+++ /dev/null
-* some notes on the relation of XML and ISIS
-
-
-XML is in widespread use as a lingua franca
-for glueing software components together.
-Several tools for this can be found at xml.apache.org.
-
-What is missing here is an efficient, easy to use
-way of storing XML data. Only the most trivial cases
-are easily mapped onto the relational data model,
-which uses flat records, consisting of a fixed number
-of fields. The data structures modelled in XML
-typically have a variable number of childs.
-Hierarchical databases like ADABAS C are well suited
-and actually used by SoftwareAG in their Tamino XML DB,
-but aren't widely and freely available.
-
-
-* ISIS to XML
-
-ISIS records can be easily and canonically converted to XML.
-Anything up to the first subfield delimiter is the body (a text node),
-subfields are attributes
-(strictly XML-ish this is ok only for non-repeated subfields).
-Other special subdivisions of field content like the typical
-<key word> may split to real child nodes.
-
-The result (as generated by make pdemo) may look like:
-$
-<isisrec id="148">
- <v69>
- <key>Educational Psychology</key>
- <key>universities</key>
- <key>Kenya</key>
- </v69>
- <v70>Okatcha, F.M.M.O.</v70>
- <v30 a="1 p."/>
- <v24>Personal statement</v24>
- <v26 c="1976"/>
- <v12 p="Tbilisi, USSR" d="1976">Symposium on the Psychological Bases of Programmed Learning </v12>
-</isisrec>
-$
-
-Instead of tag numbers and subfield characters,
-symbolic names from the FDT may be used.
-
-
-* XML to ISIS
-
-XML data structures can be
-easily and efficiently mapped to the data model of ISO2709.
-
-The general conversion (based on a SAX parser) works as follows:
-- when encountering an opening tag, look up it's name in the FDT.
- If there is no FDT provided, create one on the fly.
- If the FDT does not contain the tag name,
- create a new entry using tag number max(100,1+highest tag in FDT).
- Create a field using the tag number found and field value '+'.
-- when encountering an attribute, look up it's name in the
-> Meta metadata
- Create a new subfield entry if needed using code 'a'
- or 1+highest code used (for this tag).
- Append a subfield using the code found.
-- When encountering an empty tag (the current field ends with />),
- change the starting '+' to '-'.
-- When encountering a text node, add a field using tag number 0
- with the node's body as value.
-- When encountering a closing tag, look up it's name as for opening tags,
- add a field with an empty value.
-- As additional optimization, most text nodes can be eliminated
- by using the initial value of a node to represent an immediatly
- following text node.
-
-For example look at RDF (
-> http://www.w3.org/RDF
-,
-> http://archive.dstc.edu.au/RDU/reports/RDF-Idiot
-).
-A structure like
-$
-<DC:Creator parseType="Resource">
-<vCard:FN> Dr Jacky J Crystal </vCard:FN>
-<vCard:TITLE> Director </vCard:TITLE>
-<vCard:EMAIL> jacky@dstc.com.au </vCard:EMAIL>
-<vCard:ROLE> Researcher </vCard:ROLE>
-</DC:Creator>
-$
-canonically maps to
-$
-100 +^aResource
-101 +
-0 Dr Jacky J Crystal
-101
-102 +
-...
-$
-or, with text-node elimination, to
-$
-100 +^aResource
-101 -Dr Jacky J Crystal
-102 -Director
-...
-100
-$
-using about half the bytes it takes to store the original.
-
-If they had made an attribute what can be an attribute
-(not substructered, not repeatable) instead of a child,
-it would read (with explicitly assigned subfield codes)
-much more efficiently like
-$
-100 ^pResource^fDr Jacky J Crystal^tDirector^ejacky@dstc.com.au^rResearcher
-$
-
-Also see
-> unirec
-and
-> Struct
-
----
- $Id: xmlisis.txt,v 1.7 2003/06/23 14:43:42 kripke Exp $
projects / webpac / blobdiff