Title: Managing Namespaces in XML With Metadata Registries
1Managing Namespaces in XML With Metadata
Registries
- Judith Newton
- NIST
- jnewton_at_nist.gov
- XML Registry Project Team Meeting,
- May 21, 2003
2Agenda
- Namespaces as metadata
- Introduction to an ISO 11179-based metadata
registry (MDR) model - Naming in the MDR
- How an MDR can complement an XML registry
3What is Metadata?
- A type of data that describes and defines other
data - Content, quality and condition
- Who owns it? How was it collected? How current is
it? - How many names is it known by?
4Functional Namespaces
- Traditionally, data managers have divided up an
enterprises metadata by subject area or
stewardship domain - Business rules have been applied to these
namespaces - Intermixing happens Person metadata used by
Human Resources, Customer Service, etc.
5Previous External Namespace Arrangements
- One-to-one agreements
- Small groups of like-minded folks
- By fiat, like Wal-mart
6External Namespaces
- Communities of Interest are driving creation of
namespaces - Common schema development for subject areas
- Examples ebXML (OASIS), mathML, eCommerce
(BizTalk)
7Namespaces From Information Architecture
8Data Model
LOCATION
PERSON
ADDRESS
GEOGRAPHIC
EMPLOYEE
CUSTOMER
Latitude Longitude Altitude
Street County City Country
Name Position
Name Order History
9Good Practices for Namespace Management Tools
- Data Model
- Classification of Terms Ontology, taxonomy,
glossary, keywords - Metadata Repository or Registry
- XML Schemas
10Good Practices for Namespace Management Process
- Appoint data stewards
- Publish the semantic content of tools
- Build bridges
- Specify change mechanisms
11Good Practices for Namespace Management Goals
- Understandability - Users should readily
comprehend the data and metadata, both
structurally and semantically -
- Trustworthiness - The metadata should document
the source, collection method, security level,
and other factors so users can assess the
authority of the data - Interoperability - Enough information must be
provided to users concerning interfaces, whether
formalized or ad-hoc (or just potential)
12Example of Namespace Derivation Structure
Proposed scheme for establishing namespaces for
the U.S. government Namespaces organized by
subsetting the dot-gov domain into smaller units
by agency, for example  urnusgovgsa  In a
schema, gsa would be identified by a namespace
prefix  lt?xml version1.0 encodingUTF-8?gt lt
xsdschema xmlnsxsdhttp//www.w3.org/2001/XMLSc
hema xmlnsgsaurnusgovgsa
13Example of Namespace Prefix in an XML Instance
Document
Examples of instances qualified by the "gsa"
prefix  ltgsaAgencyNamegtGSAlt/gsaAgencyNamegt ltgs
aAgencyIDgt9986lt/gsaAgencyIDgt ltgsaContactPartyID
gt222345897lt/gsaContactPartyIDgt ltgsaOrderedQuanti
tygt100lt/gsaOrderedQuantitygt ltgsaOrderedQuantityA
mountgt399lt/gsaOrderedQuantityAmountgt  Â
14XML Technical Namespace Definition
The XML Recommendation defines a Namespace as a
conceptual space in which all names are
unique. Namespace becomes a mechanism to
distinguish among meanings of terms, for instance
bar in the legal sense and bar in the
fence-manufacturing community. In an XML Schema,
an IRI is used to define the namespace. The IRI
may not resolve to any actual content.
15Agenda
- Namespaces as metadata
- Introduction to an ISO 11179-based metadata
registry (MDR) model - Naming in the MDR
- How an MDR can complement an XML registry
16 SC 32 Data Management and
Interchange Meta Data Registry
Projects ISO/IEC 11179 Metadata Registries, Parts
1-6 Framework Classification Registry
metamodel and basic attributes Formulation of
data definitions Naming identification
principles Registration ISO/IEC TR 20943-1,
Procedures for achieving MDR content
consistency-Data elements to be published any day
now ISO/IEC TR 15452, Specification of Data Value
Domains, published in 2000. To be replaced by
ISO/IEC FDTR 20943-3, Procedures for achieving
MDR content consistency- Value Domains ISO/IEC
20944 series APIs and other interfaces
17High-level Metamodel
Conceptual_Domain
Data_Element_Concept
Value_Domain
Data_Element
18Administered Item Naming Example
Conceptual_Domain Name Country
Data_Element_Concept NameCountry Identifier
Value_Domain Name English-Language
Country Short Name
Data_Element
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22XML Name
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24Agenda
- Namespaces as metadata
- Introduction to an ISO 11179-based metadata
registry (MDR) model - Naming in the MDR
- How an MDR can complement an XML registry
25Names
- Names are associated with contexts within the MDR
- Namespaces may be contexts or classifications
- XML contexts may be namespaces, DTDs, schemas or
other structures - Other context examples include application
systems, programming languages, report headers
26Structured Names
- Scope
- Authority
- Semantic rules
- Syntactic rules
- Lexical rules
- Uniqueness rule
27Semantic Content of Names
- Semantic rules enable meaning to be conveyed
- Principle Name parts are meaningful to users
- Name parts are derived from structure sets that
identify relationships among (classify) members
28Syntax of Names
- Syntax specifies the arrangement of parts
within a name - Principle The name parts are arranged in a
specified order - The arrangement may be relative or absolute, or
some combination of the two
29Lexical Considerations of Names
- These concern the preferred and derogated
terms, synonyms, abbreviations, part length,
spelling, character set, case sensitivity, etc. - Principle All names governed by a specific
naming convention have a consistent appearance - Control word form and vocabulary
30Agenda
- Namespaces as metadata
- Introduction to an ISO 11179-based metadata
registry (MDR) model - Naming in the MDR
- How an MDR can complement an XML registry
31Lexical Rules for XML Context
- Lexical rules
- Nouns are used in singular form only. Verbs (if
any) are in the present tense. - Name parts are separated by capitalizing the
first character of the second thru nth word - All words in the name are in mixed case.
- Abbreviations, acronyms, and initialisms are
allowed. - Example CountryMailingAddressName
3211179 - XML Collaboration
lt?xml version"1.0"?gt ltshipTo
gt ltnamegtAlice Wilsonlt/namegt
ltstreetgt161 North
Streetlt/streetgt ltcitygtHappy
Valleylt/citygt
ltstategtMOlt/stategt
ltzipgt63105lt/zipgt ltcountry
codegtUSAlt/country codegt
lt/shipTogt
33The Need for XML Name Management
- XML provides a common information exchange format
without common semantics - Each community of interest is defining their own
namespaces - How can the process be standardized?
- How can we address the data warehouse problem of
semantic integrity?
34XML Name Management Using MDR Registries
- An MDR metadata registry can link the XML syntax
to common semantic content - XML namespaces can be defined as contexts or
classifications within MDR registries - Names can be defined within and among namespaces
- Naming convention principles can be applied to
XML names
35XML Name Management Using 11179 Naming Conventions
- Part 5 of ISO/IEC 11179 addresses naming
conventions developed using a set of principles - These principles can be applied to XML names
- ebXML has already produced a draft standardebXML
Core Components Dictionary Entry Naming
Conventions at - http//www.ebxml.org/specs/index.htm
36Summary
- XML names defined as contexts in MDR
- IDI links XML schema objects to MDR registry
entries (not just for names but other semantic
information as well) - XML naming conventions defined in MDR registry
- Adapt 11179-5 naming principles to XML naming
conventions
37The final version of 11179-32003 is now
available to download. 1. Go to www.jtc1.org 2.
Select Freely Available Standards at the bottom
of the left column 3. In LiveLink Go to the
Public areas 4. Scroll to 11179-3