The Principles of Web TechnologyManagement

http://purl.org/net/wtm

sopek@makolab.com

Principia Webica

Plan

Week 1: The history and current status of the World Wide WebWeek 2: Web design principles – networks & serversWeek 3: Web design principles – Web clients, web programmingWeek 4: Management of Open Source Web Servers and

databasesWeek 5: Management of Microsoft Web Servers and databasesWeek 6: Management of specific Web systems

(CMS, Web services, Intranets)Week 7: Addressing the dangerous aspects of the Web

Architectural Principles of the Web.

Network and Servers.

Understanding WEB

Information Management: A proposalTim Berners-Lee, CERN, March 1989-May 1990

http://www.w3.org/History/1989/proposal.html

Information Management: A proposalTim Berners-Lee, CERN, March 1989-May 1990

http://www.w3.org/History/1989/proposal.html

Architectural Principles of the InternetRFC 1958; B. Carpenter; June, 1996

„Fortunately, nobody owns the Internet, there is no centralized control, and nobody can turn it off. Its evolution depends on rough consensus about technical proposals, and on running code. Engineering feed-back from real implementations is more important than any architectural principles.”

Architectural Principles of the InternetRFC 1958; B. Carpenter; June, 1996

„Is there an Internet Architecture? 2.1 Many members of the Internet community

would argue that there is no architecture, but only a tradition, which was not written down for the first 25 years (…)

However, in very general terms, the community believes that the goal is connectivity, the tool is the Internet Protocol, and the intelligence is end to end rather than hidden in the network. ”

Architectural Principles of the InternetRFC 1958; B. Carpenter; June, 1996

„Is there an Internet Architecture? 2.1 Many members of the Internet community would

argue that there is no architecture, but only a tradition, which was not written down for the first 25 years (…)

However, in very general terms, the community believes that the goal is connectivity, the tool is the Internet Protocol, and the intelligence is end to end rather than hidden in the network. ” (…)The key to global connectivity is the inter-networking layer. The key to exploiting this layer over diverse hardware providing global connectivity is the "end to end argument".

General Design IssuesRFC 1958; B. Carpenter; June, 1996

3.1 Heterogeneity is inevitable and must be supported by design. Multiple types of hardware must be allowed for, e.g. transmission speeds differing by at least 7 orders of magnitude, various computer word lengths, and hosts ranging from memory-starved microprocessors up to massively parallel supercomputers. Multiple types of application protocol must be allowed for, ranging from the simplest such as remote login up to the most complex such as distributed databases.

3.2 If there are several ways of doing the same thing, choose one. If a previous design, in the Internet context or elsewhere, has successfully solved the same problem, choose the same solution unless there is a good technical reason not to. Duplication of the same protocol functionality should be avoided as far as possible, without of course using this argument to reject improvements.

General Design IssuesRFC 1958; B. Carpenter; June, 1996

3.3 All designs must scale readily to very many nodes per site and to many millions of sites.

3.4 Performance and cost must be considered as well as functionality.

3.5 Keep it simple. When in doubt during design, choose the simplest solution.

3.6 Modularity is good. If you can keep things separate, do so.

TCP/IP http://en.wikipedia.org/wiki/TCP/IP

TCP/IP is named from two of the most important protocols in it:

the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking

protocols defined in this standard.

TCP/IP http://en.wikipedia.org/wiki/TCP/IP

TCP/IP http://en.wikipedia.org/wiki/TCP/IP

DNS http://en.wikipedia.org/wiki/Domain_Name_System

The Domain Name System (DNS) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network.

Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.

DNS http://en.wikipedia.org/wiki/Domain_Name_System

DNS http://en.wikipedia.org/wiki/Domain_Name_System

The Domain Name SyntaxRFC 1035, RFC 1123, and RFC 2181.RULES:The right-most label conveys the top-

level domain; for example, the domain name www.example.com belongs to the top-level domain com.

The hierarchy of domains descends from right to left; each label to the left specifies a subdivision, or subdomain of the domain to the right.

DNS http://en.wikipedia.org/wiki/Domain_Name_System

The tree of subdivisions may have up to 127 levels.

Each label may contain up to 63 characters. The full domain name may not exceed a total length of 253 characters in its external dotted-label specification

DNS names may technically consist of any character representable in an octet. However, the allowed formulation of domain names in the DNS root zone, and most other sub domains, uses a preferred format and character set. The characters allowed in a label are a subset of the ASCII character set, and includes the characters a through z, A through Z, digits 0 through 9, and the hyphen.

DNS http://en.wikipedia.org/wiki/Domain_Name_System

This (last) rule is known as the LDH rule (letters, digits, hyphen). Domain names are interpreted in case-independent manner. Labels may not start or end with a hyphen.

A hostname is a domain name that has at least one IP address associated. For example, the domain names www.example.com and example.com are also hostnames, whereas the com domain is not.

DNS http://en.wikipedia.org/wiki/Domain_Name_System

This (last) rule is known as the LDH rule (letters, digits, hyphen). Domain names are interpreted in case-independent manner. Labels may not start or end with a hyphen.

A hostname is a domain name that has at least one IP address associated. For example, the domain names www.example.com and example.com are also hostnames, whereas the com domain is not.

DNS resolution http://en.wikipedia.org/wiki/Domain_Name_System

DNS construction guarantees uniqueness

Lab work 5.

1) Remeber: http://purl.org/net/wtm

Explore the web for topics:a. TCP/IP protocol stackb. Web Architecturec. DNS and addressingd. Main transfer technologies (Fiber Optics, Copper Wire,

Wireless Links)e. IPv4 and IPv6 – when we will use up all the address

space ?f. Convergence: Network, Telephony, TV on the TCP/IP

networks

3 pages per topic