Assignment - 1
Modeling and simulating behavior of a business process as discrete event system (DES) using Petri net
Software Requirements Engineering SEN-570
S.M. Saiful Islam ID # 0712004 Program - MSE
February 16, 2008
1. INTRODUCTION............................................................................................................................. 3 2. DESCRIPTION OF THE BUSINESS PROCESS ......................................................................... 3 2.1 WELL ARTICULATED BEHAVIOR ................................................................................................... 3 2.2 LOGIC OF TRANSLATING THE BEHAVIOR OF THE PROCESS INTO DES........................................... 4 2.3 DES MODEL DEVELOPED USING HPSIM ....................................................................................... 5 2.4 SIMULATION RESULTS OF THE MODEL IN TERMS SEQUENCE OF EXECUTION OF STEPS ................. 5 3. VERIFICATION OF THE MODEL WITH RESPECT TO THE STATED BEHAVIOR ..... 17
1. Introduction
This document described the modeling and simulating behavior of the business process of a Message Board of a well collaboration tool as discrete event system (DES) using Petri net.
2. Description of the Business Process
The message board is a tool that provides message communication within a group of people. This is a module of a web collaboration tool. Here a member of the group can create a message. That message will be distributed to the message board of the member of the groups. An email is being also sent to email account of the group members. Any member can reply the message from the message board or from the email client. That will create a message thread. This message threading can be continued for an indefinite level by all the member of the group.
2.1 Well Articulated Behavior
Following are the well articulated behavior of the message board: Step 1: A member of a group creates a message in his message board and passes the message to the message server for further processing. Step 2: Message server create message for group members and distributes this message to members’ message boards. Step 3a: In the message board user can reply to the message Step 3a1: Reply message will create new message in the Message server as message thread. Step 3a2: This process can continue indefinite time, i.e. the user can reply against reply. Step 3b: In the message board user might not reply to the message Step 4: Message server send request to the Email List Server for email sending to the members’ email Step 5: Email List Server distribute email to the member’s email account Step 5a: In the email client the user can reply to the email message Step 5a1: Reply to the email will create new request to the email list server for message creation Step 5a2: The email list server will send request to the Message server for new message creation as message thread. Step 5a3: This process can continue indefinite time, i.e. the user can reply against reply. Step 5b: In the email client the user might not reply to the email message.
2.2 Logic of translating the behavior of the process into DES
For translating the business process of message board 10 positions and 18 transitions have been taken. Following are the list of positins: 1. Message Board (Start Position – Initial Token 1) 2. Message Server 3. Message Board 1 4. Message Board 2 5. Message Board 3 6. Email List Server 7. Email Client 1 8. Email Client 2 9. Email Client 3 10. Email List Server (Duplication of no. 6. For facilitating representation) Following are the transitions:: 1. Create/Reply Message (Create Message is Start Transition, Reply Message is subsequent transition) 2. No Reply Message (End of 1 message Path) 3. Distribute Message 4. Reply Message 1 5. Reply Message 3 6. Reply Message 2 7. Reply Email 1 8. Reply Email 2 9. Reply Email 3 10. Create Reply Message 11. Process Email List 12. No Reply Email 1 (End of 1 message Path) 13. No Reply Email 2 (End of 1 message Path) 14. No Reply Email 3 (End of 1 message Path) 15. No Reply Message 1 (End of 1 message Path) 16. No Reply Message 2 (End of 1 message Path) 17. No Reply Message 3 (End of 1 message Path) For controlling the behavior of the simulation different time effect has been used.
2.3 DES Model developed using HPSim
Following figure depicts the model of the Message Board DES developed using HPSim.
