25 gRPC interview questions and answers for developers!

What is gRPC?

gRPC is an open-source framework developed by Google that enables efficient communication between distributed systems by providing a language-agnostic, high-performance Remote Procedure Call (RPC) mechanism.
What are the advantages of using gRPC over traditional REST APIs?

gRPC offers advantages such as high performance, bi-directional streaming, support for multiple programming languages, automatic code generation, efficient data serialization using Protocol Buffers, and built-in authentication and load balancing.
What is Protocol Buffers?

Protocol Buffers is a language-agnostic data serialization format used by gRPC. It allows efficient encoding and decoding of structured data, making it faster and more compact compared to other formats like JSON or XML.
Explain the concept of bi-directional streaming in gRPC.

Bi-directional streaming in gRPC enables both the client and server to send multiple messages asynchronously over a single connection. It allows efficient real-time communication and is particularly useful for applications like chat systems or real-time collaborative editing.
How does gRPC handle data serialization and deserialization?

gRPC uses Protocol Buffers for data serialization and deserialization. Protocol Buffers allow the definition of message types and generate code for various programming languages, making it easy to send and receive structured data between clients and servers.
What is the difference between gRPC unary RPC and streaming RPC?

Unary RPC is a simple request-response mechanism where the client sends a single request and waits for a single response from the server. Streaming RPC, on the other hand, allows the client or server to send multiple messages over a stream, either unidirectionally or bidirectionally.
How does gRPC handle error handling and status codes?

gRPC uses status codes to indicate the result of an RPC call. It provides a rich set of status codes, including standard HTTP status codes, to represent different error scenarios. Additionally, gRPC allows developers to define custom status codes for application-specific errors.
What are interceptors in gRPC?

Interceptors in gRPC are middleware components that can intercept and modify RPC messages both on the client and server side. They enable cross-cutting concerns like logging, authentication, or monitoring to be implemented in a reusable manner.
Explain the concept of gRPC reflection.

gRPC reflection is a mechanism that allows clients to dynamically discover the available gRPC services and their methods provided by a server. It enables clients to obtain service definitions without the need for pre-generated code or a service registry.
What is the role of protocol negotiation in gRPC?

Protocol negotiation in gRPC allows the client and server to agree on a common communication protocol and version. It ensures compatibility between the client and server implementations and allows for graceful handling of protocol mismatches.
How does gRPC handle authentication and authorization?

gRPC provides built-in support for authentication and authorization through the use of security mechanisms such as Transport Layer Security (TLS) and JSON Web Tokens (JWT). It allows developers to enforce secure communication and control access to gRPC services.
What is the role of service contracts in gRPC?

Service contracts in gRPC define the structure and behavior of gRPC services using Protocol Buffers. They specify the methods, input and output message types, and any service-specific options or constraints.
Explain the concept of bidirectional streaming in gRPC.

Bidirectional streaming in gRPC enables both the client and server to send multiple messages asynchronously over a single connection. It allows real-time communication and is particularly useful for scenarios like real-time dashboards or collaborative applications.
How does gRPC handle load balancing?

gRPC provides built-in support for load balancing through the use of load balancer implementations. These implementations distribute incoming RPC requests across multiple backend servers, ensuring scalability and fault tolerance.
What is the role of deadline and timeout in gRPC?

Deadline and timeout in gRPC allow clients to set a maximum duration for an RPC call. If the call exceeds the specified deadline or timeout, the client can cancel the call to prevent long-running or stalled operations.
What is the difference between gRPC and GraphQL?

gRPC is a high-performance RPC framework for efficient communication between distributed systems. GraphQL, on the other hand, is a query language and runtime for APIs that enables clients to request specific data and shape the response according to their needs.
What are the different authentication mechanisms supported by gRPC?

gRPC supports various authentication mechanisms such as SSL/TLS-based authentication, and token-based authentication using JWT, OAuth2, or custom authentication schemes. The choice of mechanism depends on the specific security requirements of the application.
What is the role of backpressure in gRPC?

Backpressure in gRPC is a flow control mechanism that allows the client to signal the server to slow down the rate of data transmission. It ensures that the client can handle the incoming data without being overwhelmed by the server.
How does gRPC handle the versioning of APIs?

gRPC uses Protocol Buffers to define the structure of messages, allowing for forwards and backward compatibility. It provides mechanisms such as adding optional fields or using one of the constructs to handle changes in the API schema.
Explain the concept of the gRPC gateway.

gRPC gateway is a tool that generates a reverse proxy server, allowing clients to access gRPC services using traditional HTTP/JSON-based APIs. It enables interoperability between gRPC and RESTful services.
What are the trade-offs of using gRPC compared to traditional HTTP-based APIs?

Some trade-offs of using gRPC include the learning curve of Protocol Buffers, the need for additional tooling for API exploration, the lack of widespread support in some programming languages, and potential challenges in debugging due to binary data serialization.
What are the best practices for securing gRPC communications?

Best practices for securing gRPC communications include enabling transport security with TLS, implementing authentication and authorization mechanisms, validating and sanitizing user input, and staying updated with security patches and updates.
How does gRPC handle service discovery?

gRPC does not provide built-in service discovery mechanisms. It is common to use service registries like etcd, Consul, or Kubernetes to register and discover gRPC services dynamically.
What are the performance considerations when using gRPC?

Performance considerations when using gRPC include optimizing Protocol Buffers serialization, leveraging the benefits of HTTP/2, implementing efficient streaming patterns, considering the network latency, and choosing appropriate data compression techniques.
How can you handle backward compatibility in gRPC when making changes to the service contracts?

To handle backward compatibility in gRPC, it is important to carefully design the service contracts using Protocol Buffers, avoiding breaking changes whenever possible. When making changes, it is recommended to follow versioning practices, uses optional fields, and maintain support for older clients by handling deprecated fields or messages.