I. System Boundary and Participant Participants Actor definition: Anything that is meaningful interactive interaction through the system boundary and system: 1. Do not belong to system 2. Direct and System Interaction -> Participants determine the determination of the system boundary 3. Significant interaction 4. Anything
The second point of "direct" should pay attention to: If a customer buys a ticket through the ticket seller, then for the ticketing system, the ticket sellers are participants and the customer is not. The difference between business modeling and system modeling: For For the ticketing system, when the business modeling, we describe the customer to book tickets, may have the head of the ticket center to ask the ticketing situation. But when the system models, they are not our object, We describe the description of the ticket salesman to sell and provide ticketing conditions, so both are different stages of modeling.
In some automated systems, time is often an external thing that triggers the system, so participants are time and cannot be ignored.
Identify participants: When you face a system, you should ask these questions: Who uses the system? Who changed system data? Whoever gets information from the system? Who needs the support of the system to complete the daily work? Who is responsible for managing and maintaining the normal operation of the system • Is the system to deal with those hard devices? Is it interacting with other systems? Who is interested in the results of the system? Time, climate, etc. After you answer these questions, your answer is basically covered. Participant's candidates.
Identify the importance of participants: 1. According to the participant identification system: Therefore, for the function of the full system, the system participants you identify Ning Duo will not be less. 2. Test the deployment phase You may learn about the system by recognizers Integrity .3. The participant is not very important. But you should consider the generalization relationship between the participants, avoid the repetition of the use case. II. Identify the incident, clear system event, is correctly established system use case Necessary condition.
System events are divided into two categories: system external events and system internal events external events are specific work for external participants on system interactions, and internal events are triggered by the system, usually trigger by time.
Method of identifying events: Brainstorming Method - Subject Probabine Princess, describing the possible things that can happen, as far as possible, it is the principle of Ningdom not less, but you can sort according to the importance of the incident, which can deepen Your understanding of the system.
Usually listed identified events into a table: What is the 3A table ACTOR ACTION AIM participant? ... ... ...
III. Identification case use case definition: Use case is a set of use case instance case example definition: a series of actions performed by the system to generate the resulting value of the participant's observable
Usage points: 1. Located in the system - must be run by the system 2. Target-oriented - use cases must have a destination 3. Dynamic-can observe the result, and is interacting in the boundaries and outside. 4. User View - Participants Observing 5. Particle size - is a set of instants with common goals or can be gathered
The recognition case is starting from business modeling, that is, we describe the use case is the identification behavior from the user's point of view, which describes the use case is a pure business language, not a technical language. For example, describe the tax payment Instead, not the J2EE architecture. Therefore, the user's naming is also from the user's perspective, describing the user's ability to do with a purpose, there is a result of the result.
The particle size of the use case should not be too thin. Excessive decomposition can cause the error described in the example: 1. The step of interacting into a use case, rather than use a series of steps as an example. For example, the user login is a use case, the wrong approach is Enter the request to enter the username as a usage case. 2. Some system internal activity in the necessary processing, verify the user, connect the database, send SQL request, etc., is actually the user login this interaction. The steps of the steps. 3. Take the work of the recognition case as a relational database analysis: referred to as a four-wheeled carriage, that is, Crud (CRUD (CRUD UPDATE DELETE). For example, the management user is a use case, but it may become an increased user , Query the user, modify the user, and delete the user's "system is the data increase" episode error.
A key principle of identification example is: Standing at the user's perspective, not standing in the system, not standing in data.
Through the establishment of system events, you can draw an example example, but you should remember that "the essence of the use case is text", so we will ultimately use the example to convert the use case document. You can use the following example format writing case document: Sample number : Case name: Use example: Participant: front condition: Benefits to start this use case The system and environmental state of environment: End the system and environmental state of the system and environmental status: 1 .... × ××× 2 ... ×××× 3 .... ×××× extension points: 2A. ×××× 2A1 .... ××××× Supplementary description: pre-conditions and post conditions can react with example Interdependent relationship. It can also prevent some use cases from missing
The relationship between the use case: expansion extends, including include, generalization
