Telerik blogs

Wondering what the difference is between web services and APIs? Learn when to use each to build robust, scalable and efficient applications.

The online world is widely interconnected, with various systems seamlessly interacting with each other behind the scenes to provide you with a functional user experience. We might not notice it, but many of the actions we take for granted these days that seem simple on the surface typically require multiple components working in unison.

For example, let’s take an activity many of us frequently do—ordering a product on an ecommerce website. Depending on the site, every interaction you take goes through separate systems, from the moment you land on the page to the time the items arrive at your doorstep. Here’s a condensed outline of the different pieces of the puzzle that might make up a typical online shopping experience:

  • Viewing and searching for available items need an inventory system to keep track of availability.
  • Placing items in a virtual shopping cart requires an interface to track them as you navigate through the site.
  • Different providers calculate and provide options for knowing how long it takes and how much it costs to ship the product to you.
  • A payment processor will securely handle and store your credit card details for future visits.
  • Order management systems track your order status and send exciting notifications to let you know your item is on its way.

Unless you’re part of the team building this type of software, we usually don’t consider how things work under the hood. The ability of each of these components to communicate with each other is crucial for the entire system to function. An ecommerce site without inventory or order management systems won’t ensure you can make a successful purchase. If any of these steps break down, your experience won’t be a positive one.

This interconnectivity between systems we take for granted is powered by web services and APIs (application programming interfaces). Both of these are essential components that make up the building blocks of modern software engineering, and are the glue that lets us do everything from ordering online to watching the latest popular TV show to posting about our lives on social media. Without them, we wouldn’t have the rich interactive experiences we enjoy on the modern internet.

Despite their importance in keeping complex applications running smoothly, web services and APIs are often confused or incorrectly used interchangeably. This confusion happens because web services and APIs simplify data exchange between systems. However, they handle these tasks in distinct ways. Understanding these differences is crucial to building scalable and maintainable software products your customers love to use.

In this article, we’ll discuss web services and APIs, their differences and where each is more suitable for building applications that require interconnecting parts.

What Are Web Services?

A web service is a standardized way for different systems to communicate with each other over a network. Typically, this communication happens over the internet but can also occur between networks behind a firewall or on-premises. Web services allow applications to exchange information and perform various operations using standardized protocols. These protocols help keep the exchanged data consistent, enabling smooth interaction between systems, regardless of the underlying platform.

Some of the key features that define a web service are:

  • Remote accessibility: Allows communication and data transfer over a network, permitting interaction between distributed systems.
  • Standardized protocols: Utilizes widely accepted network protocols such as HTTP, SOAP and REST for consistent and reliable communication.
  • Interoperability: Allows compatibility across various platforms, including operating systems, programming languages and hardware architectures.
  • Broad use cases: Supports a wide range of applications due to its standardized approach, from simple data retrieval to complex enterprise-level integrations.

Web services work best when multiple systems require a standard way to communicate with each other. An example of where web services are beneficial is with enterprise resource planning (ERP) systems. ERP systems are commonly used in larger organizations that span multiple departments, each with its own systems containing different infrastructures. Web services can provide each department a standard way to transmit information regardless of the systems they’re using.

When managing a large-scale business, a web service can simplify the overhead of juggling different systems with its standard form of communication across the board. However, web services also have some weaknesses. They’re more complex to implement and maintain than APIs due to stricter formatting when using protocols like SOAP. Communication between web services also carries some overhead since it needs extra processing to parse the information received, leading to slower response times compared to other methods.

What Are APIs?

We can define an API as an intermediary that helps different software applications communicate with each other. It allows systems to directly communicate with other systems through various methods, from standard network protocols like HTTP and REST to other methods used in modern software like WebSockets and GraphQL. APIs abstract the complexities of the underlying system and provide a simple interface for developers to interact with external services and data sources.

Among the main features that define an API are:

  • Versatility: Facilitates communication and interaction between web, mobile and desktop applications.
  • Direct communication: Acts as a direct interface between software systems to enable easy and effective data exchange.
  • Specific use cases: Built to handle specific tasks and functionality, allowing for targeted connectivity between services.
  • Flexibility: Allows diverse communication methods and protocols for different needs, such as WebSockets for real-time data exchange and GraphQL for more control over fetching data.

APIs are much simpler than web services since they allow quick integration into other systems. For instance, Stripe is a company that provides payment processing for businesses, and they offer a robust API that enables developers to integrate this service into their systems. Developers can use Stripe’s API to add payment processing or subscription management to their applications as needed and gather reports for each service. The flexibility and ease of APIs help organizations integrate with other systems quickly.

Despite their advantages, APIs also have a few shortcomings. Their flexibility often leads to inconsistent implementations when integrating with different services or even on the same service. Also, APIs can become difficult to maintain over time, especially APIs that lack proper versioning or documentation. These issues and others can increase the amount of development effort and nullify the benefits of rapid iteration.

Tools like Progress Telerik Fiddler Everywhere can help you overcome many of these issues by capturing API traffic and filtering by different criteria like URL or protocol. With these details, you can compare them to what you expect in your applications or edit them using Fiddler Everywhere’s API Composer to make developing APIs easier than ever.

