Distributed Collaborations Using Network Mobile Agents Anand Tripathi, Tanvir Ahmed, Vineet Kakani and Shremattie Jaman Department of computer science University of Minnesota, Minneaplis MN 55455

Anand Tripathi Professor Department of Computer Science & Engineering University of Minnesota Minneapolis MN Program Chair for IEEE 20th Symposium on Reliable Distributed Systems (SRDS 2001) October 2001 IEEE 20th Symposium on Reliable Distributed Systems (SRDS 2001)

Content Introduction Overview of the Approach Description of a Collaboration Plan Collaboration Using Network Agents Related Work Conclusion Feature Work

Introduction Focus On: Building Distributed Collaborations Using Mobile Agent Distributed Collaborations: *a number of physically distributed users *cooperate on some common tasks *share an environment composed of objects Mobile Agents: *an object capable of migrating autonomously *perform tasks on behalf of a user

Introduction Motivations: *ensure members participate only by using prescribed protocols *can execute remote coordination operations *be shared objects in workflow system *migrating the user’s agent instead of moving the user physically

Introduction Contributions: *develop a methodology for building a distributed collaboration environment with *specifying a collaboration plan using XML then *interfacing such a specification with a mobile agent based middleware Important features: *designers need to specify only the XML plan without *being concerned about the management of the mobile coordination agents and *the security issues

Approach Design Steps First Step: *using DTD for defining roles, shared objects, and operations associated with a collaborative task *providing rules for associating privileges with roles, and coordination actions with operations

Elements Participant Roles: a set of responsibilities and tasks for a participant towards the goal of the collaborative activity. Shared Objects: a collaborative activity whose operations are executed by the participants based on their roles. Privileges: the security policies in a collaboration that are based on the participants’ roles. Coordination Operations: actions to be executed when a certain task is required in the collaboration.

Approach Design Steps Second Step: *using XML for specifying the collaboration plan, in conformance with the rules given by the DTD. *the convener is responsible for preparing this specification.

Approach Design Steps Third Step: * realizing a distributed collaboration using mobile agents.

Approach Design Steps Third Step: realizing a distributed collaboration using mobile agents. UCI: User Coordination Interface UCI is constructed as a collection of mobile agents obtained from the convener. When a certain task is executed, UCI dispatches agents to other UCIs, also it receives and executes agents come from other UCIs.

Approach Design Steps Third Step: * realizing a distributed collaboration using mobile agents.

Example: A Collaborative Authoring System Task: writing, reviewing, and editing different parts of the document Three roles: author, editor, and reviewer Shared objects: the chapter’s contents, the reviewer’s comment and the editor’s comment. Coordination operations: 1.At chapter level 2.At reviewer level 3.At editor level

*XML is a project of the World Wide Web Consortium (W3C), and the development of the specification is being supervised by their XML Working Group. A Special Interest Group of co-operation contributors and experts from various fields contributed comments and reviews by .World Wide Web Consortium (W3C) *XML is a public format: it is not a proprietary development of any company. The v1.0 specification was accepted by the W3C as Recommendation on Feb 10, 1998.The v1.0 specification About XML (eXtensible Markup Language)

Features of XML XML is –Extensible introduce your own tags –Portable DTD (Document Type Definition) –Structured Need to follow the grammar specified in DTD –Descriptive. The elements are free to describe the meaning of what they contain

About DTD (Document Type Descriptor) DTD is a set of rules that defines what tags appear in a XML document DTDs are used to describe the structure of XML document. a DTD can be considered as a database schema (schema of object-oriented or object-relational databases) if a XML document is considered as a database.

Some Symbol in DTD <!DOCTYPE : declaration of the document type [ : marks the start of the DTD <!ELEMENT : define tag and its relation with other tags (elements) <!ATTLIST : attribute of a element +, *, ?, | : symbols represent the elements allowed +, elements must be used one or more times *, elements is optional and can be used multiple times ?, optional but if use, only use once |, use either elements but not both #PCDATA : insert text ]> : end of DTD

Description of a Collaboration plan

An Example of Collaboration Plan Specification

About Ajanta Ajanta is a Java-based system for programming mobile agents in distributed system. The Ajanta system provides facilities to build customizable servers to host mobile agents, and a set of primitives for the creation and management of agents. Support for security is an integral part of the Ajanta system.

About Ajanta--Main Component Agent Agent-server Name-registry

Ajanta’s Main Component --Agent It implements the generic functionality of a mobile agent. It can request various from its local host. It can request migration to another host. It supports the concept of itineraries.

Ajanta’s Main Component --AgentServer It provides the generic functionality to host agents. It creates protected domains for their execution. It transfers agents from one server to another. It respond to various agent control functions.

Ajanta’s Main Component --Name Registry The server maintains a domain registry, which is a simple database that keeps track of the agents currently executing on it.

Implementation of the Collaborative Authoring System Each user performs his tasks in the collaboration through the UCI In this paper the approach is to implement a UCI by extending Ajanta’ AgentServer class. Programmers can extend AgentServer class by writing a subclass of AgentServer

Implementation of the Collaborative Authoring System Each user performs his tasks in the collaboration through the UCI In this paper the approach is to implement a UCI by extending Ajanta’ AgentServer class. Programmers can extend AgentServer class by writing a subclass of AgentServer

Implementation of the Collaborative Authoring System The Structure of a UCI: A document manager object: It reads the XML plan; It maintains the shared object space; Its interface enables the user and the visiting agents to process any part of a document User interface object: It is implemented as a collection of mobile agents; Through the user interface, operation of the document manager are executed

Implementation of the Collaborative Authoring System

Related Work Mobile agent system Computer-supported collaborative work Coordination specification Workflow management Role-based security

Conclusion The main contribution of this paper is in developing a methodology for building a distributed collaboration system using a high level specification in XML, and then interfacing this specification with a mobile agent based middleware to realize the desired system.

Future Work Developing a general application level exception handling model Developing a more general collaboration specification in XML

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