Beyond Schemas

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Beyond Schemas

• Extending Schemas with the Schema Adjunct
  Framework

Scott Vorthmann, Extensibility Jonathan Robie,
Software AG
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Extending Schemas

• Goals
• Provide extensibility for schema languages,
  similar to libraries in programming languages
• Schema language and programming language
  independence
• Allow extensions to the data associated with
  types declared in schema languages
• Allow processing to use this data in a
  language-independent way

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DTDs associate, validate
ltcustomergt ltcustNamegt lt/custNamegt
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DTDs associate, validate
lt!ELEMENT customer (name , shippingAddress ,
bi lt!ELEMENT name (PCDATA)gt
ltcustomergt ltcustNamegt lt/custNamegt
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DTDs associate, validate
lt!ELEMENT customer (name , shippingAddress ,
bi lt!ELEMENT name (PCDATA)gt
ltcustomergt ltcustNamegt lt/custNamegt
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Java associate, validate
checkCreditRating(n)
ltcustomergt ltcustNamegt lt/custNamegt
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Query associate, validate
empty ( FROM d IN //deadbeats,
c IN this WHERE d/name
this/name RETURN d )
ltcustomergt ltcustNamegt lt/custNamegt
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DTDs associate, enhance
lt!ELEMENT collection (item )gt lt!ATTLIST
collection ordered (true
false ) 'true' duplicates
(allowed prohibited ) 'allowed' gt
ltcollectiongt ltitemgt Hi Mom! lt/itemgt
ltitemgt Hi Dad! ltitem /gt lt/collectiongt
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DTDs associate, enhance
lt!ELEMENT collection (item )gt lt!ATTLIST
collection ordered (true
false ) 'true' duplicates
(allowed prohibited ) 'allowed' gt
ltcollection orderedfalse duplicatesallowed
gt ltitemgt Hi Mom! lt/itemgt
ltitemgt Hi Dad! ltitem /gt lt/collectiongt
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Schemas associate, enhance
ltelement name "person"gt
ltcomplexType content "elementOnlygt
ltsequencegt ltelement ref "name"/gt
ltelement ref "iq"/gt
ltelement ref "gender"/gt
lt/sequencegt lt/complexTypegt
lt/elementgt ltsimpleType name "iq" base
"decimal"/gt
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Schemas associate, enhance
ltpersongt ltnamegtAlexander B. Poindexterlt/namegt
ltiqgt53lt/iqgt ltgendergtMalelt/gendergt lt/persongt
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Schemas associate, enhance
ltsimpleType name "iq" base "decimal"/gt
ltpersongt ltnamegtAlexander B. Poindexterlt/namegt
ltiqgt53lt/iqgt ltgendergtMalelt/gendergt lt/persongt
Basedecimal!
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Whats not in a schema language?

• Database mappings?
• Algorithmic validation?
• Indexing strategies?
• Data bindings to OO systems?
• Does it ever stop?

• Data types?
• Input masks?
• Boundary conditions?
• Uniqueness constraints?
• Primary/foreign keys?
• Inheritance models?
• Co-occurrence constraints?

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In fact, just yesterday...

• Makoto MURATA, Relaxer
• Name mapping XML lt--gt Java
• Specifying alternative mappings (e.g. choosing
  which container type)
• Identifying the location of earlier versions of
  definitions

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Schema Adjunct Framework

• Associate data with XML node types
• Data is represented in any language
• The processor for this language may be
• Known in advance, (or)
• Identified by means of a namespace

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Adjuncts and Associations
ltschema-adjunct target"http//www.example.com/pat
-admit.xdr" xmlnssto
"http//www.example.com/xml-store.xsd"gt ltelement
which 'admission'gt ltstorootable/gt
ltstoindexgttextlt/stoindexgt lt/elementgt
lt/schema-adjunctgt
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Associations
ltschema-adjunct target"http//www.example.com/pat
-admit.xdr" xmlnssto
"http//www.example.com/xml-store.xsd"gt ltelement
which 'admission'gt ltstorootable/gt
ltstoindexgttextlt/stoindexgt lt/elementgt
lt/schema-adjunctgt
lt?xml version"1.0"?gt ltSchema name"pat-admit.xdr
"gt ltElementType name"admission"
content"eltOnly" order"seq"gt ltAttributeType
name"id" dttype"string" required"yes /gt
ltattribute type"id"/gt ltelement
type"patient-name"/gt ltelement
type"age"/gt lt/ElementTypegt lt/Schemagt
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Associations
ltschema-adjunct target"http//www.example.com/pat
-admit.xdr" xmlnssto
"http//www.example.com/xml-store.xsd"gt ltelement
which 'admission'gt ltstorootable/gt
ltstoindexgttextlt/stoindexgt lt/elementgt
lt/schema-adjunctgt
Isnt this a lot like XSLT?
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SAF Implementations

