COMP90015 practice exam PDF

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COMP90015 Distributed system practice exam questions...

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The University of Melbourne COMP90015 Distributed Systems Semester 2, 2020 Final Examination School of Computing and Information Systems COMP90015 Distributed Systems Reading Time: 15 minutes Writing Time: 2 hours Open Book Status: Open Book – Online. Authorized Materials: You are permitted to make use of material available on the Web in general, including course notes, recordings, materials on LMS, and research literature and websites. This paper has 2 pages including this page Identical Examination Papers: The examination paper is available as either a PDF or Word document. The documents have identical content and differ only in minor formatting ways. Common Content: none Instructions to students: • The total marks for this paper is 40. • The examination is worth 40% of the subject assessment. • Attempt all questions - partial credit is available. • You are required to submit a single document that contains all of your answers. Acceptable document formats include PDF, Word, or a plain text file. Please include your student number at the top of the first page of the document, prepare your answers in the same order as the questions given in the exam paper, and number your answers with the same numbering as in the exam paper. • You may type your answers, include diagrams/images if you wish, and you may draw and scan images to include in the document. You may prepare all of your answers on paper, using handwritten answers if you wish, and simply scan all of your answers into a single PDF document and submit that way if you wish. Make sure that all scanned material and diagrams/images are clearly legible. • You must adhere to the Academic Integrity Declaration. In particular, in each of your answers, cite all materials that you sourced information from. • Unless you have a special time allowance, you have an examination time of 2 hours and 15 minutes to complete and upload your answers document, for it to be considered "on time". After the examination time, you have an additional late submission period of 30 minutes to submit your answers document - submissions in this period will be considered "late". The late submission period cannot be used as additional exam time. The Subject Coordinator may request evidence of technical issues or a late penalty may apply. After this period you will not be able to upload your answers document. • You may submit multiple times (unlimited), but only the final (last) submission will be looked at for assessment. If the final submission is within the late period then your submission will be considered late, as above. You will not be able to revert to an earlier submission. Paper to be held by Baillieu Library: yes

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COMP90015 Distributed Computing

Q.1 [10 marks] Suppose you are going to build a Group Communication middleware using fundamental communication primitives. Define and explain the essential aspects of the Group Communication API that you would implement. Give examples of how an application developer would make use of the API. Define and explain a fault-tolerance model and security model for your Group Communication middleware. Discuss the inter-process communication protocols and messages that you would use to implement your middleware with the given fault-tolerance and security models. Discuss the threading model that you would use and how this relates to your middleware design. Q.2 [10 marks] The Network File System (NFS) discussed in lectures is a very different kind of distributed file system solution to contemporary systems like DropBox, OneDrive or GoogleDrive. Explain the major differences of NFS to the contemporary systems (choose one of them) and discuss the differences in terms of advantages and disadvantages. Use NFS as an example to explain the concept of eventual consistency. Explain how NFS eventually becomes consistent and explain the tradeoffs involved. Q.3 [ 10 marks] A software company is required to build a data storage management system with the following high-level requirements. Many organizations such as scientific research institutions, enterprise businesses, and industries actively collect, store, retrieve, and manipulate the data on a day to day bases from geographically distributed data sources and users. A typical scale of data, in this case, is between Terabytes to Petabytes. These organizations need an efficient distributed system that provides data storage and retrieval services. It also warrants user management (authentication/authorization/access control lists), and stringent data security with fast and efficient access through relevant tools (GUIs and API access). The data can be stored on an individual organization’s on-premise infrastructure or on any third party managed infrastructure such as a Cloud. The data belongs to a variety of application types depending on its domain. In addition, many users of this system store the vast majority of the data into an archive and rarely access (around 90%) while the remaining data is actively retrieved and concurrently manipulated by multiple users. Discuss what aspects you will consider when designing and implementing the distributed system to facilitate the above requirements. Discuss your approach, challenges, and a possible solution, in terms of choice of architecture, application components, technologies, etc., towards building this system. Q.4 Recall the Event-based middleware that you used in your project work for Project 2B and Project 3. (a) [3 marks] Explain the threading model that the middleware used. Give an advantage and disadvantage of this threading model. (b) [2 marks] List and briefly explain all of the threads (or thread types) that the middleware creates. (c) [5 marks] The Event-based middleware uses a number of threads. However, it is possible to refactor the middleware to use a single thread. Discuss what this would entail with respect to sockets and messaging. END OF EXAMINATION

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