Platform as a Service is a term that can be fairly confusing for many people. Normally the term is associated with Google App Engine from Google and Force.com from Salesforce.com as the main references for this model. From a technical point of view, it is aimed to provide a similar type of value to the one that is currently provided by many of the application servers i.e. it provides a generic container that can host different applications and shield them from the details of the underlying operating system, network, database implementation. Unlike most of the existing application servers it was designed for massive scaling from day one. Another big difference is in the way it is being consumed. With PaaS you don’t need to install any software and go through all the hoops to setup a cluster environment etc. PaaS is provided as a hosted service that is pre-configured and installed. You get a production ready environment right at the start.
Key Characteristics of a Cloud/SaaS Enabled Application Platform
Last week I came across David Mitchel Smith presentation from Gartner. David provided a good definition to the main PaaS characteristics. A snippet from his presentation covering this area is given below:
What’s interesting is the great emphasize on Multitenancy support. The fact that the platform is going to be shared between multiple applications and potentially even different customers require various levels of tenancy support and isolation to ensure that even though were taking advantage of the fact that we can share resources between applications, each application needs to be able to use the platform as if it is running on its own dedicated resources. Another interesting point is the need for XTP support. Many would view XTP as a niche that is normally referenced in the high end part of the market, so it is fair to ask why would XTP fit into a general PaaS solution? XTP represents a model for supporting enterprise transaction processing applications in an extremely scalable environment. In our case, scalability is not necessarily driven from the demand of a particular application but from the fact that many applications are going to run on a shared environment. A PaaS targeted to enterprise applications would need to provide support for this level of scalable transaction processing support as a core service.
Can you run your existing business applications with GAE or Force.com?
No. Unfortunately as in anything in life reality can really spoil the party.
Force.com was designed to make it simple to run business applications that are database centric i.e. CRM, Reporting etc. It provides a rich set of high level services that make building such applications extremely simple. Google provides a more generic application platform and recently announced support for Java which is a big step towards reducing vendor lock-in concerns. Google seems to be geared for consumer based applications. Force.com offers a more high level platform that is based on its proprietary services. This means that in order to take advantage of their service you will need to go through a complete re-write.
Force.com is based on a database centric architecture. They also seem to be limited in scalability as they partition their database per application. This means that if your application needs to scale more than what a single database can provide, you can find yourself pretty much locked.
Google's recent support for Java makes their offering closer to standard JEE application servers, however their current support impose a lot of limitations due to their sandbox model. These limitations mean that at the end of the day GAE can be applicable only to a small set of relatively simple applications. Since there is no guarantee or control over the resources that you are going to receive from their underlying infrastructure, it is likely that the application performance will be unpredictable and will therefore be affected by other applications that are sharing the same hardware.
The fact that the platform as a service shields you from the details of the underlying infrastructure is what makes it simple and that is both the advantage and limitation. You can’t control the environment, you can’t choose your operating system, you can’t install your own set of services and you can’t control the performance characteristics of this platform.
This puts a huge adoption barrier for most current enterprises.
IaaS vs PaaS
Infrastructure as a Service provider provides a hosted service model that offers plain machine level access. This model is also known as Server as a Service. The fact that you get access to the bare metal allows you to run almost any application on this hosted environment. Unlike PaaS, IaaS gives you extreme flexibility. You can choose your own operating system, install any package that you want, you can setup your firewall, security etc. Amazon is known to be the leader in this space and also provides a set of services on top of their infrastructure such as SimpleDB, SQS and MapReduce. Having said all that, this flexibility comes at the cost of complexity. In many cases you will need to install your own software, configure it, tune it etc. before you could make it run effectively on the cloud. Many application developers don’t have the skill-set to do that. This exposes many operational challenges as many organizations are not geared to support this type of environment from their own IT. The high level services provided by Amazon are still proprietary and would require a complete re-write if you plan to use such services.
PaaS for Enterprise applications – doing it right
The ideal solution would be to combine the best of the two worlds i.e. the flexibility of IaaS and simplicity of PaaS, and here is how:
- Build a Generic PaaS on top of AWS – To build a PaaS we don’t need to re-invent the wheel. Unlike Google and Force.com we don’t need to own the infrastructure, we can actually use Amazon infrastructure or even better build our PaaS such that it can be portable between Amazon IaaS and a VMware IaaS. By doing so, the PaaS can provide us the ability to deploy applications in a simple way just as in GAE but would still enable us to control the environment, install our own software and get the full flexibility that IaaS provides.
