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DMTF Tutorial
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WBEM Discovery
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URI | XML | CIM-XML | CLP | Discovery | CQL
WBEM Discovery is any mechanism that allows the discovery of the location of WBEM Servers. Although WBEM has already defined one discovery specification, this does not preclude additional discover mechanisms from being added in the future.
WBEM Discovery using the Service Location Protocol (SLP)
WBEM Discovery using SLP is defined in two specifications:
- WBEM Discovery using The SLP(DSP0205)
- WBEM SLP Template(DSP0206)
Objectives
- Provide a mechanism that allows WBEM Clients to discover WBEM Servers
- Use existing standards and protocols for rapid development and deployment
- Provide a mechanism that scales from small environments to enterprise environments
- Provide WBEM Clients sufficient information in the advertisement related to management capabilities to determine the WBEM Servers of interest
- Scope the level of advertisement to avoid security holes
SLP
WBEM Discovery using SLP requires Service Location Protocol (SLP) version 2.0. The SLP is defined by the Internet Engineering Task Force (IETF) in RFC 2608.
The SLP provides a flexible and scalable framework for providing clients, represented by User Agents (UA), with access to information about the existence, location, and configuration of services, represented by Service Agents (SA).
Traditionally, clients have had to know the name and access method of services. The SLP eliminates this requirement. With SLP, the client requests a type of service that contains information regarding the requested services.
The SLP uses Directory Agents (DA) that offer a centralized repository for advertised services. This feature enables the SLP to scale from very small to very large environments.
WBEM Servers acting as Service Agents (SA) advertise their services. WBEM Clients acting as User Agents (UA) query for the WBEM Server(s). A Directory Agent (DA) might be deployed in environments where there are many User Agents and Service Agents exist.
For each service access point (protocol/port) supported, the WBEM Server must supply an advertisement. For example, if a WBEM Server supports CLP and CIM-XML, it would supply at least two advertisements. Note that the WBEM Server would supply more than two advertisements if multiple ports were supported by the supported protocols. For example, it would supply four advertisements if it supported CLP over Telnet and SSH and CIM-XML over HTTP and HTTPS.
WBEM SLP Template
The information that can be discovered is defined in the WBEM SLP Template. The following attributes are defined in this template:
- template-type=wbem
- template-version=1.0
- template-description=This template describes the attributes used for advertising WBEM Servers.
- template-url-syntax
The WBEM URI that addresses the WBEM Server.
Example: template-url-syntax=https://192.168.0.1:5989
- service-hi-name
This string is used as a name of the WBEM Service for human interfaces.
- service-hi-description
A description of the WBEM Service.
- service-id
The ID of this WBEM Server.
- CommunicationMechanism
The protocol supported by the WBEM Server.
- OtherCommunicationMechanismDescription
The description of the protocol supported if it is not standard.
- InteropSchemaNamespace
The namespace within the target WBEM Server where the CIM Interop Schema is implemented.
- ProtocolVersion
The version of the protocol.
- FunctionalProfilesSupported
The operations supported by the WBEM Server.
- FunctionalProfileDescriptions
Descriptions of the operations supported by the WBEM Server.
- MultipleOperationsSupported
This specifies whether the WBEM Server supports batch operations.
- AuthenticationMechanismsSupported
The authentication mechanism supported by the WBEM Server.
- AuthenticationMechansimDescriptions
Descriptions of the authentication mechanisms supported by the WBEM Server.
- Namespace
The namespace(s) supported by the WBEM Server.
- RegisteredProfilesSupported
The Profile(s) supported by the WBEM Server.
Examples:
DMTF:WBEM Server
DMTF:Profile Registration
SNIA:Array
SNIA:Storage Library
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