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Contents: Overview What is XML? Mapping rules A simple class Association of low multiplicity

Contents: Overview What is XML? Mapping rules A simple class Association of low multiplicity Association of high multiplicity Hierachy Intermediate conclusion XML as a bridge - Exporting from MS-Access - Importing into FastObjects The XML reality. XML model. XML Database. XML:

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Contents: Overview What is XML? Mapping rules A simple class Association of low multiplicity

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  1. Contents: • Overview • What is XML? • Mapping rules • A simple class • Association of low multiplicity • Association of high multiplicity • Hierachy • Intermediate conclusion • XML as a bridge • - Exporting from MS-Access • - Importing into FastObjects • The XML reality

  2. XML model XML Database XML: Just an additional path in the data modelling flow chart?

  3. Each XML document (a database?) … • is a (long) string (stored in a text file) • consists of • a header (conc. XML version and character set) • (if necessary:) a reference to a structure definition file • data (= a „mixture“ of tags and content) • Content and all tags (!) can be defined by the user. • Structure information can be generated automatically on the basis of the • XML documents. (-> first: create data and second: generate the structure)

  4. This is the begin tag of an object Mapping of a simple class and here is the corresponding end tag An object A set of objects The corresponding document type definition (DTD) (a class definition) indicating „many; at least one“

  5. Mapping of an association of low multiplicity Mapping multiplicity 0..*

  6. XML Schema: just another DDL Again: mapping multiplicity 0..*

  7. Mapping of an association of high multiplicity

  8. An XSL transformation using an XSLT style sheet

  9. And here is the result (displayed by OPERA browser)

  10. Mapping of a hierachy

  11. A client („Kunde“) element based on this DTD is as follows: Remark: This mapping rule differs from the corresponding one in The Book.

  12. Who‘s gonna use these concepts? Nobody. Nowadays data is stored in network or relational databases, but isn‘t stored in XML databases/documents. So, what‘s left (for XML)?

  13. XML as a bridge between heterogeneous databases [so-called Message-oriented middleware (MOM) architecture]

  14. Exporting a simple relation as part of an MS-Access database

  15. Importing an XML document into a FastObjects database (screen shot)

  16. Conclusions: • The XML path is just another path in data modelling, but it is of no importance in industry. Native XML database systems won‘t have a commercial future. • Import/export of data will be done on an XML basis. All database systems (will) offer interfaces for that basis.

  17. Reality The XML reality Relational Database (e.g. Access) Network Database (e.g. UDS) Object- oriented Database (e.g. POET) XML data model XML- DB XML document

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