School of Engineering and Information Technology
ITECH7410 - Software Engineering Methodologies Assignment 2, 2018/17Assignment 2 – Formal System
SpecificationOverviewThe purpose of this assessment is to provide students with the opportunity to apply knowledge and skills developedduring the semester with particular reference to the formal specification of a system through the use of Z notation.Students complete the assignment in groups of two.
As described in this course’s third study guide, Software Analysis, Modelling and Specification, a FormalSpecification (Technique) is one that has a rigorous mathematical basis and one of its advantages is that it can bemathematically checked for completeness. The course’s fourth study guide, System and Software Design, alsostates that by using formal methods it is possible to derive a formal design from a formal specification and then beable to prove that the design and specification are functionally equivalent.
Your text, Software Engineering: A Practitioners Approach (Pressman, 2010) indicates that formal methods provideframeworks that allow people to specify, develop and verify systems in a structured and systematic way and that themathematical based specification language used in formal methods ensures a greater chance of consistency,completeness and lack of ambiguity in a specification. Pressman also discusses formal specification languages andtheir common components – syntax, semantics and sets of relations. Of the four formal specification languages heidentifies – OCL, LARCH, VDM and Z – he provides useful discussion with respect to OCL and Z.
In this assignment, you will use the Z specification language to provide the sets, relations and functions in schemasto specify the Container Control System (CCS) described below. Your schemas should provide the stored data thatthe system accesses and alters and identify the operations that are applied to change the state as well as therelationships that occur within the system. Remember, as specified in Spivey’s 2001 text, The Z Notation: AReference Manual, schemas are utilized to illustrate both static and dynamic aspects of a system. Static aspectsinclude such things as the states a system occupies and the invariant relationships that continue to exist as thesystem moves between states. Dynamic aspects include the changes of state that occur, possible operations andthe relationships between their inputs and outputs. Remember also you should always be conscious of the fact thata specification tries to describe what the system must do without saying how it is to be done (Spivey, 2001).
Keep all the above in mind as you read the following information. You are required to create a set of Z schema thatadequately describes the CCS. Your assignment should include at least one state space and provide schema for theprescribed functions (including error handling) described below.Page 1 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17Timelines and ExpectationsMarks: Assignment will be assessed based on a mark out of 100
The following information is a summary from your Course Description:Percentage Value of Task: 20% of the course marksDue: Week 11, Friday 4:00pm(21/09/2018)
Minimum time expectation: 20 hours (per student)
This is a group assignment. Groups must contain two students.
Learning Outcomes AssessedThe following course learning outcomes are assessed by completing this assessment:S1. Critically analyse and use complex decision making to research and determine the appropriateSoftware Engineering tools and methodologies to utilize in a given situationS2. Apply professional communication skills to support and manage the engineering of a large softwaresystemS3S4A1A2Review, critically analyse and develop artefacts to define processes for quality assurance, riskmanagement and communication in large software development projectsImplement quality assurance activities in order to verify user requirements and validate designdecisionsAnalysis of a large system development problem to decide upon the best methodological approachDevelopment of appropriate artefacts to support and manage the software engineering process suchas change control and configuration managementRequirementsDemonstrate an understanding of particular concepts covered in lectures, tutorials, laboratories and reading toprovide the specification requested. This may require further reading and research beyond the material discussed inclass.Page 2 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
School of Engineering and Information TechnologyITECH7410 Software Engineering Methodologies Assignment 2, 2018/17Assessment Details
This assignment will be assessed by your lecturer/tutor. The assignment requires you to produce a formalspecification containing the components identified below.Background – Container Control System (CCS)
As a Software Engineering consultant, your task is to develop a formal specification in Z for the Container ControlSystem (CCS). The CCS is a new computerized system to be developed for the storage and handling of accountsfor freight companies and truck container deliveries/pickups to/from the Port of Melbourne (PoM) container terminals.
This system could be quite complicated. However, to simplify the system for this assignment only the following detailwill be included in the proposed system (we do not for example track individual containers but only truck deliveriesand pickups and ship loading and unloading and we assume one container size only (standard twenty-footequivalent unit (TEU)):
Container Terminal
The PoM currently has four container terminals in Melbourne but the system must be written to seamlessly handle atleast twice that number.Each terminal has a unique name and storage capacity (in number of containers and tonnes) that must be stored inthe proposed system.
