chapter 7 a case study: applying the activity analysis approach

Chapter 7A Case Study: Applying the Activity Analysis Approach

Object-Oriented TechnologyFrom Diagram to Code with Visual Paradigm for

UML

Curtis H.K. Tsang, Clarence S.W. Lau and Y.K. Leung

McGraw-Hill Education (Asia), 2005Dr. Hussein Al-Zoubi

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Objectives After you have read this chapter, you should

be able to understand each step of the Activity

Analysis Approach apply the Activity Analysis Approach to

system development

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The Case Study This case study describes the

development of a mail order system by applying the Activity Analysis Approach (A3).

Throughout this case study, we will show the main steps and the artifacts produced in A3 in one iteration of the development process.

Typically, due to the complexity of modern systems, several iterations are necessary in order to elicit and model all the requirements specified.

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Activity Analysis Approach Activity Analysis Approach has four distinct

workflows: business modeling, requirement, analysis and design.

In the business modeling workflow, develop activity diagrams to model the operation of the organization.

In the requirement workflow, identify the scope of the system and develop the use case models of the target system.

In the analysis workflow, analyze the use case descriptions to create domain class diagrams and system-level sequence diagrams.

Finally, in the design workflow, we develop low-level collaboration, state and sequence diagrams to model the realization of the use cases.

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Business Modeling - Domain Analysis (Workflow) The business modeling starts with information

gathering about the business processes of an organization.

The goal is to identify the candidate activities which are targets for computerization. The Designer can collect the information through the following ways:

Interviews with users Questionnaires Documents describing the business procedures Domain experts Standards and terminologies in the business domain

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Business Modeling - Domain Analysis (Workflow) (cont’d)

Problem Statement (workflow)The chief executive officer of a mail order company is interested in computerizing its business process. The major business activities of the company can be briefly described as follows:• The company aims to provide high quality mail order

services to all registered members of the company.• An individual or a company can register to become a

member by filling the registration form and sending it to the customer service department.

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Business Modeling - Domain Analysis (Workflow) (cont’d)

• A member can order items by filling an order form and sending it to the customer service department. The customer service department will verify the membership and forward the order to the sales department. If the order can be processed through existing stock, the sales department will process the order and issue delivery notes to the inventory department. Otherwise, the sales department will issue a purchase order to the supplier. When all items are available, the inventory department delivers the items to the member, and the accounts department issues an invoice to the member.

• When the accounts department receives an invoice from a supplier, it verifies that the items in the purchase order have been received, and issues payment to the supplier.

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Business Modeling - Business Process Analysis Apply the

elaborator(Problem_Statement[workflow], Swimlane_Activity_Diagram) manipulator to develop an activity diagram.

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Business Modeling - Business Process Analysis (cont’d)

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Business Modeling - Determining the System Scope The Designer can then discuss with the

stakeholders of the system and decide on the business activities that are required to be computerized.

Let’s assume that the Designer and the stakeholders have agreed to computerize the business activities related to membership, sales, ordering and inventory control of the mail order company.

We can now proceed with the requirements workflow (the next workflow of the Activity Analysis Approach).

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Requirements In this workflow, we start with a set of

activities that we wish to computerize and prepare a more detailed (use case level) problem statement.

We then conduct a textual analysis on this problem statement to identify the actors and use cases. By elaborating on the use cases, the use case descriptions can be used as the input to the analysis workflow.

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Requirements - Domain Analysis (Use Case Level)

After determining the scope of the system, we can prepare a (use case level) problem statement to describe the required activities.

The problem statement should give enough details for identifying the responsibilities of individual users, and describe the procedure for them to perform their tasks.

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Requirements - Domain Analysis (Use Case Level) (cont’d)

Problem Statement (Use Case Level) A customer registers to become a member by filling the

membership form and mailing it back to the company. A member who has not been active (i.e. no transactions) for a period of one year will be removed from the membership list and needs to apply for reinstatement of the lapsed membership.

A member should inform the company of any change in personal details, such as home address, telephone numbers, etc.

A member makes an order by filling out a sales order form and faxing it to the company. Alternatively, the Customer Service Assistant can handle the order over the phone.

The Customer Service Assistant always checks the validity of membership before entering the sales order information into the system.

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Requirements - Domain Analysis (Use Case Level) (cont’d)

The Order Processing Clerk checks the availability of the ordered items and holds them for the order. If all the items are available, the Order Processing Clerk will schedule delivery.

The Inventory Control Clerk controls and maintains an appropriate level of stock and is also responsible for reordering new items.

If there is a problem with an order, members can phone the Customer Service Assistant who will follow up the sales order.

Members may return defective goods within 30 days and get their money back.

Each task carried out by the system will have the name and ID of the staff member concerned recorded into the system.

