You might have heard words like REST thrown around when it comes to software development. REST is a very commonly used API architecture, and developers widely use it to design software APIs. Application programming interfaces are vital for any software application, and REST is one of many architectures that are used for APIs.

Nowadays, gRPC architecture is gaining popularity, and it also claims to solve some problems traditionally associated with REST APIs. But where do they differ? And which one should you use for your application? To know the answer to these questions, we need to understand more about gRPC vs REST and in what scenarios they perform better. But before we get into all that, let's look at what APIs are and what they bring to the table for microservices.

What is API?

Software apps can interact and communicate with one another through the use of application programming interfaces - APIs, which operate as technical mediators. An API is in charge of sending a user's request to the system, which then receives a reply from the system.

Imagine you're ordering a phone online. You go to a site that is linked to the web, and it sends information about your query to a server. The server then gets the information, analyzes it, and, after taking the necessary steps, replies to us with the details displayed on our screen. This becomes possible with APIs.

The API outlines how to perform such client requests, what data structures to use, and the standards that clients must adhere to. It also describes the kinds of queries that one program can send to another. Both gRPC vs REST architecture styles are widely used for designing APIs.

APIs and microservices

Applications can either have a monolithic architecture or a microservice architecture. All of the software's functions and modules are contained in a single unit or codebase in a monolithic application. A microservice application, in contrast, consists of numerous smaller units that interact with one another over interfaces like the HTTP protocol.

The main problem with the monolithic style is that it gets harder to change, update, and expand the system as engineers attach new functions and services above the pre-existing foundation. A change to one aspect of the application may have a detrimental effect on other sections. The code of a monolith gradually becomes so intertwined and challenging to comprehend after being scaled, updated, and changed numerous times that a complete system redesign is required.

This issue is solved with microservices. This architectural design divides a monolith into its constituent components, each of which is then run as a separate application. Each of these apps is called a microservice. Then, these distinct microservices connect using APIs. This collection of microservices linked by APIs comes together to build a bigger architecture design. APIs enable connection and communication between each component incorporated into a microservice architecture. Some popular approaches to creating APIs are GraphQL, RPC, and REST.

What is RPC?

An RPC - Remote Procedure Call - is a web architecture that enables you to execute a service on a remote server using a predefined form and get a response with the same format. The style of the server performing the query, whether a local or remote server, is not considered by RPC design.

RPC

Image Source itrelease.com/Author Junaid Rehman

The basic function of an RPC API request is the same as that of a REST API. The RPC API requests specify the interactional guidelines and the techniques that make interaction possible. Later, the user calls these functions using parameters. The request string of URLs contains the parameters used to call operations.

To create API requests, the RPC system uses a client-server structure. RPC interprets the information the user requests and transmits it to the server. While the internal communications within the servers are concealed, the server responds to the user. The RPC model also enables a user to ask for a service in a particular manner. RPC has the advantage of supporting remote procedure calls in both decentralized and on-premises scenarios.

What is REST?

REST - Representational State Transfer - refers to a client-server architecture in which users have access to backend information via JSON or XML communication. An API is considered RESTful if:

  • It has a consistent interface and provides particular app resources to the API clients.
  • The server and client work separately and independently. Only the URIs pointing to the application's components will be known to the client.
  • It is stateless. This means that only the client saves any state information. The server won't save any state data about the client query.
  • Application assets that are provided by the API must be cacheable.
  • It has a layered architecture.

It is an application of contemporary architectural designs that depend on several restrictions to allow data transmission in hypermedia networks. A RESTful web API needs URL-encoded arguments to connect to services using HTTP protocols. REST APIs have been extensively embraced in contemporary web design to create stateless, extensible, and dependable APIs.

Each component that combines the microservice system can be displayed to the user or customer as an asset when the REST API is made publically accessible. This resource can be queried using the HTTP GET, POST, PUT and DELETE commands.

How does REST work?

REST uses HTTP protocol as the default communication protocol when working with services that are specified in API requests. A resource is a thing that is comparable to an object in object-oriented design. The RESTful resource has actions and attributes, much like an object. In general, REST implementations typically give less thought to RESTful actions and instead concentrate more on the attributes of a resource. RESTful solutions are those that just use attributes to represent a RESTful resource.

REST

In a RESTful API, the user submits a query to a URL - Uniform Resource Locator, which causes a reply with a payload in JSON, XML, or any supported data format. This payload represents the resource the user wants. Common client requests include

  • An HTTP method that specifies what is to be processed on the resource
  • The path of the resource
  • The header that has data about the query
  • A client-specific message payload

In the Accept field of the header, the user specifies the data types they are capable of receiving. A content-type header that identifies the message delivery format employed in the response body is sent by the API server along with the data payload it delivers to the user making the query. A reply code that informs the user of the result status of the API call is also included in the response body.

