We can change the server !!

let mut client = GreeterClient::connect("http://[::1]:50051").await?; The address is "http://[::1]:50051". [::1] is the IPv6 loopback address, which is equivalent to localhost in IPv4. The server is running on port 50051.

If you want to connect to a different gRPC server, you can modify this address to match the address where your gRPC server is running. For example: let mut client = GreeterClient::connect("http://127.0.0.1:50052").await?;

In this case, the client is attempting to connect to a gRPC server running on 127.0.0.1 (localhost) and listening on port 50052.

#[tokio::main]: This is an attribute provided by the Tokio runtime for asynchronous programming. It indicates that the main function will be executed within the Tokio runtime.

let addr = "[::1]:50051".parse()?;: This line parses the string "[::1]:50051" into a network address. [::1] is the IPv6 loopback address, and 50051 is the port number. The ? is used for error propagation, so if parsing fails, it will return an error.

async fn say_hello(&self,request: Request,) puspose of self in the above function is.... In the context of gRPC and Tonic (the gRPC library for Rust), it's common to see &self as a parameter in service methods, even if the method doesn't directly use self. This is because the self parameter is often required by the gRPC framework. It's a way for Tonic to know the context of the service instance when handling the request.

In your specific example, &self might not be used explicitly within the say_hello method, but it's a common pattern to include it in gRPC service implementations. If MyGreeter has associated data or methods that need to be accessed within the service methods, having &self allows you to access them.

TONIC:

tonic is a Rust gRPC framework that is used to build and interact with gRPC services. It is built on top of the tokio runtime, providing asynchronous and non-blocking communication patterns. The tonic library facilitates the development of both gRPC servers and clients in Rust. some key uses of the tonic dependency: gRPC Server Implementation,gRPC Client Implementation, IDL (Interface Definition Language) Support= (.proto files),Async/Await Support,Integration with Tokio.

PROST:

prost is a Rust crate that provides support for Protocol Buffers (protobuf) code generation. It's commonly used in conjunction with the tonic crate to generate Rust code from .proto files, allowing you to define and use gRPC services and message types in a concise and type-safe manner. some key uses of the prost dependency: Protocol Buffers Code Generation, Automatic Serialization and Deserialization.

TOKIO: tokio is a runtime for writing asynchronous and concurrent code in Rust. It's widely used in the Rust ecosystem, especially in networking, I/O, and other scenarios where asynchronous programming is beneficial. Below are some common use cases for the tokio dependency: some key uses of the tokio dependency: Asynchronous I/O,Concurrency and Parallelism,Async/Await Syntax

TONIC-BUILD: The tonic-build crate is used as a procedural macro for code generation in Rust, especially in the context of gRPC services and Protocol Buffers. The ? operator is part of Rust's error handling mechanism, and it is used to propagate errors in a concise and ergonomic way.When you use tonic-build to generate code from .proto files, you typically include it in your build.rs