TCP Listener on Microsoft Azure with Service Fabric


Getting TCP listener to run on Microsoft Azure is always an interesting topic to work on. Previously, I did one experimental TCP listener on Azure Cloud Service and it works quite well.

Today, I’d like to share with you my another experiment which is hosting a TCP Listener on Microsoft Azure with Service Fabric.

Step 0: Installing Service Fabric SDK

Most of the time, it’s better to run the Visual Studio 2017 in Administrator mode otherwise debugging and deployment of Service Fabric applications may have errors.

Before we can start a new Service Fabric application project on Visual Studio, we first need to make sure Service Fabric SDK is installed.


Visual Studio will prompt us to install Service Fabric SDK.

The template that I use is Stateless Service under .NET Core 2.0. This project template is to create a stateless reliable service with .NET Core.

Step 1: Add TCP Endpoint

In the ServiceManifest.xml of the PackageRoot folder of the application project, we need to specify an endpoint that our TCP Listener will be listening to. In my case, I am using port 9005. So I need to add an endpoint as shown below in the ServiceManifest.xml.

<Endpoint Name="TcpEndpoint" Protocol="tcp" Port="9005"/>

Step 2: Create Listeners

In the StatelessService class, there is a CreateServiceInstanceListeners method that we can override to create TCP listeners with the following codes.

protected override IEnumerable CreateServiceInstanceListeners()
    var endpoints = Context.CodePackageActivationContext.GetEndpoints()
        .Where(endpoint => endpoint.Protocol == EndpointProtocol.Tcp)
        .Select(endpoint => endpoint.Name);

    return endpoints.Select(endpoint => new ServiceInstanceListener(
        serviceContext => new TcpCommunicationListener(serviceContext, ServiceEventSource.Current, endpoint), endpoint));

Then in the RunAsync method, which is the main entry point for our service instance, we can simply include the code for TCP Listener to receive and send message to the clients.runasync.png

Step 3: Create Service Fabric Cluster


There are a few simple steps for us to follow in order to create a new Service Fabric cluster on Microsoft Azure.

Firstly, we need to specify some basic information, such as cluster name, OS, and default VM credentials.


Configure basic settings for a new Azure Service Fabric cluster.

Secondly, we need to define Node Types. Node types can be seen as equivalent to the roles in Cloud Service. Node types define the VM sizes, the number of VMs, and their properties. Every node type that is defined in a Service Fabric cluster maps to a virtual machine scale set.

We can start with only one node type. The portal will then prompt us to select one VM size. By default, it only shows three recommended sizes. If you would like to find out more other specs with lower price, please click on “View All”.

I once use A0 (which coasted USD 14.88) for experimental purpose. However, it turns out that the newly created service fabric cluster is totally not connectable with a status saying “Upgrade service unreachable”. The funny thing is that the status was only shown after everything in the resource group is setup successfully which strangely took about one hour plus to finish. So I wasted about one hour for that. Hence, please use at least the recommended size for the VM.


We need to specify the VM spec for each of the node type.

A very interesting point to take note is that, there is a checkbox for us to configure advance settings for node type, as shown in the following screenshot. The default values here will affect things such as the Service Fabric dashboard URL we use later. It’s fine to leave them as default.


Default values in the advanced settings of node type.

Thirdly, we need to configure the security settings by specifying which Key Vault to use. If you don’t have any suitable key vault, then it will take about one minute to create a new key vault for you. After the new key vault is created, you may be prompted with an error stopping you to proceed, as shown in the following screenshot.


New key vault created here by default is not enabled for deployment.

To fix the error, we first need to visit the Key Vaults page. After that, we need to find out the key vault we just created above. Then we proceed to tick the corresponding checkbox to enable the key vault access to Azure VM for deployment, as shown in the following screenshot.


Enable it so that Azure VM can retrieve certificates stored as secret from the key vault.

Now, if we got back to the Step 3 of the service fabric cluster setup, we can get rid of the error message by re-selecting the key vault. After keying a certificate name, we will need to wait for 30 seconds for validation. Then we will be given a link to download our certificate for later use.


Let’s download the cert from here!

This marks the end of our service fabric cluster setup. What we need to do is just to click on the “Create” button.

The creation process took about 40 minutes to complete. It actually went through many stages which are better described in the article “Azure Service Fabric Cluster – Deployment Issues”, written by Cosmin Muscalu.

