Sequence Diagrams Essay

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Home appliance control system Sequence Diagram To operate the HAC System, user needs to operate each home appliance either by direct contact or by a remote control system. Sequence Diagram will explain the operation by a remote control system. To connect to the remote system, user needs computer embedded communication devices such as a cell phone, a PDA, or a laptop computer. The Home appliance control system is controlled either by a cell phone or a by palm top or by a PC. They are connected either through wireless application protocol (WAP), the Internet, or intranet. It controls various appliances such as a microwave, TV etc. The HACS system receives commands from remote devices that are manipulated by user. The system in turn dispatch commands to respective appliances that will perform the actions. HACS is responsible for keeping track of the states of the devices. If something goes wrong, it will notify the user by sending messages back to the remote devices as well as emergency department if necessary. The following picture gives an overview of how this system is going to work. [pic] 1 Authentication [pic] Flow of events: 1. After user connects the remote system, user needs to log on to the system using valid username and password. • A logon attempt shall limited to 3 times for security precaution. 2. After all use of the system, user shall log out the system and communication between user and remote system is disconnected. 2 Operate TV [pic] Flow of events: 1. After user log onto the system, remote system asks HACS controller a list of appliances. 2. User simply chooses the TV from the appliance list. 3. Remote system asks the command list of a TV. 4. HACS controller asks a TV a list of commands. 5. A garage door returns the list of commands to the HACS controller then HACS controller

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