2. Grid Computing, B. Wilkinson, 20042.1 Reading Assignments Since there is no assigned textbook, there will be a few reading assignments. Purpose is to consolidate your understanding. Materials posted on home page from link “reading/on-line materials” at end of section on lecture materials.

3. Grid Computing, B. Wilkinson, 20042.2 First Reading Assignment "The Anatomy of the Grid: Enabling Scalable Virtual Organizations" by I. Foster, C. Kesselman, and S. Tuecke Int. J. Supercomputer Applications, 2001.

4. Grid Computing, B. Wilkinson, 20042.3 We said that grid computing is now based upon Internet protocols and interconnections. So let’s first review some well-known Internet technologies.

5. Grid Computing, B. Wilkinson, 20042.4 Networked Computers, Internet and World Wide Web Technology - Basics Some really basic stuff!

6. Grid Computing, B. Wilkinson, 20042.5 Network Protocol TCP/IP (Transmission Control Protocol/Internet Protocol) - standard that establishes basic low level rules for networked computers to communicate and pass data. Higher level protocols build on top of TCP/IP.

7. Grid Computing, B. Wilkinson, 20042.6 Network Interfaces Computers connect to the Internet through a network interface (mostly Ethernet). Each network interface has a unique 48-bit address called a MAC (Media Access Controller) address, which is assigned during manufacture of the interface. Allocation of addresses controlled by IEEE Registration Authority.

8. Grid Computing, B. Wilkinson, 20042.7 Internet Protocol (IP) Address Slightly higher level - assigned to interfaces and hence computers. Example 129.49.82.1 (IP version 4). Divided into fields to allow various network decoding arrangements. IP address can be static or dynamically changing. Mapped to MAC address with a software table.

9. Grid Computing, B. Wilkinson, 20042.8 Some Network Protocols (on top of TCP/IP) Telnet An insecure Internet protocol that allows you to connect to another computer on the Internet. FTP (File Transmission Protocol) Standard insecure Internet protocol to exchange files.

10. Grid Computing, B. Wilkinson, 20042.9

11. Grid Computing, B. Wilkinson, 20042.10 Network services (servers) Implementation of a protocol with a set of capabilities. Example - FTP server FTP protocolTelnet protocol TCP protocol IP protocol FTP server

12. Grid Computing, B. Wilkinson, 20042.11 Secure Connections Secure connections needed in many computer related activities, including e- business and grid computing. Telnet and FTP are very insecure - information is transmitted in clear text.

13. Grid Computing, B. Wilkinson, 20042.12 SSL Protocol (Secure Socket Layer) Proposed by Netscape Communications and adopted widely - Latest version SSL 3.0. Uses Public Key Cryptography - see later in course. Can be used with FTP (SFTP) and other protocols (e.g. HTTTPS). Transport Layer Security protocol (TLS) subsequently proposed to SSL - no major differences.

14. Grid Computing, B. Wilkinson, 20042.13 World Wide Web Started in earnest in early1990’s when HTTP developed at CERN and Mosaic browser at NCSA. HTTP (Hypertext Transfer Protocol) - basic way of accessing web pages. World wide web expanded at an amazing rate (1 million hosts in 1993 to 200 million+ hosts in 2004.

15. Grid Computing, B. Wilkinson, 20042.14 Domain Name For ease of use by humans, names are used rather than IP addresses. Example cs.wcu.edu Conversion between IP address and name done by a domain name service, a distributed name database.

16. Grid Computing, B. Wilkinson, 20042.15 URL (Uniform Resource Locator) Way of identifying and accessing a web page: Example http://www.cs.wcu.edu/~abw/index.html “how” Type of transaction (protocol) “where” Address or name of server “what” Resource requested

17. Grid Computing, B. Wilkinson, 20042.16 Mark-up Languages A way of describing information in a document. Standard Generalized Mark-Up Language (SGML) - a specification for a mark-up language ratified in 1986. Key aspect - using pairs of tags that surround information - a begin tag and a matching end tag. Example CS 493 home page

18. Grid Computing, B. Wilkinson, 20042.17 HyperText Markup Language (HTML) A mark-up language used in web pages. “Hypertext” refers to the text’s ability to link to other documents. “Markup” refers to providing information to tell browser how to display page and other things.

