Frequently Asked Questions


1.

Figure 4.2 on page 35 shows a client and a listener. What is the difference?

the wbem architecture differentiates between two types of management: 1. operators entering commands to configure items and enquire about their status. 2. operators receiving information about events and alarms which have occurred in the system. the major distinction between these two is in what actually starts the interaction between the operator and the managed system. in the first case, the operator starts the interaction; in the latter, an event occurring in the system is the original stimulus. the software which acts on behalf of an operator entering commands is known as a wbem client. the software acting on behalf of an operator waiting to receive details of events and alarms is called a listener.

2.

I understand that the WBEM server acts as a broker between the clients and providers, but how much checking does it do? Does it, for example, check the types and ranges of properties in an instance that a client is creating before it passes those parameters to the provider?

although this question is reasonable, given the content of this chapter, to understand the answer you unfortunately need more information about the way a cim model is constructed. i have therefore replicated this question as faq 20 on page 84.

3.

If I use an open source WBEM server in a product that I sell, will legal issues arise?

open source code is normally copyrighted and released subject to a licence. it is essential that you (and your lawyers) read those licences very carefully. generally, the open source licences range from `here's the code, do what you want with it, but don't prosecute us if it doesn't work` to the gnu general public licence (gpl), which is long and complex. using open source software in a product that you are selling is easy and legal to do, but you (and all your programmers) must be aware of the licensing issues and treat them with respect. openpegasus is one of the better open source c++ wbem servers and its licence is reproduced on page 313 of this book. as you can see, it is effectively of the `do what you want but don't prosecute us` type.

4.

What type of database is used for the repository? Do I need to use a commercial database for the repository?

the wbem/cim specifications mandate no particular type of data storage for the repository; each wbem server implementation is different. although each wbem server implementation comes with a default repository, the implementations generally try to provide a clean interface so that any type of data store can be used; perhaps flat files on disk, perhaps a sophisticated database, perhaps linked lists in memory. openpegasus, for example, comes with a very simple (and very inefficient) repository comprising a disk file for each class, the content of each being stored in xml. this is very useful for debugging as the repository files can be browsed using a normal text editor, but it may be too inefficient in space or processing time for a production system.

Answers

1.

The WBEM architecture differentiates between two types of management:

  1. Operators entering commands to configure items and enquire about their status.

  2. Operators receiving information about events and alarms which have occurred in the system.

The major distinction between these two is in what actually starts the interaction between the operator and the managed system. In the first case, the operator starts the interaction; in the latter, an event occurring in the system is the original stimulus.

The software which acts on behalf of an operator entering commands is known as a WBEM client. The software acting on behalf of an operator waiting to receive details of events and alarms is called a listener.

2.

Although this question is reasonable, given the content of this chapter, to understand the answer you unfortunately need more information about the way a CIM model is constructed . I have therefore replicated this question as FAQ 20 on page 84.

3.

Open source code is normally copyrighted and released subject to a licence. It is essential that you (and your lawyers ) read those licences very carefully . Generally , the open source licences range from "here's the code, do what you want with it, but don't prosecute us if it doesn't work" to the GNU General Public Licence (GPL), which is long and complex. Using open source software in a product that you are selling is easy and legal to do, but you (and all your programmers) must be aware of the licensing issues and treat them with respect. openPegasus is one of the better open source C++ WBEM servers and its licence is reproduced on page 313 of this book. As you can see, it is effectively of the "do what you want but don't prosecute us" type.

4.

The WBEM/CIM specifications mandate no particular type of data storage for the repository; each WBEM server implementation is different. Although each WBEM server implementation comes with a default repository, the implementations generally try to provide a clean interface so that any type of data store can be used; perhaps flat files on disk, perhaps a sophisticated database, perhaps linked lists in memory.

openPegasus, for example, comes with a very simple (and very inefficient) repository comprising a disk file for each class, the content of each being stored in XML. This is very useful for debugging as the repository files can be browsed using a normal text editor, but it may be too inefficient in space or processing time for a production system.




A Practical Approach to WBEM[s]CIM Management
A Practical Approach to WBEM[s]CIM Management
ISBN: 849323061
EAN: N/A
Year: 2006
Pages: 152

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