Internet, TCP/IP, and HTTP concepts

Make sure that you are familiar with the relevant key elements of the Transmission Control Protocol/Internet Protocol (TCP/IP) and the Hypertext Transfer Protocol (HTTP). If necessary, review the HTTP specifications listed in these topics.

Subtopics

TCP/IP protocols
TCP/IP is a family of communication protocols used to connect computer systems in a network. It is named after two of the protocols in the family: Transmission Control Protocol (TCP) and Internet Protocol (IP). Hypertext Transfer Protocol (HTTP) is a member of the TCP/IP family.
IP addresses
Each server or client on a TCP/IP internet is identified by a numeric IP (Internet Protocol) address. The two types of IP address are the IPv4 (IP version 4) address and the IPv6 (IP version 6) address.
Host names
A host, or web site, on the Internet is identified by a host name, such as www.example.com. Host names are sometimes called domain names. Host names are mapped to IP addresses, but a host name and an IP address do not have a one-to-one relationship.
Virtual hosting
HTTP includes the concept of virtual hosting, where a single HTTP server can represent multiple hosts at the same IP address. You can use virtual hosting in web support by setting up URIMAP resources.
Port numbers
In a server, more than one user process can use TCP at the same time. To identify the data associated with each process, port numbers are used. Port numbers are 16-bit, and numbers up to 65535 are possible, although in practice only a small subset of these numbers is commonly used.
IANA media types and character sets
The Internet Assigned Numbers Authority (IANA) is the international body responsible for assigning names for protocols used on the Internet. Use these links to find out more about the names.
The components of a URL
A URL (Uniform Resource Locator) is a specific type of URI (Universal Resource Identifier). A URL normally locates an existing resource on the Internet. A URL is used when a web client makes a request to a server for a resource.
The HTTP protocol
The correct format for HTTP requests and responses depends on the version of the HTTP protocol (or HTTP specification) that is used by the client and by the server.
Status codes and reason phrases
In the HTTP response that is sent to a client, the status code, which is a three-digit number, is accompanied by a reason phrase (also known as status text) that summarizes the meaning of the code. Along with the HTTP version of the response, these items are placed in the first line of the response, which is therefore known as the status line.
Reserved and excluded characters
To assist with the correct transmission and interpretation of an HTTP request, the use of certain characters in a URL is restricted. These characters must be converted to a safe format when the request is transmitted.
HTML forms
In HTML, forms are areas delimited by a <form> tag, containing text input boxes, buttons, check boxes, and other features of a graphical user interface. Forms are used by web applications to allow end users to provide data to be sent to the server.
Chunked transfer-coding
Chunked transfer-coding, also known as chunking, involves transferring the body of a message as a series of chunks, each with its own chunk size header. The end of the message is indicated by a chunk with zero length and an empty line.
Pipelining
Pipelining involves a client sending multiple HTTP requests to a server without waiting for a response. Responses must then be returned from the server in the same sequence that the requests were received.
Persistent connections
Persistent connections between a web client and a server can be reused for more than one exchange of a request and a response.
HTTP basic authentication
HTTP basic authentication is a simple challenge and response mechanism with which a server can request authentication information (a user ID and password) from a client. The client passes the authentication information to the server in an Authorization header. The authentication information is in base-64 encoding.

Parent topic: CICS and the web

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Last updated: Thursday, 27 June 2019