Service Modeling Language Manages IT Assets

The SML standard establishes a common vocabulary for disparate tools and has the backing of a number of big vendors.

February 1, 2007

8 Min Read
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A high-powered working group is striving to improve IT management and data-center automation with a common language to describe heterogeneous IT assets. The Service Modeling Language is an XML-based schema to define, or model, information about hardware, software, applications and services.

This common language will make it easier to share information among disparate IT tools and provide a foundation for automating common tasks, such as application provisioning, configuration management and asset monitoring. SML also is being positioned as a way to overcome the barriers to federation and reconciliation of disparate data in CMDBs (configuration management databases).

The outlook for the standard is a good one, judging by the big vendors that have backed it and the progress made thus far: The most recent draft of the specification was released in Nov. 2006, and the specification may be submitted to a standards body this quarter.FROM THE GROUND UP

SML seeks to address the basic weaknesses of conventional IT management, which compartmentalizes the technology infrastructure. The tools for managing those compartments have their own nomenclature to identify assets, making it difficult to share information among tools or to automate common IT tasks.

To better manage apps and business services, IT must have a holistic view of the infrastructure and understand the dependencies among its components. All the major IT management software vendors, for instance, are pushing CMDBs, which model how changes to one system may affect applications or services. However, the information used to populate a CMDB (or to link multiple CMDBs) is gathered and stored by third-party tools that use different conventions for identifying assets. The upshot is that federating and reconciling a data store from Vendor A with a CMDB from Vendor B is complex and painful. (To learn more about CMDBs, see CMDBs: An IT Goldmine? .)

Enter SML. The basic goal of the working group is to create a grammar that describes everything in an IT environment--hardware, software, applications and, eventually, services--in a unified way. With a common vocabulary in place, third-party tools can more easily share information about the assets they manage.

It's no surprise that many of the players behind SML--BMC, EMC, Hewlett-Packard, IBM and Microsoft--are also architecting their management products around CMDBs. The easier it is to bring asset data into CMDBs, the more they will be adopted by customers. It's also no surprise that the CMDB Federation Working Group, which is developing its own specification to simplify the linking of third-party data stores, is considering support for SML.But SML is more than just a common vocabulary to describe assets. It's also a way to model dependencies, whether in a single app or across a service. Developers might use SML to model all the software components required to run an app, for instance. The IT operations group would then use this model to deploy and manage the actual app servers.

SML also could be used to create policy-based templates describing how hardware, applications and services should be built and deployed, which can speed provisioning. Such templates could be used to monitor compliance by defining a desired state for a component and comparing that with its actual state. A switch, for example, may require a particular port to be closed, and an IT management tool that speaks SML could test for compliance.

Although SML shows promise, it's still a work in progress. The second version of the spec was published in Nov. 2006 and is still open for public comment (see At press time, the working group hadn't yet decided which standards body to submit the spec to, but an announcement is likely sometime this quarter. Once the spec is turned over to a standards body, it must still go through a series of reviews, debate and comments before a final draft is approved, which means SML may not emerge as a standard until at least 2008.

SML is now in the hands of a multiparty working group, but it has its roots in a Microsoft technology known as SDM (System Definition Model), a model-based language to define IT assets and services and simplify configuration and deployment of IT systems. SDM was included in Visual Studio 2005. Microsoft also submitted SDM to the SML working group as a starting point for the existing SML specification.

In July 2006, Microsoft announced that Visual Studio System Center and other products will support a prestandard version of SML. Microsoft's Service Desk, a management platform that includes a CMDB, also includes an SML validator. Service Desk is available in a beta release.The Distributed Management Task Force's CIM (Common Information Model) offers much of what SML aims to do and is in wide use. SML proponents say they are evolving CIM by writing definitions in native XML, making SML built for Web services from the ground up. Today, there's a host of software for building, parsing and validating XML schemas, which will make it easier for vendors to create tools that can understand SML. By contrast, a DMTF specification exists for representing CIM in XML, but it requires complex transformations.

That said, the SML working group says it will use CIM definitions wherever possible and will work closely with the DMTF to avoid reinventing the wheel. Given the overlap of the CIM and SML objectives, the DMTF is one of several possible candidates to oversee SML.

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SML by itself is a language for modeling information about assets. It requires other components to exploit the value of a common modeling language. Thus, the success of SML is tied into other efforts to simplify management and provisioning and promote automation. As mentioned, the CMDB Federation Working Group is considering including SML objects as one of the object types recognized by the federation's spec. This would make it easier to import data into a CMDB or link third-party CMDBs. Given that BMC, HP, IBM and Microsoft are members of the CMDB and SML working groups, its inclusion is likely.

Another key area is the management interface used to acquire information about assets. Though SML defines the properties of IT assets, the specification doesn't say how to interface with an asset to query its properties.


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SML in its element

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Two technologies can fill this need. One is WS-Management (PDF), a DMTF standard backed by Microsoft, Intel and others. It uses Web services to exchange data among devices. The other is WSDM (Web Services Distributed Management), an OASIS standard promoted by IBM and HP, among others. The latter makes it easier for IT management tools from disparate vendors to interoperate and provides a common Web services mechanism that manufacturers can use to expose the management interface on their products.

Although the major backers of WS-Management and WSDM will continue to support each technology, IBM and Microsoft are also converging the two specifications into a single spec tentatively called WS-Unified Management. "We are working to have a common interface to query the status of an object so there will be a very close relationship between SML objects and WS-Unified Management interfaces into them," says Ric Telford, VP of autonomic computing at IBM. A road map, released in March 2006, expected that convergence specifications would be published over the next 18 to 24 months.

Technology Editor Andrew Conry-Murray can be reached at [email protected].0

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