

  4. The Object Group Paradigm • Object group: • A dynamic collection of server objects that cooperate in order to deliver some service and maintain shared state • Group method invocations: • Refer to the act of invoking a method on an object group • The method is executed by a certain number of servers in the object group, depending on the invocation semantics ObjectGroup Client Server Server Server

  5. Group Method Invocation (GMI) • Internal GMI • For “closed” communication among members of a group • Two types: • Synchronous: return value is an array • Asynchronous: returns void; values returned through callback • External GMI • For “open” communication originated from external clients • Two types: • Anycast: one member executes the invocation; useful for read operations • Multicast: all members execute the invocation; useful for write operations

  6. Synchronous Internal Invocations int[] values = group.getValue(); intgetValue() { // return value } Synchronous invocation S1 S2 S3

  7. Asynchronous Internal Invocations ValuesCB cb = new ValuesCB(); group.getValue(cb); public classValuesCBimplements Callback {void results(Object value){...} }\ intgetValue() { // return value } S1 S2 S3

  8. External invocations: example C1 S1 S2 S3 C2 Multicast invocation: table.bind(“name”, obj); Anycast invocation: table.lookup(“name”);

  9. View Synchrony • View Synchrony All servers that survive from one view to the same next view execute the same set of invocations in the original view • View synchrony does not admit executions like this: S1 S2 S3 S4

  10. Java RMI • Java RMI protocol:enables objects residing in different JVMs to communicate through remote method invocations Client Server method() return x Stub Server-sideRMI Runtime JVM1 JVM2 Network

  11. Extending Java RMI • RMI group at Javasoft designed Java RMI in order to be extensible • TheRemoteRef interface enables programmers to write their own references to remote objects on the client-side • Unfortunately,RemoteRefs were not sufficient • There was no possibility to modify the behavior of RMI on the server side Client Stub Server-side RMI Runtime Server RemoteRef

  12. Multicast RMI The Jgroup Approach (Previous Version) Client Server Server Statically generated – implements the remote interface Method dispatchers ClientProxy Server Proxy Server Proxy Server-side RMI Runtime Server-side RMI Runtime RMI Stub RMI Stub Fixed stub for server proxy

  13. Designing a New Java RMI API • Java Software Requesto 078: a new Java framework • Fully customizable, on both the client- and the server-side • Based on Dynamic Proxy Classes (JDK 1.3)(No need for static stub generators) • Two different versions: • One-to-one (remote method invocations) • Voted down in JSR-078 • Being included in the "Davis" release of Jini • One-to-many (group method invocations) • To be developed... • We partecipated in the Java software process

  14. Jini Extensible Remote Invocation (JERI) Client Server foo() bar() Dynamically Compiled Stub foo() bar() invoke() Dispatcher InvocationHandler dispatch() executeCall() ObjectEndpoint ServerEndpoint networkcommunication

  15. Jgroup with 1-to-1 Customizable RMI Client Server Server Customized InvocationHandlerand Dispatcher Jgroup ClientProxy Jgroup Server Proxy Jgroup Server Proxy Jgroup Multicast RMI

  16. Jgroup with 1-to-Many Customizable RMI Client Server Server Server Customized ObjectEndpoint and ServerEndpoint Jgroup ClientProxy Jgroup Server Proxy Jgroup Server Proxy Jgroup Server Proxy Multicast RMI

  17. Thank You! http://cs.unibo.it/projects/jgroup

More Related