API Protocols: Picking the Right Protocol For Your Use Case

Choosing the proper API protocol can be challenging but selecting the one that will fit your needs is essential. In this post, we’ll explore some of the most common protocols and help you decide which is right for you.

Why Do We Need API Protocols?

There are a few reasons why we need API protocols.

First, they help ensure that data is transmitted securely and efficiently.

Second, they help standardize how data is formatted, making it easier for different systems to communicate with each other.

Third, they can help reduce the amount of coding required to integrate different systems.

Finally, they can provide a level of abstraction, making it easier to change the underlying implementation without affecting the overall system. In short, API protocols play an essential role in modern software development and are likely to become even more critical in the future.

What Are the Different Types of API Protocols?

An API, or application programming interface, is a set of rules and standards that define how software components can interact.

For example, APIs can access web services, exchange data between applications, and allow two-way communication between devices. There are many different API protocols, each with its advantages and disadvantages.

SOAP (SIMPLE Object Access Protocol)

SOAP is a platform-independent protocol that uses XML data format. It’s often used in enterprise environments because it can easily integrate with legacy systems built when SOAP was the industry standard and before the introduction of REST and JSON.

However, SOAP is complex and challenging to use, which is why newer standards have replaced it. In addition, XML is not always easy to parse and has a lot of formatting content, making the messages larger than other data formats.

REST (Representational State Transfer)

Another popular API protocol is REST. REST is a simpler alternative to SOAP that uses HTTP commands to access web services.

Standard HTTP commands are GET for retrieval, POST for creation, PUT for updating, and DELETE for removal of data. It’s often used in mobile and web applications because it’s easy to use and lightweight. It’s most common to use the JSON data format with REST.

GraphQL (Graph Query Language)

The GraphQL API protocol is a query language for APIs that enables you to request specific data from a server.

Facebook created GraphQL in 2012 and open-sourced it in 2015. GraphQL is often compared to REST as it provides a way to fetch data from a server. However, GraphQL has several advantages over REST.

For example, GraphQL can specify the data you want to receive and make sure you receive only that data.With REST, you may receive more data than you need, which can be wasteful.

In addition, GraphQL enables you to make multiple requests in one request, which can be more efficient than making multiple REST requests. Finally, GraphQL provides a more robust and flexible way to fetch data from a server.

RPC (Remote Procedure Call)

RPCs allow one program on one device to ask another to do a task. The caller process is the program that makes the requests, and the server process is the one that receives them.

There are three flavors of RPC.

The callback version is when the caller submits a request and asks the server to call back to the client with the response. The callback is a non-blocking process.

The broadcast version is when the caller submits messages to many servers and expects to receive many responses, though it may never hear from some servers.

The batch mode version is when the caller submits messages to a pipeline or queue on the server and does not expect any responses.

RPC supports XML and JSON data formats. Interface Definition Language (IDL) is commonly used to define the data exchange structure.

gRPC (Google Remote Procedural Call)

Created by Google, gRCP provides a set of custom functions to enable inter-application services, which is employed when the application doesn’t use a standard protocol.

The gRPC standard includes load balancing, health checking, tracing, and authentication support. A protocol buffer sends the data, a technique that organizes the data in a structured way. When you create a service, you use protocol buffering to start and specify the data structure the service will use.

Internal vs. External

Internal APIs are APIs intended for use by developers within your own company. External APIs are exposed to and used by developers outside your company.

Whether an API is internal or external often dictates which protocol you should use. For example, suppose you’re building an API for use by developers within your company. In that case, you may choose a SOAP protocol because it’s easy to integrate with existing internal systems.

However, suppose you’re building an API for use by developers outside your company. You may want to use a REST protocol with the JSON data format because it’s easy to use, lightweight, and the industry standard. Even converting an existing SOAP service to REST is preferable when dealing with external APIs.

Protocols vs. Data Formats

The protocols above were sometimes split and are often associated with their data format. For example, XML is the default data format for SOAP, and REST is usually associated with JSON (though it can use XML also). Likewise, RPC has its JSON and XML versions.

Data formats are the shape, structure, and encoding of the data sent over the wire. Formats don’t include the methods and headers used in the request. Data formats are just that, a format for the data.

Protocols can include a data format, but they also describe how to make requests (which methods to use) and often have extra metadata, such as error codes.

So while choosing a data format is essential, it’s more important to first select the protocol that best fits your use case and then worry about the format.

Security Considerations

Another consideration is whether the use is internal to your network or external over the public internet.

For example, if you only use the API internally, security may not be a big concern. However, safety becomes critical if the API is available over the public internet. It’s currently the industry standard to use SSL (Secure Sockets Layer) when exchanging data over the internet.

What API Protocol Should You Use?

When choosing an API protocol, it’s essential to consider the type of data the API will exchange and the needs of the applications that will be using the API.

Whether an API is internal or external often dictates which protocol you should use.

For example, if your API performs a single call and much data comes back, maybe SOAP makes the most sense there. On the other hand, if there are frequent small calls to the APIs, then REST or JSON are appropriate.

It’s also important to consider the capabilities of the intended client systems. Some older systems may only support SOAP or RPC.

If you’re creating greenfield APIs with no legacy systems to consider, choose REST and JSON.

Ultimately, deciding which protocol to use depends on various factors, and there’s no one-size-fits-all solution. However, by carefully evaluating the requirements of both the API and the applications that will use it, it should be possible to choose a protocol that’s well suited to the task at hand.

This post was written by Steven Lohrenz. Steven is an IT professional with 25-plus years of experience as a programmer, software engineer, technical team lead, and software and integrations architect. They blog at StevenLohrenz.com about things that interest them.