The system must maintain the current tonnage and current number of containers in the container terminal.
When the container terminal is full no further deliveries of containers can be made to that container terminal and nounloading of containers from ships can occur before some are loaded onto a ship for shipping to their destination orsome are picked up by trucks and taken away from the terminal.
Only five trucks can deliver into a particular container terminal at any one time and only five trucks can pick upcontainers from the container terminal at any one time. During busy times each container terminal maintains twoqueues of trucks - waiting to deliver and waiting to pick up.
Trucks wanting to deliver should only be entered into the waiting queue when there is sufficient room in the containerterminal for all the container(s) that the truck holds i.e. the system needs to know that the current storage plus all theloads currently in the queue will not exceed the container terminal’s capacity tonnage or number of containerscapacity.Page 3 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17For simplicity, we will say that a berth is always available for a ship to load or unload.
A container terminal cannot load more containers onto a ship than are currently stored at the terminal.A container terminal cannot unload more containers from a ship than there is available space at the terminal.When a container terminal is loading containers onto a ship, operational and safety considerations dictate that notrucks can deliver any containers to that container terminal (i.e. they must wait in the delivery queue).The system willensure that all deliveries and pickups currently executing are completed before loading starts.
Similarly when a container terminal is unloading containers from a ship, operational and safety considerations dictatethat no trucks can pick up any containers from that container terminal (i.e. they must wait in the pickup queue). Thesystem will ensure that all deliveries and pickups currently executing are completed before unloading starts.
Trucks
The system maintains a list of registered trucks, their registration, owner and their empty weight (in tonnes).
As each loaded truck arrives at the container terminal, it is weighed to ascertain the weight of the containers on thetruck. This is calculated as the difference between the weight of the loaded truck and its empty weight. The numberof containers on the truck is also registered.
If there is sufficient room in the container terminal then the container(s) are placed in the container terminal and arecord is kept of the number and tonnage delivered against both the truck registration number and the freightcompany providing the container(s).
When container(s) are placed on a truck to take them away from the terminal, the truck is weighed to ascertain theweight of the containers on the truck and the number of containers taken away is also recorded.Freight Companies
The system will maintain a record of each freight company that assigns trucks to deliver containers to the containerterminal and also each freight company that allocates trucks to pick up containers from the terminal.Details to be kept include the freight company’s name, address and phone number.
Ships
The system will keep a record of all ships that have been registered to load or unload containers for the PoM.The ship’s name, nationality (flag) and capacity (in number of containers and tonnes) will be stored.Page 4 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17The ship's captain can specify the number of containers and the tonnage to be loaded/unloaded onto/from the ship.
When loading a ship, the number of containers and tonnage to be loaded cannot be greater than the ships capacityand cannot be more than the available number of containers and tonnage in storage. The ship cannot load until allcurrently executing deliveries and pickups have completed (any new truck deliveries and pickups are placed in theappropriate queue). The system will keep a record of the number of containers and tonnage loaded onto the shipand adjust the remaining storage capacity in the container terminal and ship appropriately.
When unloading a ship, the number of containers and tonnage to be unloaded cannot be greater than the remainingstorage capacity in the container terminal. The ship cannot unload until all currently executing deliveries and pickupshave completed (any new truck deliveries and pickups are placed in the appropriate queue).The system will keep arecord of the number of containers and tonnage unloaded from the ship and adjust the remaining storage capacity inthe container terminal and ship appropriately.
