'In-Line' data in EML2 using base64 encoding

[Dan Higgins]

Peter,

There is nothing bad about your suggestion, but it is only one of a 
variety of ways data can be 'related' to the metadata in eml2. Since we 
have an 'in-line' option, we need to figure out how to handle it.

There are some difficulties with your zip file method. The url reference 
in the 'online/url' would probably have to be a relative file url since 
one cannot know the complete path on a new machine. Presumably the 
relative location is relative to the eml metadata file, but that may not 
be the current working directory. And, once unzipped, a user can always 
move the data file and mess up the relative file url. Also, I don't 
think zip files can be directly added to a SOAP container if we go that 
way in SEEK.

Dan

---

Peter McCartney wrote:

> Whats so bad about putting it in a separate file and sending both in a 
> zip package? just put the filename in the distribution/online/url element.
>  
> Peter McCartney (peter.mccartney at asu.edu <mailto:peter.mccartney at asu.edu>)
> Center for Environmental-Studies
> Arizona State University
>  
>
>     -----Original Message-----
>     *From:* Dan Higgins [mailto:higgins at nceas.ucsb.edu]
>     *Sent:* Friday, May 23, 2003 10:01 AM
>     *To:* Eml-Dev (eml-dev at ecoinformatics.org); Christopher Jones
>     *Subject:* 'In-Line' data in EML2 using base64 encoding
>
>     Hi All,
>      
>     We at NCEAS have had several discussions about how to 'in-line'
>     data in eml2 documents. One method is to encode arbitrary data in
>     base64 format. The EML2 spec even says "encode the data using a
>     text encoding algorithm such as base64, and then include that in a
>     CDATA section" in the 'inline' documentation.
>
>     In looking into the subject, I discovered the reference below
>     which points out that base64 encoded data DOES NOT need to be
>     inside a CDATA section since it contains no special XML characters!
>
>     Dan
>     -------------------------
>
>
>           from: http://www.xml.com/axml/notes/CDprob.html
>
>
>           CDATA Sections and Binary Data
>
>     A lot of people would like a way to package up any old binary data
>     and include it in an XML file. The conventional XML answer to this
>     would be to store it separately and point at it with an unparsed
>     entity <http://www.xml.com/axml/target.html#dt-unparsed>. Which is
>     fine, but that's not what people want; they want to include the
>     data right in the file, which is a reasonable way to go if you're
>     going to transmit it over the network.
>
>     When you look at CDATA, you might get the impression that you
>     could maybe jam your binary data in a CDATA section. You'd be
>     right, but you'd have to guarantee that it never included a byte
>     sequence that looks like ]]>. There is a trick you can use to get
>     around that, but it's awkward:
>
>     <![CDATA[Use *two* CDATA sections when you need to embed a
>     "]]]]><![CDATA[>" in the data ]]>
>
>     Another way to go would be to encode the binary data in base64 or
>     some other technique that's guaranteed never to contain a <; but
>     if you're going to do that, you don't need a CDATA section; any
>     old element would do. Perhaps this is a good use for XML's
>     notation attributes <http://www.xml.com/axml/target.html#notatn>.
>
>     ----------------------
>     from: http://lists.xml.org/archives/xml-dev/199910/msg00388.html
>
>>As Tim says in his annotation, if you use Base64 then you don't need the
>>CDATA section as _none_ of the XML reserved chars appear in the Base64
>>character set (A-Za-z0-9/+).
>    
>
>
>-- 
>*******************************************************************
>Dan Higgins                                  higgins at nceas.ucsb.edu
>http://www.nceas.ucsb.edu/    Ph: 805-892-2531
>National Center for Ecological Analysis and Synthesis (NCEAS) 
>735 State Street - Room 205
>Santa Barbara, CA 93195
>*******************************************************************
>


-- 
*******************************************************************
Dan Higgins                                  higgins at nceas.ucsb.edu
http://www.nceas.ucsb.edu/    Ph: 805-892-2531
National Center for Ecological Analysis and Synthesis (NCEAS) 
735 State Street - Room 205
Santa Barbara, CA 93195
*******************************************************************