APIs and Web Services are those two terms that get overlapped and confused with each other. You might have heard these words used interchangeably quite often. Although they do have a few overlaps, the concept of both is different. So let’s get started with the basics and help you to understand the difference and similarities between them.

What Is a Web Service?

Web Services are a web application component. It is a set of technologies and rules that allows two or more components on the web or internet to interact with each other. These components can be anything from a web server to a web browser. As defined by the World Wide Web Consortium(W3C), Web Services render a standard way of communication between software applications that run on different frameworks or platforms. Web Service is a system designed to support interoperable interactions between machines over a network. Therefore, web services need the network to operate.

The first web service used is WSDL (Web Services Description Language) - which is a set of rules that are used to describe web services and is written in XML. Apart from that, web Services mostly use SOAP (Simple Object Access Protocol) - a messaging protocol that shares XML data via HTTP (HyperText Transfer Protocol) requests. It is mainly associated with Service Oriented Architecture (SOA).

Overall, a web service is nothing but a connection technology that enables two or more components aka services to interoperate. These are the bridge between components on the web. Each of these components or programs does things that other programs need, whether it’s featuring a database, computation, or executing scripts. Technically, web services send data back and forth through HTTP requests. These requests often return textual data in XML or JSON form.

But what are APIs then? Let’s check!

What is an API?

The term API stands for Application Programming Interface. It is a set of routines, object classes, data structures, or protocols offered by libraries or operating systems to support application development. It enables two otherwise distanced entities to communicate in a standardized way. An API is similar to a messenger that receives requests and informs the system what a user wants to do and then returns the response.

To help you understand the concept of API, let’s see a scenario. You are probably familiar with the process of searching for flights or trains online. On the application or website, you will get the drop-down menu to choose departure city, date, destination, return date, class and other variables. To book your flight or train, you interact with the database of airlines or railways respectively to check if there’s any seat available for you. But what if you are not using a railways or airways website or app that aggregates information from their databases. Instead, you are using a third-party travel website that checks different databases and provides the information you have asked for. In that case, with your query, that website will interact with API to get information from different systems over the internet to check prices, availability and book seats. After that, it delivers the response back to the travel website and finally shows it to you.

So an API could be anything in any form. The only thing that it has to be is a way of communication with a software component. But how is it different from web services?

Key Difference Between Web Services and APIs

Web Services vs APIs. Clearly, both Web Services and APIs are a means of communication. The basic difference between them is as follows:

• Web Services provide interaction between two machines over a network while APIs acts as an interface between two different applications for interoperability.
• Web Services requires a network connection while APIs may or may not require a network for their operability.
• While APIs can use any protocols or design patterns, web services mostly use SOAP and sometimes REST, XML-RPC, or UDDI.
• Many public APIs are transparent with open documentation and self-service portals for rapid developer onboarding. However, web services offer specific data or functionality to certain patterns only.
• Moreover, each web service is an API but all APIs are not web services because a web service might not perform all the operations that an API would do.
• APIs features efficiency, wide reach, personalization, data ownership, time-effectiveness, programming language independence, and easy integration with GUI; Web Services offer loose coupling, synchronous and asynchronous functionality, document exchange support while supporting remote procedure calls.
• As web services need SOAP protocol to transfer data over the network, it does not have a lightweight architecture. On the other hand, APIs have a lightweight architecture as most of their required libraries and data are running on the .NET framework.
• Web Services provides support for HTTP only while APIs support HTTP/s, URL Requests/Response Headers and so on.

Now that you understand that API is an interface that enables to build on the data and functionality of another application, web service is a network-based resource to fulfil a certain task. Both the API and Web Services are useful at their core. If you want to develop an application for your business, hire developers who have vast experience and knowledge in the related field.

Source: Decipher