Making calls

Making a call to the operation exposed from the service can be done using any tool or library that can execute the HTTP requests. The first obvious choice would be just a web browser. But a web browser is convenient only for executing GET requests (as for getting a list of books from our bookstore service). If you need to execute other methods such as POST or PUT or provide additional request parameters, header values, and so on, you will need to use some alternatives. The first choice could be cURL, a command-line tool for transferring data using various protocols. Let's look at other options we have.

Spring RestTemplate

If you need to call a service from another service, you will need a HTTP client. Spring provides the very useful RestTemplate class. It gives you a synchronous client-side HTTP access, simplifies communication with HTTP servers, and enforces RESTful principles. It handles HTTP connections, leaving application code to provide URLs (with possible template variables...