1. Implementing Distributed Workflow Systems from XML Specifications
Vineet Kakani
Dept of Computer Science
University of Minnesota

2. Project Goals Specification of a generic workflow
Construction of workflow from high level specifications
Rapid construction of any workflow

3. Project Contributions
Use of XML for specifying the workflow entities
Design and Implementation of a generic distributed collaboration facility built using agents

4. Publications Distributed Collaborations using Network Mobile Agents
To appear in ASA/MA 2000
By Anand R Tripathi, Tanvir Ahmed, Vineet Kakani and Shremattie Jaman
Implementing Distributed Workflow Systems from XML Specifications
Submitted to CSCW 2000

5. Approach Overview Devising a XML schema Description of a Workflow Plan
Shared Objects
Roles
Privileges
Coordination Operations
Interfacing plan with generic coordination facility

6. Steps in building distributed Workflow
Environment
Schema
XML
Specification
of a
Plan
Agent based
Distributed
System
using Ajanta

7. Outline of Presentation
Workflow
definition
examples
XML schema and example of Workflow Plan using an authoring system
Design of an agent based middleware
Conclusions and Future work

8. Workflow What is workflow ? Examples Document Workflow
Internet Based Workflow

9. Document Workflow Book Authoring Feedback Reviewer 1 Book Reviewer 2
Editor
Feedback
Author

10. Internet based Workflow
Online Purchase
Inventory
Control
Item
Processing N 1
Assembling
Delivery
Process
Shipment Notice
Commodity Delivered
Order
Financial
Institute

11. Workflow Models Short Term Workflow Medium Term Workflow
Example - Online Shopping
Medium Term Workflow
Example - Project Proposal
Long Term Workflow
Example - House Loan

12. Example Authoring System

13. XML : Plan XML Specification for Workflow Plan and Role <PLAN>
5/17/2019
XML : Plan
<PLAN>
<ROLE ROLE_ID="doc:author"
ROLE_NAME="author"
OBJECT_REF="doc"
ROLE_INTERFACE="ajanta.UserInterface">
<PRINCIPAL URN="URN:ans:A"/>
</ROLE>
<ROLE ROLE_ID="doc:reviewer"
ROLE_NAME="reviewer"
<PRINCIPAL URN="URN:ans:B"/>
<PRINCIPAL URN="URN:ans:C"/>
</PLAN>
XML Specification for Workflow Plan and Role

14. XML : Object XML Specification for an Object <OBJECT OBJ_ID="doc"
OBJ_NAME="Document"
OBJ_TYPE="multipart/alternative">
<ACL/>
<STATUS/>
<OBJECT OBJ_ID="doc:ch1"
OBJ_NAME="Chapter1"
<OBJECT OBJ_ID="doc:ch1:content"
OBJ_NAME="Contents"
OBJ_TYPE="text/plain">
....
</OBJECT>
XML Specification for an Object

15. XML : Access Control XML Specification for Role Based Access Control
<ACL>
<ACL_ENTRY>
<GROUP ROLE_REF="doc:author"/>
<PERMISSION NAME="read"/>
<PERMISSION NAME="update"/>
</ACL_ENTRY>
<GROUP ROLE_REF="doc:reviewer"/>
<ACL_ENTRY TYPE="negative">
<PRINCIPAL URN="URN:ans:C"/>
</ACL>
XML Specification for Role Based Access Control

16. XML : Operation XML Specification for an Operation
<OPERATION OP_ID ="doc:ch1:con:publish"
OBJECT_REF="doc:ch1:content"
OPERATION_NAME="Content_Publish">
<ACL>
<ACL_ENTRY>
<GROUP ROLE_REF="doc:author"/>
<PERMISSION/>
</ACL_ENTRY>
</ACL>
<CLONE_OBJECT>
<TARGET ROLE_REF="doc:reviewer"/>
</CLONE_OBJECT>
</OPERATION>
XML Specification for an Operation