What is gRPC?

gRPC - Google Remote Procedure Call - is a subtype of the RPC design. gRPC is a high-performance global, open-source RPC architecture that guarantees flexibility and speed for microservice architecture. Function calls are used by gRPC to ensure customer interaction in microservices created using various coding languages. 

This technique implements RPC API requests using the HTTP 2.0 standard, but neither the server nor the API programmer is made aware of HTTP. As a result, the complication is decreased because there is no reason to worry about how RPC principles are translated into HTTP.

Google Remote Procedure Call seeks to speed up data transfer across microservices. To allow remote return and calling, it is based on a strategy that identifies a service, establishes the methodologies, and specifies the pertinent variables.

Additionally, it uses an IDL - Interface description language - to specify the RPC API paradigm, making it simpler to identify remote functions. The IDL employs Protocol Buffers by default to define the service interface and the format of the payload messages.

How does gRPC work?

The HTTP/2 protocol, streaming, and protocol buffers or protobufs are used by gRPC APIs to transmit messages. A serialization standard called protobuf allows for the automatic creation of user libraries and the straightforward construction of microservices. In proto files, API designers describe the operations and messages that are sent across servers and clients.

The protoc compiler loads the files and creates user and server software for communicating with remote services. Compared to XML or JSON formats, messages encrypted with protocol buffers are considerably smaller, making processing less CPU-intensive.

Additionally, using HTTP/2, gRPC APIs bring various improvements to RPC design. The protocol adds a binary format layer that splits packets into smaller, binary-framed messages, rendering them transportable and small. The execution of many calls inside a single channel is made possible by HTTP/2's support for multiple simultaneous queries with the bidirectional communication architecture.

The HTTP/2 transport protocol supports multiple concurrent streams, but gRPC APIs expand this functionality via channels. Each channel can accommodate several streams running simultaneously via many concurrent connections. Channels offer a straightforward method of connecting to the API server at a given address and port. A client stub can also be made via channels.

gRPC vs REST: comparison

Google created gRPC as an RPC variant to deal with some of the limitations of existing API architecture styles. It solves some problems associated with REST APIs, but gRPC APIs face certain issues due to it being a more recent technology. There are many use cases where REST APIs may be better suited to your application. You can decide which of these APIs might work better with your software once you know the differences between the two.

HTTP 1.1 vs HTTP 2

The request-reply approach used by REST APIs is based primarily on HTTP 1.1. This means that the model must process every query individually if a microservice gets many queries from multiple clients, which drags down the whole system. REST APIs can be developed on HTTP 2, but as the communication architecture is still request-response, they are unable to fully utilize the benefits of HTTP 2, including bidirectional compatibility and streaming interaction.

gRPC APIs do not encounter this challenge. It adheres to a client-response connection model and is based on HTTP 2. gRPC can accept many queries from various clients and process those requests at the same time via streaming information. These circumstances permit bidirectional communication with streaming interaction. Additionally, gRPC supports unary interactions like those created by HTTP 1.1.

gRPC APIs can manage:

  • Unary interactions
    If a client makes a single request, but just one reply is given in return.
  • Server streaming
    It is known as server streaming whenever a server answers a client query with a stream of messages. The server also sends a status message to wrap up the procedure after providing all the data.
  • Client-streaming
    This occurs when the client delivers a sequence of messages, and the server responds with a single message.
  • Bidirectional streaming
    This allows for data transmission in both ways because the server and client channels are independent of one another.

Browser support

Since most web API interaction happens online, browser support is a key consideration in the gRPC vs. REST debate. Browser support is likely one of the key benefits of REST APIs over gRPC. All browsers offer full REST API capability and browser support. The functionality for gRPC in browsers, however, is still relatively restricted. Unfortunately, transitions across HTTP 1.1 and HTTP 2 need gRPC-web as well as a proxy layer. As a result, gRPC APIs tend to end up being primarily utilized for internal or private systems, for example, in API applications employed for the backend information and functionality of specific organizations.

Multiplexed streams are used with the HTTP/2 protocol. As a result, numerous customers can send queries in parallel without needing to open a new TCP session for each one. Additionally, the server can use the existing link to deliver messages to clients.

The representational state transfer model has widespread browser support because it integrates HTTP 1.1. HTTP 1.1, which REST enables, uses a TCP handshaking method for each query. REST APIs frequently have latency problems as a result since the handshake takes time.