- JEE as first class citizen – Many of the existing enterprise applications are built in JEE. Making JEE a first class citizen within our PaaS environment will enable you to leverage the existing skill-sets within those organizations. Similar to the standard model that has more than one implementation out there, reducing the lock-in factor significantly.
- Pre-configured for extreme scalability – All the services provided through the PaaS will need to be implemented and pre-configured for extreme scaling and come with a production ready setup to enable dynamic scaling and fault-tolerance.
Next generation application Server?
Yes, In my opinion, PaaS represents the next wave in middleware technology. One that is targeted for virtualized enterprises, one that was designed for scale-out from the get go, one that fits the new way of delivering SaaS applications and one that can be extremely simple to use. The current PaaS players i.e Google and Salesforce and to a lesser degree Microsoft represent one type of player, those that own it all, i.e. the infrastructure and the platform. There is already a new emerging category of players in the PaaS market, Application PaaS players. Application PaaS players would specialize on delivering only the platform and not the hardware and network infrastructure. They act as the bridge that will enable portability between different infrastructure providers including the internal IT (a.k.a private-cloud). The application PaaS players will also be segmented in similar ways to the way application servers are segmented today, i.e there would be the one targeting the low-end consumer market in similar ways to Google App Engine, the ones that will be aimed toward the high end of the market and those who will be specialized in certain languages or development framework, i.e. Ruby/ Java/ .Net etc. In the PaaS type of world, those who would be able to provide a holistic solution that works smoothly across all the application tiers would have an advantage over those who are providing point solutions.
What about my existing applications ?
Most people would categories PaaS as a platform that is delivered through the internet. That statement would make the idea behind PaaS irrelevant for a large part of the existing enterprise applications, as a majority of them are not ready to run their application in a hosted service over the internet. Let’s examine that statement:
Many of the existing IT run farms of application servers in their internal IT. Those application servers are running in an internal data center that is not that different from any other hosted services, only that it is a specialized hosted service tailored for the needs of the specific organization. I would therefore argue that those organizations that are already running such application server farms would find it easier to evolve such server farms to PaaS model than to change their entire IT infrastructure into internal cloud. The reason is that those applications were already written to run in an application container model, therefore a large part of the transition work can be done within the container implementation and outside the application code. Targeting them first would therefore be potentially easier transition than trying to transform all your other applications into a virtualized environment.
I know that there are many people out there that would argue that internal PaaS is not a PaaS because it doesn’t answer the exact definition of PaaS. However in my view the similarities exceed the differences and the value to the enterprise would be almost identical to the one that I would receive by any of the internet based PaaS platform.
Will I lose control?
PaaS will provide the internal IT much better control over the applications that are running on their environment. You can have high visibility as to ways the application consume resources. In the same way, you can control fairly tightly the application security, scalability, resource management and fault-tolerance which can finally be managed in a consistent way across all the applications.
Final words
Platform as a Service represent the next generation application server IMO. GAE and Force.com are most known references in the market for that model. Both tries to offer the complete stack and that’s both their advantage and limitation. There already is a new category of Application PaaS providers that specialize on providing PaaS on top of existing infrastructure providers. There would be generic PaaS providers (similar to GAE) geared for the low end part of the market and those that are geared for the high end of the market. There would also be more vertical PaaS providers (Similar to Force.com) i.e. those that will provide PaaS for a certain segment of applications or segment of the market such as Online Gaming PaaS, Telco PaaS etc. A good example for such a service is Twilio. As I outlined in my recent post (Google App Engine plus Amazon AWS: Best of both worlds), this is not just a theory but a reality in the making. GigaSpaces' contribution to this new reality is our new cloud framework on Amazon EC2. Geva Perry provides an excellent overview of other good examples that follows that same line his post What's Really Exciting About Cloud Computing.
References:
- Google App Engine plus Amazon AWS: Best of both worlds
- Waiting to see if App Engine or an alternative gets there first
- What's Really Exciting About Cloud Computing.
- JavaSpaces and the Next Big Thing
- Space-Based Architecture for AppEngine
- GigaSpaces as Alternative to GoogleAppEngine for the Enterprise
- GigaSpaces introduces portable PaaS
- Google Brings App Engine's Pros and Cons to Java
- Google App Engine and The Java Web; The Wrong Java?
