HTTP Header

• HTTP Header
  • Pragma
  • WWW-Authenticate response header

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HTTP Header

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Pragma

The Pragma HTTP/1.0 general header is an implementation-specific header that may have various effects along the request-response chain.

It is used for backwards compatibility with HTTP/1.0 caches where the Cache-Control HTTP/1.1 header is not yet present.

Pragma is not specified for HTTP responses and not a reliable replacement for the general HTTP/1.1 Cache-Control header

• although it does behave the same as Cache-Control: no-cache, if the Cache-Control header field is omitted in a request.
• Use Pragma only for backwards compatibility with HTTP/1.0 clients.

Syntax

Pragma: no-cache

• no-cache: Forces caches to submit the request to the origin server for validation before releasing a cached copy.

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WWW-Authenticate response header

• WWW-Authenticate
  • Header type Response header
  • Forbidden header name no
• defines the authentication method that should be used to gain access to a resource.
• sent along with a 401 Unauthorized response.

Syntax

WWW-Authenticate: <type> realm=<realm>[, charset="UTF-8"]

Directives

Directives	Note
<type>	Authentication type. A common type is “Basic”. IANA maintains a list of Authentication schemes.
realm=<realm>	A description of the protected area. If no realm is specified, clients often display a formatted hostname instead.
charset=<charset>	Tells the client the server’s prefered encoding scheme when submitting a username and password. The only allowed value is the case insensitive string “UTF-8”. This does not relate to the encoding of the realm string.

Examples

• server response contains a WWW-Authenticate header

WWW-Authenticate: Basic
WWW-Authenticate: Basic realm="Access to the staging site", charset="UTF-8"