95-702Distributed Systems 1!Master of Information System Management 95-702 Distributed Systems Lecture 1: Introduction95-702Distributed Systems 2!Master of Information System Management Course Web Site • http://www.andrew.cmu.edu/course/95-702/95-702Distributed Systems 3!Master of Information System Management How Related to Other Courses 95-702 Distributed Systems 95-843 Service Oriented Architecture 95-774 Business Process Modeling 95-831 EA 95-712 Java95-702Distributed Systems 4!Master of Information System Management Course Technologies • IDE (Netbeans) • Java Web Applications (Glassfish) • Message Oriented Middleware (Sun’s Message Queue ) • Web Services (JDK 6, Glassfish) • Distributed Objects (Java RMI, and EJB’s) • Mobile platform (Android)95-702Distributed Systems 5!Master of Information System Management Getting Started Notes • See the schedule for instructions on getting started with the course technologies. • The installation includes Netbeans, Glassfish and the Android emulator. • Not to be turned in but please begin this assignment now and let us know of any problems. • Homework 1 is also assigned.95-702Distributed Systems 6!Master of Information System Management Structure of the Course • Lectures / class participation • Demonstrations (with your active involvement) • Homework (pencil and paper and programming) The secret is to start early. • Two Midterms • Final examination95-702Distributed Systems 7!Master of Information System Management Readings • Readings from the required text are assigned for each lecture -- read them in advance. • Readings from the web will also be assigned. • For this week, read Coulouris chapters 1 and 295-702Distributed Systems 8!Master of Information System Management Grading • Homework/Programming (5-7) 48% • 2 Midterms 16% • Final Exam 30% • Labs 6% • We will be very fussy about deadlines. One second late is late. • All times are Adelaide times. Blackboard may show Pittsburgh times. We will work from Adelaide time. • Use the discussion board for all queries with a response that should be heard by the entire class.95-702Distributed Systems 9!Master of Information System Management Characterization of Distributed Systems • Components are located on networked computers and execute concurrently. • Components communicate and coordinate only by passing messages. • There is no global clock. • What was the “Pony Express” like?95-702Distributed Systems Pioneer Plaque Early 70’s 10!Master of Information System Management95-702Distributed Systems 11!Master of Information System Management Main Motivations for Constructing DS • Communications and Resource sharing. • We want to share: Programs Data CPU cycles Files Printers Etc..95-702Distributed Systems Four Important Integration Styles • Shared Files • Shared Database • RPC • Messaging 12!Master of Information System Management95-702Distributed Systems 13!Master of Information System Management Challenges in Constructing DS • Heterogeneity of components • Openness • Security (Eve and Mallory) • Scalability • Failure handling • Concurrency of components • Transparency Which of these are not challenges when constructing standalone systems?95-702Distributed Systems 14!Master of Information System Management Example Distributed Systems • The internet A collection of diverse networks A very large distributed system providing services such as email, file transfer, telnet, and recently, WWW, Web Services, and multimedia • Intranets (a portion of the internet separately administrated) and connected to the internet via a router • Mobile and ubiquitous computing • Sensor networks95-702Distributed Systems 15!Master of Information System Management intranet!ISP!desktop computer:!backbone!satellite link!server:!☎"network link:!☎"☎"☎"A typical portion of the Internet95-702Distributed Systems 16!Master of Information System Management A typical intranet the rest of email serverWeb serverDesktopcomputersFile serverrouter/firewallprint and other serversother serversprintLocal areanetworkemail serverthe Internet95-702Distributed Systems 17!Master of Information System Management Portable and handheld devices in a distributed system LaptopMobilePrinterCameraInternetHost intranetHome intranetWAP Wireless LANphonegatewayHost site95-702Distributed Systems 18!Master of Information System Management Resource Sharing and the Web • A server is a running program on a networked computer that accepts requests from programs running on other computers to perform a service and respond appropriately • The requesting processes are referred to as clients • WWW, Web Services, networked printers and email fit this model95-702Distributed Systems 19!Master of Information System Management The World Wide Web(1) • Created by Sir Tim Berners-Lee at European centre for nuclear research (CERN) in Switzerland in 1989 (Knighted 2003) • Provides a hypertext structure allowing documents to contain links to other documents • Is an open system (can be extended and implemented in new ways, standards are public and widely implemented)95-702Distributed Systems 20!Master of Information System Management The World Wide Web (2) • The web is based on three main standard technological components (1) HTML for presentation of content and Links (2) URL’s to point to a resource and specify a protocol (3) HTTP to describe the request and reply protocol95-702Distributed Systems 21!Master of Information System Management Web servers and web browsers Internet!Browsers!Web servers!www.google.com!www.cdk3.net!www.w3c.org!Protocols!Activity.html!http://www.w3c.org/Protocols/Activity.html!http://www.google.comlsearch?q=kindberg!http://www.cdk3.net/!File system of!www.w3c.org!95-702Distributed Systems 22!Master of Information System Management A Request May Cause • A simple file transfer • A process to be run on the server and content sent to the browser (CGI programs, servlets, JSP pages, etc.) • Program code to be downloaded and executed in the browser
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