Progress on High Level Concepts

XML in EDA

Design Automation Technical Committee Report by

Alex Zamfirescu

June 19, 2001

Major XML Progress Relevant to EDA

XML Schema Recommendation

After two and a half years, the World Wide Web Consortium (W3C) has released its XML Schema Recommendation. It defines shared markup vocabularies and the structure of XML documents that use those vocabularies, and it provides hooks to associate semantics with them.

The XML schema specification consists of three parts.

One part defines a set of simple data types, which can be associated with XML element types and attributes; this allows XML software to do a better job of managing dates, numbers, and other special forms of information.
The second part of the specification proposes methods for describing the structure and constraining the contents of XML documents, and defines the rules governing schema-validation of documents.
The third part is a primer, which explains what schemas are, how they differ from DTDs (Document Type Definitions), and how someone builds a schema..

Unlike DTD, XML schemas are written in XML syntax, which although more verbose than DTD, they can be created with any XML tools.

In conjunction with XML Namespaces, XML Schema is the language for building XML applications.

W3C group is run jointly by the MIT Laboratory for Computer Science in the USA, the National Institute for Research in Computer Science and Control in France and Keio University in Japan.

SIMPLE SCHEMA: TREX and RELAX

TREX and RELAX are alternatives to the XML Schema Language, which is now in final review at W3C but has been criticized as too complex, especially for developers with limited programming resources.

TREX (Tree Regular Expressions for XML) is the brainchild of James Clark, who served as technical lead for the W3C's XML 1.0. But when it came to XML Schema Language specs, Clark has criticized them as "too complicated." He said he began work on an alternative because "there is a genuine need for a straightforward, easy-to-learn XML schema language." Clark is now serving as chair of the TREX Technical Committee, seeking to establish a TREX standard within the Boston-based OASIS consortium.

To keep it simple, "TREX limits its scope to describing and validating the structure and content of an XML document," according to the OASIS committee. "It does not attempt to specify any application processing semantics."

For those interested, Clark offers:

a TREX tutorial at http://thaiopensource.com/trex/tutorial.html.

the current TREX specs at http://thaiopensource.com/trex/spec.html.

RELAX (REgular LAnguage description for XML) was started as another alternative to the XML Schema Language specifications by Makoto Murata, one of the members of the working group on those specs, who thought they were leaning toward benefiting vendors rather than advancing XML technology.

A tutorial on RELAX is available at http://catcode.com/relax_tut/index.html.

The OASIS efforts may meld TREX and RELAX into a simplified schema language that could offer developers an alternative for defining and describing XML documents.

Topic Maps

This specification provides a model and grammar for representing the structure of information resources used to define topics, and the associations (relationships) between topics.

http://www.topicmaps.org/xtm/1.0/

DAML

The DARPA Agent Markup Language (DAML) Program officially began in August 2000. The goal of the DAML effort is to develop a language and tools to facilitate the concept of the semantic web. The DAML language is being developed as an extension to XML

http://www.daml.org/

Table 1 summarize the DAML features compared against XML DTD, XML Schema and Resource Description Framework (RDF).

Table 1: Features compared
Feature	XML DTD	XML Schema	RDF(S)	DAML+OIL
bounded lists				X
cardinality constraints	X	X		X
class expressions				X
data types		X		X
defined classes				X
enumeration	X	X		X
equivalence				X
extensibility			X	X
formal semantics				X
inheritance			X	X
inference				X
local restrictions				X
qualified constraints				X
reification			X	X

Discussion:

bounded lists

rdf:Seq and rdf:Bag don't provide any indication that the list is complete (e.g. "these are 5 children of X" vs. "X is known to have exactly these 5 children")

DAML uses a first/rest structure to represent unordered bounded lists, with nil representing the end of the list

rdf:parseType="daml:collection" provides a shorthand and RDF syntax compatibility

cardinality constraints

limit the number of statements with the same subject and predicate

the Kleene operators ? (0 or 1), * (0+), and + (1+) in XML DTD provide basic cardinality constraints

DAML supports cardinality, minCardinality, and maxCardinality

class expressions

wherever a Class is referenced, DAML+OIL also allows an expression involving unionOf, disjointUnionOf, intersectionOf, or complementOf

data types

RDF Literals are essentially strings
DAML+OIL (March 2001) adds XML Schema data types

defined classes

DAML allows new classes to be defined based on property values or other restrictions of an existing class (e.g. Child is a Person with age < 18) or class expressions.

enumeration

XML DTD allows specification of a restricted set of values for a given attribute

DAML provides oneOf

equivalence

to support reasoning across ontologies and knowledge bases, DAML supports equivalentTo for classes, properties, and instances

additional mapping constructs may be added to future versions of DAML

extensibility

RDF and DAML allow new Properties to used with existing Classes
RDF has been used to define DAML+OIL
DAML+OIL may similarly be used to define future languages such as DAML-Logic

formal semantics

DAML+OIL semantics have been expressed in both model-theoretic and axiomatic forms

inheritance

XML Schema attribute groups formalize DTD use of parameter entities in attribute definitions, but this isn't full inheritance

RDF and DAML support subClassOf and subPropertyOf

inference

DAML+OIL constructs such as TransitiveProperty, UnambiguousProperty, inverseOf, and disjointWith provide additional information for reasoning engines

future versions of DAML are expected to support rules, proof-checking, etc.

