Q&A: Sam Greenblatt

Sam Greenblatt, SVP and chief architect of CA's Linux Technology Group, says open software and modeling will push app server progress; Linux is seen as the inevitable platform of choice to run the corporate enterprise. We asked about that in this Q&A interview.

Q: Are people asking too much of application servers? Is middleware being standardized/commoditized, or is it starting to splinter as specialized apps emerge 'higher up the stack'? What has been the real progress, if any, in distributed system development and deployment over the last five years?

A: The application servers are based on the well-known and long established concept of separating the specification of the operation of a system from the details of the way that system uses the capabilities of its platform. Before middleware began to be standardized over the past five years, the industry began to splinter because there was a requirement for a open, vendor-neutral approach to provide for a stacking of architecture: business logic, application logic, underlying platform. We have seen many attempts to create a model to unify the stack and make it independent of proprietary platforms. These platforms include CORBA, J2EE, .NET, Web services and other Web-based application platforms (WebSphere and WebLogic). We have just started to move application development that is portable, interoperable and reusable through architectural separation of concerns. The use of Model Driven Architecture [MDA] provides a federation of systems because it provides a means for using models to direct the specification of understanding, design, construction, deployment, operation, maintenance and modification. So therefore the real progress in application servers is based on the standardization of the stack through open software and modeling.

Q: How does Linux change development? Is it the developer's platform of choice in 2005? Will they all use Virtual Machine [VM] technology to turn their development stations into multiheaded monsters? Does Linux truly change perceptions in terms of price points and maintenance costs for software? Is Longhorn a Linux killer or is it the other way around?

A: Legacy business applications are usually hosted on a mainframe. This conversion to Linux exposes the application's functionality and Linux may not be appropriate for transactional-based systems that encompass a majority of business applications. We must integrate the functionality so that applications can be distributed -- and the applications can be distributed through middleware that may or may not be Linux. This requirement leads us to have applications that have high transaction rates span across multiple architectures transparently. Components that make up the internal structure of these applications must be tightly coupled, and development must create a platform for creation that enables not only Linux but also many virtual environments such as Windows, Unix and S390. A typical workstation will be Intel-based and probably running Linux with VM technology. Microsoft has discovered the need to do multiple operating environments, thus the acquisition of Connectix. The key is the flexibility, then price point. Linux today is the right price point. So it will become the platform of choice.

Q: We have written about the Model Driven Architecture. Since platforms and targets always seem to change it makes sense. But developers often prefer to burn models than build from them. Code generation is always suspect. Yet some of the RAD initiatives of BEA and IBM are about just that -- code generation -- though they don't go to the lengths of MDA. Any comments on those contentions?

A: Sitting on the board of OMG, you would imagine that I believe in the precepts of MDA. It is not until RAD supports that modeling of events, security, pervasive services, directory and transactions independent of underlying platforms by specifying behavior and resources that true insulation from technology primitives is achieved. There is no contention one must specify their RAD in models to truly achieve an open platform-independent application.

About the Author

Jack Vaughan is former Editor-at-Large at Application Development Trends magazine.

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