System Analyst UML practice manual-Chapter 1

Chapter 1

1. The professional background of the user and the system analyst is different. It is inevitable that there will be misunderstandings and omissions in communication interviews. The following countermeasures try to relieve the work pressure of the system analyst:

1) Use a UML diagram to guide interviews to reduce missing requirements. During the interview, the system analyst uses multiple different diagrams to clarify the different perspectives of requirements and reduce omissions.

2) quickly generate executable program fragments and highlight misunderstandings through presentation.

3) package changes, so that when demand changes, you can track the changes and quickly modify the changes, and avoid the ripple effect of changes and spread out.

2. system analysts mainly use the following UML diagrams.

1) behavior

Use Case Diagram)

Activity digraphs)

State Machine Divisor)

Sequence Diagram)

2) structure chart

Class digraphs)

3. Not all objects are suitable for software objects. Candidate objects must meet the following two conditions:

1) Professional things or concepts used by business personnel during enterprise operation;

2) The system will also be used in information technology or need to be saved.

4. For the attributes of an object, the system analyst also needs to understand its definition, data type, possible range value, and initial value in the enterprise, don't forget to know how this property was run.

5. For object encapsulation, system analysts should master the following points:

1) known operations. Objects generally only disclose their own operations to other objects and interact with each other by calling known operations;

2) encapsulate attributes. Encapsulate property values and do not disclose them to other objects;

3) encapsulation method. Only disclose the operation to other objects, but do not disclose the method.

If you need to interact with other objects or even use the attributes or operations of the object, remember to strictly abide by the following three items:

1) do not directly mention the attributes of objects;

2) The execution method of the object cannot be assumed;

3) only operations on objects can be used.

There is a benefit of strictly observing the encapsulation of objects. When the demand changes and the code needs to be rewritten, the changes will be limited to the attributes and methods of the object, without any ripple effect, it will not trigger a chain reaction. Because the internal components of the software are easy to replace and replace, the service life of the software is prolonged, and the subsequent maintenance costs are also low, so enterprises get high ROI. However, the first thing to pay is a high development cost.

6. determine whether an association is used:

1) in the professional concept of the enterprise field, there is a fixed static relationship between the two objects that needs to be stored;

2) in information technology, the system will use these static relationships and must save them to the database.

Determine whether an aggregation relationship is used:

1) meets the above association conditions;

2) In the professional concept of the enterprise field, the two objects have a static relationship of Whole-Part.

Determine whether a composite relationship is used:

1) The above aggregation relationship is met;

2) The Part object can only link one Whole object. When the Whole object is canceled, the Part object must be canceled.

7. System Use Cases: express the interaction between users and information systems. -- (system executors will guide the entire development program)

Business Use Cases: express the interaction between customers and enterprises. -(Business executor)

8. The Model-Driven Architecture development program is divided into the following three stages:

1) CIM-focuses on the system environment and requirements, but does not involve the internal structure and operation details of the system;

2) PIM-focuses on the internal details of the system, but does not involve the specific platform of the real system;

3), MSPS-focus on the details of system implementation to specific platforms.

For detailed steps, refer:

1) CIM-1: Define the business process and generate the business case model;

2), CIM-2: Analysis of business processes, generate activity diagram;

3), CIM-3: define the system scope, generate the system use case diagram;

4) PIM-1: analyze the system process and generate the system case description;

5), PIM-2: Analysis of business rules, generate a state chart;

6), PIM-3: define static structure, generate class diagram;

7), PIM-4: define operations and methods, generate a sequence diagram.

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