This chapter is primarily intended to introduce readers to various RESTful design concepts involving design strategies and best practices; we expect that readers already have a basic understanding of software design concepts, client-server architecture, and basic data exchange formats, such as JSON and XML.

We assume readers have a basic understanding of web architecture, HTTP methods, headers, and related client-server concepts. However, we strongly encourage our readers to refresh their knowledge of design principles such as SOLID, OO designs, enterprise integration, SOA, and microservice architecture fundamentals.

In the first chapter, we learned about RESTful principles such as client-server, statelessness, cacheable, and layered, and we'll recognize and apply those principles to the low-level yet functional APIs in this chapter. Also, we will learn RESTful API design strategies and best practices that can help us to meet the challenge of any time, anywhere, and any device.

Let's think of an example—assume you're going to an event, where along with other activities there will be a screening of the film Solo (the latest in the Star Wars series), and you know that some of your friends joining the party aren't familiar with Star Wars and the earlier sequels. So being a tech geek, you wanted to help your friends with a simple mobile application that can send search results to your WhatsApp group as messages with details...

From the API examples that we've seen so far, you might have observed that they're straightforward, unambiguous, easy to consume, well-structured, and most importantly accessible with well-known and standardized HTTP methods.

By now, we have a fair understanding of the APIs, and that they are one of the best possible solutions for resolving many digitization challenges out of the box; with our earlier examples, we also know who is consuming those APIs. Now let's ponder how we can create such usable APIs and expose them for consumption. Are there any basic and necessary principles for designing APIs that we must take into account even before we delve into API design? What should the API allow the consumers to do with it? What do the consumers want to do with it? To answer our questions, we will need to understand the following API design...

Before we discuss API design goals, principles and practices, let's touch upon the primary roles of a software architect, solution architect, software designer, or anyone who's ready to take responsibility for designing RESTful APIs.

To produce successful APIs, an API designer should have or do the following:

• Be well-versed in REST fundamentals and API design best practices
• Be acquainted with API design patterns to create a modern API design
• Focus on the factors discussed in this chapter such as API design goals and best practices that can improve the application developer's experience
• Translate the business domain into several APIs by having a clear understanding of the business vision and its functions
• Closely work with API developers and help them with their day-to-day constraints and to deal with their existing legacy...

Let's think about who the consumers of any web service APIs are. Will it be another system, another software application, or an end-user? Mostly, the consumers of the APIs are another software application or another system itself. So, we can conclude that the customers of any API will be the app developers who give life to the software make it purposeful and usable by their programming codes. So the APIs are heavily dependent on the application developers or app developers.

So application developers should be the primary focus of API design, and for them to consume the APIs, there should be defined and accessible business functions. Please do remember that without any application developer or app developers ready to use the API, the API will cease to exist.

The following is a list of best practices used by API designers to produce APIs that app...

To create flexible, scalable, and secure APIs, an API designer needs a set of guidelines. We'll discuss the following essential principles:

• Ubiquitous web standards
• API flexibility
• API standardization
• API optimization
• API granularity
• API sandbox or playground

By doing so, we will be able to understand how following them will help us to design high-quality RESTful APIs.

As we discussed in the Goals of RESTful API design section, API designers should embrace the existing web standards and develop their API design and platforms, resulting in ubiquitous communication between the RESTful APIs and clients.

Let's ask ourselves a few questions that will help us to derive better...

Now that we understand the roles and responsibilities of an API designer, the API design best practices, and the API design core principles, we can cover one more essential API design aspect called the rules of APIs. The best practices and design principles are guidelines that API designers try to incorporate in their API design. However, the rules of API need to be amended in the API design to make our APIs RESTful. So, this section is dedicated to RESTful API rules such as the following:

• Use of Uniform Resource Identifiers
• URI authority
• Resource modelling
• Resource archetypes
• URI path
• URI query
• Metadata design rules (HTTP headers and returning error codes) and representations
• Client concerns (versioning, security, and hypermedia processing)

We're confident that having a clear understanding of these rules will move us closer to design and begin...

As part of design strategies, we looked at what an API is and its importance for connecting devices with various other devices and technologies in the digitization era. We examined a few essential API design characteristics, such as affordance, leveraging, and maximizing existing web infrastructure, along with API design goals, such as consistency, simplification, flexible yet stable APIs, and how it is essential for an API designer to focus on the APP developers—the consumers of the APIs.

We also briefly discussed the role of an API designer and how they need to follow design principles and rules, so that they can create better RESTful APIs. We concluded this chapter by giving the necessary rules for RESTful APIs, along with some dos and don'ts.

So, we've set a strong foundation and the path for you to get your hands on API programming in our next two...

We encourage readers to refer to https://www.packtpub.com/all for various reference materials and a vast collection of books on RESTful services and APIs.