An HTTP server also has the ability to delegate work to gateway programs.
解答例
The Common Gateway Interface (CGI) specification defines a mechanism by which HTTP servers communicate with gateway programs.
A gateway program is referenced using a URL.
The HTTP server activates the program specified in the URL and uses CGI mechanisms to pass program data sent by the client to the gateway program.
Data is passed from the server to the gateway program via command-line arguments, standard input, or environment variables.
The gateway program processes the data and returns its response to the server using CGI (via standard input, for example).
The server forwards the data to the client using the HTTP.
A browser displays information to a client/user as pages or documents (referred to as "web pages" or "web sites").
A language is used to define the format for a page to be displayed in the WWW.
The language is called Hypertext Markup Language (HTML).
A WWW page is transmitted to a client as an HTML document.
The browser executing at the client parses the document and displays a page based on the information in the HTML document.
HTML is a structural language that is comprised of HTML elements that are nested within each other.
An HTML document is a text file in which certain strings of characters, called tags, mark regions of the document and assign special meaning to them.
These regions are called HTML elements.
Each element has a name, or tag.
An element can have attributes that specify properties of the element.
Blocks or components include unordered list, text boxes, check boxes, and radio buttons, for example.
Each block has properties such as name, type, and value.
The following provides an example of the structure of an HTML document:
Each HTML element is delimited by the pair of characters "<" and ">".
The name of the HTML element is contained within the delimiting characters.
The combination of the name and delimiting characters is referred to as a marker, or tag.
Each element is identified by its marker.
In most cases, each element has a start and ending marker.
The ending marker is identified by the inclusion of an another character, "/" that follows the "<" character.
HTML is a hierarchical language.
With the exception of the HTML element, all other elements are contained within another element.
The HTML element encompasses the entire document.
It identifies the enclosed text as an HTML document.
