Sun Java System Web Server 6.1 SP9 Administrator's Configuration File Reference

Chapter 5 MIME Types

This chapter discusses the MIME types file.

The sections are:


The MIME types file in the config directory contains mappings between MIME (Multipurpose Internet Mail Extensions) types and file extensions. For example, the MIME types file maps the extensions .html and .htm to the type text/html:

type=text/html exts=htm,html

When the Sun Java System Web Server receives a request for a resource from a client, it uses the MIME type mappings to determine what kind of resource is being requested.

MIME types are defined by three attributes: language (lang), encoding (enc), and content-type (type). At least one of these attributes must be present for each type. The most commonly used attribute is type. The server frequently considers the type when deciding how to generate the response to the client. The enc and lang attributes are rarely used.

The default MIME types file is called mime.types.

Determining the MIME Type

During the ObjectType step in the request handling process, the server determines the MIME type attributes of the resource requested by the client. Several different server application functions (SAFs) can be used to determine the MIME type, but the most commonly used one is type-by-extension. This function tells the server to look up the MIME type according to the requested resource’s file extension in the MIME types table.

The directive in obj.conf that tells the server to look up the MIME type according to the extension is:

ObjectType fn=type-by-extension

If the server uses a different SAF, such as force-type, to determine the type, then the MIME types table is not used for that particular request.

For more details of the ObjectType step, see the Sun Java System Web Server 6.1 SP9 NSAPI Programmer’s Guide.

How the Type Affects the Response

The server considers the value of the type attribute when deciding which Service directive in obj.conf to use to generate the response to the client.

By default, if the type does not start with magnus-internal/, the server just sends the requested file to the client. The directive in obj.conf that contains this instruction is:

Service method=(GET|HEAD|POST) type=*~magnus-internal/* fn=send-file

By convention, all values of type that require the server to do something other than just send the requested resource to the client start with magnus-internal/.

For example, if the requested resource’s file extension is .map, the type is mapped to magnus-internal/imagemap. If the extension is .cgi, .exe, or .bat, the type is set to magnus-internal/cgi:

type=magnus-internal/imagemap       exts=map
type=magnus-internal/cgi            exts=cgi,exe,bat


If the type starts with magnus-internal/, the server executes the Service directive in obj.conf matches the specified type. For example, if the type is magnus-internal/imagemap, the server uses the imagemap function to generate the response to the client, as indicated by the following directive:

Service method=(GET|HEAD) type=magnus-internal/imagemap fn=imagemap

What Does the Client Do with the MIME Type?

The Service function generates the data and sends it to the client that made the request. When the server sends the data to the client, it also sends headers. These headers include the MIME type attributes are known (which is usually type).

When the client receives the data, it uses the MIME type to decide what to do with the data. For browser clients, display the data in the browser window.

If the requested resource cannot be displayed in a browser but needs to be handled by another application, its type starts with application/, for example, application/octet-stream (for .bin file extensions) or application/x-maker (for .fm file extensions). The client has its own set of user-editable mappings that tells it which application to use to handle which types of data.

For example, if the type is application/x-maker, the client usually handles it by opening Adobe® FrameMaker® to display the file.

Syntax of the MIME Types File

The first line in the MIME types file identifies the file format and must read:

#--Sun Microsystems MIME Information

Other non-comment lines have the following format:

type=type/subtype exts=[file extensions]

Sample MIME Types File

Here is an example of a MIME types file:

#--Sun Microsystems MIME Information
      # Do not delete the above line. It is used to identify the file type.
      type=application/octet-stream      exts=bin,exe
      type=application/oda               exts=oda
      type=application/pdf               exts=pdf
      type=application/postscript        exts=ai,eps,ps
      type=application/rtf               exts=rtf
      type=application/x-mif             exts=mif,fm
      type=application/x-gtar            exts=gtar
      type=application/x-shar            exts=shar
      type=application/x-tar             exts=tar
      type=application/mac-binhex40      exts=hqx

      type=audio/basic                   exts=au,snd
      type=audio/x-aiff                  exts=aif,aiff,aifc
      type=audio/x-wav                   exts=wav

      type=image/gif                     exts=gif
      type=image/ief                     exts=ief
      type=image/jpeg                    exts=jpeg,jpg,jpe
      type=image/tiff                    exts=tiff,tif
      type=image/x-rgb                   exts=rgb
      type=image/x-xbitmap               exts=xbm
      type=image/x-xpixmap               exts=xpm
      type=image/x-xwindowdump           exts=xwd

      type=text/html                     exts=htm,html
      type=text/plain                    exts=txt
      type=text/richtext                 exts=rtx
      type=text/tab-separated-values     exts=tsv
      type=text/x-setext                 exts=etx

      type=video/mpeg                    exts=mpeg,mpg,mpe
      type=video/quicktime               exts=qt,mov
      type=video/x-msvideo               exts=avi

      enc=x-gzip                         exts=gz
      enc=x-compress                     exts=z
      enc=x-uuencode                     exts=uu,uue

      type=magnus-internal/imagemap      exts=map
      type=magnus-internal/parsed-html   exts=shtml
      type=magnus-internal/cgi           exts=cgi,exe,bat
      type=magnus-internal/jsp           exts=jsp