17. XML : Agent Action XML Specification for Agent Action
<OPERATION OP_ID="doc:status"
OBJECT_REF="status"
OPERATION_NAME="UpdateStatus">
<ACL/>
<AGENT_ACTION>
<TARGET ROLE_REF="doc:reviewer"/>
<REMOTE_METHOD
METHOD_NAME="updateOp"/>
</AGENT_ACTION>
</OPERATION>
XML Specification for Agent Action

18. Implementation of Workflow using Mobile Agents
Integration of XML description and generic coordination facility
Coordination facility - built using
Ajanta System
Next :
Ajanta Overview
Agent Based Implementation environment
Implementation Issues

19. Ajanta Overview A Java based framework for programming mobile agents
Agent - an autonomous entity migrating from node to node
Key Features
Security
Authentication
Access Control
Resource Protection

20. Agent-Agent Communication Server- Server protocol
Ajanta (cont.)
Agent-Agent Communication
Agent Migration X Y Y
Agent Server 1
Agent Server 2
Server- Server protocol
Host A
Physical Network
Host B
A Mobile Agent System

21. Role of Mobile Agents in Workflow
To encapsulate
Role specific protocols and interfaces
Security privileges based on user’s role and identity
Dynamic alteration of workflow policies by updating the mobile agents
Supporting Disconnected Operations

22. Agent-based Implementation Environment
Plan Creation and Consistency Checking
XML Plan preparation
Parsing and Consistency Checking
Plan Distribution with Authentication
Role specific Plan Distribution
Bare User Coordination Interface(UCI) derived from AgentServer Class

23. (cont.) Creation of Role Based User Interface
UCI populated with objects and user interface
User Interface - from Convener or
default generic interface
Execution of Coordination Operations
Access Control
Precondition Check
Cloning/Agent Action
Launching of Agents

24. Plan Creation and Distribution
User A
User B 3 3 2 2
XML
specifications
Convener 1 3 2
Plan Creation and Consistency Checking
Role C 1 2
Authentication 3
Plan Distribution

25. System Level View Convener User A User B Role Based User Interface
Generic Coordination Facility
Get Plan
Convener
Get Plan
Role Based User Interface
Role Based User Interface
Generic Coordination Facility
Generic Coordination Facility
User A
User B

26. User Coordination Interface
5/17/2019
User Coordination Interface
Role Based User Interface
Document Manager
AGENT
from a remote
user’s UCI
Proxy
Objects obtained from Convener
AccessProtocol
Agent Environment
UCI Implementation as an Agent Server

27. User Interface for Author Role

28. Execution of Coordination Operations
User A
User B
Communication
Network
User Interface
User Interface a b c d a b c d
Shared Objects
Shared Objects
Agent-based Coordination Facility
Agent-based Coordination Facility
Dispatching of a Coordination Agent

29. Implementation Issues
Node Serialization not supported by current DOM Model
implemented our own version
DOM allows only string values to be stored in the XML tree

30. Conclusion
Main Contribution : methodology for building distributed workflow systems using a high level specification
Able to leverage an agent based middleware and its security architecture
Generic Specification for implementing any workflow/collaboration

31. Future Work Dynamic System Behavior
Dynamic delegation of access rights
Adding entities to workflow dynamically
Manipulation of different MIME types of objects through User Interface

33. XML DTD : Plan Schema and Example for Workflow Plan and Role 5/17/2019
<ROLE ROLE_ID="doc:author"
ROLE_NAME="author"
OBJECT_REF="doc"
ROLE_INTERFACE="ajanta.UserInterface">
<PRINCIPAL URN="URN:ans:A"/>
</ROLE>
<ROLE ROLE_ID="doc:reviewer"
ROLE_NAME="reviewer"
<PRINCIPAL URN="URN:ans:B"/>
<PRINCIPAL URN="URN:ans:C"/>
</PLAN>
<!DOCTYPE PLAN [
<!ELEMENT PLAN (ROLE+, OBJECT+,
OPERATION+)>
<!ELEMENT ROLE (PRINCIPAL+)>
<!ATTLIST ROLE
ROLE_ID ID #REQUIRED
ROLE_NAME CDATA #REQUIRED
OBJECT_REF IDREF #REQUIRED
ROLE_INTERFACE NMTOKEN #IMPLIED
>
<!ELEMENT PRINCIPAL EMPTY>
<!ATTLIST PRINCIPAL
URN CDATA #REQUIRED
......
]>
Schema and Example for Workflow Plan and Role