Date and Time
Normally the date and time of each operation (truck delivery, truck pick up, ship loading, ship unloading) would berecorded. However to simplify this assignment those aspects will be ignored. Instead, a sequential count of eachoperation for each container terminal should be kept. Therefore, there should be a history of the order of truckdelivery, ship loading, ship unloading and truck pickup operations that take place for each container terminal. Thereis also a need to keep track of the operation order between terminals. Therefore a global sequential number of theoperations at terminals should be kept as well
The system would be able to say for example, that at container terminal SWANSON, count 999 involved the deliveryof 2 containers of 3.5 (1.5 and 2.0) tonnes respectively by the truck registered AAA203 (owned by Gunner Myson)from freight company Freight’s Rates. The global operation 12337 at WEBB was a container pickup of 1 containerweighing 2.0 tonnes by a truck with registration ABA713 and requested by the On The Way freight company. Thenext operation at SWANSON, with Global No of 12340 and Count of 1000 was a Pickup of 2 containers weighing 2.5tonnes for the Container Carriers freight company. Global event number 12338 occured at VICTORIA and it was theun-loading of 2000 containers weighing 3500.0 tonnes from the Southern Star container ship and Global eventnumber 12339 at APPLETON was the loading of the Liberian Princess container ship with 1500 containers weighingin total, 2000.0 tonnes. Sometime and some events later, Global event number 12500 at VICTORIA with a count of650 was the loading of the Southern Star with 1200 containers at 2500.0 total tonnage.The following table gives an example of this record of events:Page 5 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17Global No ContainerTerminalCount Operation VehicleIdentifierQty Tonnes FreightCompany12336 SWANSON 999 Delivery AAA203 2 3.5 Freight’sRates12337 WEBB 555 Pickup ABA713 1 2.0 On TheWay12338
VICTORIA
600
Un-Load
Southern Star
2000
3500.0
12339 APPLETON 750 Load LiberianPrincess1500 2000.012340 SWANSON 1000 Pickup QWE810 2 2.5 ContainerCarriers…
…
…
…
…
…
…
…12500
VICTORIA
650
Load
Southern Star
1200
2500.0
…
…
…
…
…
…
…
…...
Assessable Tasks/Requirements
You are to create a set of Z schemas that adequately describes the CCS. It should include at least one state spaceand the following operations:• An initialization operation called Init.
• An operation Enter_new_container_terminal that an operator uses to enter the details of a new containerterminal into the system. Assume the new container terminal is currently empty.• An operation Accept_delivery that an operator uses to signal to the system to begin delivery (placing in thecontainer terminal) of x quantity and y tonnes of containers from a truck. Note that the system must do acheck to see if that storage capacity is available in the container terminal. If it is not then an error messagemust be output and no truck delivery occurs. Additional information needed by this routine is the truckregistration and the freight company’s name. If successful, this operation stores all necessary details into thesystem for that delivery. If five trucks are already delivering then this new truck will be placed in a queuewaiting for its turn to deliver.
• An operation Accept_pickup that an operator uses to signal to the system to begin pickup (placing on thetruck) of x quantity and y tonnes of containers from the container terminal. Additional information needed bythis routine is the truck registration and the freight company’s name. If successful, this operation stores allnecessary details into the system for that pickup. If five trucks are already picking up then this new truck willPage 6 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17be placed in a queue waiting for its turn to pickup.
• An operation Leave_delivery_queue. This operation is run by the system operator each time there is adelivery queue for a container terminal and the driver of a specified truck decides that the anticipated waitingtime is too long and leaves the queue. The operation outputs to the operator the list of trucks in the queueafter the specified truck is removed. If no trucks are left in the queue a reasonable error message should beproduced.
• An operation Unload_ship that an operator uses to signal to the system to begin unloading (placing in thecontainer terminal) of x quantity and y tonnes of containers from the ship. Note the system must check thatall deliveries and pickups have stopped before unloading can commence. A suitable message must beoutput until this has been achieved. The system must also do a check to see if the quantity and tonnagestorage capacity is available in the container terminal. If this check fails, then an error message must beoutput and no ship unloading occurs. (From an operational perspective, the operator may, after consultation,try the operation again with adjusted values to have a successful ‘partial’ unload but you do not need to beconcerned with this as the functionality already described would accommodate this process). Additionalinformation needed by this routine is the ship identifier. If successful, this operation stores all necessarydetails into the system for that unloading.
• An operation Container_terminal_account that outputs the total number and tonnage of containersdelivered to a particular container terminal by ALL freight companies in a specified time period (in thissimplified system, that is the total quantity and tonnes delivered between two specified global count valuese.g. 10000 and 10500).
• An operation Ships_total_account that outputs the total number and tonnage that a particular ship hasloaded from ALL container terminals in the total history of the system.• An operation Freight_company_account that outputs the total number and tonnage of containers deliveredto and the total number and tonnage picked up from ALL container terminals for each freight companybetween two specified global count values.
