What is a web service?

We use web services every day, but we rarely stop to think about what the web actually is. If someone asked you to explain it, where would you start? Let’s begin with what makes something a web service.

What is the web?

Think of a spider’s web: many strands form an interconnected whole. Documents scattered across the internet connect through links in much the same way. We call this interconnected collection of documents the web.

When you open a browser, look up information on a website, and follow a link to another page, you are using the web. Technologies such as HTML, HTTP, and URLs work together to make this possible. We will examine them one at a time in the following pages.

What is a service?

A service is a function or activity provided to meet someone’s needs. Ordering a drink at a café, opening a bank account, transferring money, and borrowing a library book are all examples.

A service usually involves a request¹, a process that handles it², and a result³.

For example:

• A café takes your order¹, makes your drink², and serves it to you³.
• A bank receives a transfer request¹, moves the money², and provides confirmation³.

What makes it a web service?

A web service makes a function that meets a user’s needs available over the internet. Users usually access it through a browser or an app.

Many services that once required visiting a physical location are now available wherever you have an internet connection.

Familiar examples include:

• Messaging → WhatsApp
• Online shopping → Amazon
• Financial services → PayPal
• Buying and selling secondhand goods → eBay

Our goal is to build an AI agent and make it available as a web service. That means learning both how to implement the agent and how web services are put together.

Exercises

Decide whether each statement is True or False.

1. The web is a collection of documents on the internet connected through links.
2. You can only use a web service through a web browser.
3. A service handles a user’s request and provides a result.