信息系统开发(共15页).doc

精选优质文档-倾情为你奉上Information System Development and Database DevelopmentIn many organizations, database development from the beginning of enterprise data modeling, data modeling enterprises determine the scope of the database and the general content. This step usually occurs in an organization's information system planning process, it aims to help organizations create an overall data description or explanation, and not the design of a specific database. A specific database for one or more information systems provide data and the corporate data model (which may involve a number of databases) described by the organization maintaining the scope of the data. Data modeling in the enterprise, you review of the current system, the need to support analysis of the nature of the business areas, the need for further description of the abstract data, and planning one or more database development project. Figure 1 shows Pine Valley furniture company's enterprise data model of a part. 1.1 Information System Architecture As shown in figure 1, senior data model is only general information system architecture (ISA) or a part of an organization's information system blueprint. In the information system planning, you can build an enterprise data model as a whole information system architecture part. According to Zachman (1987), Sowa and Zachman (1992) views of an information system architecture consists of the following six key components: Data (Figure 1 shows, but there are other methods that). Manipulation of data processing (of a data flow diagram can be used, with the object model methods, or other symbols that). Networks, which organizations and in organizations with its main transmission of data between business partners (it can connect through the network topology map and to demonstrate). People who deal with the implementation of data and information and is the source and receiver (in the process model for the data shows that the sender and the receiver). Implementation of the events and time points (they can use state transition diagram and other means.) The reasons for the incident and data processing rules (often in the form of text display, but there are also a number of charts for the planning tools such as decision tables). 1.2 Information Engineering Information systems planners in accordance with the specific information system planning methods developed information system architecture. Information engineering is a popular and formal methods. Information engineering is a data-oriented creation and maintenance of the information system. Information engineering is because the data-oriented, so when you begin to understand how the database is defined by the logo and when information engineering a concise explanation is very helpful. Information Engineering follow top-down planning approach, in which specific information systems from a wide range of information needs in the understanding derived from (for example, we need about customers, products, suppliers, sales and processing of the data center), rather than merging many detailed information requested ( orders such as a screen or in accordance with the importation of geographical sales summary report). Top-down planning will enable developers to plan more comprehensive information system, consider system components provide an integrated approach to enhance the information system and the relationship between the business objectives of the understanding, deepen their understanding of information systems throughout the organization in understanding the impact. Information Engineering includes four steps: planning, analysis, design and implementation. The planning stage of project information generated information system architecture, including enterprise data model. 1.3 Information System Planning Information systems planning objective is to enable IT organizations and the business strategy closely integrated, such integration for the information systems and technology to make the most of the investment interest is very important. As the table as a description, information engineering approach the planning stage include three steps, we in the follow-up of three sections they discussed. 1. Critical factors determining the planning Planning is the key factor that organizational objectives, critical success factors and problem areas. These factors determine the purpose of the establishment of planning and environment planning and information systems linked to strategic business planning. Table 2 shows the Pine Valley furniture company's key planning a number of possible factors, these factors contribute to the information systems manager for the new information systems and databases clubs top priority to deal with the demand. For example, given the imprecise sales forecasts this problem areas, information systems managers in the organization may be stored in the database additional historical sales data, new market research data and new product test data. 2. The planning organizations set targets Organizations planning targets defined scope of business, and business scope will limit the subsequent analysis and information systems may change places. Five key planning targets as follows: organizational units in the various sectors. organizations location of the place of business operations. functions of the business support organizations handling mission of the relevant group. Unlike business organizations function modules, in fact a function can be assigned to various organizations modules (for example, product development function is the production and sale of the common responsibility of the Ministry). types of entities managed by the organization on the people, places and things of the major types of data. Information System data set processing software applications and support procedures. 3. To set up a business model A comprehensive business model including the functions of each enterprise functional decomposition model, the enterprise data model and the various planning matrix. Functional decomposition is the function of the organization for a more detailed decomposition process, the functional decomposition is to simplify the analysis of the issue, distracted and identify components and the use of the classical approach. Pine Valley furniture company in order to function in the functional decomposition example in figure 2 below. In dealing with business functions and support functions of the full set, multiple databases, is essential to a specific database therefore likely only to support functions (as shown in Figure 2) provide a subset of support. In order to reduce data redundancy and to make data more meaningful, has a complete, high-level business view is very helpful. The use of specific enterprise data model to describe the symbol. Apart from the graphical description of this type of entity, a complete enterprise data model should also include a description of each entity type description of business operations and a summary of that business rules. Business rules determine the validity of the data. An enterprise data model includes not only the types of entities, including the link between the data entities, as well as various other objects planning links. Showed that the linkage between planning targets a common form of matrix. Because of planning matrix need not be explicit modeling database can be clearly described business needs, planning