Frequently Asked Questions

1.	The common models are large and difficult to understand. Can I simply ignore them and write my own models?
2.	How does describing a user and his account in the User Model actually cause the validation of the user to occur?

Answers

1.

The straight answer is "yes." Nothing breaks in the WBEM architecture if the DMTF models are not used; the classes contained in these models are simply loaded into the WBEM server by a client (the mof compiler) just like any other classes. However, this is something that you might like to think about very carefully : the common and core models are complex, but not (completely) out of awkwardness on the part of the writers ”they are complex largely because the areas that they cover are complex. If you have a system for which there is, as yet, no common model then you might still like to consider taking the core model from the DMTF. Using this will at least give your model basic structure and possibly even allow you to make your model standard in the future. In addition, most devices are likely to be able to make use of other parts of the common models: do you have hardware, software, users, operating systems which must be managed? If so, then the common models might be useful to you. There is one further reason for using the standard models. Recently, I was creating an instance of CIM_EthernetPort and assumed that there would be a property for the MAC address of the port. When I looked at the common model, I was puzzled to see that an array was defined to contain the MAC addresses. I am no expert on Ethernet ports and spoke with a colleague who patiently explained to me the conditions under which several MAC addresses would be associated with an Ethernet port. Had I created the model of an Ethernet port myself , I would, out of ignorance, have defined a single MAC address. Sometime in the future this could have given me trouble. By using the common models you are also using the expertise of the people who wrote them and, in many areas, that expertise might be deeper than yours.

2.

It does not. CIM is a means of describing management data in a standard and, one hopes, logical form. The User Model allows you to store the information associated with the user's passwords, access lists, etc. in a standard form. It does not provide the code actually to authenticate the user and control his or her access.