Distributed System Concepts and Architectures 2.3 Services

1. Distributed System Concepts and Architectures2.3 Services Fall 2013 Prepared by: Zhongli Ding email: zding2@student.gsu.edu

2. Overview • What is operating system • Basic services • Fundamental services • Popular technique and applications • Reference

3. What is operating system • Software between end user and hardware • Manages computer resource: memory, input/output devices • Allows an application program to interact with other system resources • Services provider

4. Basic services • Program development • Editors and debuggers • Access to I/O devices • An input and produces output are always required in every program by I/O devices. The operating systems hides the user the details of underlying hardware for the I/O. So the operating systems makes it convenient for the users to run programs by providing I/O. • Controlled access to files • Ensure that all access to system resources is controlled.

5. Basic services(continued) • System access • Access to the system from outsiders requires user authentication • Program execution • The purpose of a computer system is to allow the user to execute programs. So the operating systems provides an environment where the user can conveniently run programs. The user does not have to worry about the memory allocation or multitasking or anything. These things are taken care of by the operating systems.

6. Basic services(continued) • Error detection and response • Internal and external hardware errors • Memory error • Device failure • Software errors • Arithmetic overflow

7. Basic services(continued) • Accounting • Collect usage statistics • OS keeps track of some information, such as what kind of resources used, how many users etc • Monitor performance • Used to anticipate future enhancements • Used for billing purposes

8. Fundamental services • Primitive services • Communication: exchange of information between processes • Synchronization: coordination of events • Send and receive primitives can be synchronous or asynchronous • Processor multiplexing

9. Fundamental services (continued) • Services by system servers: the service provider of the system • Name server: used to locate users, processes or machines • Network server: used to translate address and locations obtained from name server • Time server: synchronization of processes to maintain a total order of event occurrences • File server: managing shared file system resources

10. Fundamental services (continued) • Value added services • Web server: accepts requests from the clients, processes it and returns a response • Group server: manages creation and termination of groups of interacting processes

11. Popular Technique & Application • Cloud computing • Cloud storage • Extends from cloud computing

12. Cloud computing • Comes from the development of: • Distributed computing • Parallel computing • Utility computing • Network storage technologies • Virtualization • Load balance

13. Cloud storage • As provider of file system manage service, cloud storage is very popular in recent years • Example: • Google drive, Amazon cloud drive, icloud, dropbox, skydrive, and many many other net disks. • Access, manage, share

14. References • Advanced Operating Systems, Brown, R.L. 2006 • http://ieeexplore.ieee.org.ezproxy.gsu.edu/stamp/stamp.jsp?tp=&arnumber=1658969 • http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=138323 • Cloud Storage as the Infrastructure of Cloud Computing, JiyiWu. 2010 • Cloud Computing learning, Kalagiakos, P. 2011

15. THANK YOU