In order to facilitate runtime binding for structured information exchange between autonomic elements, each interface and model should be described in a machine-readable manner. This section highlights the two prevalent standards that provide this capability

• Web Services Description Language, WSDL [34]: WSDL (developed by the W3C) is an XML-based description language for defining the message formats for interacting with an interface using Web services. Although not a recommendation, WSDL 1.1 is widely deployed today. Version 2.0 is expected to be a W3C recommendation.
• XML Schema, XSD [35]: XML schema is an XML-based language for documenting in a machine-readable manner the structure of an XML document. In XML-based interactions for the management domain, this is used to document the structure of the data models such that formal validation and processing of the data can be carried out.

Data models

IT systems need an abstract mechanism to represent data pertaining to all aspects of the system. In order for autonomic managers to monitor and control elements, they require a well-defined and structured representation of the objects. This section highlights some of the standards pertaining to IT models.

• Common Information Model (CIM): Developed by Distributed Management Task Force (DMTF), the most significant part of the CIM standard is the object-oriented CIM schema [4], which is a data model that describes managed objects and elements in an IT environment and their properties and supported operations including modeling of the relationships between them. Use of the CIM schema allows information to be shared among autonomic managers. The CIM schema itself is documented in a language called Managed Object Format (MOF).
• Web Services CIM, WS-CIM: This DMTF standard [5] defines a translation from the MOF format for CIM into XML schema. This allows CIM model definitions to be transported over the Web-service management protocols, such as WS-Management [6].

Analysis and planning

In the autonomic manager architecture, the analysis and planning functions provide the necessary intelligence to facilitate decision making down to lowest possible level in the hierarchical autonomic management model. In this section we outline the standards that span this decision making.

• WS-Policy: This standard [14] provides a general-purpose mechanism for describing and communicating policies relating to a Web service. This emerging standard gains significant importance in light of the fact that resource monitoring and control are moving to be exposed as Web service endpoints.
• CIM Simplified Policy Language (CIM-SPL): This is a CIM-compliant policy specification language from the DMTF.
• Service Modeling Language (SML): This is a recently announced modeling language [15] being developed by multiple companies. Although not strictly a policy specification language, SML defines a modeling language based on XML schema that is intended to allow formal modeling of IT systems, including constraints and declarative policies, by using Schematron language [29]. It is expected that such operational models will allow autonomic managers to monitor and enforce service deployment and operational constraints specified by system designers and IT operators in the various stages of the service life cycle, including design, deployment, and operation.
• Business Process Execution Language (BPEL): BPEL [27] is a language that models business processes as Web services allowing businesses to implement a service-oriented approach to business processes.

Although there are emerging standards (as above) to enable analysis and planning for autonomic managers, additional standards need to be defined for hierarchical autonomic policies for expressing operator constraints and partitioning the given policy to all managers in the hierarchy.

Knowledge

The Configuration Management Database (CMDB), a fundamental component of the Information Technology Infrastructure Library (ITIL) [30] framework is an emerging standard for the repository of information of an IT system. In addition, standards will need to be defined for interacting with the CMDB (data and interchange).

Figure 3: Groups of autonomic managers in a complex system
click image for larger view
 

Security standards

Given the nature of the autonomic system, robust security architecture is required to prevent a compromised autonomic manager from impairing the operations of the system. Some of the standards that provide the security infrastructure for systems that use Web services are highlighted in this section.

• WS-Security: Given the strong reliance of SOAP-based messaging for interaction between autonomic elements, a comprehensive standard that provides confidentiality, integrity, and authentication for SOAP-based messages is crucial. WS-Security [16] from OASIS meets these requirements.
• WS-Trust: This specification [17] defines extensions to WS-Security to provide a framework for requesting and issuing security tokens, and to broker trust relationships.
• WS-SecureConversation: This specification [18] defines extensions for WS-Security and WS-Trust for establishing and sharing security contexts.
• WS-SecurityPolicy: This specification [19] defines the policy assertions for use with WS-Policy that relate to WS-Trust, WS-Security, and WS-SecureConversation.
• Transport Layer Security (TLS)/Secure Socket Layer (SSL): The adoption of Web-services-based security standards will take place gradually over time. In the meantime, TLS/SSL is commonly used to provide message integrity and confidentiality over HTTP.
• Security Assertion Markup Language (SAML): SAML, developed by OASIS [20], is an XML-based framework for communicating user authentication, entitlement, and attribute information.
• WS-Federation: Autonomic managers may need to interact across security domains. The WS-Federation specification allows security information to be shared across security realms.

In this section, we have highlighted some of the important standards used for enabling autonomic behavior. A critical aspect of the interaction is the external interfaces of each element/manager. Details on protocols and standards for external interfaces are given in the next section.