Azure Notification Hub SDK on .NET Standard and WNS Raw notification

Update: Thanks to the beloved-by-community Jon Galloway, I can finally connect with the engineers working on the library. Hopefully, the team can push out a fix soon.

I have been using Azure Notification Hub for a very long time to send push notifications to my UWP apps on Windows 10. Since the introduction of .NET Core 1.0, I have gradually been moving my projects from .NET Framework to .NET Core. However, Microsoft.Azure.NotificationHubs was always the blockers due to the lack of support for .NET Standard.

Tl;dr version:

  • 2.0.0-preview1 and preview2 have issue sending WNS Raw message.
  • After 8 months, 2.0.0 was released with the same issue.
  • There was no place to report the issue.
  • There was no source code.
  • The fix is only 1 LOC, but I spent much more time to make the decompiled code compile back.
  • And now I have still no way to report the issue nor contribute the fix.
Read More

The curious case of missing Authorization header

I have been wasting time on a small issue adding Authorization header into HttpClient.

The code was plain and simple:

Specifically, I was writing a .NET Core console app, following this wiki page and trying to access However, I kept getting 401 Unauthorize response and response.RequestMessage.Headers was completely empty.

After having spent some time searching for solution on the Internet but to no avail, I opened Fiddler to see the actual HTTP requests. Turns out, this was what happened behind the scene:

There were actually 2 requests. The first one has the Authorization header and returns a 302 Found. Automatic redirection of HttpClient triggers the second request, and this one didn’t have any Authorization header.

Normally I can just stop there, accept that how things work in .NET and find a workaround. But since .NET Core is open source on GitHub, I decided to dig a bit deeper to understand the reason of this implementation. A quick search about redirection on the corefx repo in GitHub gave me the exact commit that I need: And voila, I could see the line in RedirectHandler.cs that causing the issue:

and I could also see the reason in SocketsHttpHandler.cs:


I finally solved my curious case, and I hope this post is useful to you. Feel free to leave me a comment and let me know if you have any suggestion on securely implement the redirection with Authorization header.


Interesting notes on Docker Windows containers

In this post, I collected some useful links and notes when trying out Docker on Windows with Windows containers.

Useful images

Useful commands

Some notes

  • You do not see the Mount/Disk setting in Docker when using Windows container instead of Linux container because this is not necessary according to the documentation. However, you have to pass in correct parameter for the volume; for instance, C:\data_in_host:C:\data_in_container  or C:/data_in_host:C:/data_in_container  instead of C:/data_in_host:/data_in_container . Check the following links for more information:
  • You cannot test with http://localhost:{host_port} on Windows. You will have to use either http://{host_name}:{host_port} or http://{container_ip}:{container_port}. To find out container IP, you can use docker inspect --format '{{ .NetworkSettings.Networks.nat.IPAddress }}' container_name.

Links & Examples

Deploying ASP.NET Core applications to Docker containers

How to integrate Teamcity and GitLab CI

I note down the step I did to integrate TeamCity build server and GitLab CI pipeline. I am using TeamCity 2017.1.15 and GitLab 10.0.3.

What you will get with this integration:

  • Small green tick for each commit showing that a build has run successfully on the commit
  • Bigger tick for each merge request (MR) showing that a build has run successfully on the head of the merge request
  • Ability to enforce a successful build before any MR can be merged

How to set up the integration

Tldr, you need to go through 3 main steps:

  1. Enable TeamCity integration in your GitLab project settings
  2. Enable TeamCity build configuration to monitor and trigger build for all (CI) branches
  3. Enable “Commit status publisher” build feature

Read More

Migrating Legacy UUID of MongoDB to standard UUID

MongoDB has a legacy format for UUID which causes problem where the UUID is interpreted differently on different platforms, and the standard UUID solves that exact problem.
However, the C# driver defaults to use legacy format and requires switching to standard format explicitly.

Moreover, after switching to standard format, you might get Exception due to existing UUID. You can fix that Exception by using the Python script below to migrate legacy UUID to standard UUID while maintaining the same C# GUID translation:

After running the script, you can then replace ‘my_collection’ by ‘my_collection_new’.
Based on your actual need, you may also replace CSHARP_LEGACY with JAVA_LEGACY or PYTHON_LEGACY or other legacy format (

Hope this help!