 Hello everyone welcome to this session I am Priyanka Bidla and today we are going to see about system modeling and one of the type of system modeling that is context model. These are the learning outcomes of this video lecture. At the end of this session students will be able to define system model then introduce some types of UML diagram that is unified modeling language and students will be able to show how the system being placed in an environment. These are the contents we will be covering in this session now we see the system modeling it is an abstract view of system that ignores system details it represents graphically that describes the system which is to be developed they describe business process they problem to be solved and the system is to be developed. System modeling helps the analyst to understand the functionality of the system and models are used to communicate with customers and here natural language is used to write both user and the system requirements. Now recall user and system requirements before moving towards pause this video for few seconds and you have to think on the requirements. Yes there are two types of requirements first user requirements and then system requirements as I said natural language is used to write both requirements however system requirements are more detailed than the user requirements. So usually prefer natural language for user requirements and use of natural language can be confusing and difficult to understand. So for system requirements use graphical system model therefore graphical representation is preferred for system requirements now we see different system models to represent the system from different perspectives. So there are four perspectives we will see one by one perspective first external perspective where you model the context or environment of the system then interaction perspective means the interactions between a system and its environment or you can say that between the components of a system. Next the third is the structure perspective from the name we can say that model the organization of a system or the structure of the data that is processed by the system. Then last that is behavioral perspective where you can model the dynamic behavior of the system and how it responds to the events. Let us see UML diagram and their types UML stands for unified modeling language already you knew that it is object oriented language for writing software blueprints UML diagram has five types. So first is the activity diagram it shows the activities involved in a process or in data processing then next that is use case diagram it shows the interactions between a system and its environment then third type sequence diagram it shows interactions between actors and the system and the between system components also then class diagram it shows the object classes in the system and the associations between these classes there is association between class to class known as class diagram and finally that is state diagram. It shows the states means how the system reacts to internal as well as external events. So these are the total five types of UML diagram now we are moving towards context model let us see about context model first and then we will see about context model example that is mhcpms the context model shows how the system is being modeled it is placed in an environment with other system they show what lies outside the boundaries in short it shows the boundaries of system however they do not show the types of relationship between the systems in the environment and the system that is being specified. So normally they show that the environment includes several other automated systems this involves working with system stakeholders then employees to decide what functionality should be included in the system and what is provided by systems environment these decisions should be made early in the process to limit the system cost and the time needed for understanding the system requirements and design let us see the context model of mhcpms this is the example of context model the mhcpms that is mental health care patient management system it is an information system for the patient that is intended for use in clinics it consists of PRS means patient record system then admission system prescription system appointment system HC statistics system and management reporting system these systems are interconnected with each other then it forms context model of mhcpms it is simple context model that shows the patient's information system and the other system in its environment you can see that the mhcpms is connected to an appointment system and a more general patient recorded system with which it share the data then the system is also connected to system for management reporting and hospital bed allocation and a statistics system HC statistics system collects information for research and then after this finally it makes use of prescription system to generate prescriptions for patients medication this is the UML activity diagram activity diagrams are intended to show the activities that make up a system process and the flow of control from one activity to another it includes number of notations like circles rectangles rectangles with round corners arrows and solid bars we will see the details of these notations one by one so the start of a process is indicated by a field circle and the end by a field circle inside another circle the next rectangles with round corners represent activities that are the specific sub processes that must be carried out and arrows represent as usual the flow of work from one activity to another then solid bar is used to indicate the activity coordination overall it may include objects in activity charts the system that are used to support different processes now we will see the advantage and disadvantage of context model the advantage of relying on other systems for patient information is that avoid duplicating data and the major disadvantage is that using other systems may make it slower to access information and MHC PMS cannot be used if these systems are unavailable these are the references of this video lecture