UML reference manual
Part II Based Overview
Chapter 11 Extended Machine 11.1 Overview UML provides several expansion mechanisms, allowing the modeling to make some universal extensions without changing basic modeling languages. These expansion mechanisms have been designed to facilitate storage and use without understanding all semantics. For this reason, the extension can be stored and used as a string. For tools that do not support extension mechanisms, the extension is just a string, which can be imported as part of the model, stored, and can also be passed to other tools. We expect backend tools to design a variety of expansions that define specific syntax and semantics for extended extensions. This extension method is likely to not meet a variety of requirements, but it holds most of the modes of the UML Trend in a simple manner that is easy to implement. The expansion mechanism includes constraints, labeling values, and constructors. Be sure to remember that the expansion is a standard form of violations of UML and uses them to cause interactions. The modeling should be carefully weighted and consideration before using the expansion mechanism, especially when the existing mechanism works reasonably. Typically, extended for specific application domains or programming environments, but they have led to the emergence of UML dialects, including all dialects and disadvantages. 11.2 Constraint constraints is a semantic limit represented by a text expression. Each expression has an implicit interpretation language, which can be formal mathematical symbols, such as set-theoretic represents symbols; or a computer-based constraint language, such as OCL; or a programming language, such as C ; or pseudo code or informal natural language. Of course, if this language is informal, its explanation is also informal, and it is to be explained by people. Even if the constraint is represented by a formal language, it does not mean that it is automatically constrained. Constraints may indicate constraints and relationships that cannot be expressed by UML representation. The constraint is particularly useful when statement of global conditions or affecting the conditions of many elements. Constraints are represented by string expressions in a large bracket. The constraint can be attached to the table element, dependence, or notes. Figure 11-1 shows several constraints. Figure 11-1 Constraint 11.3 Tag value tag value is a pair of strings - a tag string and a value string - stores some information about elements. The tag value can be associated with any independent element, including model elements and expression elements. The tag is the name of some of the characteristics you want to record, and the value is the value of the feature of the given element. For example, the tag can be Author, and the value is the name of the person responsible for the element, such as Charles Babbage. The tag value can be used to store any information of the element, which is especially useful for storage project management information, such as elements, development status, deadline, and test status. In addition to the internal meta-model attribute, any string can be used as a tagname (this is because tag and attributes are considered to be an elementality of an element and can be accessed together by the tool), and some tagnames have been predefined. See Chapter 14). The tag value also provides a way to link an additional information independent of the implementation with an element. For example, the code generator needs additional information about the code type to generate a code from the model. Typically, there are several ways to correctly implement the model, and the modeling must provide guidance. Some tags can be used to tell which implementation of the code generator. Other tags can be used to join tools, such as project plan builders and report writers. The tag value can also be used to store information about the constitutive model element (we will discuss below). The tag value is represented by a string, and the string has a tagname, the equal number, and a value. They are placed in a crosbit (as shown in Figure 11-2). The bid value in the chart is often omitted, only in the drop-down table. Figure 11-2 Tag value 11.4 Structure type Many modeling modes wish to make a modeling language for a particular application domain, bringing some risks, because the language of the scrimming is not easy to understand, but people still try Do this.
