# .NET and More > Silverlight >  Single Instance

## RobDog888

I am heading up a massive project at work and its starting off with a simple SL browser app that will interface with the phone systems.

In a terminal server environment, I need to be able to re-user a particular browser instance without making a change to the session's IE setting which specifies to re-use instances.

I dont believe there is a way for SL to detect if its got multiple or no instances running at startup?

I hate to rely upon this but foregoing anything else, there should be a IE commandline parameter to specify re-use any open IE instance but it wont specify which instance to use. The case where my SL browser is open yet the agent may have a knowledge base broewser instance open shouldnt be touched.

I have a call center controller app that will be screen popping this SL app with a basic shell command as far as I can tell in its config option page settings.

Ideas?

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## RobDog888

More info...

The initial design is as follows...

This third party app will shell out the file path and a unique identifier specifying the call record in the database. Then my helper app will start up and read in the commandline argument of the unique identifier of the customer. I will make a web service call to retrieve detailed information about that customer.

Now the added complexity. When the next call comes in they dont want another instance of the helper application and also still receive in "startup" parameters. But if its already running then there will be no Application_Startup event. 

Given that it will be used with 1000+ agents we dont want to use a browser but the OOB to save resources.

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## RobDog888

Changed direction and decided to go with WPF as my backup since we are on a time crunch.
Did discover a few ways for single instance and can post them up tomorrow.

Passing command line arguments to an OOB SL instance looks to be completely unsupported. More on this tomorrow too.

I could probably write a blog or article on this now if there was a solution. Oh well.

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