Getting to Know Containers

Containers have sparked genuine interest over the last few years. As a developer, I’ve had my fair share of “It Works on My Machine” days, where I spent an interesting amount of my time trying to identify why my code doesn’t run in a given environment. Did I make a mistake? Did someone else make a mistake? Uncertainty, risk and the Human Factor definitely make for adrenaline packed all-nighters.

Quick Thoughts

Businesses need to be agile to compete in today’s global economy. Programmers use various tools and techniques in order to meet this business requirement. The challenge is great and quite complex. Going too fast without the right approach can lead to ephemeral success.

I believe that Microservices give us the agility and architectural patterns that empower us to scale and create value at a far greater pace for the business compared to using a traditional tiered architectures approach.

Forget about 3-tier architectures, they just doesn’t scale. Stateless services need to rebuild their internal state for every call, and they can generate tremendous pressure on data stores. Consequently, this generates back pressure that bubbles up through the layers of our solution and reaches out to the edge. Back pressure then translates into unavailable services. The key is Data Locality and Stateful Services.

Speaking at DevTeach 2016

Years ago, I attended the DevTeach conference and was fortunate to participate in conversations that helped me overcome many challenges over the years that followed. This week I had the opportunity to speak at DevTeach in Montreal. For this event, I chose a topic that I’m really passionate about and needed to cover a lot of ground in a short amount of time.

The talk had a progression from a public cloud, to an architectural pattern, to a hyper-scale microservice platform and finally about a programming model.

My goal with this talk is primarily to introduce Actors and Service Fabric. Then provide attendees with additional information in the downloadable slides about the patterns that I feel are important to consider when building microservices.

Caught by surprise, I had a full room and a lot of great questions. Thanks everyone for making this a success.

Geo-HA Service Fabric Cluster

One of the biggest challenges that we face when we build an Internet-scale solution, is high availability across geographic locations (Geo-HA). Why is this important? Well, there can be a few different reasons. The most common reason, is to be able to survive data center outages. Another reason, is to bring services closer to end users so that we can provide good user experiences.

Geo-HA brings challenges to the table. For example, should we use an Active-Passive or Active-Active strategy for data across regions? Keeping in mind that Active-Active is difficult to get right, we need to take time to analyze and to make the correct choices. We need to consider our Disaster recovery (DR) plan, target RPO and RTO. Azure has a whole bunch of mechanisms for replication, backup and monitoring, so how do we decide what’s the right combination?

Today’s Internet-scale services are built using microservices. Service Fabric is a next-generation middleware platform used for building enterprise-class, Tier-1 services. This microservices platform allows us to build scalable, highly available, reliable, and easy to manage solutions. It addresses the significant challenges in developing and managing stateful services. The Reliable Actors API is one of two high-level frameworks provided by Service Fabric, and it is based on the Actor pattern. This API gives us an asynchronous, single-threaded programming model that simplifies our code while still providing the advantages of scalability and reliability guarantees offered by Service Fabric.

A Service Fabric cluster is HA within its geographic region by default. Thinking about our heritage of on premise data centers, we’ve poured thousands of man-hours to deploy Disaster Recovery sites in secondary physical locations, because we know that everything is possible. Over the past few years, we’ve experienced many interesting scenarios, for example, a cut cable, or a faulty DNS entry broke the Internet. So why should we do anything differently in the cloud? We must treat each region as we treat our own data centers and think about Geo-HA.

The rest of this post is about taking high availably to the next level by deploying a Geo-HA Service Fabric cluster.

Why Service Fabric?

There are definitely a lot of reasons to consider Service Fabric. Surprisingly, they originate from multiple perspectives because Service Fabric is beneficial to IT Pros, Developers and above all else the business.

Data Locality is Important

Never would have imagined that the laws of physics would be so important in a world where virtualization is the new normal.

Data Locality, refers to the ability to move the computation close to the data. This is important because when performance is key, IO quickly becomes our number one bottleneck. Data access times vary from milliseconds to seconds because of many factors like hardware specifications and network capabilities.

Let’s explore Data Locality through the following Scenario. I have eight files containing data about multiple trucks, and I need to Identify trips. A trip consists of many segments, including short stops. So if the driver stops for coffee and starts again, this is still considered the same trip. The strategy depicted below is to read each file and to group data points by truck. This can be referred to as mapping the data. Then we can compute the trips for each group in parallel over multiple threads. This can be referred to as reducing the data. And finally, we merge the results in a single CSV file so that we can easily import it to other systems like SQL Server and Power BI.

The single machine configuration results were promising. So I decided to break it apart and distribute the process across many task Virtual Machines (TVM). Azure Batch is the perfect service to schedule jobs.