In the era of cloud computing, web services are considered the key technology in making computer systems talk to each other and, more specifically, making application frontends talk to their backends, and sometimes to other third-party integrations. Whenever you share something to your favorite social media network, exchange messages with your friends, or pay for something online using your credit card, there is a web service, sitting far away in some computer in the cloud, being invoked upon your action!
In this chapter, we are going to cover the following topics:
- What are web services?
- Creating and calling RESTful services using JAX-RS
- Using Postman to test your RESTful services
- Accepting and processing user parameters
- Producing JSON responses
- Uploading files
- Server-sent events
