Working with CIM

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					                  Working with CIM
                       Ellen Stokes

14 October 2002         GGF6 / CGS-WG   1
• CIM refresher
• Managed Object Format (MOF)
     – What is MOF
     – Working with MOF
•   Model guidance
•   Extending the CIM schema
•   Using a CIMOM
•   Mapping CIM to other representations
     – XML
     – LDAP
14 October 2002           GGF6 / CGS-WG    2
                    CIM Refresher
• CIM is one of the approaches in the industry for enabling
  the management of real world managed objects
• 4 pieces
     –   Modeling language and syntax (MOF – Managed Object Format
     –   Management schema (core, common, extension)
     –   Protocol to encapsulate syntax and schema (XML/HTTP)
     –   Compliance document, but no test suites
• CIM object managers (CIMOM) are implementations, but
  not part of the CIM standard
     – The Open Group’s Pegasus project is producing a CIMOM
       reference implementation jointly with DMTF Interop WG
• API for CIMOM access by applications (by The Open

14 October 2002              GGF6 / CGS-WG                           3
     Managed Object Format (MOF)
      Modeling Language & Syntax
• Meta schema is formal definition of the model
    – Terms are defined to express model, usage, and semantics
    – Constructs
         • class (abstract, concrete, association), property, method
         • qualifiers, references, initializers, instance declarations
         • compiler directives (locale & namespace info)
• Managed Object Format (MOF) is the language used to
  describe management information
    – Textual form
    – Derived from IDL (Interface Definition Language) from The Open
    – Can be encoded in Unicode (UCS-2) or UTF-8
14 October 2002                   GGF6 / CGS-WG                          4
                               ManagedElement (in MOF)
// ==================================================================
// ManagedElement
// ==================================================================
[Abstract, Version ("2.7.0"), Description (
   "ManagedElement is an abstract class that provides a common "
   "superclass (or top of the inheritance tree) for the "
   "non-association classes in the CIM Schema.") ]
class CIM_ManagedElement {

     [MaxLen (64), Description (
        "The Caption property is a short textual description (one-"
        "line string) of the object.") ]
     string Caption;

     [Description (
        "The Description property provides a textual description of "
        "the object.") ]
     string Description;

     [Description (
        " A user-friendly name for the object. This property allows "
        "each instance to define a user-friendly name IN ADDITION TO its "
        "key properties/identity data, and description information. \n"
        " Note that ManagedSystemElement's Name property is also defined "
        "as a user-friendly name. But, it is often subclassed to be a "
        "Key. It is not reasonable that the same property can convey "
        "both identity and a user friendly name, without inconsistencies. "
        "Where Name exists and is not a Key (such as for instances of "
        "LogicalDevice), the same information MAY be present in both "
        "the Name and ElementName properties.") ]
     string ElementName;
14 October 2002                                      GGF6 / CGS-WG            5
                  Working with MOF
• MOF is text
• No tools available to help create MOF
     – Disregard the MOF Editor located at the tools URL below – it
       doesn’t work
• Use your favorite text editor
• Read the CIM spec; look at examples
• Use the existing CIM schema as template for developing
  your schema
• Use a MOF compiler to check for syntax errors (Intel
  CIM compatibility checker)
• CIM certification test suite beta release (use same tools
  URL above)

14 October 2002               GGF6 / CGS-WG                           6
                    Model Guidance
• Understand what’s already modeled
   – Mostly at structural, device, and OS levels
   – Current schema doesn’t do cluster and distributed environments justice
• Model managed/manageability information; if it’s not useful for
  management, then don’t model it
• Remember CIM normalizes everything (small pieces) and
  defines relationships between all the pieces; follow suit
• Don’t assume that your schema automatically subclasses from
  managedElement (the root of all CIM schema) just because
  you’re developing a new schema
   – Reuse, subclass from, and integrate with existing schema elements
• Use a UML tool to do schema design
   – Visualization helps to show how your new schema fits with existing CIM
• Above all, there is no right or wrong way – modeling is an art!

  14 October 2002             GGF6 / CGS-WG                           7
       Extending the CIM Schema
• Subclass from existing schema
     – CIM provides basic building blocks, for example, there is job schema from
       which the job submission interface model can be derived
• Reuse properties
• Integrate with existing models
     – May require changes to existing schema
     – Try to limit to no changes, but if changes needed, use the ‘deprecated’
       qualifier to indicate how changed
• Use the existing qualifiers:
     – ‘experimental’ to delineate what new and may change until firm
     – ‘version’ to indicate from CIM version this new schema is built
• Qualifiers provide a way to introduce additional semantics
     – But beware, other systems will ignore these extensions if they don’t
       recognize them (but won’t crater system)
• Don’t add new data types – this breaks CIM compatibility
     – Can sometimes add new data type by introducing a new qualifier, for
       example, octetstring, to further qualify the format of a string property

14 October 2002                   GGF6 / CGS-WG                                   8
        Management Environment
                        Management Application
                                     HTTP Server

                          CIM Object Manager                      Schema + instance
   Provider interface


                                                                        Pegasus, SNIA


14 October 2002                            GGF6 / CGS-WG                              9
                  Using a CIMOM
• Download Pegasus and follow instructions

14 October 2002       GGF6 / CGS-WG      10
              Mapping: CIM to XML
• A Metaschema Mapping in which the XML schema is
  used to describe the CIM metaschema, and both CIM
  classes and instances are valid XML documents for that
     – CIM DTD is used to describe in a generic fashion the notion of a
       CIM class or instance. CIM element names are mapped to XML
       attribute or element values, rather than XML element names.
     – MOF is encapsulated in XML so there is no additional work to
       describe new/changed CIM schema in XML.
• CIM/XML spec
• Example CIM/XML
     – and locate
       link for xml representation of CIMv2.7
• Tool to generate XML representation
     – <Obtain where ???>

14 October 2002               GGF6 / CGS-WG                           11
            Mapping: CIM to LDAP
• Not one-size-fits-all, but rather a set of
  guidelines / alternatives / strategies for
  mapping CIM to LDAP
     – Classes
     – Associations
     – Data types

14 October 2002       GGF6 / CGS-WG        12

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