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Rohan Mahy Sharon Chisholm Lada Lhotka IETF 72 - Dublin. Representing Netconf Data Models using Document Schema Definition Languages (DSDL). Outline. What is DSDL? Scope of DSDL for NETCONF Overview Drafts Vocabularies Used Next Steps Open Issues. What is DSDL?.
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IETF 72 - DublinRepresenting NetconfData Models using Document Schema Definition Languages (DSDL)
What is DSDL?
Scope of DSDL for NETCONF
DSDL = Document Schema Definition Languages (http://www.dsdl.org)
Family of standards ISO/IEC 19757
DSDL uses a modular approach to schema languages
Part 1: Overview
Part 2: RELAX NG – regular-grammar-based validation
Part 3: Schematron – rule-based validation
Part 4: NVDL – Namespace-based Validation Language
Part 5: DTLL – Data Type Library Language
Part 6: Path-based integrity constraints
Part 7: CRDL – Character Repertoire Description Language
Part 8: DSRL – Document Schema Renaming Language
Part 9: Datatype- and Namespace-aware DTDs
Part 10: Validation management
(as determined by WG)
(DSDL for NETCONF)
The goal is a theoretical two-way mapping of features, and a real non-lossy one-way mapping.
A layered approach leveraging existing DSDL technologies
Off-the-shelf tools/libraries can be immediately used for validation, instance editing and transformations (XSLT)
The smarter the tool/library, the more semantics can be validated or processed but even baseline tools can do useful work
The mapping uses 3 parts of the DSDL standard (ISO/IEC 19757), two standard annotation vocabularies and several new NETMOD-specific annotations
A software tool is available that translates most of YANG semantics
Output is an annotated RELAX NG schema
New individual draft summarizing the experience from implementing YANG->DSDL translator – plugin for pyang application
Very complementary to -mahy draft
It tries to formulate principles that the WG mapping draft should state
It contains a section describing mapping details for each YANG statement.
RELAX NG – grammatic constraints, datatypes
Schematron – semantic constraints, user-specified rules (must statement in YANG)
DSRL – default values of leaf nodes
Dublin Core terms – module metadata (author, revision, ...)
RELAX NG DTD compatibility annotations – YANG description and reference.
NETMOD-specific annotations – few new attributes attached to RELAX NG <element>.
The implementation revealed several issues that have to be resolved (preferable in Dublin); some of them may require changes or clarifications in YANG.
Finish the chartered DSDL mapping draft (due in September 08). It will be based on merging two existing individual drafts:
Update the implementation:
alignment with the draft
implement mappings of YANG extension mechanisms
Handling of rpc and notification
YANG allows multiple root nodes, XML just one.
(For a complete list of issues, visit the NETMOD session on Friday)
YANG modules describe the contents of agent configuration datastores, with two exceptions:
rpc specifies signature of a new NETCONF RPC method.
notification defines a NETCONF notification.
Generate separate schemas for the configuration data tree, RPCs and notifications.
Work with a „conceptual tree“ that harbors the three types of content in different subtrees.
YANG allows for multiple root nodes, but well-formed XML document must have exactly one.