King’s College London This paper is part of an examination of the College counting towards the award of a degree. 

Examinations are governed by the College Regulations under the authority of the Academic Board. Examination Period Module Code Module Title June 2021 6CCS3SAD Software Architecture and Design Format of Examination 

Start time Time Allowed Instructions Rubric Written questions 2nd June, 8.00am BST (GMT +1) Two Hours You are permitted to access any materials you wish, but this is not mandated and is not expected. You may use a calculator if you find this helpful. ANSWER ALL QUESTIONS The rubric for this paper must be followed and extra answers should not be submitted. For answers that are handwritten, write with blue/black ink on light coloured paper. Include the Module code, question number and student number on every page to be submitted. For an- swers that are typed, use the template provided. Submission Deadline 10am Submission Process Work must be submitted to the level 6 Informatics Assessments KEATS page. Your work must be submitted as a PDF file. If you have prepared some answers on computer, and some on paper (which have then been digitised), you may upload at most two PDF files one for computer-prepared answers, one for digitised answers. Do not duplicate answers across the two PDFs if you do this, the computer-prepared answer will be taken. You should check that your work displays correctly after it has been uploaded. ACADEMIC HONESTY AND INTEGRITY Students at Kings are part of an academic community that values trust, fairness and respect and actively encourages students to act with honesty and integrity. It is a College policy that students take responsibility for their work and comply with the universitys standards and re- quirements. By submitting this assignment, I confirm that this work is entirely my own, or is the work of an assigned or permitted group, of which I am a member, with exception to any content where the works of others have been acknowledged with appropriate referencing. I also confirm that I have read and understood the Colleges Academic Honesty & Integrity Policy: https://www.kcl.ac.uk/governancezone/assessment/academic-honesty-integrity Misconduct regulations remain in place during this period and students can familiarise them- selves with the procedures on the College website at https://www.kcl.ac.uk/campuslife/acservices/academic-regulations/assets-20-21/g27.pdf 2021 Kings College London June 2021 6CCS3SAD 1. a. Explain the distinction between assembly connectors and delegate con- nectors, and show the UML notations used for these. [5 marks] b. Draw the component diagram of a component C which requires inter- faces IA and IB, and provides an interface IC dened to have opera- tions op1(x : int) : String, op2(s : String,i : int), op3(s1 : String) : String. Include an interface specication of IC. [5 marks] c. Explain what is meant by a Web service. Describe the general Web service architecture and explain the dierences between SOAP-based Web services and REST Web services. [5 marks] d. Explain the purpose of the Front controller enterprise pattern, and draw an example architecture showing the application of this pattern within an ecommerce system involving product search, add-to-cart and checkout actions. [5 marks] e. Explain the purpose of the Data access object enterprise pattern. In which tier of an EIS would a data access object component occur? Ex- plain the benets of adopting the pattern. [5 marks] Page 2 SEE NEXT PAGE June 2021 6CCS3SAD 2. a. Give a precise denition in terms of required/provided interfaces of what it means for one component C 2 to be substitutable for another compo- nent C 1 within an architecture AX . [5 marks] b. Explain how the MVC architecture diers from the Blackboard architec- ture. Which would be most appropriate for a program development tool which has an interactive text editor for writing programs, and an uneditable graphical view window to show the structure of the code? [10 marks] c. Design and draw the UML architecture diagram of the following mobile app, using suitable architecture patterns. You only need to draw the parts of the system which deal with restaurant booking, not preferences. Justify the choice of the patterns. The system is a restaurant nder app which: 1. Enables a user to register and set their preferences for price and type of cuisine (eg., Italian, Vegetarian, etc). 2. Enables a user to search for restaurant(s) matching their preferences within a specic distance of a location/their current location. The location and restaurant locations are shown on a map view. 3. Opens a link to a booking site for a selected restaurant. Page 3 SEE NEXT PAGE [10 marks] June 2021 6CCS3SAD 3. a. Explain the purpose and structure of the COM+ notication service for loosely-coupled events, and draw a UML sequence diagram of a typical interaction between components communicating via the service. [10 marks] b. Explain how this service ensures that both the receiver of a notication is unaware of the identify of the sender, and that the sender is unaware of the identity of the receiver(s). [5 marks] c. Explain the purpose of the online/oine DAO pattern, and how it man- ages the situation where a mobile app uses information from a remote data source. Consider two cases: (a) the data of existing information does not change over time (eg., the coordinates of airports); (b) data is liable to change (eg., currency exchange rates). [10 marks] Page 4 SEE NEXT PAGE June 2021 6CCS3SAD 4. a. Consider the holiday reservation system shown in Figure 1. The system enables customers to book integrated holidays, and uses components to book ights, hotel stays and car hires for these holidays, with selected providers. A loyalty programme operates for holiday bookings (ie., cus- tomers get discounts on holidays if they have booked with the service previously), and a carbon osetting scheme operates for ight bookings. The payment and conrmation of a holiday should be atomic and should pay and conrm the possibly three elements of the holiday in one step. What are the defects with the existing system, given these requirements? Redraw the system to improve the structure, to address these defects. [10 marks] b. What COM+ service(s) would be relevant for this system? Explain the rationale for using the service(s). [5 marks] QUESTION 4 CONTINUES ON NEXT PAGE Page 5 Figure 1: Holiday booking system SEE NEXT PAGE June 2021 6CCS3SAD c. Explain the dierences between stateless and stateful session beans in Java EE, and explain how each type of bean is typically used in a Java EE architecture. [10 marks] Page 6 FINAL PAGE