In preparation for Gartner Application Architcture, Development and Integration (AADI) conference scheduled for Novemeber I am developing a PaaS Scenario presentation. We have recently published a PaaS Reference Architecture research , a PaaS market assessment research and are working on the PaaS road map and more. Below is a brief Q&A on PaaS for the prospective attendees that I wanted to share here.
1 What is platform as a service (PaaS)?
Simply speaking, PaaS is middleware as a service. PaaS is the middle layer in the big-picture Cloud architecture(Systems Infrastructure or IaaS below it and applications or SaaS above it). All of the middle-layer technologies you know from the traditional on-premises deployments apply in the cloud as well. These are the application servers, DBMS, ESBs, Portals, Messaging, BPM and other middleware technologies. There is more than 10 categories of middleware that we track that are available from some vendors as a service. However of all of these, two stand out: the application platform as a service (APaaS) and the integration as a service. APaaS is the extended application server (with development tools and a data store) and integration as a service is self-explanatory. So when you hear people talk about PaaS they may actually mean APaaS (like Force.com or App Engine) or they may mean any one of multiple specialized middleware as a service offerings. Or they may mean the complete comprehensive suite of all middleware.
2 Who should care about PaaS and why?
Technology Vendors: The middleware platform is where the programming model and basic architecture of applications is determined and where standards for interoperability and portability are established. Vendors in the business software space all care about the middle layer a lot for that reason. In the Cloud this is no different – the vendors that emerge as leaders in PaaS will have major influence on the evolution of cloud computing. There are no established leaders here so far although Salesforce.com, Google and Microsoft are already making strategic investments in that direction along with a few dozen small players like LongJump, Engine Yard and many others.
Application ISVs: Most application ISVs either already do or plan to offer all or some of their functionality as a service. To do so they have to find a technical way of converting their applications from single-tenant on-premises model to multi-tenant cloud model. Some will simply use hosting services and will make no changes to the application itself (managing each customer-tenant as a separate instance of the application). This model is not sustainable long term and, lacking any resource sharing, it is not cloud. Some others will develop the multi-tenancy support themselves. This can work well, but is expensive, time-consuming and creates long-term burdens that the ISV will have to live with for a long time. The more strategically-thinking ISVs turn to PaaS providers. This is the same as the developers of new on-premises applications would use a third-party application server and other middleware rather than develop their own. It is the only long-term sustainable approach for ISVs. Today there is still some risk in choosing a PaaS (or more likely an APaaS) provider as the standards are not yet established and as a result, all of the three approaches are used by some ISVs.
IT software projects: The difference today between using an on-premises development environment (a WebSphere, a .NET platform or another) and using a PaaS (Force.com, App Engine, Heroku or another) is that the PaaS requires minimal time for procurement and is priced by subscription rather than a large up-front license fee. The PaaS technologies are also in some cases much easier to use as many use model-driven metadata-based design and execution tools. Large projects “in a hurry” and small projects with limited budgets are the primary direct IT users of PaaS today. Integration as a service is also often used by IT organizations for advanced B2B integration projects. Many IT organizations also use PaaS today as pilot experimental alternative to traditional models – in preparation for the future.
There is MUCH more to say, some other day.
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