Develop Web Service API (php) and test C# desktop App

We need to develop a Web Service API for a system that we already have. The customer have a software installed locally that needs to communicate with a central system. We pretend that this communication will be done by a WebService API, which we request now to develop. This project has 2 components: - API Interface, to be installed on a php web server and working on mySQL database - A C# software that will interact with the API interface (for tests and demo) To reduce the complexity of deployment, we require that development made can be made on server that uses CPANEL (like any web page). So we do not have access to the machine where this will be deployed, so we do not have any special feature that we can enable or specific ports. If you do not have access to this kind of toll, you should use XAMPP ([login to view URL]) to allow you to make the development. We already have a database (that could be adjusted as needed), where the API will have to work over it. We will provide a database example of what we have. Any necessary change should be necessary to discuss with us. The development should need to have a structure code to allow an easy reading and understanding of code. The API will have to protect against attacks that could damage/corrupt the DB, or any kind of way to damage the system using the methods proposed. The error message should be ready to support multiple languages. Any translations should be done by us. Per language should exist a file, that can allow easily allow us to add a new language.