Step 4: Publish App from Visual Studio

After the service fabric cluster is done, we can proceed to publish our application to it.

In the Solution Explorer, we simply need to right-click on the Service Fabric project and choose Publish, as shown in the following image.


Solution Explorer

A window will popup and prompt us that the Connection Endpoint is not valid, as shown below.


Failed to connect to server and thus we cannot publish the app to Azure.

Now, according to the article from the link “How to configure secure connection”, we have to install the certificate that we downloaded earlier from Azure Portal in Step 2.

Since there is no password for the pfx file, we simply need to accept all default settings while importing the certificate.

Now if we go back to the Publish window, we will see a green tick icon appearing at the side of the Connection Endpoint. Now, we are good to proceed to do a publish. The deployment of a simple TCP Listener normally takes less than one minute to finish.

Step 5: Open Port Access

After the deployment is done, we need to open up the 9005 port that we specified above in Step 2. To do so, we need to visit the Load Balancer used by the service fabric cluster to add a new rule for the port 9005 to be accessible from public.


Add a new load balancing rule for the service fabric.

The process of adding a new rule normally takes about three minutes to complete.

Please take note that we need to note down the Public IP Address of our load balancer as well.


The Public IP Address of a load balancer can be found in its Overview panel.

Step 6: Open Up Service Fabric Explorer

Finally, we need to open up the Explorer for our service fabric cluster. To do so, we can retrieve the dashboard URL in the Overview panel of the service fabric cluster.


The Service Fabric Explorer URL is here.

To access the Explorer, we first need to select a certificate that we downloaded earlier to authenticate ourselves to the Explorer, as shown in the screenshot below.


Selecting a certificate on Google Chrome.

Step 7: Communicate with TCP Listener

Now, if we build a simple TCP client to talk to the server at the IP address of the load balancer that we noted down earlier, we can easily send and receive response from the server, as shown in the screenshot below.


Hooray, we receive the response from the application on Azure Service Fabric!

So yup, that’s all for a very simple TCP Listener which is hosted on Microsoft Azure.

I will continue to research more about this topic with my teammates so that I can find out more about this cool technology.


Setup Ubuntu Server at Tokyo and Transform it to Desktop with RDP Installed


While waiting for lunch, it’s nice to do some warmups. Setting a server overseas seems a pretty cool warmup to do for developers, right? Recently, my friend recommended me to try out Vultr which provide cloud servers. So today, I’m going to share how I deploy a Ubuntu server which is located in Tokyo, a city far away from where I am now.

Step 1: Choosing Server Location

Vultr is currently available in many cities in popular countries such as Japan, Singapore, Germany, United States, Australia, etc.


Step 2: Choosing Server Type and Size

Subsequently, we will be asked to select the type and size for the server. Here, I choose 60 GB SSD server with Ubuntu 16.04 x64 installed. I tried with Ubuntu 17.10 x64 before but I couldn’t successfully RDP into it. Then the latest Ubuntu 18.04 x64 is not yet tried by me. So ya, we will stick to using Ubuntu 16.04 x64 in this article.


Step 3: Uploading SSH Key

Vultr is friendly to provide us a tutorial about generating SSH Keys on Windows and Linux.

The steps for creating SSH key on Windows with PuTTYgen is as follows.

Firstly, we need to click on the “Generate” button on PuTTYgen.


Secondly, once the Public Key is generated, we need to enter a key passphrase for additional security.

Thirdly, we click on the “Save Private Key” button to save the private key on somewhere safe.

Fourthly, we copy all of the text in the Public Key field and paste it to the textbox in Vultr under the “Add SSH Key” section.


Step 4: Naming and Deployment

Before we can deploy the server, we need to key in the hostname for the new server.

After we have done that, then we can instruct Vultr to deploy the server by clicking on the “Deploy Now” button at the bottom of the page.

Within 5 minutes, the server should finish installing and booting up.

Step 5: Getting IP Address, Username, and Password

In order to get the user credential to access the server, we need to click on the “Server Details” to view the IP address, username, and password.

Step 6: Updating Root Password

The default password is not user-friendly. Hence, once we login to the server via PuTTY, we need to immediately update the root password using the command below for our own good.

# passwd

Step 7: Installing Ubuntu Desktop

Firstly, let’s do some updating for the packages via the following commands.

# sudo apt-get update
# sudo apt-get upgrade

This will take about 2 minutes to finish.

Then we can proceed to install the default desktop using the following command.

