The Relationships in the Unified Modeling Language - Essay Example

UML: Unified Modeling Language The Unified Modeling Language (UML) is a standard graphical language used for specifying, visualizing, constructing, and documenting the artifacts of software systems as well as non-software systems, and for business modeling purposes. Being a standard language for writing software blueprints, the UML represents a collection of best engineering practices that has proven successful in the modeling of large and complex systems. It is exclusively used to visualize, specify, construct and document the artifacts of a software-intensive system, and is appropriate for modeling systems ranging from enterprise information systems to distributed Web-based applications and even to hard real time embedded systems. It is a highly expressive language, addressing all the views needed to develop and deploy such systems. The UML has gained substantial industry support from various organizations through the UML Partners Consortium and has been approved by the Object Management Group (OMG) as a criterion. The UML provides the rules and the vocabulary for conceptual and physical representation of a system. Additionally, UML renders the guidelines to create and read well-formed models of systems. Employing UML, application architects and programmers can make a blueprint of a project that visualizes the relationship between elements of software, which in turn makes the actual development process of the software easier. The originator of UML, the Rational Rose from Rational Software, is the most popular visual modeling tool. The UML is a modeling language that focuses on capturing, communicating and levering knowledge. However, the UML is not restricted to modeling software systems; it can also be utilized for modeling non-software systems. It helps in visualizing a system in that it can be used to visually depict a system before it is deployed. It helps in specifying systems in that it addresses "what" is required of system, and "how" the system may be deployed. By constructing a system, UML applies for guiding the realization of a system similar to a "blueprint", and by documenting a system UML applies for capturing knowledge about a system throughout its development (Xpdian.com, 2009). Relationships in UML: 1. Dependency: It is a semantic relationship between two things in which a change to one thing (independent element) may affect the semantics of another thing (dependent element). Graphically, a dependency is rendered as a directed dashed line, including labels. 2. Association: It is a structural relationship that describes a asset of links, a link being connection among objects. Graphically, an association is rendered as a directed solid line, including a label, and often containing adornments like multiplicity, role names, etc. 3. Generalization: It is a specialization/generalization relationship in which objects of the specialized element (child) can be substituted for objects of the generalized element (parent). Graphically, a generalization is rendered as a solid line with a hollow arrowhead pointing to the parent. 4. Realization: It is a semantic relationship between classifiers, in which one classifier defines a contract that another classifier guarantees to execute. This relationship is seen in two places, between interfaces and the classes or components that realize them, and between use cases and collaborations that realize them. Graphically, a realization is rendered as a cross between generalization and a dependency relationship (Xpdian.com, 2009). UML defines nine types of diagrams: Class Diagrams: Class diagrams are the backbone of every object oriented method, including UML, and are most common diagrams found in modeling object oriented systems. Class diagrams address the static view/ structure of a system. Object Diagrams: Object diagrams represent static snapshots of instances of the things found in class diagrams. In other words, these diagrams describe the static structure of a system at a particular time. They are designed to test class diagrams for accuracy. Use Case Diagrams: Use case diagrams are used for organizing and modeling the behavior of a system. They model the functionality of a system using use cases and actors. They address the static use case view of a system. Sequence and Collaboration Diagrams: Both sequence and collaboration diagrams are kinds of interaction diagrams. Interaction diagrams address the dynamic view of a system. A sequence diagram is an interaction diagram in concerned with the time ordering of messages among classes. A collaboration diagram focuses on the structural organization of the objects that send and receive messages. Both sequence diagrams and collaboration diagrams are isomorphic, i.e. you can take one and transform it into another. State Chart Diagrams: State chart diagrams address the dynamic behavior of a system in response to external stimuli. In other words, these diagrams are particularly useful in modeling responsive objects whose states are triggered by specific events. Activity Diagrams: An activity diagram is a special kind of a state chart diagram that shows the flow of control from activity to activity within a system. They address the dynamic view of a system, and important in modeling the function of a system illustrating the flow of control among objects. Component Diagrams: Component diagrams address the static implementation of a system, and describe the arrangement of physical software components such as source code, run-time (binary) code, and executables. Deployment Diagrams: Deployment diagrams show the configuration of run-time processing nodes and the components that live on them. They address the static deployment view of the system architecture, depicting the physical resources in a system including nodes, components, and connections (SmartDraw.com, 2009). Due to the increasing demand in strategic value of software in many companies, industries look for numerous techniques, to automate the production of software and to improve quality and reduce cost and time-to- market, including visual programming, component technology, patterns and frameworks. Business enterprises also seek techniques to handle the complexity of systems as they continually increase in scope and scale. Particularly, they identify the demand to solve architectural problems, such as concurrency replication, physical distribution, load balancing, fault tolerance and security. In addition to this, the development of the World Wide Web has worsened these architectural problems. Therefore, the Unified Modeling Language (UML) was designed and developed in order to respond to these diverse needs (Xpdian.com, 2009). Advantages of the DMBS approach to application development: Database Management System embeds numerous features to assist the development process of diverse applications. Firstly, application programs must be as independent as possible from details of storage and data representation. The DBMS efficiently provides an abstract view of the data to isolate application source code form such details. Secondly, a DBMS embraces and utilizes a variety of advanced techniques to store and retrieve data easily. This feature is of highest importance especially if the data is being stored on external storage devices. Thirdly, if the data is always read through the DBMS, the DBMS may impose integrity constraints on the data. For instance, prior to inserting the salary information for an employee, the DBMS may check whether the department budget is not being exceeded. Additionally, the DBMS may also impose access controls that govern what data is visible to different classes of users. Fourth advantage is when multiple users share data, centralizing the administration of data can offer significant advancements. Programming experts, who understand the quality of data being managed, and how different groups of users use it, are responsible for organizing the data representation to minimize redundancy and to return the storage of the data to make its retrieval efficient (eStudents.co.cc, 2001). A DBMS agendas concurrent accesses to the data in such a way that users can think of the data as being accessed by only one user at a given instant of time. Furthermore, the DBMS also protects users from the effects of system failures. And lastly, the DBMS distinctly offers support to many important functions that are common to many applications that access data stored in the DBMS. This, in alliance with the high-level interface to the data, urges quick development of applications. Such applications are likely to show more robustness than applications developed from scratch, since many significant tasks are managed by the DBMS instead of being implemented by the application (eStudents.co.cc, 2001). References 1. eStudents.co.cc. (2001). ADVANTAGES OF A DBMS. Retrieved October 23, 2009, from http://estudents.co.cc/database-management-systems/advantages 2. SmartDraw.com. (2009). What is UML. Retrieved October 22, 2009, from http://www.smartdraw.com/resources/tutorials/Introduction-to-UML 3. Xpdian.com. (2009). What is the UML. Retrieved October 23, 2009, from http://www.xpdian.com/WhatistheUML.html Read More