DEDSL and XML tools

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DEDSL and XML tools
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DEDSL API

• A previous paper proposed a Java API for DEDSL
• An implementation was produced for DEDSL PVL
  concrete syntax
• Used JACC to develop a parser for PVL
• DEDSL PVL rules were embedded in the code
• User Attributes difficult to handle

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Interface

• Needs to provide information about
• Descriptors
• Attributes
• Entities
• Dictionary

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Additional benefits from JAVA Interface

• Can be used for several underlying
  implementations e.g. PVL and XML
• Easily used in Remote Method Invocation (RMI) for
  network access to Dictionary
• Can be used as basis for producing CORBA IDL
  which can be input to idltojava tool

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Further considerations

• JavaCC
• produces SimpleNode alter this to implement
  java.swing.tree.TableNode in order to be able to
  generate good GUI
• Provide basic parsing must provide additional
  checking etc in extra coding
• Entities, Dictionary properties and Attributes
  are provided as SimpleNode trees which may be
  traversed

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Interface

• public interface DedslDictionary
• public int getDedslNumberOfDescriptors()
• public String getDedslDescriptorNames()
• public SimpleNode getDedslDescriptor(String
  descriptorName)
• public int getDedslNumberOfAttributes()
• public String getDedslAttributeNames()
• public SimpleNode getDedslAttribute(String
  attributeName)
• public int getDedslNumberOfEntities()
• public String getDedslEntityNames()
• public SimpleNode getDedslEntity(String
  entityName)
• public int getDedslNumberOfDictionaryProperti
  es()
• public String getDedslDictionaryPropertyNam
  es()
• public SimpleNode getDedslDictionaryProperty(S
  tring propName)
• public SimpleNode getDedslEntityAttribute(
  String ent, String att)

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Minimum set of API

• public String getDedslDescriptorNames()
• public String getDedslAttributeNames()
• public String getDedslEntityNames()
• public SimpleNode getDedslEntityAttribute(
  String ent, String att)

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Problems

• Difficult very difficult to support over the
  long term

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Use of XML

• XML hope is that COTS and Open Source tools will
  be available
• Will thereby minimise the amount of code needed
• Will make any tools we develop much easier to
  maintain

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Example XML tools

• SAX libraries
• DOM libraries
• Dom4J
• JDOM
• JAXB
• Castor

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METS API

• Chose JAXB API
• However JAXB only deals with DTDs at the moment.
• Lots of additional code needed.

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METS toolkit
The JAXB specification is still in early
pre-release development. Although a preliminary
early version implementation of the class
generator has been released, it only accepts as
input a subset of the XML DTD language XML
schema is not supported at all. Thus, all of the
base classes as well as the METS schema-specific
class used in the toolkit were constructed
manually, following the JAXB API specification.
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Use of Schema

• Schema has additional information about data
  types and specification of elements
• Namespaces allow more flexibility
• Code generators have more to work with

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Castor

• Castor generates code from XML Schema
• Castor is a supports a large number of XML Schema
  capabilities

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Next steps

• Develop draft XML Schema concrete syntax for
  DEDSL
• Should lead to WB
• Enhance capabilities of Castor generated code by
  addition of a small number of classes to deal
  with inheritance