Apache 2 Pocket Reference

Chapter 5. Document Metainformation

Once the request URL has been translated and access controls have been applied, Apache determines certain characteristics of the document to be returned, such as the language, content type, character set, and encoding of the document. The content handler and possibly input and output filter chains are also set up at this point (configuration of handlers and filters is covered in the following chapters).

The main module involved in this phase of request handling, apart from the core, is mod_mime; other modules set up specialized metainformation. Content handlers may change any of these attributes later.

Note that unless otherwise stated, file extension arguments are case-insensitive and may be specified with or without a leading period (.).

Standard Document Attributes

Four standard document attributes are used for content negotiation. Clients indicate preferences in Accept* request headers, and the attributes of the selected document are used to set response headers.

Content language

The natural language of the document, such as en-gb for British English, es-mx for Mexican Spanish, or zh for unqualified Chinese. The client’s preferences are indicated in the Accept-Language header, and the language of the selected document is returned in the Content-Language header.

Content type

The MIME type of the document, such as text/html or image/png; preferences are indicated with Accept, and the document MIME type is returned in Content-Type.

Character set