Service Modeling Language (SML) and Service Modeling Language Interchange Format (SML-IF) are a pair of

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...

-based specifications created by leading

information technology Information technology (IT) is a set of related fields within information and communications technology (ICT), that encompass computer systems, software, programming languages, data processing, data and information processing, and storage. Inf ...

companies that define a set of

instance document extensions for expressing links between elements, a set of

XML Schema An XML schema is a description of a type of XML document, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntactical constraints imposed by XML itself. These constrai ...

extensions for constraining those links, and a way to associate

Schematron Schematron is a rule-based validation language for making assertions about the presence or absence of patterns in XML trees. It is a structural schema language expressed in XML using a small number of elements and XPath languages. In many implem ...

rules with global element declarations, global complex type definitions, and/or model documents. The SML

specification A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard. There are different types of technical or engineering specificati ...

defines model concepts, and the SML-IF

describes a packaging format for exchanging SML-based models. SML and SML-IF were standardized in a

W3C The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working together in ...

working group chartered to produce W3C Recommendations for the Service Modeling Language by refining the “Service Modeling Language” (SML) Member Submission, addressing implementation experience and feedback on the specifications. The submission was from an industry group consisting of representatives from BEA Systems, BMC, CA, Cisco, Dell, EMC, HP, IBM, Intel, Microsoft, and Sun Microsystems. They were published as

W3C Recommendation The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working together in ...

s on May 12, 2009. In the market and in applying by vendors, SML is seen as a successor/replacement for earlier developed standards like DCML and Microsoft's (in hindsight) proprietary System Definition Model or SDM. See for a historically helpful relation between SDM and DCML, and for the joint pressrelease announcing SML. In the Microsoft section of it the sequel role to SDM is mentioned.

Fast Formal Facts about SML

SML is a language for building a rich set of constructs for creating and constraining models of complex IT services and systems. SML-based models could include information about configuration, deployment, monitoring, policy, health, capacity planning, target operating range,

service level agreement A service-level agreement (SLA) is an agreement between a service provider and a customer. Particular aspects of the service – quality, availability, responsibilities – are agreed between the service provider and the service user. T ...

s, and so on. An SML model is a set of interrelated

documents. An SML model could contain information about the parts of an IT service, as well as the constraints that each part must satisfy for the IT service to function properly. Constraints are captured in two ways: *

documents: constrain the structure and content of the XML instance documents in a model. SML uses

1.0, but allows later versions as well. SML also defines a set of extensions to

to constrain references, and identity constraints (key, unique, ...) that apply to sets of documents. * Rule documents: constrain the structure and content of documents in a model. SML uses

and

XPath XPath (XML Path Language) is an expression language designed to support the query or transformation of XML documents. It was defined by the World Wide Web Consortium (W3C) in 1999, and can be used to compute values (e.g., strings, numbers, or ...

1.0 for rules, but allows later versions as well. Once a model is defined, one of the important operations on the model is to establish its validity. This involves checking whether all model documents satisfy the

and rule document constraints.

SML-Based Models

Models provide value in several important ways:Common Model Library - link no longer resolves
# Models focus on capturing all invariant aspects of a service/system that must be maintained for the service/system to be functional. They capture as much detail as is necessary, and no more. # Models are units of communication and collaboration between designers, implementers, operators, and users; and can easily be shared, tracked, and revision controlled. This is important because complex services are often built and maintained by a variety of people playing different roles. # Models drive

modularity Modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a system into varying ...

Re-use Reuse is the action or practice of using an item, whether for its original purpose (conventional reuse) or to fulfill a different function ( creative reuse or repurposing). It should be distinguished from recycling, which is the breaking down o ...

, and

standardization Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organiza ...

. Most real-world complex services and systems are composed of sufficiently complex parts.

and

of services/systems and their parts is a key factor in reducing overall production and operation cost and in increasing reliability. # Models represent a powerful mechanism for validating changes before applying the changes to a service/system. Also, when changes happen in a running service/system, they can be validated against the intended state described in the model. The actual service/system and its model together enable a self-healing service/system – the ultimate objective. Models of a service/system must necessarily stay decoupled from the live service/system to create the control loop. # Models enable increased automation of management tasks. Automation facilities exposed by the majority of IT services/systems today could be driven by software – not people – for reliable initial realization of a service/system as well as for ongoing lifecycle management.

References

{{Reflist

External links

W3C Service Modeling Language Working Group home page

W3C public working drafts of SML/SML-IF specification
XML markup languages