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Requirements - Use Case Analysis: Finding Actor and Use Cases

Apply the Transitor(Problem_Statement [use case level], Actor_List) manipulator to identify all the actors. Customer Service Assistant

(Membership registration, placement of order)

Order Processing Clerk (Process order)

Inventory Control Clerk (Inventory control)

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Requirements - Use Case Analysis: Finding Actor and Use Cases (cont’d)

Actor Name: Customer Service AssistantDescription: The Customer Service Assistant is responsible for the maintenance of membership records, handling of goods returns, creating sales orders, monitoring sales order status and validating membership status.

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Actor Name: Order Processing ClerkDescription: The Order Processing Clerk is responsible for processing sales orders, submitting reorder requests, requesting necessary deposits from members and scheduling delivery of goods to the members.

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Actor Name: Inventory Control ClerkDescription: The Inventory Control Clerk is responsible for ordering and reordering of goods. The Inventory Control Clerk uses the system to update the stock level when goods have been received.

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Apply the Transitor(Problem_Statement[use case level], Use_Case_List) manipulator to identify all use cases.

The following are the use cases of the mail order system: Check order status Place order Handle goods return Update membership record Archive membership

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Register new member Process order Schedule delivery Order goods Receive goods Deliver goods

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Requirements - Use Case Analysis: Prioritizing Use Cases

The use cases are prioritized according to their relative importance in the system.

The developer evaluates the risks and the significance of the use cases to the stakeholders of the system.

The developer and stakeholders of the system can meet to decide on the priority of the use cases.

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Requirements - Use Case Analysis: Prioritizing Use Cases (cont’d)

Priority Rank Use Case ReasonHigh Process order Directly improves the efficiency of

the business process and affects the system architecture

High Place order Same as aboveHigh Check order status Improve efficiency and quality of

customer serviceMedium Order goods Ordering goods is less often than

processing order but still is one of the major business processes

Medium Deliver goods Improve the control of stock level

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Requirements - Use Case Analysis: Prioritizing Use Cases (cont’d)

Priority Rank

Use Case Reason

Medium Schedule delivery Improve the efficiency of the goods delivery team

Medium Receive goods Improve the control of stock level

Medium Handle goods return Same as aboveLow Update membership

recordSmall impact on the system architecture

Low Register new member

Same as above

Low Archive membership

Same as above

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Requirements - Use Case Analysis: Describing Use Cases

Apply the Elaborator(Use_Case, Use_Case_Description) manipulator to develop the use case description.

The purpose of this manipulator is to give a detailed description of the use cases which can then be used for constructing other diagrams, such as the interaction diagrams, state diagrams, class diagrams, etc.

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Requirements - Use Case Analysis: Describing Use Cases (cont’d)

Use case name Process OrderUse case ID UC-200Primary actor(s)

Order Processing Clerk

Secondary actor(s)Brief description

The Order Processing Clerk selects a sales order from the system. He/she then checks each line item in the sales order for the availability of stock before finding the stock for each line item. The system records the name of the Order Processing Clerk who handles the sales order.

Preconditions The sales order is stored in the system.

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Flow of events 1. The Order Processing Clerk selects a sales order. The system displays the items and quantities of the order.2. The Order Processing Clerk checks the availability of each item.3. The Order Processing Clerk holds the stock items for the sales order. The system changes the order status to “filled”.

Post-conditions The sales order status is changed to “filled” and the stock items are held for the sale.

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Alternative flows and exceptions

If an item is not available from stock, the sales order status of the item is changed to “hold”. If the number of reorder item exceeds the reorder limit of the member, the clerk will print out a “request deposit” letter to the member, and the sales order is marked as “deposit pending”. When the deposit is received or if the reorder amount does not exceed the reorder limit of the member, the system then forwards a reorder request to the inventory control clerk. The sales order status is changed to “filled” when the stock items have been received, and the system will notify the order processing clerk.

Non-behavioral requirements

The system should be able to handle 2,000 sales orders per day.

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AssumptionsIssues Can the available items be delivered first?Source User Interview Memo 21, 8/9/01

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Requirements - Use Case Analysis: Structuring Use Case Model

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Analysis The analysis workflow is to develop the

domain class model and start the dynamic modeling.

First, we develop the domain class model by applying the transitor(problem statement, domain class model) manipulator.

Using this manipulator, we can construct the class model for the system (static modeling) and analyze the dynamic behaviors of the use cases (system modeling).

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Analysis - Domain Analysis-Problem_Statement(Class Level)

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Analysis - Static Modeling (Use_Case_Description)

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Analysis – System Modeling: Elaborating Use Cases Apply Elaborator(Use_Case, Activity_Diagram)

Apply Elaborator(Use_Case, Activity_Diagram)

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Analysis - System Modeling: Elaborating Use Cases (cont’d)

Parent use case name

Process Order

Parent use case ID UC-200Instance name A deposit is required before the sales order can be processed.Instance ID UCIS-200-1Environmental conditions and assumptions

All items of the order are available.

