You are to produce a set of object-oriented models that represent the operations of the taxi service company described below in Problem Scenario. The graphical models are to be produced using a software drawing package such as Microsoft Visio or Microsoft PowerPoint and follow the UML Version 2.0 convention. Also describe the graphical models in plain English so that an independent reader will have a clear understanding of your models.
The specific models you are to produce are:
- Use case description and diagrams for a dispatch call from the dispatcher.
- The activity diagram for the processing of a fare payment by the passenger.
- The sequence diagram for security camera operations.
- The state machine diagram for security camera operations.
- The class diagram for all described elements of the information systems.
You will notice that not all elements of a Functional Requirements Specification have been required in this assignment. That is because the complexity involved in a full specification requires more time than you reasonably would have available to do the work.
The Empire Taxi Company is a service company that provides facilities and services to owners of taxi cabs who affiliate with Empire. The information services provided are passenger call logging and dispatch, GPS location tracking, security camera and audio logging and electronic fare payments and logging. Empire also leases to the cab owners the metering, GPS, telecommunications and call handling and response equipment in the cars.
The computerised call dispatch system is operated by a dispatcher in the Empire head office. When a passenger calls for a taxi the call handlers get a passenger name, pick up address, pick up time and destination. When the information is provided the call handler will also enter a vehicle type code and fare concession code if applicable. The default vehicle type code is standard car but options exist for station wagon, mini-bus and wheelchair taxi. Concession code applies to pensioners who receive a subsidised fare.
This information is transmitted by the dispatcher to all available taxis within a 5km radius of the pick-up address. The dispatch system identifies the taxis to receive the dispatch information from their transmitted GPS location. If no taxis are within the 5km zone then the dispatch system provides the identities of the 3 nearest taxis to the pick-up address. The first driver to send an accept message is given the dispatch information via a wireless link to a processor and touch screen in their taxi.
The fare metre in the taxi is linked to the electronic payment system (EFTPOS). If the passenger pays by credit card the fare is automatically loaded into the EFTPOS system. The payment details from the EFTPOS system are transmitted via the wireless link to Empire’s communications processor which opens a connection to the bank’s payment system. The transmissions from the bank system are retransmitted to the taxi over the wireless link. The communications processor logs the auditing details of each transaction, these being the date, time, bank BSB, card type, card number, taxi terminal identifier, operator identifier, transaction value and transaction completion status (either paid or declined). When a fare is paid in cash the driver can enter the payment amount and a cash payment code.
The in-car security system consists of a camera and an alarm button. The camera records a 5 second video and audio stream of the taxi interior to an in-car 1 TB solid state drive (SSD) every minute. This stream is compressed and tagged with the date, time, GPS location, alarm status and vehicle identifier. If the vehicle alarm is activated the video and audio commence and the instantaneous video and audio streams, with the tagging information, are transmitted to Empire until the alarm is de-activated by the driver. These streams can be switched to play on a monitor in the security office and are simultaneously recorded to disc at Empire’s head office.
The in-car GPS location system operates continuously and provides location information every 10 seconds to the in-car security system and, by radio transmission, to the central dispatch system. The dispatch system holds the GPS location information in order to find the taxis for dispatching.
Every day at 11:55pm the fare management system at Empire reports the last 24 hours fare payments for each taxi cab and sub-totals them by payment type by driver. It also provides a time-stamped log of every transaction.