34. XML DTD : Objects Schema and Example for Object
<!ELEMENT OBJECT (ACL, STATUS,METHOD*, OBJECT*) >
<!ATTLIST OBJECT
OBJ_ID ID #REQUIRED
OBJ_NAME CDATA #REQUIRED
OBJ_TYPE CDATA #REQUIRED
CODE_BASE NMTOKEN "null"
OBJ_DATA CDATA "null"
>
<!ELEMENT METHOD ( ACL, PARAMETER*)>
<!ATTLIST METHOD
METHOD_NAME NMTOKEN #REQUIRED
<!ELEMENT STATUS OPERATION_PERFORMED*)>
<!ELEMENT OPERATION_PERFORMED EMPTY>
<!ATTLIST OPERATION_PERFORMED
OP_REF IDREF #REQUIRED
OPERATOR CDATA #IMPLIED
<OBJECT OBJ_ID="doc"
OBJ_NAME="Document"
OBJ_TYPE="multipart/alternative">
<ACL/>
<STATUS/>
<OBJECT OBJ_ID="doc:ch1"
OBJ_NAME="Chapter1"
<OBJECT OBJ_ID="doc:ch1:content"
OBJ_NAME="Contents"
OBJ_TYPE="text/plain">
....
</OBJECT>
Schema and Example for Object

35. XML DTD : Access Control
<!ELEMENT ACL (ACL_ENTRY*)>
<!ATTLIST ACL
ACL_NAME CDATA #IMPLIED
ACL_OWNER CDATA #IMPLIED
>
<!ELEMENT ACL_ENTRY ((PRINCIPAL|GROUP), PERMISSION*)>
<!ATTLIST ACL_ENTRY
TYPE (positive|negative) "positive"
<!ELEMENT GROUP EMPTY>
<!ATTLIST GROUP
ROLE_REF IDREF #REQUIRED
<!ELEMENT PERMISSION EMPTY>
<!ATTLIST PERMISSION
NAME (execute|update|read) "execute"
<ACL>
<ACL_ENTRY>
<GROUP ROLE_REF="doc:author"/>
<PERMISSION NAME="read"/>
<PERMISSION NAME="update"/>
</ACL_ENTRY>
<GROUP ROLE_REF="doc:reviewer"/>
<ACL_ENTRY TYPE="negative">
<PRINCIPAL URN="URN:ans:C"/>
</ACL>
Schema and Example for Role Based Access Control

36. XML DTD : Operation Schema and Example for Operation
<!ELEMENT OPERATION (ACL, PRE_CONDITION* (CLONE_OBJECT | AGENT_ACTION+))>
<!ATTLIST OPERATION
OP_ID ID #REQUIRED
OBJECT_REF IDREFS #REQUIRED
OPERATION_NAME NMTOKEN #REQUIRED
>
<!ELEMENT PRE_CONDITION EMPTY>
<!ATTLIST PRE_CONDITION
OP_REF IDREFS #REQUIRED
<!ELEMENT CLONE_OBJECT (TARGET*)>
<!ELEMENT TARGET EMPTY>
<!ATTLIST TARGET
ROLE_REF IDREFS #REQUIRED
<OPERATION OP_ID ="doc:ch1:con:publish"
OBJECT_REF="doc:ch1:content"
OPERATION_NAME="Content_Publish">
<ACL>
<ACL_ENTRY>
<GROUP ROLE_REF="doc:author"/>
<PERMISSION/>
</ACL_ENTRY>
</ACL>
<CLONE_OBJECT>
<TARGET ROLE_REF="doc:reviewer"/>
</CLONE_OBJECT>
</OPERATION>
Schema and Example for Operation