Inputs A sales order of available itemsInstance flow description

The Order Processing Clerk selects a sales order. The system displays the items and quantities of the order. The Order Processing Clerk checks the availability of each item. The system confirms all items are available. The Order Processing Clerk holds all items of the order. The system updates the status of the sales order to “filled”.

Outputs The sales order is filled.

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Process Order

Parent use case ID

UC-200

Instance name The sales order can be processed and filled.Instance ID UCIS-200-1Environmental conditions and assumptions

All items of the order are available.

Inputs A sales order of available itemsInstance flow description

The Order Processing Clerk selects a sales order. The system displays the items and quantities of the order. The Order Processing Clerk checks the availability of each item. The system confirms all items are available. The Order Processing Clerk holds all items of the order. The system updates the status of the sales order to “filled”.

Outputs The sales order is filled.

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Process Order

Parent use case ID UC-200Instance name An item needs to be reordered.Instance ID UCIS-200-2Environmental conditions and assumptions

Some stock items are not available, and the amount of the items needed to be reordered exceeds the preset reorder limit of the member.

Inputs A sales order of a stock item costs $1,000, and the preset reordering limit of the member is $2,000.

Instance flow description

The Order Processing Clerk selects a sales order. The system displays the items and quantities of the order. The Order Processing Clerk checks the availability of each item. An item which costs $1,000 is not available. The Order Processing Clerk submits a reorder request. The sales order is marked as “deposit pending”.

Outputs The sales order is marked as “hold” and a reorder request is submitted.

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Parent use case name Process OrderParent use case ID UC-200Instance name A deposit is required before the sales order can be

processed.Instance ID UCIS-200-3Environmental conditions and assumptions

Some stock items are not available, and the amount of items needed to be reordered exceeds the preset reorder limit of the member.

Inputs A sales order of a stock item costs $5,000, and the preset reordering limit of the member is $2,000.

Instance flow description

The Order Processing Clerk selects a sales order. The system displays the items and quantities of the order. The Order Processing Clerk checks the availability of each item. An item which costs $5,000 is not available. The system prints a deposit request letter to the member. The sales order is marked as “deposit pending”.

Outputs The sales order is marked as “deposit pending” and a request deposit letter is sent to the member.

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Design Design Workflow is to analyze and design how

object collaboration is achieved for the performance of use cases.

We first elaborate each of the action states in the activity diagram (representing a use case) using a collaboration diagram.

We can generate the MVC (Model, View and Control)-level sequence diagram for the scenario by translating the collaboration diagrams corresponding to the action states of the path in the activity diagram.

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Design (cont’d) For objects with complex dynamic behaviors,

especially control objects or subsystems, we model them by using state diagrams.

In the process, we apply the view aligners to revise the activity diagram (use case level) and class diagram to maintain consistency among models.

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Design - Elaborating the Flow of Events For objects with complex dynamic behaviors,

especially control objects or subsystems, we model them by using state diagrams.

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Design - Elaborating the Flow of Events (cont’d)

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Design - Elaborating the Flow of Events (cont’d)

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Design - Generating MVC Sequence Diagrams Having created the collaboration diagrams for

the action states of the activity diagram, we can generate MVC sequence diagrams by tracing paths in the activity diagram and translating the collaboration diagrams of the action states in the path into an MVC sequence diagram.

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Design - Generating MVC Sequence Diagrams (cont’d)

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Normal Scenario

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An Alternative Scenario

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Another Alternative Scenario

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Design - Revising the Class Diagrams After we have drawn the sequence diagram for

the process order use case, the class diagram is refined by adding the operations and the attributes identified in the sequence diagrams.

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Design - Revising the Class Diagrams (cont’d)

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Design - Performing State Analysis on the Control Object(s) In the MVC sequence diagram, the control

object glues all other objects together, handles the control flow and deals with all other transaction-related requirements.

Consequently, a control object is usually complex enough to be modeled by a state diagram.

For example, the activity diagram of the process order use case together with the collaboration diagrams can be used to construct the state diagram for the control object ProcessOrderControl.

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Design - Performing State Analysis on the Control Object(s) (cont’d)

ProcessOrderControl

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Design - Revising the Class Diagram(s) After refining the sequence diagrams for the

system, we can revise the class diagrams according to the operations and attributes identified in the sequence diagrams.

The design class diagram now provides design information for the classes required for the implementation of the process order use case.

Hence, the implementation work for the process order use case can be carried out.

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Design - Revising the Class Diagram(s) (cont’d) For other use cases, the work flows of the

activity analysis approach can be repeated to develop the design of the classes required for the implementation of the use cases.

The design class diagram will then be incrementally refined by going through the development process iteratively.

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Design - Revising the Class Diagram(s) (cont’d)