DeepakG_[MS]: Today we are going to discuss Windows Management Instrumentation..

DeepakG_[MS]: we have with us today Tarun Anand, who works as a Technical Evangelist at Microsoft, India. Prior to joining Microsoft in India, Tarun was working with Microsoft at Redmond as a developer on the same CLR, that you and I see in action today...

DeepakG_[MS]: So I am sure he has lots of unique insights to offer. Over to you Tarun, lets start with a brief intro to WMI..

Tarun_[MS]: Hi Folks

Tarun_[MS]: Long Long time ago there were different ways of doing management based on what you were "managing" like networks, os, apps etc etc. Each vendor had their own proprietary way of doing the management of each piece.

Tarun_[MS]: So, as is usual in computer industry people saw this as getting out of hand and wanted to have a unified way of doing management

Tarun_[MS]: .... enter WBEM

Tarun_[MS]: or Web basaed Enterprise management - a standard developed by DMTF org

Tarun_[MS]: The WBEM standard was implemented by many vendors and WMI is Microsoft's implementation of that standard. The way WMI works is that you have an app/os/device/network to be managed a provider that provides you with the management information for these managed objects a manager that keeps track of all providers and stores their information in a repository and finally a consumer that can ask the manager for information/events that it is interested in

Tarun_[MS]: for e.g. a consumer app can send a mail to the administrator when the cpu on a machine has reached 99% utilization, for this it subscribes to the cpu utilization event via WMI and it gets alerted when the "interesting" event occurs. That is a brief intro to WMI.

DeepakG_[MS]: Is it possible to define my own events?

Tarun_[MS]: You can define your own events for this you have to do 2 things -

Tarun_[MS]: define your event class in a .mof (Managed Object Format) file and then define the appropriate WMI interfaces on the event class in your class implementation. You also need to run mofcomp.exe on the .mof file to register your events with WMI

DeepakG_[MS]: (Satya): The consumer can only request for the information or can act on the provider basing on the information?

Tarun_[MS]: it can do both...

DeepakG_[MS]: (Saurabh_MVP): Tarun .. can u elaborate on the .mof .. file and how to use it in .NET?

Tarun_[MS]: well .mof was used in the old days

Tarun_[MS]: instance of MSFT_AppProfEventSetting

{
ClassName = "MyCustomEvent";
Description = "My new custom event";
ProviderGUID = "{8F366B62-E078-4388-B601-C0AB493BDDDC}"; Type = "Generic";
GUID = "{79AE076F-777E-461B-AF40-A3D4594EA3BC}";
}

Tarun_[MS]: so this is how you define the event in a .mof file

Tarun_[MS]: in .net however your task is easier.... he ... he... just like everything else you need to just put attributes to your class/assembly to indicate the equivalent of .mof file

Tarun_[MS]: let me see if there is an example lying around

Tarun_[MS]: [assembly:Instrumented("Root/Default")]
// Let the system know you will run InstallUtil.exe utility against
// this assembly
[System.ComponentModel.RunInstaller(true)]
public class MyInstaller: DefaultManagementProjectInstaller {} // Create a management
public class MyEvent: System.Management.Instrumentation.BaseEvent
{
public string Event_Name;
}
public class Sample_EventProvider
{
public static int Main(string[] args)
{
MyEvent e = new MyEvent();
e.Event_Name = "Hello"; // Raise a management event
}
}
Tarun_[MS]: in short you are defining attributes on the assembly. You are defining an event that inherits from BaseEvent and then you can fire it using Instrumentation. Fire call in your app

DeepakG_[MS]: (Saurabh_MVP): Tarun .. I have heard Raj C talking about the new "WMI Server" product .. can you shead .. some more highlights of it ? And how will it help instrumentation in an distributed scenario?

Tarun_[MS]: well .. don't know much about WMI Server but I suspect it is an integrated server to help you manage various objects in a distribute computing environment, like servers, OS, storage etc etc... Instead of connecting to each server to monitor it, you could go to this server to monitor your network.

DeepakG_[MS]: (Saurabh_MVP): hmmm that's intresting bit of code .... but suppose I add instrumentation in my application .. how much performance hit does a .NET application take? Since I believe the current implementation of .NET is Interoping with unmanaged code...

Tarun_[MS]: it will add a performance hit to your application, so you will have to be careful which events you want to expose but the interop layer is very thin and not that much of a bottleneck as compared to the number of events, and information that you want to expose

DeepakG_[MS]: (Saurabh_MVP): well Tarun, I was thinking of adding a instrumentation in an enterprise application ... so that it can be managed easily ... Saurabh_MVP: are there any other options .. for adding Management and Instrumentation ?

Tarun_[MS]: well there are other options but if you want to remain portable across the various windows platforms and want a consistent api for any kind of management then go for WMI you can also use the profiling apis/event log

DeepakG_[MS]: Let me give some examples of how you can use WMI in day today life..Lets say you want to move to a new application across your company. Now this application has some unique hardware requirements... especially, lets say it requires more RAM. Now you need to take stock of amount of RAM present in each machine in your enterprise - how do you do that...

DeepakG_[MS]: WMI to the rescue..

DeepakG_[MS]: here is a code snippet that evaluates Physical Memory of a machine..

DeepakG_[MS]: strComputer = "atl-dc-01"
Set wbemServices = GetObject("winmgmts:\\" & strComputer)
Set wbemObjectSet = wbemServices.InstancesOf("Win32_LogicalMemoryConfiguration")
For Each wbemObject In wbemObjectSet
WScript.Echo "Total Physical Memory (kb): " & wbemObject.TotalPhysicalMemory
Next

DeepakG_[MS]: so using AD, you can enumerate machines on your network

DeepakG_[MS]: and then go on using WMI to find amount of RAM present in each machine. You can then do anything with that data - like isolate machines that need hardware upgrades.

DeepakG_[MS]: (Justin): for example, wmi will send email to dba when my sql database size reaches the hard disk limit. Is it what the purpose of WMI ?

Tarun_[MS]: yes that is definitely up the alley of WMI. You can do other interesting things as well.. audit violations for one and load balancing based on load information given by WMI

DeepakG_[MS]: Ok then, with this we come to an end of this week's chat session...

DeepakG_[MS]: Thanks Tarun for taking time out from your tight schedule..