Payload data structure

If we are looking at the payload data structure while looking at gRPC vs REST, gRPC APIs serialize payload data using Protocol Buffers by design. This method is lighter as it makes the messages smaller and allows for a highly compressed structure. Protocol buffers are in binary format; therefore, for data exchange, it serializes and deserializes the information. Protobuf can automatically translate heavily written messages into the client and server programming languages.

REST, however, mostly uses JSON or XML forms to deliver and receive information. JSON is the most widely used format because of its adaptability and capacity to communicate dynamic data without adhering to a precise structure, although it does not require any. JSON's human-readability quality, which Protobuf can't yet match, is another important advantage.

JSON is not, however, as quick or lightweight once it involves data transfer. This is due to the requirement that JSON should be serialized and translated into the programming languages employed on both the server and client end when using REST. This is an additional step in the data transmission process, which could harm efficiency and increase the likelihood of mistakes.

Code generation

Engineers must employ third-party tools like Postman for code generation for API queries since, and unlike gRPC, the REST API lacks built-in code generation facilities. As opposed to this, gRPC offers native code generation features because of its protoc compiler, which supports many programming languages. Code generation is especially advantageous for microservices that combine numerous services created on multiple platforms and languages. Overall, its built-in code generation makes constructing the software development kit - SDK - easier.

REST API, on the other hand, does not provide native code generation features. You must utilize a third-party program to produce code generation for API calls in several languages. Although it's not a hassle, it's important to note that gRPC doesn't rely on any other services for code generation.

When to use REST APIs

When comparing gRPC vs REST, the most extensively employed and well-liked APIs for integrating infrastructures built on microservices are REST APIs. REST APIs are likely to continue to be the default option for app connection for a very long time, regardless of whether you are creating an internal network or an open platform that opens its assets to the remainder of the world. REST APIs are also perfect for systems requiring rapid iteration and HTTP protocol standards.

REST APIs could be your first choice for web services development, microservices, and app interfaces because third-party technologies universally support them. Unlike gRPC, it has wide browser support and isn't limited to private systems. This can make REST APIs very useful in many contexts.

It is also easier to learn REST, as it has a wide range of API documentation available on the internet. This simpler learning curve is very important if you're on a time crunch. You can save a lot of time researching and learning and start implementing immediately. RESTful APIs are also easier to integrate into applications. They offer better scalability as well. If you want to expand your application soon, it might be better to use REST APIs. The lack of state and confidentiality can cause problems with representational state transfer in certain applications. If your application has a payment option, gRPC may be a better option.

When to use gRPC APIs

In both gRPC vs REST, the majority of third-party tools still do not provide built-in functionality for gRPC compliance. As a result, gRPC APIs are mostly used to create internal systems or structures that are inaccessible to outside users. With that qualification in mind, the following situations could make use of gRPC APIs:

  • Microservices connections

gRPC APIs are especially helpful for linking architectures made up of light microservices where the effectiveness of message delivery is crucial due to its low latency and fast bandwidth communication.

  • Multi-language systems

gRPC excels at handling communications in a polyglot context thanks to its native code generation capability for a broad range of programming languages.

  • Real-time streaming

If real-time communication is necessary, your system can transmit and receive data in real time without having to wait for Unary client-response interaction thanks to gRPC's capability to handle bidirectional streaming.

  • Low-power and low-bandwidth networks

Such networks can benefit from gRPC's usage of serialized Protobuf sessions since they provide lightweight communication, improved efficiency, and quickness. For example, a network that would profit from the gRPC API is the Internet of Things.

How does AppMaster help?

Programming has changed a lot in recent decades, with new technologies and frameworks making developers' tasks easier. No-code generation takes this to the next level. People don't have to go through steep learning curves and can develop applications quicker with no-code platforms like AppMaster.

AppMaster helps you create source code from scratch according to the specific needs of your application. The generated code will belong to you, and you can modify it according to your needs. You can create the various modules that your application needs with AppMaster. This is far less expensive and time-consuming than getting an entire development team to do the same.

Developers can send queries between the backend microservices architecture using the gRPC protocol using AppMaster's no-code generating platform. We will add API to both gRPC web services development as well as gRPC mobile apps the following year to increase gRPC support.

Conclusion

Representational state transfer was the go-to approach when it came to API development in the past. But between gRPC vs REST, gRPC APIs are slowly becoming more popular. Despite the various features that make it stand out, some problems, like the lack of browser support and API documentation, make it difficult to employ it everywhere. However, with technological advancements and community growth, we can hope that gRPC will overcome today's challenges.

Finally, choosing between REST or gRPC, or even any of the other API methodologies like GraphQL or SOAP, depends on the specific needs of your project. Some applications might need the benefits that gRPC offers, while others might require the basic functionality that REST provides. You need to evaluate your application's functions and use cases to choose between these two capable technologies.