If the work of the requirements analysis phase is summarized as a preparational specification manual, this simplified approach is often leading to the neckstakes of the project. It is recommended to use the following steps to form a software demand: obtain user needs → Analyze user needs → write demand documents → Review Demand Documents → Administrative requirements. Let's first discuss the procedure of the first two steps (access user needs, analyze user needs).
Get user needs
This is a one of the most important tasks. The following is an activity that needs to be performed (shown in Figure 1) for user needs (shown in Figure 1).
● Understand all user types of the client and potential types. Then, based on their requirements, the overall goals and systems of the system are determined.
● Interviews and investigate users. The way to communicate can be different forms of conference, telephone, email, group discussion, simulation presentation and other different forms. It should be noted that every exchange must be recorded, and can be classified for the results of communication, which is easy to analyze activities. For example, demand can be subdivided into functional requirements, non-functional requirements (such as response time, average failure working hours, automatic recovery time, etc.), environmental restrictions, design constraints.
● Requirements analysts further analyze and organize the needs of users collected. Here are a number of common guidelines:
(1) Everything is known for the user, and the reasons why it is determined by the demand for users;
Figure 1 Access to user needs
(2) Transfer the expression of "how to implement" into "What is achieved", because the goal of the demand analysis is "what", not "how to do";
(3) Analysis of implied demand derived by user needs, and identifying the implied demand for users (it is possible to implement user needs), this is often easily ignored, often because of implied demand Not sufficient, causing a change in demand.
● Demand analysts will submit the needs of users to the user and the developer's related personnel in an appropriate manner. Everyone confirms whether the results submitted by the needs analyst person truly reflect the user's intention. Demand analysts need to perform the following activities in this task:
(1) Clearly identify the undetermined demand items (there is often a lot of such premature items at the beginning of demand analysis);
(2) make the demand in accordance with the overall goal of the system;
(3) Guarantee the consistency between demand items to solve the possible conflicts between demand items.
Analyze user needs
In many cases, analyzing user needs is parallel with access to user needs, and provides a channel for customers, users, and developers, such as different participants such as customers. These models provide an abstraction of demand, providing a visualized bridge. The analysis of user needs is similar to obtaining user requirements, which distinguishes to describe the model when analyzing user needs to obtain a more clear demand. Analyze user needs requires the following activities:
● Describe the overall structure of the system in a graphical manner, including the boundary and interface of the system;
● Provides visualization interface through prototype, page stream, or other way, users can make their own evaluation;
● Systematic feasibility analysis, technical feasibility, environmental analysis, cost analysis, time analysis, etc.
● Describe the system's function item, data entity, external entity, entity relationship between the relationship between the entity, and the state transition between the entities.
Figure 2 DFD Schematic
There are many ways to model modeling, the most commonly used data flow map (DFD), entity relationship (ERD), and use case (USE case). DFD As a main method of structural system analysis and design, DFD has been widely used, and DFD is especially suitable for expression of MIS systems. DFD uses four basic elements to describe the behavior, process, entity, data stream, and data storage of the system. The DFD method is intuitive and easy to understand, and the user can easily obtain the logical model of the system and physical model, but the timing relationship of the activity cannot be judged from the DFD map. Figure 2 depicts a DFD schematic diagram of a project. ERD method is used to describe the correspondence between system entities, and the demand analysis phase uses the logical relationship of entities in the system in the system, and uses Erd to describe the relationship between physical tables in the design phase. Demand analysis phase uses Erd to describe the objects in the real world. Erd only focuses on the relationship between the data in the system, and lacks a description of the system function. If the ERD is combined with the DFD, the system needs to be more accurately described.
User Case is usually used in object-oriented methods to acquire software requirements. Use Case describes the behavior of the system by describing the interaction between "system" and "actors". By decomposing system objectives, all steps describing the actors in order to achieve these goals. The most important advantage of the USE case method is that it is user-oriented, and users can constantly refine their needs according to the USE CASE they own. In addition, using USE CASE can easily obtain test cases for system functions.
Continue to introduce three steps (write demand documents, review demand documents, management requirements), and discuss related practices.
Write demand documentation
Demand documents can be described using natural language or formal languages, and can also add a graphical expression and model characterization. Demand documents should include all users' needs (functional requirements and non-functional requirements).
Review demand document
After the demand document is completed, it needs to be formally reviewed as the basis for the next phase of work. The general review is divided into two categories of user review and peer review. The description of the user and the developer for the content of the software project is based on demand specifications; the standards for user acceptance is based on the content in the demand specification specification, so the user's opinion is the first time. The purpose of peer review is to discover those potential defects or errors at the beginning of the software project, avoiding these errors and defects to the subsequent phase of the project.
Administrative demand
Figure 1 Requirements Change Process
The changes in demand are inevitable, how to manage software needs in a controllable manner, and have important significance for the smooth progress of the project. If users have completed users in a hurry, it is often meant to mean unstable demand. Therefore, demand management should ensure that the needs of demand analysis has been fully implemented. For the management of changes in demand, mainly use the requirements change process and the management method of the demand tracking matrix. Demand Change Process and Demand Tracking Matrix are shown in Figures 1 and 2, respectively.
Figure 2 Requirements Tracking Matrix
Frequently Asked Questions and Suggestions
Q, what is the difference between the customer and the end user?
A, can be used to illustrate the difference between them.
Figure 3 Demand Acquisition Channel Schematic
Software demand comes from two aspects of system engineering and customers, where customers are the main demand providers (system engineering requirements are also from customers). Customers need to collect their end users' needs and consider their own needs, and then provide the developer. If the customer has not taken the needs of the end user, the development is easy to do, because the system ultimately meets the demand for end users.
Q, how to conduct user interviews?
A, first, be sure to determine the purpose and outline of the interview in advance. Second, because users often don't know what needs to provide, developers are required to guide.
Q, what is the user interview content?
A, first, please describe how they complete their current work and abstract with the user out a workflow or work model. Then, after obtaining the user's recognition, explain how you do these functions to the user, and explain which links can be implemented with automation. Q. Which way is it best to do?
A, different needs analysis have different characteristics. Nothing is still completely replaced by other methods, otherwise, there will be no different demand modeling methods. In general, DFD ERD can be used to describe those of the functional hierarchical requirements; USE CASE is adapted to describe complex demand for functional structures. The purpose of doing demand analysis is to establish a model of demand, and different subsystems may use different modeling methods.
Q, how to do prototypes, what is the purpose of prototype?
A, usually use prototype analysis methods to help developers further acquire user needs or allow user to confirm demand. The development partner often provides users with a 墒 墒 魑 魑 ⒃ 诮缑 嫔 贾 贾 帽 匾 菔 δ 菔 堋 堋 堋 堋 堋 堋 堋 堋 堋Tip Yun 谒 谒 鏥 Isual Basic, Delphi, etc.) To quickly generate user interface, you can also use web production tools such as FrontPage to generate user visible pages.
The purpose of prototype is often acquisition. But sometimes use prototypes to verify key technologies or technical difficulties. For technical prototypes, the interface is often ignored.
