Today I have built a RavenDB 4.0 cluster that spanned over 3 machines. This post is to document the process  needed to build and secure the cluster on Ubuntu 16.x using Digital Ocean droplets with custom SSL certificates.

This is a completely manual process from creating the user, setting ravendb settings.json and setting LetsEncrypt certificates.

Getting Ready

Digital Ocean Droplets

Let’s start by creating 3 droplets with the following spec:

• Ubuntu 16.x operating system
• 2GB Ram, 1 vCPU, 50GB SSD

You can choose to increase the specs as you require. However, for RavenDB community, license 3 vCPU are included in the community license. Any more are not available unless you have a paid license. https://ravendb.net/buy

SSL Certificates 

For this demo, we will be using LetsEncrypt ssl certificate for each of the nodes in the cluster.

However, you could use your own paid wildcard ssl certificates without any change in the process outlined here.

The easiest way to acquire LetsEncrypt ssl certificate is to use this service here. https://www.sslforfree.com

If you are not using a wildcard certificate, you will need to obtain a certificate for each ravendb node you have in the cluster. You are required to have an active and valid domain name for this process.

Go through this process of validating the sub-domain names and downloading the certificate files.

Once you downloaded the certificates, you must generate a PFX file to be able to use the certificates with RavenDB.

Use openssl to generate the PFX file. On windows 10, run “bash” to get a bash command line, which have openssl already installed.

Navigate to the location of the extracted certificates. I placed mine somewhere easy and simple to get to “c:\temp\certs”

provide an export password for your newly created pfx file.

You should now have a file called “certificate_combined.pfx”.

Go ahead and import this PFX file in your system by double clicking on the file name (you will need this for later use).

You can verify you have everything right, open  “Manage user certificates”

Installation

Now that we have done the initial preparation from setting up the droplets to generating the SSL certificate, we can move on to the actual installation and configuration of RavenDB.

This process will need to be repeated on each node in the cluster.

Step 1 – Login

Digital Ocean would have sent you an email for each droplet with username and password. I am using Putty to SSH to the droplet and change the password.

Step 2 – Upload Certificate

Use WinSCP to upload the PFX certificate. Login using the same credentials used for Putty and upload the PFX file to root directory.

Step 3 – Run Bash file

I have written installation bash script that run through the process of downloading ravendb binaries, installing them, configuring the service, etc.

Please DO NOT run script files from the internet without reading them first .

You can find it at https://github.com/Sarmaad/ravendb-cluster

Back to Putty, while you are at the root directory, clone the repository:

cmd> git clone https://github.com/sarmaad/ravendb-cluster

This will download the latest stable scripts from github. Then run the following commands:

cmd> cd ravendb-cluster/ubuntu
cmd> chmod +x install.sh
cmd> ./install.sh db01.sarmaad.com /root/certificate_combined.pfx password123!

This script will prepare your environment, download ravendb linux packages (currently version RavenDB-4.0.3-patch-40033-linux-x64 *at the time of writing*) and configure ravendb settings with the correct certificate details and data folder location.

After the scripts completes successfully, make sure to add your FQDN/sub-domain in hosts file so ravendb service can bind to the correct domain.

cmd> echo “128.199.224.104 db01.sarmaad.com” >> /etc/hosts

Then start ravendb service by executing:

cmd> systemctl start ravendb

Check the logs to make sure the service started correctly and without any issue:

cmd> tail /var/log/syslog

You are looking for ravendb service started and listening for requests.

This is what you are looking for in the logs for a successful ravendb service installation/running

Step 4 – Test the Node

Type in the sub-domain directly in your browser and test that the browser prompting for client certificate. If you are prompted, then you have successfully installed a ravendb node.

If you have installed the certificate in your system, choose the certificate from the list and access the node.

Cluster Configuration

Now that we have the 3 nodes up and running (db01, db02 and db03) we are going to login to db01 and start the cluster formation.