What Are the Differences Between Web Services and APIs?

If you’re like me when I began learning about web services and APIs, you’re likely thinking that web services and APIs are the same thing. On the surface, they sound almost identical—both communicate with other systems over a network, allowing for information interchange. While both services offer similar functionality, they also have important distinctions that can make a difference in how teams build applications. One way to understand these differences is using analogies from the real world.

Web services can be thought of as a set of encyclopedias. An encyclopedia contains a standardized collection of information and details in a consistent and structured format. You can pick any book from the set, and you’ll see they have a specific arrangement, making it easy to find and understand the information you seek across any volume in that set. Even today’s online version of the encyclopedia—Wikipedia—follows this pattern, where every page follows the same design and structure. If you use Wikipedia once, you’ll know how to parse that information the next time you land on another article.

Conversely, APIs can be imagined as a book from your local bookstore or library. Most books cover specific material in detail, and you can find books on a wide range of topics. Books are also structured in different ways, even when covering the same subject. For instance, cooking-related books can teach you different cooking methods or only offer step-by-step recipes for foods from a particular region of the globe. Every author writes their books in the way they believe conveys their message the best.

One way to distinguish between a web service and an API is to look at all web services as APIs, but you can’t consider all APIs as web services. Following the analogy mentioned above, encyclopedias are books, but not all books are encyclopedias. Some more practical differences between web services and APIs are:

  • Web services are generally used for web-based communication, where developers use APIs in a broader context beyond web applications, like desktop and mobile apps.
  • Web services communicate using standard protocols like HTTP and SOAP, while APIs use those protocols and more, like WebSockets and GraphQL.
  • Web services follow strict communication rules, such as SOAP requiring a specific structure, while APIs have much more flexibility.

When You Should Use Web Services and APIs

Knowing whether web services or APIs fit your situation best while developing software is essential. Each has its strengths that serve some use cases better than others. Here are a few scenarios where a web service or API fits the bill.

Use a Web Service If …

  • You need interoperability between varied technologies: Using standardized communication protocols makes web services ideal to help integrate systems that use different infrastructure and allows these platforms to communicate seamlessly. For example, Enterprise Resource Planning (ERP) systems in large organizations will benefit from using consistent protocols to guarantee consistency between varied systems across departments.
  • You need consistent and reliable messaging between applications: Communication protocols like SOAP offer a consistent messaging structure widely used and accepted by development teams, facilitating the implementation of web services for applications requiring a more rigid structure. Banking and financial institutions require strict security and compliance when managing money transactions, customer information, and financial records, and web services can help maintain these records in order.
  • You’re working with legacy systems: Older applications might not support communication protocols used by newer environments but can still integrate across systems using HTTP, letting web services act as a bridge between legacy and modern technologies. Some organizations, such as government entities and banks, maintain mission-critical systems that are decades old because they’re prohibitively expensive to replace. Web services are one of the better ways to help these obsolete systems remain in service.

Use an API If …

  • You need rapid development and integration: The lightweight and flexible nature of APIs make them an excellent choice when you want to quickly implement new functionality to an application without the extra overhead. For instance, if you’re developing a product that allows external services to fetch information from your database, using APIs can provide flexible methods to allow others to integrate what they need quickly.
  • You want to communicate between different types of applications: If you need to share data between desktop, web and mobile applications, an API is better suited to handle information exchange between multiple platforms. Most mobile apps these days also have web-based or desktop interfaces that provide the same data in different formats powered by APIs, providing a unified path for development teams to implement new functionality across all platforms.
  • You’re working with real-time applications: APIs go beyond standardized protocols, providing additional benefits like low latency and simultaneous two-way communication that web services cannot do. Applications that require instantaneous and live updates, such as business collaboration tools or stock trading platforms, benefit from using the WebSocket API, while architectures requiring high-performance latency communication, like microservices, work great with gRPC.

Wrapping Up

Web services can help connect systems using a standardized approach to help with consistent communication across networks, which is beneficial for legacy systems or complex enterprise integrations. However, this rigidity can make web services more difficult to implement and adds some overhead during processing. APIs offer flexibility and speed, making it much easier to adopt new functionality using different communication protocols and across various platforms. This adaptability comes at the potential cost of inconsistent implementation and added maintainability costs.

With the increase of interconnected systems, understanding the differences between web services and APIs for software development is an essential skill for building robust and scalable applications. Whether you are integrating legacy systems running on distinct infrastructures or needing to quickly implement functionality across different communication methods and platforms, knowing the strengths of each will help teams build efficient and effective software.


Dennis Martinez Profile Photo
About the Author

Dennis Martinez

Dennis Martinez is a freelance automation tester and DevOps engineer living in Osaka, Japan. He has over 19 years of professional experience working at startups in New York City, San Francisco, and Tokyo. Dennis also maintains Dev Tester, writing about automated testing and test automation to help you become a better tester. You can also find him on LinkedIn and his website.

Related Posts

Comments

Comments are disabled in preview mode.