Fiddler doesn't capture traffic with "GetAsync"

Question

I'm trying to debug a call to my ServiceStack web service from a .net 472 application. Fiddler has always been the obvious choice for inspecting traffic in my other applications targeting the same service.

Strangely, I cannot get Fiddler to capture any traffic when using the GetAsync() method of the JsonServiceClient. The call returns data as expected without issue, just not tracked in Fiddler:

var response = await client.GetAsync(new AroCodesRequest());

However, if I use the Get() method, Fiddler captures the traffic as expected:

var response = client.Get(new AroCodesRequest());

(Edit) Adding the following to App.config doesn't help:

  <system.net>
    <defaultProxy>
      <proxy proxyaddress="http://127.0.0.1:8888" bypassonlocal="False" />
    </defaultProxy>
  </system.net>

I've put Fiddler into troubleshooting mode, still no luck. I've been unable to find much helpful information on Google/SO, I suspect I may simply not be asking the correct question.

Update Downgrading from ServiceStack 5.6.0 to 5.5.0 has caused Fiddler to capture the traffic again. I'm guessing it has something to do with this line in the 5.6.0 release notes - https://docs.servicestack.net/releases/v5.6#service-clients-async-webproxy - I don't fully understand whats going on, I'll keep looking at it.

asynchronous operations are not guaranteed to execute the moment you call them, hence the name. They are guaranteed to execute eventually, but debugging the app and breaking execution before the eventual execution might be your problem. Can you show a bit more code around the GetAsync? — Guillaume CR
hmmm, it looks like your client class is propriertary code. There may be a bug in its implementation. Try using .Net http clients to see if you get a different result. — Guillaume CR

mythz mythz · Accepted Answer · 2019-09-11T17:32:26

In v5.6 the AsyncServiceClient uses the Proxy configured on the ServiceClient, previously it didn't. But it used the Proxy even if one wasn't configured which looks like causes this issue where setting it to null seems to unset the Proxy configuration in your Web.config.

I've changed it to only use the proxy if one was configured in this commit.

This change is available from v5.6.1 that's now available on MyGet.

Fiddler doesn't capture traffic with "GetAsync"

1 Answers