1. State Machine Models are used to model the operation and behavior of a system.
2. The Behaviour of the system is analyzed with respect to its response to internal or external events.
3. The events often cause the system to move to different states.
4. The state machine model shows system states and events that cause a transition from one state to another.
5. However, the flow of data within the system is not shown in this model.
6.state machine models are widely used in modeling real-time system as these systems are driven by stimuli from the systems environment.
7. The model assumes that, at any given time, the system is in one of the possible states.
8. A stimulus triggers a transition to a different state.
9. The problem arises when the number of possible states is more as may happen in large system models.
10. This may require some restructuring of the state models.
11. One of the possible solutions to this problem is the concept of a superstate encompassing a number of separate states.
12. The superstate is treated as a single state on a high-level model but is expanded in detail as a separate diagram.
13. The UML notation can be used for any type of state machine modeling.
14. The rounded rectangles in a model represent system states.
15. They include a brief description of the actions taken in that state.
The waterfall model:
1. The waterfall model remains one of the oldest strategies ever applied in the development of software.
2. It is also known as the classic life cycle model which divides the entire software development process into five main phases.
3. This forms the initial phase of the software development process where we obtain the customer requirements and prepares the customer requirement specification with only valid and realistic requirements usually all the stakeholders are called and vision of end product is acquired and documented.
4. Hence, we can say that there are two important facts about this phase.
5. Essay to understand even for a non-technical person end users.
6. It is enforced to displayed approach phases and processes in well-defined inputs and outputs.
7. For example, input to the system design stage is requirement specification document and output is the design document.
8.Easy to use as software development proceeds.
9. It helps to project manager in early project planning and scheduling.
10. Each stage has well-defined deliverables or milestones.
11. Testing is inherent in every phase of the waterfall model.
12. Verification at each stage ensures early detection of errors and warnings.
13. It is documentation driven, documentation is produced at every stage and it is easy to understanding for the users/customers.
14. Though the above software development process looked quite straight forward, it is now rarely used.
15.Even the organizations which remained loyal to this strategy raising serious objections which added to the failure of this strategy.
16. Customers are involved in the project during the customer requirement phase only.
17. If the customer addresses dissatisfaction after delivering the project, this would definitely cost high to the organization.
18. We just cannot expect that the customer reveals his requirement in one stroke.
19. The project cannot be developed linearly completion of one phase leading to the initiation of others but cannot redirect to the previous phase if the only failure occurs.
20. This is a time-consuming process, and also such a process leads to heavy confusion among project members. such projects cannot be truly tested or debugged.