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Sun ONE Web Server 6.1 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 ONE 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 ONE Web Server 6.1 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 whichever 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 whichever 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, the usual thing is to 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

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