- The internet:
- A connection of computer networks using the internet protocol (IP).
- IP is a simple protocol for attempting to send data between two computers.
- IP address consists of 4 numbers, each of 8 bits.
- An example to IP address is: 192.168.1.5
- TCP adds both multiplexing and guaranteed message delivery on top of IP.
- Multiplexing allows programs to use the same IP address. This can be achieved by introducing ports.
- Port: is a number given to each program or service.
- Programs access network connections using both IP address and port number.
- UDP is another protocol used by some programs like games and streaming media programs.
- DNS is a set of servers that map written names into IP addresses.
- Some operating systems maintain local cache file called hosts file.
- W3C: World Wide Web Consortium, which develop web standards.
- IETF: Internet Engineer Task Force, which develops internet standards.
- ICANN: Internet Corporation for Assigned Names and Number, which decides top-level domain names.
- Web server is a program running on a computer and listens for web page request on TCP port 80.
- Some popular web server software are: Apache and IIS.
- Web browser is a software application that displays web pages.
- Some popular web browser software are: Internet Explorer and Firefox.
- It’s a set of commands understood by a web server and sent from a browser.
- Some HTTP commands are:
- GET filename: for downloading file.
- POST filename: send a web form response.
- PUT filename: to upload file.
- Web servers may return a special “error code” number to the browser and possibly followed by an HTML document.
- Some common error codes are:
- 200: OK
- 301-303: Page moved (permanently or temporarily).
- 403: Forbidden to access this page.
- 404: Page not found.
- 500: Internal server error.
- URL is an identifier for the location of a document on a web site.
- URL consists of:
- After entering the URL into browser, the browser will:
- Ask DNS for IP address corresponding to the host of the URL.
- Connect to that IP on port 80.
- Ask the server to GET index.html
- Display the resulting page on the screen.
- Anchors: it’s a parameter added to the URL that identifies a given section of a web page.
- Port: it’s a parameter added to the URL that identifies another pot other than the default port 80.
- Query string: It’s a set of parameters passed to a web program. For example, query is sent to search program to perform search and return results.
- Hypertext Markup Language (HTML): It’s a markup language used for writing web pages.
- XHTML: A newer, more rigidly standardized specification of HTML.
- Cascading Style Sheets (CSS): It supplies stylistic information to web pages.
- PHP Hypertext Processing (PHP): It allows the web server to create pages dynamically.
- Structured Query Language (SQL): Interaction with databases.
What is Internet Protocol?
Transmission Control Protocol (TCP)
What is Multiplexing?
Domain Name System (DNS)
Hypertext Transport Protocol (HTTP)
Uniform Source Locator (URL)
Web Programming Technologies