Instructions:
Data Structures and Algorithms: Final Online Assessment Due: 31st May 2021 from 18:00 to 1st June 18:00
25 Marks Possible
Before attempting this question, you should have sat the multichoice questionnaire worth 75 marks on Blackboard. Create a new project called “Practical Assessment”. Download the file from the Practical Assessment folder on Blackboard and build the solution into your Netbeans project (or other IDE alternative). When submitting, make sure you zip up the entire src folder with the following structure; lastname_firstname_studentID.zip (using your own name and ID) and submit to the Practical Assessment folder on Blackboard BEFORE the due date and time (18:00 pm (1st June)). Late submissions will not be accepted. Anti-plagiarism software will be used on all assignment submissions, so make sure you submit YOUR OWN work and DO NOT SHARE your answer with others. Any breaches will be reported and will result in an automatic fail of the course.
Question – Factory Simulator (25 marks); Recommended Readings –Chapters 1.3, 1.4, 3.2, 4.4
The purpose of this question is to create a factory simulator – a multi-threaded program which uses the producer-consumer design pattern. A Machine can run as a thread and connects to a ConveyorBelt, once connected it creates Parcel obects to post to the belt. The ConveyorBelt encapsulates a priority queue which keeps parcels in order of their Comparable. A Dispatcher also running as a thread connects to an available ConveyorBelt, once connected it can retrieve Parcel objects. Both the Machine and Dispatcher can monitor several conveyor belts, but should only connect to one at a time. Each ConveyorBelt can only hold a limited amount of Parcel objects.
Each parcel is instantiated with a generic element, a priority, colour and a consumeTime – the time it takes to process this parcel. During creation of the Parcel, a timestamp is set (in nano second time) to indicate its creation time. A Parcel is Comparable so can be compared with another Parcel even though they might hold a different generic. The ordering is determined firstly by priority and secondly via creation time (timestamp). The class also has a toString which prints out the element and priority in parenthesis, and a consume function, which sleeps the calling code for the duration specified by the parcels consumptionTime. A Parcel can also be drawn with a Graphics object and method parameters as shown below. The specified x,y pixel coordinate represents the top left corner of the drawn box and width and height parameters determines its dimension.
The conveyor belt holds a maximum capacity of parcels in which it holds. It cannot exceed this capacity which is given to the constructor. A default capacity of 10 is used if no max capacity is specified during construction. The ConveryorBelt only allows one Machine and one Dispatcher to connect to it at a time (using a null if there is none currently connected). Only the currently connected Machine can post parcels to the conveyor belt (if not full) and only the currently connected Dispatcher can get and retrieve parcels from the conveyor belt (if any). A connected machine or dispatcher should pass themselves in as reference when posting/retrieving parcels so that the ConveyorBelt can check if they are currently connected or not. A ConveyorBelt can also be drawn with a Graphics object and the given method parameters. The specified x,y pixel coordinate represents the top left corner of the belt and width and height parameters determines its full dimension. The entire belt is drawn with or without parcels. If the belt has a connected dispatcher or machine, it should draw them as circles on each side of the belt. The example belt below has a capacity of 5, but only has 3 parcels in it with a connected dispatcher but no connected machine.
Note: As a ConveyorBelt is shared between many threads, it should be made “thread safe” so no race conditions arise in the simulator.
Part C: Create a class called Machine that runs continuously as a thread until requested to stop. When a machine is instantiated an array of ConveyorBelt objects should be passed into its constructor. It also holds the following public static variables: MIN_CONSUMPTION_TIME, MAX_CONSUMPTION_TIME, MIN_PRODUCTION_TIME and MAX_PRODUCTION_TIME. Set these initially to something suitable.
While a Machine is running, it should constantly circulate the ConveyorBelt objects that it is monitoring. If it comes across an available belt that is not full, it should try connecting to it. If the belt is full or it is unable to connect (as perhaps another machine is already connected), it simply moves on to the next ConveyorBelt in the array and repeats. If the machine successfully connects, it then starts posting Parcel objects to it. Before creating each parcel, the Machine must sleep for a random duration between min and max production time variables. A Machine should create a Parcel with a random colour, a random priority (between 1-3), a random letter (between A-Z) for its element and a random consumeTime (between min and max consumption time variables) – all passed into the Parcel constructor. Once the Machine detects that the ConveyorBelt becomes full, it should disconnect from the belt and then repeat the entire process by trying to connect to the next ConveyorBelt in the array.
Create another class called Dispatcher which also runs continuously as a thread until requested to stop. It has a similar behaviour to Machine, monitoring an array of ConveyorBelt objects passed into the constructor. However, its behaviour is slightly different. Once again, a Dispatcher will try to successfully connect to a ConveyorBelt if it is not empty and does not already have an existing Dispatcher connected to it. If it connects successfully it gets a Parcel from the ConveyorBelt and calls the consume method on it – effectively sleeping the thread for the parcels specified consumeTime. Once consumed it retrieves/removes the parcel from the belt and disconnects – repeating the process by moving to the next available ConveyorBelt in the array. Note, the Dispatcher only removes a single Parcel from the belt per connection, whereas the Machine posts multiple parcels until the belt is full per connection.
Part D: Finally, make a GUI called FactorySimulatorGUI which demonstrates an animated visual of the system. It should create FIVE ConveyorBelt objects of capacity eight. It should also maintain a List of Machine objects and a separate List of Dispatcher objects. It should have JButtons to add and remove Dispatcher or Machine threads. It should also have a JLabel which specifies the amount of current machine and dispatcher threads actively running. It also should have two JSlider’s which can adjust the MAX_CONSUMPTION_TIME or MAX_PRODUCTION_TIME static values effectively increasing the range of random duration that either the Machine takes to produce a Parcel or a Dispatcher takes to consume the Parcel. An example screenshot of a working FactorySimulatorGUI is shown below with two connected Dispatcher objects (blue) and one connected Machine object (red) monitoring the same five ConveyorBelt objects, each containing randomly coloured parcels with assigned priority numbers.