Naming the Schema

Another decision we need to make is the name for our schema (model). As you have seen, all of the core and common models belong to the CIM schema and so all class names begin with CIM_ . An obvious, and bad, first choice for schema name might be PBX. Even if our intention is never to release our schema into the public domain, the possibility of a name clash would arise if some other company started issuing models with the PBX schema name. In order to avoid this, the DMTF gives the following advice:

"CIM" and "PRS" are reserved schema names and MUST NOT be used by any company/organization other than the DMTF.

The schema name MUST be unique and MUST begin with an alphabetic character. We recommend the use of one of the following methods to assure uniqueness:

• Use a trademark registered by your company eliminating any "dot" characters from the trademark, and use the result as your schema name.

• Make use of your company or organization's registered DNS entry:

  • Use the right-most elements of your company or organization registered DNS address up to and including your company or organization name.

  • Move any elements to the right of your company or organization name to the left of that name.

  • Eliminate all "dot" characters.

  • Use the result as a prefix to your schema name.

• Use another unique name that you can be sure is unique.

Assuming that we work for the Acne Manufacturing Company, a name which we will assume for this example has been trademarked, a suitable schema name would be ACNE and our classes would have names of the form ACNE_classname. However, Acne manufactures devices other than PBXs and would like to differentiate the PBX product where necessary. There is some confusion in the DMTF's specifications about whether the class name itself may contain an underscore (see the discussion on page 192) and, to avoid possible problems, I will not use additional underscores and will use class names in the format ACNE_PBXxxxxx where xxxxx represents the rest of the class name.

Note that this may be a poor choice for various reasons: perhaps Acne uses some of the PBX's components and software on another, non-PBX, product. In this case we would like to reuse the classes that we are going to create and the inclusion of PBX in the class name would be unfortunate.