Get a License

RavenDB community license is for FREE and you can get it here. https://ravendb.net/license/request/community

You will need a license to continue building your cluster.

Once you receive your License, click on “About”  menu or the red document icon on the footer bar to navigate to about page.

Click “Register” and copy paste your license details received from Hibernating Rhinos.

Add Nodes

After you have registered your license. Click on “Manage Server” -> “Cluster” -> “Add Node to cluster”

Enter the second node you need to add, in this case is: https://db02.sarmaad.com:8080. Make sure to include the HTTPS and Port number.

You can “Test connection” to make sure your servers can reach each other (that is important that each node can reach and communicate with each other).

Then click “Add” button to add this node to cluster.

Repeat these steps for the third node and you are done.

Summary

Hopefully this blog helped you answer the question on how to setup ravendb cluster on linux infrastructure and demonstrated that is its not very hard.

Your cluster is not done yet. The topic of securing your droplets, firewalls and access restrictions are not covered here.

The guys at RavenDB done a great job with their documentation https://ravendb.net/docs/article-page/4.0/csharp/

Make sure to take your time to read it and understand how to operate and manage your new found cluster.

Often as part of an overall solution, you will need scheduled tasks to run on fixed intervals. These tasks are usually administrative, maintenance or integration. There are a lot of ways to achieve this, usually involve deploying windows services that have a scheduler built in like Quartz or using built-in windows task scheduler. One of the major advantage we have in azure functions is server-less architecture, which means no deployment required and no need to pay for a virtual machine to host our service or tasks.

Overview

In this post, I will explain how Azure Functions time trigger works and what are CRON expressions.

This post assumes you have Azure account and you are familiar with Azure Portal

Create Azure Time Trigger Function

Lets start by creating a new time triggered function in azure portal:

1. If you don’t have an existing function app, create a new one. please read my earlier post about creating azure function app
2. Open your Function App and click “New Function”
3. Find and select “Timer Trigger – C#”
4. Give it a name and accept the default schedule expression.

Congratulation, you have just created your first time triggered function. However, we skipped over the most important part, “Schedule” Expression. Let us spend sometime explaining what that is in details.

Schedule Expression (Cron Expression)

The origin of the name cron is from the Greek word for time (chronos) from Wikipidia. It expresses time scheduled jobs as a string format often segmented to 6 or 7 fields separated by a space. Let us examine the format with examples to help explain it.

These fields represent the following:

Let us try some of these expression on our newly created function

Click on “View Files” then Select file named “function.json”, change the schedule property to the expression “0/30 * * * * *”

This should trigger the function every 30 seconds starting from zero seconds.

Conclusion

Azure functions are very flexible and versatile. There are a lot of use-cases were you need to run code on time bases to perform a business function. Some of the common use-cases for time based execution like triggering a backup based on conditions, generate financial statements at the end of the month, send out weekly audit emails, etc

As I am working on a project that leverages RabbitMQ and Azure WebJobs. I needed to write webjob functions that are triggered by a message on a queue in RabbitMQ.

While searching around, I have not found an extension that integrates with Azure WebJobs in a nice way and that is how WebJobs.Extensions.RabbitMQ was born.

The library exposes 3 attributes.

RabbitQueueTriggerAttribute: this attribute will subscribe to the queue and triggers whenever a message arrives.
[RabbitQueueTrigger("queueName")]


RabbitQueueBinderAttribute: this attribute extends RabbitQueueTriggerAttribute to allow for dynamic creation of the queue and bind it to the exchange.
[RabbitQueueBinder("exchangeName", "routingKey", "errorExchangeName(optional)","autoDelete=false(optional)","durable=true(optional)","exclusive=false(optional)")]


RabbitMessageAttribute: this attribute allows you to publish a message to an exchange.
[RabbitMessage("exchangeName","routingKey","mandatory=false(optional)"]


Example of subscription example:

public void IntegrateApprovedProductToMarketPlace(
[RabbitQueueBinder("product", "product.approved", "error")]
[RabbitQueueTrigger("integration-product-approved")]
ProductApproved message, TextWriter log)
{
[handle message here]
}

Example of a publisher:

public void ProcessBulkOrders([some trigger],
[RabbitMessage("order","order.processed")]
out OrderProcessed message, TextWriter log)
{
[assign message value here]
}

The code is available on GitHub and Nuget

In my previous post, I touched on how to create a simple Azure Function and invoke it through a web request.