19. Grid Computing, B. Wilkinson, 20042.18 HTML page format Signifies an HTML document Head section includes information about document - “metadata” Body section contains text and references to images to be displayed End of document

20. Grid Computing, B. Wilkinson, 20042.19 HTML Tags Tags specify details such as type of text. Example to start bold text to end bold text to start italic text to end italic text

21. Grid Computing, B. Wilkinson, 20042.20 HTML page Hello world My name is Barry

22. Grid Computing, B. Wilkinson, 20042.21 Question What does the previous HTML page display? Answer Hello World My name is Barry

23. Grid Computing, B. Wilkinson, 20042.22 HTML page Hello world My name is Barry Line break tag - some tags in HTML are not in pairs

24. Grid Computing, B. Wilkinson, 20042.23 Attributes Many tags can have attributes which specify something about the body between tag pair. Example This text is displayed in red in Times font, about 12 pt. Attributes

25. Grid Computing, B. Wilkinson, 20042.24 More information about HTML See WCU course CS 130 (also includes JavaScript). http://www.cs.wcu.edu/~abw/CS130F04/

26. Grid Computing, B. Wilkinson, 20042.25 Extensible Mark-up Language XML Ratified in 1998 - very important standard mark-up language - a “simplified” SGML. Developed to represent textual information in a structured manner that could be read and interpreted by a computer. A foundation for web services and grid services.

27. Grid Computing, B. Wilkinson, 20042.26 Some key aspects of XML Tags always used in pairs delineate information to make it easy to process. (There is an exception, when the body between the tags holds nothing.) Tags can be nested. They can have attributes. Names of tags can be defined broadly at will. (In HTML, tags are predefined.)

28. Grid Computing, B. Wilkinson, 20042.27 XML Application Areas Used for two applications areas: –Document-centric XML –Data-centric XML

29. Grid Computing, B. Wilkinson, 20042.28 Document-Centric XML Documents usually meant for humans, although could be processing by computers. Semi-structured - some tags can be placed more-or-less anywhere, similar to HTML tags.

30. Grid Computing, B. Wilkinson, 20042.29 Sample document-centric XML Prerequisites for grid computing course Fall 2004 CS 150 Programming I or equivalent CS 151 Programming II or equivalent desirable Able to program in Java or learn quickly. Able to program in C/C++ or learn quickly. Able to use Linux system or learn quickly. For more information look at Outline.

31. Grid Computing, B. Wilkinson, 20042.30 Data-Centric XML Usually generated and meant to be read by computer programs. Structured. Nesting useful to create a clearly structured and computer-readable document.

32. Grid Computing, B. Wilkinson, 20042.31 Sample data-centric XML Department of Mathematics and Computer Science Western Carolina University Cullowhee NC 28723 Department of Mathematics and Computer Science Western Carolina University Cullowhee NC 28723 computer system type 1234 Unmanaged 16 port GigE switch.

33. Grid Computing, B. Wilkinson, 20042.32 Sample data-centric XML Department of Mathematics and Computer Science Western Carolina University Cullowhee NC 28723

34. Grid Computing, B. Wilkinson, 20042.33 Quiz 1.(Test of any prior knowledge - answer not in slides.) Where exactly is the file stored with the URL given as www.cs.wcu.edu/~abw/CS493F04 and what is its name (be careful) ? Answer

35. Grid Computing, B. Wilkinson, 20042.34 Quiz 2.Why are the FTP and telnet protocols insecure? Answer

36. Grid Computing, B. Wilkinson, 20042.35 Quiz 3.How are tags defined in HTML? Answer

37. Grid Computing, B. Wilkinson, 20042.36 Quiz 4.How are tags defined in XML? Answer

38. Grid Computing, B. Wilkinson, 20042.37 Quiz 5. A pair of XML tags with empty contents: can be written as Under what circumstances would such a construction make sense? Answer