Software-Defined Datacenter

In addition to these phases, I see different „implementations“ of the respective platform generation. Take Client-Server as one example – this can be a physical-server-only model, this also stretches to server virtualization and potentially even to „VM-oriented“ hosting or even cloud services. My friend Massimo also wrote a nice piece on this.

Evolution of Applications

One of my key observations is that there is no simple 1:1 connection between applications and platforms. With the rise of 2nd generation platforms, not all applications from the 1st platform have been dropped and immediately been available for the next-generation platform. It’s actually an evolution for applications that are still business-relevant and therefore make sense to be optimized for the next-generation platform. And here comes the important observation: I believe there are (at least) three phases in an application evolution cycle that is happening for each platform generation – or potentially even in each concrete implementation of the platform generation. I’ll call theses phases „Unchanged“, „Optimized“ and „Purpose-built“ for now:

But how does that fit in the overall platform picture? I’ll try to merge the previous two pictures into one. It also shows a potential application evolution path across platform generations. As you can see, there can be a slight overlap between „purpose-built“ of the previous and the „unchanged“ phase of the next-generation platform.

But let’s move on to two concrete examples that I see applicable.

Example 1: Network Functions Virtualization

I’ll start with Network Functions Virtualization (NFV). NFV is a Telco industry movement that is supposed to provide hardware independence, new ways of agility, reduced time to market for carrier applications & services, cost reduction and much more – basically, it’s about the delivery of promises of Cloud Computing (and Third Platform) for the Telco industry (read more about it here). The famous architectural overview as described by ETSI can be seen below:

NFV differentiates between several functional components such as the actual platform (NFVI = Network Functions Virtualization Infrastructure), the application (VNF = Virtual Network Function), the application manager (VNF manager) and e.g. the orchestration engine.

So how could this look in reality? Let’s assume the VNF manager detects a certain usage pattern of its VNF and that VNF is reaching it’s potential maximum scale for the currently deployed amount of VNF instances. The VNF manager then talks to the Orchestrator that could then trigger e.g. the scale-out of the VNF by deploying additional worker instances on the underlying infrastructure/platform resources. The worker instances of the VNF could then automatically be included in the load distribution and have instant integration into necessary backend services where applicable. All of that happens via open APIs and standardized interfaces – it looks and feels a lot like a typical implementation example for a „third platform“ including the „purpose-built“ app.

Now into a quick reality check. ETSI’s initial NFV whitepaper is from October 2012. It basically describes the destination that the industry is aiming for. And while there might be some examples where VNFs, NFVI and Orchestration are already working hand in hand, there is still a lot of work to do. Some of the „NFV applications“ (or VNFs) might have been just „P2V“’ed (1:1 physical to virtual conversion) onto a virtualization platform and basically have the same configuration, same identity and are kept as close to its physical origins as possible. This allows a VNF provider/vendor to keep existing support procedures and organizations while offering their customers a „NFV 1.0 product“ that is providing some early benefits of NFV (hardware independence, faster time to market, …). But this also implies that you transfer some of the configurations that made perfect sense in the physical world over to the virtual world – where it only makes questionable sense. In this case, I’d actually talk about a move from a „purpose-built“ app from the first platform to an „unchanged“ app on the second platform. 

One example: one physical server in a telco application had 30*300GB harddisks, had 2*4Core CPUs and 128GB RAM. It never used more than 1TB of storage and average utilization has been below 4 CPUs and 32GB RAM. The „unchanged“ version of this app would be a 1:1 conversion with all (unnecessary) resource overhead provided in a virtual machine. The „optimized“ version of this app is a right-sized application (so only 1TB storage, 4 CPUs and 32GB RAM) that is also leveraging easy configuration files for installation as well as crash-consistent and persistent data management to allow backup & restore as VM. But a „purpose-built“ version of that app would leverage the underlying NFVI APIs, would allow scale-out deployment options based on actual demand as well as optimizations that are e.g. encryption at every layer of the application to ensure global deployment models even in the face of lawful interception relevance, etc.

Example 2: Microservices, Containers & Docker

My next example are microservices and their close friends containers. They are promising a new generation of application architecture and are drivers for the „3rd platform“ architecture. One of this movements famous poster-childs is Docker. Docker is a great (new) way to package and distribute applications in „containers“ that contain applications or just pieces of a larger application architecture. Newly developed applications usually follow a scale-out design, some might be written with something like the „12 factor app“ manifesto in mind (or the 15 factors according to Pivotal). Coming back to the pictures above: a 12 factor app could be considered „purpose-built“ for the „third platform“.

But how many applications have been built for this? There are many great examples for microservices-oriented applications by the „cloud-native“ companies such as Google, Amazon, Facebook and the likes. Adrian Cockcroft also gives inspirational talks about these topics around the globe. But I actually expect many applications to stay mainly unchanged as they are optimized for their current platform. At the same time, some of them might become available as (Docker) containers as part their next release. But again – if you look into the details, you’ll find the same application in a different wrapper. RAR is now ZIP (for my German readers: „Aus Raider wird nun Twix…“). But will these potentially „single-container-applications“ run well on a Cloud-Native/third platform architecture? They might not! To put it in a picture:

Containerizing legacy applications pic.twitter.com/NXeHRhWVcz

— Kenny Bastani (@kennybastani) May 17, 2016

So in this case, it is actually important to understand these application limitations and expectations towards the platform (what about data persistence, security, platform resilience, networking, …) to make sure it runs smoothly in production. Coming back to Massimo’s blogpost – you can run your old Windows NT4 on a Public Cloud, but does it make sense?

Summary

Just like the continuous evolution of platforms that expose new characteristics and capabilities, there is also an ongoing evolution of applications. It is important to understand the key aspects of the application architecture and it’s deployment model before making a platform decision. The word „VNF“ does not necessary imply the alignment with NFV and the word „Docker“ does not automatically describe a Cloud-Native or microservices-oriented application.

Edits:

18.05.2016: added picture (containerizing legacy applications)