In this post, I want to do something more interesting that has not yet been covered in any of the template provided.

My objective is to insert a record into Sql Azure Database every time I receive a request.

For this post, we are going to assume you already have Azure Sql database up and running and already have a function app created.

Prerequisites:

1. create an Azure Sql Database from the portal.
2. create a table called LogRequest with two columns (Id [PK, int, identity] ,  Log [nvarchar(max)]
   
   I used visual studio 2015 community to connect to sql database can created the new table.
   

Function Code and Database Configuration:

1. Click on “New Function“, then select “HttpTrigger – C#“, Name your function “HttpTriggerSqlDatabase” to make it easy to locate
2. Once you get the default code view, find the small link down the bottom of the code text box called “View files“
3. Click on the “+” sign to add new file, name the file “project.json” we are going to use this file to add all required nuget packages.
   copy and paste the json content bellow and hit save.
   

   {
     "frameworks": {
       "net46":{
         "dependencies": {
           "Dapper": "1.42.0",
           "System.Data.SqlClient":"4.1.0",
           "Microsoft.WindowsAzure.ConfigurationManager":"3.2.1"
         }
       }
      }
   }
   

   
   you should start seeing the logs restoring all missing nuget packages, then compile the code.
4. Associate your database connection string to the Function App. To do that, click on the top link “Function app settings” then click the button “Go to App Service Settings”
   
   It will open your Function App settings page, then click on Data Contentions, Add
   
   once you successfully added a connection called “SqlConnection“, close the views and navigate back to your function using the breadcrumbs.
5. Click on your function named “HttpTriggerSqlDatabase”, copy the snippet bellow.
   

   using System.Net;
   using Dapper;
   using System.Data.SqlClient;
   using System.Configuration;
   
   
   public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
   {
       log.Info($"C# HTTP trigger function processed a request. RequestUri={req.RequestUri}");
   
       var successful =true;
       try
       {
           var cnnString  = ConfigurationManager.ConnectionStrings["SqlConnection"].ConnectionString;
           
           using(var connection = new SqlConnection(cnnString))
           {
               connection.Open();
               
               var rLog = await req.Content.ReadAsAsync<LogRequest>();
               
               // insert a log to the database
               // NOTE: Execute is an extension method from Dapper library
               connection.Execute("INSERT INTO [dbo].[LogRequest] ([Log]) VALUES (@Log)", rLog);
               log.Info("Log added to database successfully!");
           }
       }
       catch
       {
           successful=false;
       }
       
       return !successful
           ? req.CreateResponse(HttpStatusCode.BadRequest, "Unable to process your request!")
           : req.CreateResponse(HttpStatusCode.OK, "Data saved successfully!");
   }
   public class LogRequest
   {
       public int Id{get;set;}
       public string Log{get;set;}
   }
   

Now save the code and ensure the logs shows the function compiled successfully.

Testing the Function

Scrolling down the page to the Run section, you can invoke your API

I used LinqPad to retrieve the record from the database to verify that my data was actually saved successfully.

Conclusion

It was relatively easy to have my Azure Function connect to a database and insert a record triggered by a web request.

Using  nuget to download packages and reference them in the function is extremely useful, given that most of .Net framework and 3rd party are available as packages.

This scenario gives us the opportunity to design solutions that store request’s data into a relational database which is a step closer to real business application’s requirement.

