Web Service manual

Introduction

This 8:52 min video will give you a great introduction to RESTful Web Services and APIs:

 

What is a Web Service?

When the World Wide Web began, only text could be transmitted and viewed. Soon graphics could be transmitted and viewed too. Later, people found ways to make forms where data could be input and stored.

At this point, a web page was served up from a Web Server. This means the URL was typed in. The request was broadcast throughout the internet and, eventually, the Web Server received and recognized the request and sent back the web page.

As the World Wide Web matured, JavaScript could be written in web pages for even greater interoperability. This allowed web pages to be interactive without having to make additional requests to the server. They could be faster and more interactive. Web pages could also change based on what was selected, clicked, or entered.

But web servers could only serve up data and programs running on themselves. The desire grew to find a way to put something on additional servers on a web page; to request a service from a totally different server from within a web page and update it based on what came back. Better yet, what if you could accomplish something by sending something into the service and having it perform a function and send back the result? This would allow for truly distributed programming.

This is a reality today. These services are called web services. Because they conform to specific internet protocols, they work great over the web.

So, a web service is a “function” that lives on a machine connected to the internet and conforms to the needed protocols. You could think of it as a function call or procedure on a totally different computer.

This allows systems to be divided into smaller subsystems and run on different hardware, but still be coupled together on the web page for seamless operation and appear as a single system.