tailieunhanh - business modeling with uml business patterns at work phần 5

nó có một giá trị chiến lược kinh doanh. Mô hình thông tin là một bước đầu trong việc xác định các thông tin được lưu trữ trong một hệ thống thông tin, mặc dù các chi tiết như các vấn đề cơ sở dữ liệu (ví dụ, chìa khóa, vv) không phải là một phần của mô hình kinh doanh | The expression should be read such that the holdings collection preceding the call to the operation will add the argument to its collection and the holdings collection will contain that element after the operation has been performed. Constraints Constraints govern the possible structure or the behavior of objects or processes that is the way objects are related to each other or the way object or process state changes may occur. Constraints are used to uphold the integrity of objects as they are created and their relationships are changed and to control the behavior of objects and processes. Constraints can be divided into three categories structural operational behavioral and stimulus response. Structural Rules Structural rules are applied on types and associations and specify that some conditions that regulate the structure must always hold . be true . They are typically specified as invariants on classes. They help to define the structure of the enterprise or to relate different terms to each other and express the static aspects of the business. The structural rules are often inherent in the class diagrams through the definition of associations and multiplicity. For example Figure states that a Security object can be associated to zero or more options but one option can only be associated with one specific Security object. There are many more structural rules in the class diagram or in any class diagram expressed with UML s visual annotations for multiplicity. Figure Structural rules. Other structural rules cannot be expressed in the diagrams and must be specified in OCL. For the example in Figure let s say an Option cannot refer to another Option . be an option to an option . There is no visual way to depict this in UML but it could easily be defined in OCL as context Option inv Option If options were in fact allowed to refer to other options and if one then wanted to state that an option never should be able to refer to itself