Performance begins with design style

Arguably the most critical aspect of early API development is selecting the right design approach. Although there is rarely a “right” or “wrong” answer, each architecture offers various benefits and drawbacks: choose the best one, and the structure itself facilitates the API’s design. Choose a subpar approach, and your API could perform so poorly that it becomes self-defeating. We’re going to dig into two in this article: REST and gRPC. Although REST is very well-known, gRPC is a new take on an old concept (Remote Procedure Call, or RPC). They have intentionally distinct design emphases: REST is designed to be flexible and used in applications when a variety of outputs and formats are required, while gRPC is geared toward very specific, highly efficient uses.

Understanding gRPC

gRPC works by executing a procedure on a remote server, operating around an idea of contacts based on the client-server relationship instead of working off the architecture itself. This streamlined approach divides duties between the client and server, with the responsibility for executing belonging to the former and most of the handling and computation assigned to the latter. gRPC consists of four separate types.

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The first is unary and is the simplest of them all. In this construct, the client sends a single request message which is met with a single response from the server. This is similar to how an HTTP REST API functions.

The second is client-streaming, where a client sends a steady stream comprised of multiple messages, but the server’s reply is limited to a single response.

The third type of gRPC is server-streaming and is the mirror image of client-streaming. In this scenario, the client sends a single request and the server replies with a series of responses in a steady flow.

Finally, there’s bidirectional (sometimes referred to as “bidi”) streaming, which is the most complex construct. The client and server are in constant communication, sending and receiving multiple messages simultaneously with no defined order. Although intricately involved, bidi streaming is very flexible and doesn’t require blocking—neither side needs to wait for the other to respond before sending the next messages.

gRPC versus REST

The primary benefit offered by REST, when compared to gRPC, is its fixed, well-defined structure. It is crafted so that any REST-compliant web service can interact with textual resource representations in a stateless manner. The most common standardized interactions leverage PUT, POST, and GET, among other HTTP methodologies. Some of the characteristics of REST include its layered architecture, high level of scalability, and its ability to cache very efficiently. Its well-defined foundations make it highly discoverable and flexible as it deals with a broad range of issues and constraints. While streaming is bidirectional in gRPC (as illustrated in the four types above), REST limits communication to a one-way request from the client to the server.

gRPC is open-source and tailored to the unique client-server relationship. Its highly customizable nature makes it a good solution in numerous IoT applications. It’s incredibly efficient, making it an appealing solution for extremely low-power situations. gRPC accomplishes this by using Protocol buffer to serialize payload data into smaller, binary information (whereas REST uses JSON, comprised of larger, text-based data).

While the API contract in REST is loose and often optional, it’s very strict in gRPC and must be clearly defined in the proto file. This essentially pits flexibility (REST) against efficiency (gRPC), and what you choose depends on which of these features is more important for your application.

Key takeaways
  • REST has fixed, well-designed structure but limits communication to a one-way request from client to server.
  • gRPC is highly customizable, flexible and a good solution for numerous IoT applications.

When is gRPC a Better Option than REST?

If you’re developing an app that uses multiple programming languages, gRPC is the best choice. The required nature of gRPC significantly simplifies the creation of client libraries by auto-generating code from the gRPC schema. It shines in microservices due to its high-throughput communication, low latency, and strong API contracts. In situations that demand constant contact between the client and the server, gRPC’s emphasis on point-to-point real-time communication and support for bidirectional streaming makes it a natural choice.

Anytime you’re dealing with a situation where you have highly specific requirements (e.g., an IoT device that’s transmitting a very precise set of data), gRPC is the better option than REST. This is particularly true when the environment is constrained by the network (such as mobile iOS/Android-based apps); its lightweight message format easily facilitates working with these limitations.

With the increasing number of mobile apps that require constant data transfer, one advantage gRPC offers is rapid and simplified data transfer by leveraging protobufs. These are platform- and language-neutral systems that serialize data, drastically increasing the efficiency at which that information can be requested and communicated. Although streamlined and efficient, security isn’t compromised by the inherent simplicity. gRPC uses Google’s token-based system for SSL/TLS, creating a powerful and effective authentication system.

gRPC Pain Points

gRPC communication mechanism is less flexible than REST’s and designed for structured data. The more targeted your requirements, the better-suited gRPC is. If you’re designing an application that uses a broad range of resources to deliver outputs in numerous formats, however, gRPC’s extreme specificity becomes a limiting factor—REST is a better choice here.

Efficient development is facilitated by programmers being able to easily access a library of best practices and tutorials—this prevents having to develop everything from scratch. gRPC is relatively new and lacks an extensive library these, which can create a high barrier to entry. The good news is that decreased transport costs and demonstrable latency improvements can often make up for this.

Now you know what to do

gRPC offers a tremendous number of advantages for APIs that need high levels of data transfer with low-power devices. If you’re developing anything within the IoT, gRPC should be heavily considered. However, if you require a stateless architecture with a heavy emphasis on hypermedia in web APIs, REST might be the better architecture to pursue. It’s important to remember that the approach you choose can facilitate or hinder every subsequent operation, so careful consideration of the pros and cons of each is crucial.

Alex Sokolov

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