Simple RTD Server example

[matt....@gmail.com]

Hi, I have browsed through pretty much all threads regarding RTD server issues, and also tried to locate examples in the Samples/RTD folder but somehow I am still very unclear about the RTD workings within Excel DNA.

Is there a chance to post a simple RTD server example? I am not a big fan of reactive extensions (however, a very big fan of TPL Dataflow which equally well solves most data flow and streaming problems) and I wonder whether knowledge of Rx is necessary to get a simple RTD server in ExcelDNA running. 

Thanks

Matt

[Govert van Drimmelen]

Hi Matt,

The code in Distribution\Samples\RTD\ExcelRtdServer.dna is about as simple as it gets.

Some relevant points:

* You don't need to use Rx to make RTD servers with Excel-DNA. The Rx extensions are based on the RTD server support, but you can easily make your own RTD servers in an Excel-DNA add-in too.

* Derive from the ExcelRtdServer base class (in ExcelDna.Integration.Rtd) to base your RTD server on.

* Mark your class as [ComVisible(true)] (but remember to never mark your assembly as "Register for COM Interop" in Visual Studio.

* Override at least ConnectData (and probably DisconnectData) to be notified when a new topic is connected from a worksheet function.

* Store the Topic object that is passed to ConnectData, then call its UpdateValue member (as often as you want, and from any thread!) when the data should be updated.

* Make a wrapper function that looks like this:

    public static object MyRTDCall(string topicInfo)

    {

        return XlCall.RTD("MyRTDServers.MyServer", null, topicInfo);

    }

* Then call from a formula as =MyRTDCall("XYZ")

Please post back if you have any other specific questions, or run into any problems.

Regards,

Govert

[matt....@gmail.com]

Thank you for your prompt answer, however, the reason I am asking is because I don't see that specific example file in the mentioned folder. Could you please point me to it? I downloaded the whole code and somehow the file is not existent in the folder. Thanks

[Govert van Drimmelen]

Ah - OK, I guess it got added after the last release.

You can get the most recent check-in here: https://exceldna.codeplex.com/releases/view/119190

or view the code here: https://exceldna.codeplex.com/SourceControl/latest#Distribution/Samples/RTD/ExcelRtdServer.dna

-Govert

[matt....@gmail.com]

Thank you for pointing me to the file. I implemented it by copying the code into my own C# dll. But I am getting a "#N/A" error when calling "WhatTimeIsIt()" from within Excel. Anything that I am missing out. I am sure I correctly compile and package the dna and such forth because I can access my UDFs within the same add-in from within Excel. 

[Govert van Drimmelen]

Did you mark the class implementing the server as [ComVisible(true)]?

Did you get the namespace and class name right in the wrapper function where you call XlCall.RTD ?

-Govert

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[matt....@gmail.com]

stupid me, I got the namespace wrong, works fine now.