I am trying to understand Serverless architecture which says 2 distinct things:
you as an app developer think about your function only and not about the server responsibilities. Well, the server still has got to be somewhere. By servers, I understand here that its mean both:
- on the infrastructure side Physical Server/VM/container
- as well as the on the software side: say, Tomcat
Now, I have worked on Cloud Foundry and studied the ER i.e. Diego Architecture of Cloud Foundry and the buildpack and open Service Broker API facility of Cloud foundry. Effectively, Cloud Foundry also already works on a "similar" model where the application developer focuses on his code and the deployment model with the help of buildpack prepares a droplet with the needed Java runtime and Tomcat runtime and then uses it to create a garden container that serves user requests. So, the developer does not have to worry about where the Tomcat server or the VM/container will come from. So, aren't we already meeting that mandate in Cloud Foundry?
your code comes into existence for the duration of execution and then dies. This I agree is different from the apps/microserevices that we write in Cloud Foundry in that they are long running server processes instead. Now, if I were to develop a Java webapp/microservice with 3 REST endpoints (myapp/resource1, myapp/resource2, myapp/resource3) possibly on a Tomcat Web Server, I need:
- a physical machine or a VM or a container,
- the Java runtime
- the Tomcat container to be able to run my war file.
Going by what Serverless suggests, I infer I am supposed to concentrate only on the very specific function say handling the request to myapp/resource1. Now, in such a scenario:
- What is my corresponding Java class supposed to look like?
- Where do I get access to the J2EE objects like HttpServletRequest or HttpServletResponse objects and other http or servlet or JAX-RS or Spring MVC provided objects that are created by the Tomcat runtime?
- Is my Java class executed within a container that is created for the duration of execution and then destroyed after execution? If yes, who manages the creation/destruction of such a container?
- Would Tomcat even be required? Is there an altogether different generic way of handling requests to these three REST endpoints? Is it somewhat like httpd servers using python/Java CGI scripts to handle http requests?