• SAF is declarative, and language independent
• SAF per se is the XML syntax for adjuncts
• Supporting SAF associations is usually just one
  function
• Further support may exist for
• loading and managing adjuncts
• finding a processor that understands an adjunct

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SAF Implementations

• DOM
• NodeList assoc sa.getAssociations(node)
• XSLT
• lttemplate matchassociations(index)gt
• SAX
• extending the events

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Schema Adjunct Framework

• an XML format for stating schema-specific,
  task-specific meta-data
• alternative viewpoints
• extend schemas with task-specific meta-data
• OR
• parameterize tasks with schema-specific meta-data
  

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Schema Adjunct Syntax

• ltschema-adjunct targettarget NS URI
  xmlnsprocprocessor NS URIgt
• ltdocumentgt
• ltprocglobal-meta-data/gt
• lt/documentgt
• ltelement whichelement1/element2gt
• ltprocsome-meta-data/gt
• lt/elementgt
• ltattribute whichelement3/_at_attr1gt
• ltprocmore-meta-data/gt
• lt/attributegt
• lt!-- more element and attribute associations --gt
• lt/schema-adjunctgt

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Schema Lock-in
XML PO
PO persist
DB
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Schema-generic Processing
Schema Adjunct
XML instance
generic persist
DB
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Schema Adjunct Processors
Schema Adjunct
Schema
XML instance
adjunct processor
...
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Enabling Processing per-Schema
persist
route
compile
...
validate
analyze
transform
purchase order
invoice
HR record
catalog
config file
tax return
...
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Example Form Generation
Schema Adjunct
XML instance
form generator
HTML form
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Example Form Generation

• ltschema-adjunct targetpat-admit.xdr
  xmlnsxfgxmlformgen.xsdgt
• ltelement whichadmissiongt
• ltxfgform nameadmit-form/gt
• lt/elementgt
• ltattribute whichpatient/_at_namegt
• ltxfglabelgtPatient Namelt/xfglabelgt
• ltxfgtypegttextlt/xfgtypegt
• ltxfgtaggtpatnmlt/xfgtaggt
• lt/attributegt
• lt/schema-adjunctgt

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Schema with Embedded Adjunct

• ltSchema name "pat-admit.xdr
  xmlnsxfgxmlformgen.xsdgt
• ltElementType name admission" content
  "eltOnly
• order "seq" xfgformtrue"gt
• ltelement type patient"/gt
• ltelement type "home"/gt
• lt/ElementTypegt
• ltElementType name patient" content
  "textOnly"gt
• ltAttributeType namename dttypestring
• xfglabelPatient Name xfgtypetext
  xfgtagpatnm/gt
• ltattribute typename/gt
• lt/ElementTypegt
• lt/Schemagt

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Example Extended Validation
Schema Adjunct
Schema
XML instance
standard validation
extended validation
...
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Example Extended Validation

• ltschema-adjunct targetinvoice.xdr
  xmlnsxvalmorevalid.xsdgt
• ltdocumentgt
• ltxvalfunc namecheckZip signature...
• class... codebase.../gt
• lt/documentgt
• ltelement whichmailto/addressgt
• ltxvaltest langxpath level5gt
• checkZip( _at_zip, _at_city, _at_state ) 0
• lt/xvaltestgt
• lt/elementgt
• lt/schema-adjunctgt

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Example Indexes in XDR

• ltschema-adjunct target "http//www.example.com/p
  at-admit.xsd"
• xmlnssto "http//www.example.c
  om/xml-store.xsd"gt
• ltelement which 'admission'gt
• ltstorootable/gt
• ltstoindexgttextlt/stoindexgt
• lt/elementgt
• ltelement which 'patient-name'gt
• ltstoindexgtstandardlt/stoindexgt
• lt/elementgt
• lt/schema-adjunctgt

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Example Indexes in XDR

• Adds index definition to XDR
• Defined at the schema / data dictionary level,
  with no instance documents
• Instance documents are indexed by the database
  when stored
• Tight integration of two commercial products -
  with no shared code
• Libraries of Schema Adjuncts

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Summary
Schema Adjunct
Schema
XML instance
adjunct processor
...
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Summary
persist
route
forms
...
validate
extend
transform
purchase order
invoice
HR record
catalog
config file
tax return
...
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For More Information

• SAF toolkit freely available
• http//www.extensibility.com/saf
• Currently DOM with Associations
• Next release adds SAX
• Specification is now being revised
• you heard the latest here!