Using BPEL to implement “Classical Tutorial Course”

徐天送2004/7/29

Business ProcessContainer

BPEL ProcessIMS LD

Outline

“Classical Tutorial Course” System Design Implementation Demo Conclusion

“Classical Tutorial Course”

IntroductionBasic

skill or concept

Intermediate skill or concept

Advanced skill or concept

Summary Test

Example

Pratice

Example

Pratice

Example

Pratice

William Horton, “Designing web-based training”, New York: John Wiley & Sons, 2000

Demo

System Design

The Process of Learning Course General Learning Scenario The Use Case Diagram The Conception Diagram Change Deployment Diagram

The Process of Learning Course

We could use 3 steps to descript the Process of Learning Course, and the content is like a “Classical Tutorial Course.”

Browse Course

IntroductionBasic

skill or concept

Intermediate skill or concept

Advanced skill or concept

Summary Test

Example

Pratice

Example

Pratice

Example

Pratice

Load Course Complete Course

General Learning Scenario

Precondition: Learner had completed the authentication step.

Main Success Scenario:1. Learner Select a Course and start a Learning Process.2. Learning Process request LMS to Load the course, and LMS

return the course’s URL to Learning Process .3. Learning Process show the course introduction.4. Learner clicks NEXT button to start an activity.5. Learning Process request LMS to Load the activity, and LMS

return the activity’s URL to Learning Process .6. Learning Process show the activity content.7. Learner has done with the activity, and clicks the COMPLETE

button. (go back to step 3, except the final activity is completed.)

8. Learning Process request LMS to complete the course, and then show the complete page.

Sequence Diagram

Send LOADCOURSE Message

new

CourseURL

SendNEXTACTIVITY Message

Lookup ActivityActivityURL

RequestCompleteActivity Service

RequestCompleteCourse Service

(Repeat)

:WebServer

Select a Course

Show Introduction

Next Activity

Show Activity

Complete Activity

Show ActivityComplete

Complete Course

Show CourseComplete

:ProcessContainer

:LearningProcess

loadCourse

nextActivity

completeActivity

ACK

completeCourse

ACK

RequestLoadActivity Service

RequestLoadCourse Service

:WebServiceServer

LoadCourse:WebService

new

Lookup CourseBind

CourseURLCourseURLCourseURLCourseURL

LoadActivity:WebService

new

Bind

ActivityURLActivityURLActivityURLActivityURL

CompleteActivity:WebService

new

BindACKACKACK

CompleteCourse:WebService

new

BindACKACK

ACK

:CourseDBLearner

SendCOMPLETEACTIVITY Message

SendCOMPLETECOURSE Message

The Use Case Diagram

Learner could learn a course through 3 steps to accomplish the course.

LMS provide some LMS functions and the course contents to support the course.

The Conception Diagram Change

學習者

學習內容 課程架構

課程

學習系統

串序引擎

學習

組成

播放

擁有

擁有

註冊

擁有

課程

學習者

學習內容 課程架構

LearningProcess

學習系統

ProcessContainer

Join

組成

Run

descript

註冊

Request Servi ces

Provide

Knows

擁有

陳孟哲 , Level A 領域模型 , “IMS Learning Design 串序引擊的設計與實作” ,　國立台北科技大學資訊工程系碩士班 , 2004年 7月

Conception Diagram with Process

Deployment Diagram

ExternalWeb Service Server

Web Server BPEL Engine

HTML SOAP

SOAP

(LMS Services)

(Learning Process)

Browser

(Course Content)

SOAP

4. Request Service

1. Browse Course

2. Authentication orOther Supported Service

3. Join Process

(Learner)

Implementation

Use Tools Process Design Implementation: use <sequence> Receiving more than one messages

problem Alternative Implementation: use <flow> Testing

Use Tools

BPWS4JBPEL Engine + Editor

Oracle BPEL Process ManagerBPEL Engine + Editor

Systinet Developer for EclipseWeb Services Integration Develop Environme

nt

Activity Diagram

Learning Process LMS

Map to BPEL Activity

Receive

Invoke

Reply

BPEL

Implementation: use <sequence>

LoadCourseScope

BrowsCourseScope

CompleteCourseScope

The Course Content Scope

NextActivityScope

CompleteActivityScope

While

Process

Receive A

Receive B

Receive C

Receiving more than one messages problem

Process

Receive A

Receive B

Receive C

Message AMessage B

Process

Receive A

Receive B

Receive C

Represents the process current state

Wait Message B!

Result: The process’s instance hangs!

Throw Exception!

Process

Receive LOADCOURSE

Receive NEXTACTIVITY

Receive COMPLETECOURSE

Receive COMPLETEACTIVITY

usrID (Correlation Set)

The Process with Correlation Set

LOADCOURSE

BPELEngine

Process

Receive LOADCOURSE

Receive NEXTACTIVITY

Receive COMPLETECOURSE

Receive COMPLETEACTIVITY

usrID (Correlation Set)

COMPLETECOURSE

NEXTACTIVITY

COMPLETEACTIVITY

Check TokensIn each message

LOADCOURSE

NEXTACTIVITY

COMPLETEACTIVITY

COMPLETECOURSE

The First Message Initialize Correlation Set

The <Correction Set> Usage1

1. We define the “userID” as the process’s property.

2. For each message, use alias to let message part map to the property.

3. Put the property in the correlation set that we define in the BPEL.

4. Now, we must use the correlation at each <receive>, and indicate the first received message must initialize the correlation set.

The <Correction Set> Usage2

1. Declare the property of process.

2. Use alias to let the message part map to property.

WSDL File

The <Correction Set> Usage3

BPEL File

3. Declare the correction set

4. Specify that the receive activity could receiveMessage carry with the correction set

Alternative Implementation

When we use <flow> activity, the sub-activities would run concurrently.

We could use <link> to do the synchronize interaction between sub-activities.

Implementation: use <flow>

source

target

source

target

Testing1

Use static function to simulate the action that client clicks the button, and check the expected URL and Message it returns.

Testing2

Conclusion

<Correlation Set> is an important part for BPEL, it makes the process interact with other processes.

The BPEL is developing, there are still many bugs exist, and the engine doesn’t implement the spec totally.

對 Single Role的課程而言， Selection及 Sequence的課程是可以對應的。但在 Nested的 Activities和Multi-Role則還無法確定。

Future work

SellerBuyer

Supply-chain example

Buy the goods

Receive an orderPay for goods

Conform Order

Check out stocks

Purchase Order

Order number

Delivery Response

Order number

Wait For Delivery

Correlation Set

Intent:a mechanism for instance routing

Definition:“A set of correlation tokens is defined as a set

of properties shared by all messages in the correlated group. Such a set of properties is called a correlation set.”

Process

Receive A

Receive B

Process

Receive A

Receive B

Instance routing

Message B

Process

Receive A

Receive B

Message A

Process

Receive A

Receive B

Message AProcess

Receive A

Receive B

Message B

BPELEngine

Message A

Message B

Default mechanism

Another mechanism using correlation set

BPELEngine

Message A

Message B

Supply-chain example

SellerBuyer

Buy the goods

Receive an order

Wait For Delivery

Pay for goods

Conform Order

Check out stocks

Purchase Order

Order number

Delivery Response

Order number

correlation tokens

correlation group

Mapping to BPEL process

Load Course

Process

Receive

Invoke

Reply

Receive

Invoke

Reply

Receive

Invoke

Reply

Receive

Invoke

Reply

LMS Web Services

Load Course

Load Activity

Complete Activity

Complete Course

Course URL

Next Activity

Activity URL

Complete Activity

ACK

Complete Course

ACK

Deprecated!