Using rational rose and UML to develop Java EE application (i)

Objective

The key to successfully using Java EE to build enterprise applications is the same as all complex software platforms: Effective communication of requirements, formulation of correct analysis and design decisions, and identification of the best implementation options.

Companies that pursue the best visualization models can develop their software faster and build higher-quality systems. Unified Modeling Language (UML) is a visual modeling software industry standard.

Here, we'll show you how to use UML and rational Rose 2001a, the most popular UML-based software modeling and development tool that can be used to develop business applications based on Java EE.

What is UML?

Unified Modeling Language (UML), which began in 1997 as an OMG standard, is a graphical language that supports modeling and software development, providing modeling and visualization support for all phases of software development, from requirements analysis to specification, to construction and configuration.

Using UML as a visualization model is mainly to understand the important details of the system so that the requirements of the project can be clearly expressed, the solution system developed, and a choice of implementation can be clearly identified and constructed. In order to achieve this goal, rich symbols are needed to express the model software system. UML Not only provides symbolic representation for basic building blocks, but also provides methods to express complex relationships between basic building blocks. These relationships are expressed in the form of UML diagrams.

Let's take a look at how UML and rational rose help to understand, design, and implement Java EE applications.

Understand the needs

The reason for the failure of the project is usually that the requirement is not well understood or communicated. It is also easy to understand that both verbal and written languages are not rigorous.

You can use the UML use case model to develop an accurate model to represent the requirements of the system, and then use them as a basis to drive other aspects of system development. The use case acts as if it were a line on a necklace that binds all the pearls together. Use cases establish a bridge between the final user and system requirements. They can be used to backtrack between functional requirements and the system implementation itself. A use case can also be used as a connection point to connect to a detailed use case document that describes the requirements details.

Figure 1 shows a partial use case diagram of an online CD store that is extracted from both text and verbal functional requirements and then into use cases. In this example, it is obvious that the purchaser (a character made up of several lines, represented as a role in UML) can use the system in 4 ways (in UML to represent a use case).

Figure 1********

A simple use-case diagram

Each use case is precisely described by one or more scenes in the sequence diagram. Of course, in the early stages of demand capture and analysis, sequence diagrams are relatively simple and may not be complete. An example of a sequence diagram is shown in Figure 2. In rational rose, to create a sequence diagram for a use case, you can select it in the browser and choose New>sequence Diagram from the use Case menu.

Figure 2************

A sequence diagram to explain a paid use case