matrix is an important function. Regular planning matrix derived from the operational rules, it will help social development activities that top priority will be sorting and development activities under the top-down view through an enterprise-wide approach for the development of these activities. There are many types of planning matrix is available, their commonalities are: locations - features show business function in which the implementation of operational locations. unit - functions which showed that business function or business unit responsible for implementation. Information System - data entities to explain how each information system interact with each data entity (for example, whether or not each system in each entity have the data to create, retrieve, update and delete). support functions - data in each functional entities in the data set for the acquisition, use, update and delete. Information System - target indication for each information system to support business objectives. Figure 3 illustrate a possible functions - data entities matrix. Such a matrix can be used for a variety of purposes, including the following three objectives: 1) identify gaps in the data entities to indicate the types of entities not use any function or functions which do not use any entity. 2) found that the loss of each functional entities involved in the inspection staff through the matrix to identify any possible loss of the entity. 3) The distinction between development activities if the priority to the top of a system development function for a high-priority (probably because it important organizational objectives related), then this area used by entities in the development of the database has a high priority. Hoffer, George and Valacich (2002) are the works of the matrix on how to use the planning and completion of the Information Engineering The planning system more complete description. 2 database development process Based on information engineering information systems planning database is a source of development projects. These new database development projects is usually in order to meet the strategic needs of organizations, such as improving customer support, improve product and inventory management, or a more accurate sales forecast. However, many more database development project is the bottom-up approach emerging, such as information system user needs specific information to complete their work, thus beginning a project request, and as other information systems experts found that organizations need to improve data management and begin new projects. Bottom-up even in the circumstances, to set up an enterprise data model is also necessary to understand the existing database can provide the necessary data, otherwise, the new database, data entities and attributes can be added to the current data resources to the organization. Both the strategic needs or operational information needs of each database development projects normally concentrated in a database. Some projects only concentrated in the database definition, design and implementation of a database, as a follow-up to the basis of the development of information systems. However, in most cases, the database and associated information processing function as a complete information systems development project was part of the development. 2.1 System Development Life Cycle Guide management information system development projects is the traditional process of system development life cycle (SDLC). System development life cycle is an organization of the database designers and programmers information system composed of the Panel of Experts detailed description, development, maintenance and replacement of the entire information system steps. This process is because Waterfall than for every step into the adjacent the next step, that is, the information system is a specification developed by a piece of land, every piece of the output is under an input. However shown in the figure, these steps are not purely linear, each of the steps overlap in time (and thus can manage parallel steps), but when the need to reconsider previous decisions, but also to roll back some steps ahead. (And therefore water can be put back in the waterfall!) Figure 4 on the system development life cycle and the purpose of each stage of the product can be delivered concise notes. The system development life cycle including each stage and database development-related activities, therefore, the question of database management systems throughout the entire development process. In Figure 5 we repeat of the system development life cycle stage of the seven, and outlines the common database at each stage of development activities. Please note that the systems development life cycle stages and database development steps一一对应exists between the relationship between the concept of modeling data in both systems development life cycle stages between. Enterprise Modeling Database development process from the enterprise modeling (system development life cycle stage of the project feasibility studies, and to choose a part), Organizations set the scope and general database content. Enterprise modeling in information systems planning and other activities, these activities determine which part of information systems need to change and strengthen the entire organization and outlines the scope of data. In this step, check the current database and information systems, development of the project as the main areas of the nature of the business, with a very general description of each term in the development of information systems when needed data. Each item only when it achieved the expected goals of organizations can be when the next step. Conceptual Data Modeling One has already begun on the Information System project, the concept of data modeling phase of the information systems needs of all the data. It is divided into two stages. First, it began the project in the planning stage and the establishment of a plan similar to Figure 1. At the same time outlining the establishment of other documents to the existing database without considering the circumstances specific development projects in the scope of the required data. This category only includes high-level data (entities), and main contact. Then in the system development life-cycle analysis stage must have a management information system set the entire organization Details of the data model definition of all data attributes, listing all data types that all data inter-entity business linkages, defining description of the full data integrity rules. In the analysis phase, but also the concept of inspection data model (also called the concept behind the model) and the goal of information systems used to explain other aspects of the model of consistency categories, such as processing steps, rules and data processing time of timing. However, even if the concept is such detailed data model is only preliminary, because follow-up information system life cycle activities in the design of services, statements, display and inquiries may find that missing element or mistakes. Therefore, the concept of data often said that modeling is a top-down manner, its areas of operation from the general understanding of the driver, rather than the specific information processing activities by the driver. 3. Logical Database Design Logical database design from two perspectives