Most applications that are being deployed in the cloud today are “greenfield” applications: Web applications engineered specifically for deployment in the cloud on technologies intended for the cloud. Especially in the public platform-as-a-service arena, PaaS users typically deploy new projects that lack any constraints imposed by prior work and code.
However, one of the main reasons companies want to move to the cloud is to gain computing and resource efficiencies out of existing apps. If you’re not migrating your legacy apps, you’re missing most of that efficiency. Engineers end up spending precious development resources reengineering or rebuilding from scratch perfectly good applications so that they can be deployed on new cloud infrastructure.
Why reinvent the wheel when you already have apps in place that work well for your company? It just makes sense to port those applications to the cloud rather than create all-new programs.
Fortunately, there is a solution for porting applications to the cloud without the usual hassles and with minimal reengineering: use a private PaaS.
Public vs. private PaaS
Most commonly, a PaaS is an externally hosted and managed service outside of the corporate firewall. This is known as a public PaaS. However, there are security vulnerabilities inherent in the public cloud, which has the potential to aggregate a large quantity of confidential data in cloud data centers.
Often, there is little transparency in the public cloud provider’s security measures, and clients must simply trust the cloud provider to keep their data safe. In addition, cloud users rely heavily on browsers, which leave the public cloud potentially vulnerable to browser security failures. Moreover, most public PaaS providers use a “one size fits all” approach, and it doesn’t bend to accommodate the needs of existing applications.