Cs 101 ( Module 71-80)

Networking and the Internet: Web Implementations

• Software packages for accessing hypertext on the Internet are categorized into browsers and webservers.
• A browser resides on the user's computer and obtains and presents materials to the user in an organized manner.
• Examples of common Internet browsers include Firefox, Safari, and Internet Explorer.
• A webserver resides on a computer containing hypertext documents and provides access to them as requested by clients (browsers).
• Hypertext documents are transferred between browsers and webservers using the Hypertext Transfer Protocol (HTTP).
• Each document is given a unique address called a Uniform Resource Locator (URL) to locate and retrieve documents on the Web.

Networking and the Internet: HTML

• A traditional hypertext document is similar to a text file with HTML-encoded versions.
• An HTML source document consists of two sections: a head and a body.
• The head contains preliminary information about the document, while the body contains the material to be presented on the computer screen.
• The title of the document is only for documentation purposes and is not displayed on the screen.
• The body contains the material to be displayed on the screen, including headings and paragraphs.

Networking and the Internet: HTML Tags

• HTML tags are used to indicate the structure of a document.
• The <a> tag is used to create a hyperlink, and the href attribute specifies the URL of the linked document.
• The `` tag is used to include an image in a document, and the src attribute specifies the URL of the image.

Networking and the Internet: XML and Semantic Markup

• XML (eXtensible Markup Language) is a standardized style for designing notational systems for representing data as text files.
• XML is used to develop markup languages for various applications, including mathematics, multimedia presentations, and music.
• XML allows for the development of new markup languages that emphasize semantics rather than appearance.
• Semantic markup languages allow search engines to identify specific information within a document, such as ingredients in a recipe.

Networking and the Internet: Client-Server and Layered Approach

• The Internet software has four layers: application, transport, network, and link.
• The application layer uses the transport layer to send and receive messages over the Internet.
• The transport layer divides long messages into small segments, adds sequence numbers, and hands them to the network layer.
• The network layer decides the direction of a packet at each step and hands it to the link layer for transmission.
• The link layer is responsible for receiving and transmitting packets.

Networking and the Internet: Layered Approach (II)

• The transport layer is responsible for ensuring that messages are properly formatted for transmission over the Internet.
• The network layer is responsible for maintaining the router's forwarding table and determining the direction of a packet.
• The link layer is responsible for receiving and transmitting packets and dealing with communication details particular to the individual network.

Networking and the Internet: Layered Approach (III)

• The network layer and link layer constitute the software residing on the Internet routers.
• The network layer uses its forwarding table to determine the direction of a packet.
• The link layer hands the packet to the network layer to determine the direction of the next step.
• The packet is received by the link layer at the other end, and the process is repeated until the packet reaches its final destination.

Networking and the Internet: TCP/IP Protocol Suite

• The TCP/IP protocol suite is the standard for the Internet.
• TCP (Transmission Control Protocol) is a transport layer protocol that ensures reliable communication over the Internet.
• UDP (User Datagram Protocol) is a transport layer protocol that is more streamlined than TCP and is used for applications that require fast transmission.
• IP (Internet Protocol) is the standard for implementing the tasks assigned to the network layer.
• IP is responsible for forwarding and routing packets through the Internet.