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Mime

Powerpoint about MIME

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Mime

  1. 1. Elaine PullicinoB.Ed. With Computing
  2. 2. What is MIME?MIME is an acronym for Multipurpose Internet MailExtensionIt is used to describe message content typesMIME messages can containtext,images,audio,video, andother application-specific data (e.g. PDF Files,Microsoft Word Documents, and so on)
  3. 3. What is it used for?It is used to make internet messages richerIt allows applications (and users) to exchange richcontent other than textIt is an extension to the original email specification(RFC-822)It is defined in RFCs RFC-2045 through RFC-2049A Request for Comments (RFC) is a documentpublished by the Internet Engineering Task Force(IETF) describing an internet standard
  4. 4. MIME FormatMIME types are defined using a <type>/<subtype>[optional parameters] formatSome typical examples areMIME Type Extension(s)text/plain txtapplication/vnd.ms-excel xlsapplication/pdf pdftext/html htm;htmltext/css css
  5. 5. How is it used?MIME is passed as partof the content type of themessage headerContent-type:text/plain; charset=“us-ascii”The following exampleis a typical HTTPResponse header (MIMEis highlighted)HTTP/1.x 200 OKTransfer-Encoding: chunkedDate: Sat, 28 Nov 2009 04:36:25 GMTServer: LiteSpeedConnection: closeX-Powered-By: W3 Total Cache/0.8Pragma: publicExpires: Sat, 28 Nov 2009 05:36:25 GMTCache-Control: max-age=3600, publicContent-Type: text/html; charset=UTF-8Last-Modified: Sat, 28 Nov 2009 03:50:37 GMTVary: Accept-Encoding, Cookie, User-Agent
  6. 6. Support for different languagesMessage headercontent-type fieldput in the header by the client programcreating the e-mail for use by the clientprogram used to display the received messagecharset= optional parameterif absent ASCII is assumedContent-Type: text/plain; charset="ISO-8859-1"ISO-8859-1 character standard extends the basic character set ofASCII to include many of the accented characters used inlanguages such as German
  7. 7. EncodingBinary files need to be “packaged” as text in order tobe sent over the internetMIME uses a BASE-64 binary encoding scheme topackage the data for transferAs a result of this encoding, standard SMTP (SimpleMail Transfer Protocol) servers did not require anychangesEncoding transforms binary data into a stringDecoding changes the data back into its original form
  8. 8. Base 64 encoding ExampleNormal Text: Lorem ipsum dolor sit amet, consecteturadipiscing elit. Nulla mattis pulvinar ligula. Ut quis nequeut lorem mollis hendrerit. Curabitur rhoncus, neque vitaesodales condimentum.Encoded Text:TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNlY3RldHVyIGFkaXBpc2NpbmcgZWxpdC4gTnVsbGEgbWF0dGlzIHB1bHZpbmFyIGxpZ3VsYS4gVXQgcXVpcyBuZXF1ZSB1dCBsb3JlbSBtb2xsaXMgaGVuZHJlcml0LiBDdXJhYml0dXIgcmhvbmN1cywgbmVxdWUgdml0YWUgc29kYWxlcyBjb25kaW1lbnR1bS4=An online tool one can use to experiment can be found athttp://www.motobit.com/util/base64-decoder-encoder.asp
  9. 9. Sending large messagesWhen sending large messages, the message clientsplits them into smaller partsThis type of message is called a multi-part messageMulti-part messages have one the following MIMEcontent types:content-type = multipart/relatedcontent-type = multipart/mixed
  10. 10. Further ReadingMIME Reference. In MIME Types. Retrieved fromhttp://www.w3schools.com/media/media_mimeref.aspaccessed, on 21 December 2010Borenstein, N & Freed, N. (1996). MultipurposeInternet Mail Extensions (MIME) Part One: Format ofInternet Message Bodies. Retrievedfromhttp://tools.ietf.org/html/rfc2045, on 21stDecember 2010.
  11. 11. Further ReadingKozierok, C. M. (2005). TCP/IP Enhanced ElectronicMail Message Format: Multipurpose Internet MailExtensions (MIME). In The TCP/IP Guide. Retrievedfromhttp://www.tcpipguide.com/free/t_MIMEContentTypeHeaderandDiscreteMediaTypesSubtypes.htm, on 21stDecember 2010.Josefsson, S. (2006). The Base16, Base32, and Base 62Data Encodings.http://tools.ietf.org/html/rfc4648accessed on 21stDecember 2010.

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