In feature posts, we will take this a step further and emit events to trigger other Functions to perform other actions meaningful to the data received.

Creating a new Function App

In this post we will look at creating a new Azure Function App and explore a provided example.

Let’s start by creating a new Function App and walk through the setup process. (This post assumes you already have an Azure account.)

1. Add a Function App by clicking on the + icon and searching for Function App

2. fill in the details of your new function. Keep in mind, the app name is unique across the namespace, which means, you will not be able to use the same name as I used here in this tutorial.

3. Once the function app is created and deployed successfully, it will open the function home view

Now you are ready to experiment with Azure Function App. Go ahead and explore the samples provided.

Here, we are going to examine a sample under Webhook + API scenario using C# as our language.

Select Webhook + API scenario, select C# as the language, then click “Create this function”

once the function is created, Azure Portal will open this windows:

Running the function

We can run the function online by scrolling down the page to the Run section and test our newly created function and click Run.

This gives us a quick way to test our function to make sure it’s behaving as expected

Now let us try to invoke this function from Fiddler:

1. copy the Function Url from the sample function.

2. open fiddler and go to composer, choose POST as the method, paste the Function Url copied earlier

Now execute the request and you should get a result of code 200, bellow showing both raw request and response.

Conclusion

In this tutorial we have seen how to create an Azure Function App, create a sample function and run the function both online and from a desktop application.

What is really significant here, there was no server to provision, no code to compile and no configurations to enable API endpoint.

Azure Function can play a significant role in a (Micro)service solution focusing on single responsibility and agility in building a robust architecture.

In the up coming posts, we will take this further in building a real life solution using Azure Function.

It has been rather a long time since my last blog post. During the “gap” I have been working on a lot of projects and various technologies.

What I intend to with this blog series is to document my journey thus far focusing with Microsoft Azure platform and explore with examples various services offered by the platform.

These are some of the topics I would like to cover:

• Building microservices with Azure Functions
• Building a windows service that communicate with Azure ServiceBus
• Deploy docker containers using Microsoft Container Service

I will keep this page updated and link to posts as I publish them.

The format of these blogs will be a documentary of a development process, from solution design, service configuration, implementation and deployment. I intend to make the code available on my GitHub account.

If you like me to cover a specific Azure service, leave me a comment and I might add it to the above list.

Conceptually the idea is great however, when we got to those sessions I found that not having a dedicated leader for the session meant the topic often moved into different areas.

Enough about the structure and more about the actual content.

As early adopters of Cloud Computing we identify issues and concerns having greater importance compared to actual uptake of the technology.

It was interesting to hear the delegates last night speak about what they wanted from the “Cloud” providers.

“Standards” is what everyone was crying out for.  The problem with standards is that when its created those who invested in creating those standards are set to lose the most financially.  The IT industry is quite well known for creating standards and then choosing not to either accept them or implement them.

“Data portability” between providers was the other main sticking point with uptake.  There is a fear that when a company or user stops paying for the service, the Cloud provider simply turns them off and they have now lost their data.

This is a valid point, but how one company stores data (and therefore converts that data into information) is what makes people either buy or use that application.  Those different methods are called IP.  Again, why would businesses want to share IP amongst competitors if there was no financial benefit?

What was positive about the night was that this particular movement in the industry begins to open new untapped market opportunities, Services.  Across all industries, service companies are making good headway into providing what suppliers canâ€t, customer service, support, etc.

As this industry (Cloud Computing) is starting to gain legs, integration, migration, data management services are all new verticals that will spring into the foreground for people/companies to make a living from.

Overall, it was an interesting evening to attend.  The night not only provided the standard “Cloud Provider” pitches but allowed for attendees to have general chats and discussions.  One point I would make, is that I would have preferred to have a mediator in each breakout session to ensure the conversation/discussion stayed on topic.

Interesting times ahead for “Cloud” Computing and what will the catalyst be for businesses to take up Cloud Computing?

