System Modeling
- 1. Lecture Five System Modeling Assistant Lecturer Huda A. Alameen hudaa.alameen@uokufa.edu.iq
- 2. System modeling is the process of developing abstract models of a system, with each model presenting a different view or perspective of that system. System modeling has now come to mean representing a system using some kind of graphical notation, which is now almost always based on notations in the Unified Modeling Language (UML). System modelling helps the analyst to understand the functionality of the system and models are used to communicate with customers. Introduction
- 3. The Unified Modeling Language (UML) is a general purpose, developmental, modeling language in the field of software engineering, that is intended to provide a standard way to visualize the design of a system. The elements are like components which can be associated in different ways to make a complete UML pictures which is known as diagram. So it is very important to understand the different diagrams to implement the knowledge in real life systems. Unified Modeling Language
- 4. UML diagram types Activity diagrams, which show the activities involved in a process or in data processing . Use case diagrams, which show the interactions between a system and its environment. Sequence diagrams, which show interactions between actors and the system and between system components. Class diagrams, which show the object classes in the system and the associations between these classes. State diagrams, which show how the system reacts to internal and external events.
- 5. System Modeling You may develop models of both the existing system and the system to be developed Models of the existing system are used during requirements engineering. Models of the new system are used during requirements engineering to help explain the proposed requirements to other system stakeholders. You may develop different models to represent the system from different perspectives.
- 6. System Modeling UML Five Diagram Types 1. Activity diagrams 2. Use case diagrams 3. Sequence diagrams 4. Class diagrams 5. State diagrams
- 7. Context Models Context models are used to illustrate the operational context of a system - they show what lies outside the system boundaries. Social and organizational concerns may affect the decision on where to position system boundaries. Architectural models show the system and its relationship with other systems.
- 8. System boundaries System boundaries are established to define what is inside and what is outside the system. They show other systems that are used or depend on the system being developed. The position of the system boundary has a profound effect on the system requirements. Defining a system boundary is a political judgment There may be pressures to develop system boundaries that increase / decrease the influence or workload of different parts of an organization.
- 9. The context of the Mentcare system where an automated system is replacing an existing manual or computerized system, the environment of the new system is usually the same as the existing system’s environment.
- 10. Interaction models All systems involve interaction of some kind. This can be user interaction, which involves user inputs and outputs, interaction between the system being developed and other systems or interaction between the components of the system. 1. External Interaction 2.Internal Interaction Use case modeling, which is mostly used to model interactions between a system and external actors (users or other systems). Sequence diagrams, which are used to model interactions between system components, although external agents may also be included. Note:- Use case models and sequence diagrams present interaction at different levels of detail and so may be used together.
- 11. Use Case Modeling Each use case represents a discrete task that involves external interaction with a system. A use case is shown as an ellipse with the actors involved in the use case represented. Notice that there are two actors in this use case: the operator who is transferring the data and the patient record system. The stick figure notation was originally developed to cover human interaction but it is also now used to represent other external systems and hardware. Formally, The arrows in the UML indicate the direction of flow of messages.
- 12. A use case in the Mentcare system
- 13. Tabular description of the ‘Transfer data’ usecase MHC-PMS: Transfer data Actors Medical receptionist, patient records system (PRS) Description A receptionist may transfer data from the Mentcase system to a general patient record database that is maintained by a health authority. The information transferred may either be updated personal information (address, phone number, etc.) or a summary of the patient’s diagnosis and treatment. Data Patient’s personal information, treatment summary Stimulus User command issued by medical receptionist Response Confirmation that PRS has been updated Comments The receptionist must have appropriate security permissions to access the patient information and the PRS.
- 14. Use cases in the Mentcare system involving the role ‘Medical Receptionist’
- 16. Sequence diagrams Sequence diagrams in the UML are primarily used to model the interactions between the Actors and the Objects in a system and the interactions between the objects themselves. A sequence diagram shows the sequence of interactions that take place during a particular use case or use case instance.
- 17. Mechanisms The objects and actors involved are listed along the top of the diagram, with a dotted line drawn vertically from these. Interactions between objects are indicated by annotated arrows. The rectangle on the dotted lines indicates the lifeline of the object concerned (i.e., the time that object instance is involved in the computation). You read the sequence of interactions from top to bottom. The annotations on the arrows indicate the calls to the objects, their parameters, and the return values.
- 18. Sequence diagram for View patient information
- 19. Structural Models Structural models of software display the organization of a system in terms of the components that make up that system and their relationships. Structural models: 1.Static Model 2.Dynamic Model
- 20. Class diagrams Class diagrams are used when developing an object-oriented system model to show the classes in a system and the associations between these classes. When you are developing models during the early stages of the software engineering process, objects represent something in the real world, such as a patient, prescription, a doctor, etc. As an implementation is developed, you usually need to define additional implementation objects that are used to provide the required system functionality.
- 22. OOR(Object Oriented Relationship) There are two Kinds of Relationship: 1.Generalization 2.Association(Aggregation and Composition )
- 23. Generalization
- 24. Association