local restrictions

RDF associates domain and range constraints with a Property

DAML allows Restrictions to be associated with a Class/Property pair, e.g. allowing the color property to be used for the Car and Eye classes with different domains

qualified constraints

DAML restrictions allow expressions such as "all children of X are of type Person"

the DAML properties hasClassQ, cardinalityQ, minCardinalityQ, and maxCardinalityQ allow qualified restrictions such as "at most 3 of the children of X are of type Doctor"

reification

RDF and DAML allow a statement to be the subject of another statement

reification provides a standard mechanism for recording data sources, timestamps, etc. without intruding on the data model

the DAML+OIL semantics do not currently cover reification

in its initial discussions on reification, the Joint Committee has found it useful to distinguish "tagging" (making statements about asserted statements, e.g. source, timestamp, etc.) from "quoting" (making statements about unasserted statements)

IEEE P1600.1

A new working group, the IEEE Standard Upper Ontology (SUO) concerned with the basic semantics proposes a large ontology as a new IEEE standard. Opponents suggest to break it into smaller ontologies. Some ask for unique APIs (to access knowledge in the SUO) others claim that a good standard is all what it is needed.

The page at http://www.doctypes.org/cyc/cyc-xtm-20010227.html contains a technical report documenting research and development of an XML Topic Map (XTM) representation of the Upper Cyc Ontology,

(approximately 3,000 terms capturing the most general concepts of human consensus reality http://www.cyc.com/cyc-2-1/cover.html)

including a distribution of five XML topic maps(XTM)based on features of the ontology proposed by the IEEE Standard Upper Ontology (SUO) Working Group

(IEEE P1600.1 approved Dec 2000), see http://ltsc.ieee.org/suo/.

The IEEE Standard Upper Ontology in DAML has just been released (2001-06-05)

It can be found at http://www.daml.org/ontologies/172

Major Comercial XML in EDA Efforts

Many parallel efforts lead to the spread of use of XML in EDA.

XML-based symbols mapped directly to the database are now available

http://www.oasis-open.org/cover/xmlAndEDA.html

EdaXML http://www.e-tools.com/ is a natural complement to Si2's ECIX QuickData Specification: it is no longer necessary to have a subset of the EDA data, the user can combine ECIX QuickData Searchable attributes with an easy XML access to the real thing: real EDA symbol real PCB footprints, etc. EdaXML will facilitate design collaboration over the Web using XML Web servers, provide true interoperability between various EDA databases and allow linking seamlessly designs on multiple EDA platforms.

Besides Lucent, companies like Agilent Technologies, IBM and Hewlett-Packard are reportedly developing their own carrots and sticks to make sure their suppliers start QuickData library programs. And companies such as ChipData, a startup based in Dallas, and Saqqara Systems Inc. (San Jose, Calif.) are creating services to help component suppliers do just that.

XML library symbol standard (refined now by major companies) is one of the essential technologies for seamlessly integrating symbol information into EDA tools

http://dacafe.ibsystems.com/DACafe/NEWS/CorpNews2/20010411_beach.html

Beach Solutions demonstrates a new tool, called EASI-Studio™, that includes the ability to describe the programmable bus interface of any Peripheral IP block in a standard XML format. The adoption of a standard building block approach at this functional hardware-software interface level, greatly simplifies the task of integration into a System on Chip (SoC) that often involves a mix of new IP with legacy designs from several sources.

http://www.rsi-inc.com/Company/Archive/xmlpress.html

"XML Compatible" Logo leverage the power of XML and the predominance of the Internet in order to facilitate the integration and exchange of Engineering and Manufacturing data in an efficient, cost effective manner

http://www.siliconstrategies.com/equipment/eda/OEG20010402S0019

In the pilot project, Chartered and Motorola jointly developed a prototype of an electronic extensible markup language (XML) messaging format in conformance to a subset in RosettaNet's 3D8 standard for distributing work-in-progress messages between foundries and customers.

Both major IP-Repositories are using now XML.

Major concerted efforts are under way in the IEC (TC93 WG6), at NIST and Rosetta Net http://xml.coverpages.org/rosettaNet.html) to define a set of dictionaries with definitions for the electronic domain.

Other XML Resources for the EDA domain are

TDML is XML-based Interchange Standard for Waveforms and Timing Specifications at http://www.syncad.com/tdml.htm

XML in VHDL environment paper session, see http://www.eda.org/viuf/viuf.pdf

A pin map DTD at http://www.si2.org/ecix/edasymbol/doctypedef.htm

HXML - a set of DTDs representing hardware block, Control Data Flow Graphs representing behavior, and HDL intermediate format is proposed by Alternative System Concepts http://www.ascinc.com

Accellera plans include a Semantic Reference Manual (for the EDA domain) most of it formalized in XML.

In April 2001 a speaker for Lucent addressing the EDA consortium mentioned the use of XML in the design flow alongside HDLs.

NEMI plans are also based on the use of XML for CAD/CAM http://www.nemi.org/Projects/DEC/DEC.pdf

Conclusions

Solid progress in the use of XML in EDA was registered in the past year. The need for XML promotion in the EDA is no more required at this time. With the C# and .Net (new technologies from Microsoft standardized by ECMA) using XML to communicate descriptive information about components, XML will take a major role in the software development. More people will learn about the power of this simple standard, and will be able to cross the road of understanding from simple standard dictionaries to the use of ontologies. DATC "XML in EDA" study group will continue to watch and contribute to particular developments.

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