Java Reference
In-Depth Information
Consider a basic J2EE application running on WebSphere. Assume that it meets
the requirements for an application that could be run on App Engine. (See Chapter 4
for more information on the restrictions that applications might face on App Engine.)
With Amazon's Elastic Computing Cloud (EC2) you can quickly build the Linux stack
with a preconfigured Apache server and your choice of Java application server and
database. You have to support the operating system, the database, the application
server, the security, and all the same components you'd be supporting in an on-
premise environment, except the physical machine. This, no doubt, saves time and
money. But, IaaS offerings still need provisioning and long-term support at more
layers than the application. Now, on the flip side, consider this same application
running on App Engine. You don't need hardware provisioned or software installed,
and you don't need an application server or a database. All these are wrapped into
the core platform offering from Google.
Figure 1-1. Cloud vendor landscape (Source: Appirio CIO blog)
Figure 1-1 also shows the platform in the PaaS sector. It's positioned a bit
higher than the App Engine offering, and there's a reason for this. Like some other
platform vendors, encapsulates the runtime environment using its own
proprietary language. Apex, the language for development, looks and feels
like Java in many ways but doesn't support the full implementation of any JRE.
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