Figure: Message Board DES Model
2.4 Simulation results of the model in terms sequence of execution of steps
For execution of the total behavior of Message Board, 17 steps are required in this model. All the results of the steps along with simulation view have been given bellow: Step: 1 / Time: 0 =====> Start Timer: No Reply Message Start Timer: Create/Reply Message
Figure : Step 1 Step: 2 / Time: 1 =====> Start Timer: No Reply Message Enable: Create/Reply Message Position: Message Board decr. 1 token(s) Position: Message Server incr. 1 token(s)
Figure : Step 2 Step: 3 / Time: 1 =====> Enable: Distribute Message Enable: Process Email List Warning: branch conflict ! list: Transition: Distribute Message
Transition: Process Email List end list: Disable: Process Email List Position: Message Server decr. 1 token(s) Position: Message Board 2 incr. 1 token(s) Position: Message Board 3 incr. 1 token(s) Position: Message Board 1 incr. 1 token(s) Position: Message Board incr. 1 token(s)
Figure : Step 3 Step: 4 / Time: 1 =====> Start Timer: No Reply Message Start Timer: Create/Reply Message Start Timer: Reply Message 1 Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: No Reply Message 1 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 4 Step: 5 / Time: 2 =====> Start Timer: No Reply Message Enable: Create/Reply Message Start Timer: Reply Message 1 Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: No Reply Message 1 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3 Position: Message Board decr. 1 token(s) Position: Message Server incr. 1 token(s)
Figure : Step 5
Step: 6 / Time: 2 =====> Start Timer: Distribute Message Start Timer: Reply Message 1 Start Timer: Reply Message 3 Start Timer: Reply Message 2 Enable: Process Email List Start Timer: No Reply Message 1 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3 Position: Message Server decr. 1 token(s) Position: Email List Server incr. 1 token(s)
Figure : Step 6 Step: 7 / Time: 2 =====> Start Timer: Distribute Email Start Timer: Reply Message 1 Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: No Reply Message 1 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 7 Step: 8 / Time: 3 =====> Start Timer: Distribute Email Start Timer: Reply Message 1 Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: No Reply Message 1 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 8 Step: 9 / Time: 4 =====> Enable: Distribute Email Enable: Reply Message 1
Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: No Reply Message 1 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3 Position: Email List Server decr. 1 token(s) Position: Message Board 1 decr. 1 token(s) Position: Email Client 1 incr. 1 token(s) Position: Email Client 3 incr. 1 token(s) Position: Email Client 2 incr. 1 token(s) Position: Message Server incr. 1 token(s)
Figure : Step 9 Step: 10 / Time: 4 =====> Start Timer: Distribute Message Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Reply Email 1 Start Timer: Reply Email 2 Start Timer: Reply Email 3 Start Timer: Process Email List Start Timer: No Reply Email 1 Start Timer: No Reply Email 2 Start Timer: No Reply Email 3 Start Timer: No Reply Message 2
Start Timer: No Reply Message 3
Figure : Step 10 Step: 11 / Time: 5 =====> Start Timer: Distribute Message Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Reply Email 1 Start Timer: Reply Email 2 Start Timer: Reply Email 3 Start Timer: Process Email List Start Timer: No Reply Email 1 Start Timer: No Reply Email 2 Start Timer: No Reply Email 3 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 11 Step: 12 / Time: 6 =====> Enable: Distribute Message Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Reply Email 1 Start Timer: Reply Email 2 Start Timer: Reply Email 3 Enable: Process Email List Start Timer: No Reply Email 1 Start Timer: No Reply Email 2 Enable: No Reply Email 3 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3 Warning: branch conflict ! list: Transition: Distribute Message Transition: Process Email List end list: Disable: Distribute Message Position: Message Server decr. 1 token(s) Position: Email Client 3 decr. 1 token(s) Position: Email List Server incr. 1 token(s)
Figure : Step 12 Step: 13 / Time: 6 =====> Start Timer: Distribute Email Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Reply Email 1 Start Timer: Reply Email 2 Start Timer: No Reply Email 1 Start Timer: No Reply Email 2 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 13
Step: 14 / Time: 7 =====> Start Timer: Distribute Email Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Reply Email 1 Enable: Reply Email 2 Enable: No Reply Email 1 Start Timer: No Reply Email 2 Start Timer: No Reply Message 2 Start Timer: No Reply Message 3 Position: Email Client 2 decr. 1 token(s) Position: Email Client 1 decr. 1 token(s) Position: Email List Server incr. 1 token(s)
Figure : Step 14 Step: 15 / Time: 7 =====> Start Timer: Distribute Email Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Create Reply Message Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 15 Step: 16 / Time: 8 =====> Start Timer: Distribute Email Start Timer: Reply Message 3 Start Timer: Reply Message 2 Start Timer: Create Reply Message Start Timer: No Reply Message 2 Start Timer: No Reply Message 3
Figure : Step 16 Step: 17 / Time: 9 =====> Start Timer: Distribute Email Enable: Reply Message 3 Start Timer: Reply Message 2
Start Timer: Create Reply Message Start Timer: No Reply Message 2 Enable: No Reply Message 3 Warning: branch conflict ! list: Transition: Reply Message 3 Transition: No Reply Message 3 end list: Disable: No Reply Message 3 Position: Message Board 3 decr. 1 token(s) Position: Message Server incr. 1 token(s)
Figure : Step 17
3. Verification of the model with respect to the stated behavior
The stated behaviors of the Message Board have been verified with developed simulation model. The model has been able to represent all the behaviors like create message, reply message, distribute message, distribute email, reply email, not reply message, not reply email. So, it can be stated the Simulation Model is well representing the stated behaviors of the Message Board.