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CSE5306 Lecture. Quiz due at 5 PM Satur day , 25 August 2014. 1. History. 1980s: the Altair 1990s Novell Netware 2000s Distributed Systems. R U O K 1. Which of the following was NOT a precursor of today’s distributed system? a. Low -cost, high-performance minicomputers.
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CSE5306 Lecture Quiz due at 5 PM Saturday, 25 August 2014
1. History • 1980s: the Altair • 1990s Novell Netware • 2000s Distributed Systems
R U O K 1 Which of the following was NOT a precursor of today’s distributed system? a. Low-cost, high-performance minicomputers. b. High-speed local-area networks. c. Mobile phones.
1.1 Definition • [Tim Cook’s design philosophy]
R U O K 2 How does Tanenbaum define “distributed system”? a. Four jet fighters synergistically sharing target recognition radars. b. Collaborating autonomous computers that appear to be a coherent system. c. Enabling a whole new collection of desirable user experiences.
R U O K 3 What purpose does middleware serve in a distributed system? a. It joins disparate computer hardware and software. b. It standardizes computer interfaces. c. It hides computers’ differences from the user. d. All of the above. e. None of the above.
1.2 Distributed System Goals Distributed systems…. • Make resources accessible. • Keep app implementations transparent. • Open the system’s syntax & semantics. • Scale systems according to demand.
R U O K 4 According to Tanenbaum, which of the following is NOT a distributed system design goal? a. Enhance the user’s experience. b. Make resources accessible. c. Keep app implementations transparent. d. Open the system’s syntax & semantics. e. Scale systems according to demand.
Distributed System Complexity Mouse Manufactured to Military Specifications
R U O K 5 A distributed system might makewhich of the following resources available? a. Decaffeinated coffee. b. Roses on Valentine’s Day. c. Costly, seldom used peripheral devices. d. All of the above. e. None of the above.
R U O K 6 Which of the following problems might arise from designing a friendly user interface? a. Excessive system usage. b. Sabotage. c. Over budget development cost. d. All of the above. e. None of the above.
Access Transparency My GPS screen …hides its (obscure” data representation and how it accesses its (very technical) resources.
Location, Relocation & Migration Transparencies Location: People can call my cell phone (or email me) without knowing where I am. Migration: I can move my cell phone from my home to my office without two callers knowing it. Relocation: I can travel from my home to my office, while talking on my cell phone, without a caller knowing it.
Replication Transparency • Replicating a New York Stock Exchange trading terminal inside Morgan-Stanley’s Dallas brokerage firm is a great convenience to the trader. • But it cannot be used for “algorithm trading,” which depends upon nanosecond updates.
Concurrency Transparency • And that terminal must not be concurrently connected with another replicate in (competitor) Chase Bank’s brokerage firm…! • While Morgan-Stanley is buying or selling a stock, Chase must be locked out of that stock’s mutual-exclusion code segment. • Chase should not even know that Morgan-Stanley is logged in.
Failure Transparency • Twenty minutes ago, you heard the power transformer in your neighbor’s yard blow up. • A TXU service truck just pulled up. • But your electric oven is is still baking tonight’s chicken dinner. • That’s “failure transparency” (fault tolerance) hard at work in a very well designed (and expensive) distributed system. • A slow response that looks like a failure can wreak havoc on the grid.
Undesired Transparency • Access to resources several thousand miles away should not pretend to have concurrent transparency. • A distributed system should not pretend that a failed resource is simply slow, by silently moving to another resource. • Location hiding should not cause my print job to be rerouted from my busy printer to an idle one in a distant city. • Access to resources several thousand miles away should not pretend to have concurrent transparency. • A distributed system should not pretend that a failed resource is simply slow, by silently moving to another resource. • Location hiding should not cause my print job to be rerouted from my busy printer to an idle one in a distant city. • [Bean person]
Openness • An Interface Definition Language (IDL) translates the user’s syntax into the native resources’ apps and their parameters. • The designer makes a distributed system “open” by crafting a natural language interface to embody the users’ semantics. • [car dashboard & car with hood open] • An Interface Control Document (ICD) contains detailed specifications of resource interfaces that are not open to users. • “Interoperable” resources are easily swapped. • “Portable” apps run well on a wide variety of systems. • Resources can be added easily to “extensible” systems.
Scalability Distributed System # Users Administrative (Ease of Mgmt) Geographical
Pitfalls • Network reliability, security and homogeneity. • Fixed topology. • Zero latency and infinite bandwidth. • Zero transport costs. • A single, competent administrator.
Monday’s Venue Let’s meet in the library’s second-floor computer lab in the University Center at 10 AM on Monday, August 25th. It will be my pleasure then to introduce you to an old friend of mine: MATLAB…!
