RPC vs Web Sockets vs REST
API's are mechanisms that enable two software components to communicate with each other using a set of definitions and protocols. Remote Procedure Call (RPC), Web sockets and REST are three architectural styles in API design
RPC (Remote Procedure Call), WebSockets, and REST (Representational State Transfer) are all technologies used for communication between clients and servers in a networked environment. Here's a brief summary of each, along with their similarities and differences:
RPC
Remote Procedure Call: A protocol that allows a program to execute a procedure (a subroutine or a function) on a remote server as if it were local.
Synchronous and Asynchronous: RPC can be synchronous (blocking) or asynchronous (non-blocking).
Multiple Formats: Can use various data formats, including XML (as in XML-RPC) and JSON (as in JSON-RPC), and binary for gRPC.
Tight Coupling: Often requires both client and server to understand the procedure calls and their specific formats.
WebSockets
Full Duplex Communication: Provides a full-duplex communication channel over a single, long-lived connection that remains open for real-time, bi-directional communication.
Protocol: Implemented as a protocol (ws:// or wss:// for secure connections), and is an advanced technology compared to HTTP/HTTPS.
Stateful: Maintains state over the lifetime of the connection.
Real-Time Data: Ideal for applications requiring real-time updates, like chat applications or live streaming.
REST
Architectural Style: REST is an architectural style for distributed systems and not a protocol or a standard. It utilizes standard HTTP/HTTPS methods.
Stateless: Each request from client to server must contain all the information necessary to understand and respond to the request, without retaining session information.
The client-server architecture of REST decouples clients and servers. It treats them each as independent systems
Data Interchange Formats: Commonly uses JSON or XML to exchange data, can have multiple formats, like JSON and XML, within the same API.
Resource-Oriented: Operations are performed on resources, identified by URLs, using standard methods like GET, POST, PUT, DELETE.
Similarities
Client-Server Architecture: All are used to enable communication between clients and servers.
HTTP Foundation: REST directly uses HTTP, while WebSockets and RPC can be initiated over HTTP before establishing their respective communication channels.
Data Exchange: They can all exchange various types of data, albeit using different methods and protocols.
Differences
Connection Model: REST uses a stateless request-response model, while WebSockets use a stateful, persistent connection and RPC can be either stateful or stateless depending on the implementation.
Performance: WebSockets typically offer better performance for real-time applications due to the persistent connection, whereas REST can be more efficient for standard web application use cases with less frequent data exchange.
Complexity: REST is often simpler to implement for basic CRUD operations, while WebSockets and RPC might require more setup and management of the connection and data formats.
Use Cases: REST is widely used for web APIs, RPC for actions that map closely to functions or methods, and WebSockets for real-time and interactive applications.
In summary, while all three technologies serve the purpose of client-server communication, they have different models and are suited to different scenarios depending on the application's needs for state, performance, and real-time interaction.
RPC IMPLEMENTATION
Remote Procedure Call (RPC) is a versatile communication technique that can be implemented over various underlying network protocols, each with its characteristics and use cases. Here are some of the protocols that can be used with RPC:
TCP/IP (Transmission Control Protocol/Internet Protocol)
Common Use: The most common transport protocol used for network communication, including RPC. It provides reliable, ordered, and error-checked delivery of a stream of bytes between applications.
Characteristics: RPC over TCP is often used for its reliability and connection-oriented communication, which is crucial for many distributed applications.
UDP (User Datagram Protocol)
Common Use: A simpler, connectionless communication protocol that allows sending messages, called datagrams, but with no guarantee of delivery, order, or duplicate protection.
Characteristics: RPC over UDP can be faster and more efficient than TCP in scenarios where speed is critical and the overhead of establishing a connection is undesirable.
HTTP/HTTPS (Hypertext Transfer Protocol/Secure)
Common Use: Often used as a transport protocol for web-based RPC services, especially with XML-RPC and JSON-RPC, where the calls are encoded in XML or JSON format.
Characteristics: HTTP/HTTPS is stateless and widely supported, making it a good choice for web services that need to be compatible with a wide range of clients and servers.
HTTP/2
Common Use: A more efficient and improved version of HTTP, often used by gRPC, which is a high-performance RPC framework that uses HTTP/2 features like multiplexing and server push.
Characteristics: Provides a more efficient use of network resources and reduced latency by introducing header compression and allowing multiple concurrent exchanges on the same connection.
Named Pipes
Common Use: On Windows systems, named pipes provide a way for multiple processes to communicate with each other, either between a client and a server on the same machine or across the network.
Characteristics: Named pipes can be used for RPC communication, especially when both the client and server are on the same local machine or within a single trusted network.
IPC (Inter-Process Communication) Mechanisms
Common Use: Various IPC mechanisms, such as message queues, shared memory, or sockets, can be used for RPC among processes on the same machine.
Characteristics: These methods are highly efficient for local communication and are often used when performance and low latency are critical.
RPC's flexibility allows it to be utilized over different protocols, each serving specific requirements regarding reliability, speed, security, and compatibility. The choice of protocol is often dictated by the needs of the application and the environment in which it operates.
WEBSOCKET IMPLEMENTATION
WebSocket is indeed a distinct network protocol, not a technique that can be implemented over other protocols. It is defined by the IETF as the WebSocket Protocol in RFC 6455. WebSockets enable a full-duplex communication channel that operates through a single, long-standing socket connection between the client and the server.
Here's how it typically works:
Initiation Over HTTP: The WebSocket connection begins as an HTTP connection, leveraging the HTTP protocol to establish the initial handshake. The client sends a special HTTP upgrade request to the server, requesting the opening of a WebSocket connection.
Switching Protocols:
If the server supports WebSockets, it responds with an HTTP 101 Switching Protocols response header, agreeing to change from HTTP to WebSocket.
WebSocket Protocol:
Once the handshake is complete, the protocol switches from HTTP to WebSocket, and the connection remains open, allowing for two-way communication.
ws:// and wss://: WebSocket connections use their own URL scheme. The ws:// URI scheme is used for unencrypted WebSocket connections, while wss:// is used for WebSocket connections encrypted with TLS/SSL.
Because the WebSocket protocol provides a different set of features compared to HTTP (namely, persistent, full-duplex communication), it cannot be implemented over or switched to other protocols in the way that RPC can. Instead, WebSocket is designed to work compatibly with the HTTP protocol, using the existing infrastructure, such as web servers, proxies, and firewalls, which makes it particularly well-suited for web applications requiring real-time communication.