# sudo apt-get install ubuntu-desktop

This will take about 4 minutes to finish. Take note that at this point of time Unity will be the desktop environment.

After that, we update the packages again.

# sudo apt-get update

Step 8: Installing Text Editor

We are going to change some configurations later, so we will need to use a text editor. Here, I’ll use the Nano Text Editor by installing it first.

# sudo apt-get install nano

Step 9: Installing xrdp

xrdp is an open source Remote Desktop Protocol (RDP) server which provides a graphical login to remote machines. This helps us to connect to the server using Microsoft Remote Desktop Client.

sudo apt-get install xrdp

Step 10: Changing to Use Xfce Desktop Environment

We will then proceed to install Xfce which is a lightweight desktop environment for UNIX-like operating systems.

sudo apt-get install xfce4

After it is installed successfully, please run the following command. This is to tell the Ubuntu server to know that Xfce has been chosen to replace Unity as desktop environment.

echo xfce4-session >~/.xsession

Step 11: Inspect xrdp Settings

We need to configure the xrdp settings by editing the in Nano Text Editor.

nano /etc/xrdp/

We need to edit the file by changing entire of the file content to be as follows.

if [ -r /etc/default/locale ]; then
 . /etc/default.locale


Then we need to restart xrdp.

# sudo service xrdp restart

After that, we restart the server.

# reboot now

Step 12: Connecting with Remote Desktop Client

After the server has been restarted, we can access the server with Windows Remote Desktop Client.


At this point of time, some of you may encounter error when logging in via RDP. The error will be saying things as follows.

Connecting to sesman IP port 3350
sesman connect ok
sending login info to session manager, please wait...
xrdp_mm_process_login_response:login successful for display
started connecting
connecting to 5910
error-problem connecting

Problem of connecting via xrdp.

As pointed out in one of the discussion threads on Ask Ubuntu, the problem seems to be xrdp, vnc4server, and tightvncserver are installed in the wrong order. So in order to fix that, we just need to remove them and re-install them in a correct order with the following set of commands.

# sudo apt-get remove xrdp vnc4server tightvncserver
# sudo apt-get install tightvncserver
# sudo apt-get install xrdp
# sudo service xrdp restart

After the server is restarted, we should have no problem accessing our server via RDP client on Windows.





#rdp, #technology, #ubuntu

[KOSD Series] Code Review and VSTS

KOSD, or Kopi-O Siew Dai, is a type of Singapore coffee that I enjoy. It is basically a cup of coffee with a little bit of sugar. This series is meant to blog about technical knowledge that I gained while having a small cup of Kopi-O Siew Dai.


Code reviews are a best practice for software development projects but it’s normally ignored in startups and SMEs because

  • the top management doesn’t understand the value of doing so;
  • the developers have no time to do code reviews and even unit testing.

So, in order to improve our code quality and management standards, we decided to introduce the idea of code reviewing by enforcing pull requests creating in our deployment procedure, even though our team is very small and we are working in a startup environment.

Firstly, we set up two websites on Azure App Service, one for UAT and another for the Production. We enabled Continuous Deployment feature for two of them by configuring Azure App Service integration with our Git repository on Visual Studio Team Services (VSTS).

Secondly, we have two branches in the Git repository of the project, i.e. master and development-deployment. Changes pushed to the branches will automatically be deployed to the Production and the UAT websites, respectively.

In order to prevent that our codes are being deployed to even the UAT site without code reviews, we created a new branch known as the development branch. The development branch allows all the relevant developers (in the example below, we call them Alvin and Bryan) to pull/push their local changes freely from/to it.


Once any of the developers is confident with his/her changes, he/she can create a new pull request on VSTS.


Creating a new pull request on VSTS.

We then proceed to make use of the new capability on VSTS, which is to set policies for the branches. In the policy setting, we checked the option “Require a minimum number of reviewers” to prevent direct pushes to both master and development-deployment branches.


Enabled the code review requirement in each pull request to protect the branch.

So for every deployment to our UAT and Production websites, the checking step is in place to make sure that the deployments are all properly reviewed and approved. This is not just to protect the system but also to protect the developers by having a standardized quality checking across the development team.

This is the end of this episode of KOSD series. If you have any comment or suggestion about this article, please shout out. Hope you enjoy this cup of electronic Kopi-O Siew Dai. =)

#devops, #git, #kopi-o-siew-dai, #microsoft-azure, #visual-studio-online