I start to consider that there is something in a technology beyond pure marketing hype when IEEE Internet Computing dedicates a complete issue to the topic, which they did in October 2009.
So I decided to take a look and started using Google App Engine because it is free below certain quotas and also because I had some early experience of the Google Web Toolkit which is well supported by GAE.
GAE allows you to run java applications, actually classical J2EE Servlets, with a number of restrictions (for instance you cannot write to a file or open a port).
Since we recently restarted the COBOL Structure to XML Schema project, it seemed like a good idea to deploy it as a service available on the cloud. This way, developers who would like to get a sense of what the product does without investing time downloading and installing can do so.
The result is now available and I almost immediately started to get hits... and problems.
The first problem of course is that the translator is not a COBOL validating parser. I mean it is not a complete syntax checker. It is meant to process COBOL fragments that are supposed to compile OK in the first place. And yet, it is tempting to type COBOL statements in the input textarea of an HTML page, starting at column 1 instead of column 8. Today you often end up with an empty XML schema because the parser dropped everything that it did not recognize.
I guess we'll have to add more syntax checks after all.
The second problem has to do with GAE itself and Java. It has been discussed extensively on the Google App Engine group. When requests are received by GAE it picks up an instance of a VM somewhere on the cloud to service it. Chances are that this VM was last used for something totally different from running your own application. For this reason, Google actually cold starts the VM, which results in a large consumption of CPU... that counts against your quota!
Humm. That first experience has changed my view on cloud computing!
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