rfc2112.txt

<VC++网络游戏建摸与实现>源代码

     10
     34
     10
     25
     21
     26
     10
     --example-1
     Content-Type: Application/octet-stream
     Content-Description: The fixed length records
     Content-Transfer-Encoding: base64
     Content-ID: <[e-mail]>

     T2xkIE1hY0RvbmFsZCBoYWQgYSBmYXJtCkUgSS
     BFIEkgTwpBbmQgb24gaGlzIGZhcm0gaGUgaGFk
     IHNvbWUgZHVja3MKRSBJIEUgSSBPCldpdGggYS
     BxdWFjayBxdWFjayBoZXJlLAphIHF1YWNrIHF1
     YWNrIHRoZXJlLApldmVyeSB3aGVyZSBhIHF1YW
     NrIHF1YWNrCkUgSSBFIEkgTwo=

     --example-1--






Levinson                    Standards Track                     [Page 5]

RFC 2112          MIME Multipart/Related Content-type         March 1997


5.2 Text/X-Okie

   The Text/X-Okie is an invented markup language permitting the
   inclusion of images with text.  A feature of this example is the
   inclusion of two additional body parts, both picture. They are
   referred to internally by the encapsulated document via each
   picture's body part content-ID.  Usage of "cid:", as in this example,
   may be useful for a variety of compound objects.  It is not, however,
   a part of the Multipart/Related specification.

     Content-Type: Multipart/Related; boundary=example-2;
             start="<[e-mail]>"
          type="Text/x-Okie"

     --example-2
     Content-Type: Text/x-Okie; charset=iso-8859-1;
             declaration="<[e-mail]>"
     Content-ID: <[e-mail]>
     Content-Description: Document

     {doc}
     This picture was taken by an automatic camera mounted ...
     {image file=cid:<[e-mail]>}
     {para}
     Now this is an enlargement of the area ...
     {image file=cid:<950118:[e-mail]>}
     {/doc}
     --example-2
     Content-Type: image/jpeg
     Content-ID: <[e-mail]>
     Content-Transfer-Encoding: BASE64
     Content-Description: Picture A

     [encoded jpeg image]
     --example-2
     Content-Type: image/jpeg
     Content-ID: <[e-mail]>
     Content-Transfer-Encoding: BASE64
     Content-Description: Picture B

     [encoded jpeg image]
     --example-2--









Levinson                    Standards Track                     [Page 6]

RFC 2112          MIME Multipart/Related Content-type         March 1997


5.3 Content-Disposition

   In the above example each image body part could also have a Content-
   Disposition header.  For example,

     ...
     --example-2
     Content-Type: image/jpeg
     Content-ID: <[e-mail]>
     Content-Transfer-Encoding: BASE64
     Content-Description: Picture B
     Content-Disposition: INLINE

     [encoded jpeg image]
     --example-2--

   User Agents that recognize Multipart/Related will ignore the
   Content-Disposition header's disposition type.  Other User Agents
   will process the Multipart/Related as Multipart/Mixed and may make
   use of that header's information.

6.  User Agent Requirements

   User agents that do not recognize Multipart/Related shall, in
   accordance with [MIME], treat the entire entity as Multipart/Mixed.
   MIME User Agents that do recognize Multipart/Related entities but are
   unable to process the given type should give the user the option of
   suppressing the entire Multipart/Related body part shall be.

   Existing MIME-capable mail user agents (MUAs) handle the existing
   media types in a straightforward manner.  For discrete media types
   (e.g. text, image, etc.) the body of the entity can be directly
   passed to a display process.  Similarly the existing composite
   subtypes can be reduced to handing one or more discrete types.
   Handling Multipart/Related differs in that processing cannot be
   reduced to handling the individual entities.

   The following sections discuss what information the processing
   application requires.

   It is possible that an application specific "receiving agent" will
   manipulate the entities for display prior to invoking actual
   application process.  Okie, above, is an example of this; it may need
   a receiving agent to parse the document and substitute local file
   names for the originator's file names.  Other applications may just
   require a table showing the correspondence between the local file
   names and the originator's.  The receiving agent takes responsibility
   for such processing.



Levinson                    Standards Track                     [Page 7]

RFC 2112          MIME Multipart/Related Content-type         March 1997


6.1 Data Requirements

   MIME-capable mail user agents (MUAs) are required to provide the
   application:

   (a)  the bodies of the MIME entities and the entity Content-*
        headers,

   (b)  the parameters of the Multipart/Related Content-type
        header, and

   (c)  the correspondence between each body's local file name,
        that body's header data, and, if present, the body part's
        content-ID.

6.2 Storing Multipart/Related Entities

   The Multipart/Related media type will be used for objects that have
   internal linkages between the body parts.  When the objects are
   stored the linkages may require processing by the application or its
   receiving agent.

6.3 Recursion

   MIME is a recursive structure.  Hence one must expect a
   Multipart/Related entity to contain other Multipart/Related entities.
   When a Multipart/Related entity is being processed for display or
   storage, any enclosed Multipart/Related entities shall be processed
   as though they were being stored.

6.4 Configuration Considerations

   It is suggested that MUAs that use configuration mechanisms, see
   [CFG] for an example, refer to Multipart/Related as
   Multipart/Related/<type>, were <type> is the value of the "type"
   parameter.

7.  Security considerations

   Security considerations relevant to Multipart/Related are identical
   to those of the underlying content-type.










Levinson                    Standards Track                     [Page 8]

RFC 2112          MIME Multipart/Related Content-type         March 1997


8.  Acknowledgments

   This proposal is the result of conversations the author has had with
   many people.  In particular, Harald A. Alvestrand, James Clark,
   Charles Goldfarb, Gary Houston, Ned Freed, Ray Moody, and Don
   Stinchfield, provided both encouragement and invaluable help.  The
   author, however, take full responsibility for all errors contained in
   this document.

9.  References

   [822]       Crocker, D., "Standard for the Format of ARPA
               Internet Text Messages", August 1982, University
               of Delaware, RFC 822.

   [CID]       E. Levinson, J. Clark, "Message/External-Body
               Content-ID Access Type", 12/26/1995, RFC 1873
               Levinson, E., "Message/External-Body Content-ID
               Access Type", February 1997, RFC 2111.

   [CFG]       Borenstein, N., "A User Agent Configuration
               Mechanism For Multimedia Mail Format
               Information", September 23, 1993, RFC 1524

   [DISP]      R. Troost, S. Dorner, "Communicating Presentation
               Information in Internet Messages:  The Content-
               Disposition Header", June 7, 1995, RFC 1806

   [MIME]      Borenstein, N. and Freed, N., "MIME (Multipurpose
               Internet Mail Extensions): Mechanisms for
               Specifying and Describing the Format of Internet
               Message Bodies", June 1992, RFC 1341.

9.  Author's Address

   Edward Levinson
   XIson, Inc.
   47 Clive Street
   Metuchen, NJ  08840-1060
   USA
   [phone]
   <[e-mail]>









Levinson                    Standards Track                     [Page 9]