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Sunday, March 14, 2010

Expressing SNMP SMI Datatypes in XML Schema Definition Language

Mark Ellison and Bob Natale (eds), IETF Internet Draft

Members of the IETF Operations and Management Area Working Group WorkingGroup have published a revised Internet Draft for "Expressing SNMP SMIDatatypes in XML Schema Definition Language." The memo defines the IETFstandard expression of Structure of Management Information (SMI) basedatatypes in Extensible Markup Language (XML) Schema Definition (XSD)language. The primary objective of this memo is to enable the productionof XML documents that are as faithful to the SMI as possible, using XSDas the validation mechanism.

Background: "Numerous use cases exist for expressing the managementinformation described by SMI Management Information Base (MIB) modulesin XML. Potential use cases reside both outside and within the traditionalIETF network management community. For example, developers of someXML-based management applications may want to incorporate the rich setof data models provided by MIB modules. Developers of other XML-basedmanagement applications may want to access MIB module instrumentationvia gateways to SNMP agents. Such applications benefit from the IETFstandard mapping of SMI datatypes to XML datatypes via XSD.

MIB modules use SMIv2 (RFC 2578) to describe data models. For legacyMIB modules, SMIv1 (RFC 1155) was used. MIB data conveyed in variablebindings ('varbinds') within protocol data units (PDUs) of SNMP messagesuse the primitive, base datatypes defined by the SMI. The SMI allowsfor the creation of derivative datatypes, 'textual conventions' ('TCs').A TC has a unique name, has a syntax that either refines or is a baseSMI datatype and has relatively precise application-level semantics.TCs facilitate correct application-level handling of MIB data, improvereadability of MIB modules by humans and support appropriate renderingsof MIB data.

Values in varbinds corresponding to MIB objects defined with TC syntaxare always encoded as the base SMI datatype underlying the TC syntax.Thus, the XSD mappings defined in this memo provide support for valuesof MIB objects defined with TC syntax as well as for values of MIB objectsdefined with base SMI syntax. Various independent schemes have beendevised for expressing SMI datatypes in XSD. These schemes exhibit adegree of commonality, especially concerning numeric SMI datatypes, butthese schemes also exhibit sufficient differences, especially concerningthe non-numeric SMI datatypes, precluding uniformity of expression andgeneral interoperability..."

http://xml.coverpages.org/draft-ietf-opsawg-smi-datatypes-in-xsd-06.txtSee also the IETF Operations and Management Area Working Group WG Status Pages: http://tools.ietf.org/wg/opsawg/

1 comment:

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In typical SNMP use, one or more administrative computers called managers have the task of monitoring or managing a group of hosts or devices on a computer network.