That doesnâ€t seem to be a big problem until our CruiseControl CI server kicked in, downloaded our updated code and failed building the upgraded projects.

Fortunately there is a very quick solution to this little problem.  There are a couple of requirements.

1. You need to have VS2010 RC installed somewhere
2. You need to download the .Net Framework 4.0 (I recommend the full version and not just the Client Profile, it ensures you donâ€t miss anything)

To fix, do the following:

1. download and install the .Net Framework 4.0 on the CI server (then restart the server)
2. on the computer where VS2010 RC is installed go to the following path:
   %programfiles%MSBuildMicrosoftVisualStudio
3. copy the v10.0 folder located in that directory into the CI server at the same path (or wherever our MSbuild path is on the CI server)
4. Once that is done, edit the ccnet.config file at the <msbuild><executable> tag and change it to the new .Net 4.0 Framework installed (you should only need to change the section “v3.5” to “v4.0.xxxxx”

Hope this helps

Yes, I was one of these 38, enduring two days with only 2.5 hours of sleep. Nothing else mattered, but delivering the promised goods. My team of 4 – successfully and proudly delivered this service: ChefMeUp.com

Since this is a technical blog, I wont bore you with the emotional details of the three days, but I will introduce you to the team that made this happen.

Casey Butler – Role: PR/Marketing
Casey is a start-up founder and a musician who has come to StartupCamp Sydney to practice business and polish his skills for the real world. His role in building the business case and drumming the PR and marketing is critical to the success of the project. BTW, he flew all the way from Melbourne to be here in Sydney.

Dave Trindall – Role: Developer
Dave is an active developer specialises in the Microsoft technology stack. His dedication to development have lead him to StartupCamp Sydney III to demonstrate his knowledge and experience. Daveâ€s newest website launch is his meaningful short URL service found at: http://ko.ly/

Brett Samuel – Role: Graphic Designer
Brettâ€s background is business development and entrepreneurship. has successfully established and sold his last business, Brett gravitated to StartupCamp Sydney III to learn and share the experience of a new atmosphere and innovation.

Sarmaad Amin – Role: Developer
Sarmaad is a .Net enterprise application developer that have worked on may successful IT projects. He came to StartupCamp Sydney III to explore new innovation and develop ideas in a different environment that cultivate innovation. His experience in software development contributed to the successful completion and launch of the project at StartupCamp Sydney.

“ChefMeUp.com is a project born in 11 hours , from zero code to completion 100% borrowed code free”

Thatâ€s right, the website was completed and fully functional with 11 hours of nothing but pure development and excitement.

This is a short run down of the technology.

I have opt-in to use LLBLGen Pro as our ORM layer with Microsoft SQL Server 2008. The front end is designed and coded using ASP.NET MVC 2 RC 2, yes, using Visual Studio 2010 RC.

I have to say, this is the fasted development I have been involved in, even for a fully functional prototype and without using the MVC framework, I doubt it would have finished on time.

the features of the application includes:

• complete login/registration system for Chefs to list their services
• paypal integration for registration payment
• twitter integration for posting to twitter network and update from it.
• Bing map integration to display the chefs/restaurant registered in the network.

basically all the necessary plumping to operate a web 2.0 style vertical industry service directory business. which in our case we choose Chef and other cooking services.

have a look at our presentation. BTW, I wasnâ€t there because I was building the better website…

Check out the website ChefMeUp.com and let me know what you thing and if you are interested in the source code, send me an email or leave a comment on this post and I would send you a copy.

now to go and get some more sleep, happy coding…

Over the past few years IDP Solutions has provided many customers with solutions to manage online stores and capture data and convert that into important business information.

With all that knowledge of what online business owners required we took the step into creating MYOBSync.  MYOBSync does what is says, Syncs between MYOB and your online cart.

Make sure you put the dates between the 6th and 9th of July in your calendar to come see us at the Expo.  Weâ€ll be in stall 105.

Hope to see you then.