Iam trying to develop a POC (to show for inverstors) for my idea that has to communicate to a SMS gateway,using the message obtained, it has to communicate to another system like webservice etc.
Right now Iam using POJOs(with some getters and setters) with an assumption that those (converted) values from the external system. The target systems which I have to communicate with are basically very secured and charge for utilizing their services.
Provided with an minimal assumption, is it advisable to create a simulator which mimics the behaviour of those external systems.
Please provide your suggestions.
It's very advisable.
If you're simulating a system that is a web service, then you can create a simulator in minutes. Drop some static files into Apache or Tomcat or other web server. These files would return exactly what the other system would return. In another words, they would have a content of the responses of the real system. For example: geo_response_us.xml, geo_response_canada.json, etc.
If you need more clever simulation then you would write JSP/Servlet/whatever that would change output according to some URL parameters.
I think it's better to have a simple external system to simulate the real external system rather than creating mocks in memory of the execution environment in your case. This way your investors would be able to relate to your demonstration more easily, as you would substitute Ferrari for a horse cart instead of just saying "imagine there is a Ferrari somewhere here".