You should provide robust versions of each operation that are capable of handling any possible error conditions. Forexample, if the ship or truck is not correctly registered in the system an appropriate error message must be given.You should also add a narrative to explain any schemas or logic that you have used. Authorship should be madeclear. You might be asked to explain and answer questions about your work.Page 7 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17Additional InformationGeneral Comments
The submission must be presented in a professional, clear and concise manner. If you need further system
information please use your initiative and make reasonable and logical assumptions. Questions of a general nature(for example to clarify some part of the assignment requirements) can also be sent to the discussion forum but theseshould not in any way provide solutions or parts thereof.Readings
The following resources will assist you with this assignment:
• Weeks 4 and 5 study materials and Section 4 of study guide three;
• The Z Notation: A Reference Manual (Spivey, 2001);
• Chapter 21, sections 21.5, 21.6 and 21.7 of Pressman (2010);
• Solutions for problem 2 of week 6 tutorial problems;
• The Z Resources section of your Moodle shell; and
• Introduction to Z Notation - http://www.youtube.com/watch?v=qfEe9luJmVEPage 8 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17SubmissionOne group member should submit an electronic copy of the CCS Formal Specification via Moodle. Partnerstudents please refer to your course lecturer for submission instructions. Please refer to the Course Descriptionfor information regarding late assignments, extensions, special consideration, and plagiarism. A reminder allacademic regulations can be accessed via the university’s website, see:http://federation.edu.au/staff/governance/legal/feduni-legislation/feduni-statutes-and-regulations
Marking CriteriaWork will be assessed according to the following:
• Your CCS Formal Specification must complete the items detailed within the Assessable Tasks/Requirementssection of this document.• Your CCS Formal Specification should be presented as business or management style report which adheres toacademic writing presentation standards. Where applicable, it must contain high quality academic presentation,expression and features as outlined in:o Federation University’s Assignment Layout and Appearance Guidelines; General Guide to Writing and Study Skills, General Guide to Referencing; ando Features of Academic Writing (from UEfAP.com)Page 9 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17Marking RubricStudent Name andNoItemDescriptionMarkerDateGlobal VariablesCorrect declaration and initialisation5State Space SchemaCorrect declaration and type for variablesCorrect predicatesInit OperationCorrect initialisation of variables5Enter_new_container_terminal OperationAccept_deliveryOperationAccept_pickupOperationLeave_delivery_queue OperationUnload_shipOperationContainer_terminal_account OperationShips_total_accountOperationFreight_company_account OperationCorrect schema for entry, error and successCorrect robust expressionCorrect schema for test of available room, successfuldelivery, successful queueing and errorCorrect robust expressionCorrect schema for successful pickup, successfulqueueing and errorCorrect robust expressionCorrect schema for removal of truck, list of trucks inqueue and errorCorrect robust expressionCorrect schema for test of delivery and pickups stopped,available room, successful unloading, updating of systemand errorCorrect robust expressionCorrect declaration and type for variablesCorrect predicatesCorrect schema for report and error (no ship in system)Correct robust expressionCorrect declaration and type for variablesCorrect predicatesReportAdheres to guidelines given for assignment (Anyassumptions must be clearly stated and appropriate)Max. MarksPage 10 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh510101010101010105Student Mark
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ITECH7410 Software Engineering Methodologies Assignment 2, 2018/17Total MarkCourse MarkComments:
Feedback10020Assessment marks will be made available in fdlMarks, Feedback to individual students will be provided via Moodle or asdirect feedback during your tutorial class.PlagiarismPlagiarism is the presentation of the expressed thought or work of another person as though it is one's own withoutproperly acknowledging that person. You must not allow other students to copy your work and must take care tosafeguard against this happening. More information about the plagiarism policy and procedure for the university can befound at:
http://federation.edu.au/students/learning-and-study/online-help-with/plagiarism.Any support material must be compiled from reliable sources such as the academic resources in Federation Universitylibrary which might include, but not be limited to: the main library collection, library databases and the BONUS+ collectionas well as any reputable online resources (you should confirm this with your tutor).ReferencesPressman, R.S. (2010). Software Engineering: A Practitioners Approach (7007-126782-3Spivey, J.M. (2001). The Z Notation: A Reference Manual (2nded.). Oxford, England: Author.http://spivey.oriel.ox.ac.uk/wiki2/files/zrm/zrm.pdfthed). McGraw-Hill. ISBN: 978-Page 11 of 11 CRICOS Provider No. 00103D ITECH7410_Assignment2_sem9_2018_201817_T_Keogh