Distributed Systems

Distributed Systems

• A group of computers working together to appear as a single computer to the end-user.
• A collection of independent components located on different machines that share messages to achieve common goals.

Centralized System vs Distributed System

• Centralized system: State stored on a single computer, simpler, easier to understand, and can be faster for a single user.
• Distributed system: State divided over multiple computers, more robust, more scalable, and more complex.

Why Build a Distributed System?

• One interface to the end-user.
• Maximize resources and information while preventing failures.
• Reliability: if one system fails, it won't affect the availability of the service.
• Dependency on cloud and scaling.

Characteristics of Distributed Systems

• Growing and everywhere in modern applications.
• Rely on distributed systems such as networks, LAN/Internet, distributed real-time systems, parallel processing, cloud computing, distributed artificial intelligence, and distributed database systems.

Essential Components of Distributed Systems

• Network that connects all components.
• Hardware or software that communicates with each other through IP addresses.
• Messages passed between machines containing data that systems want to share (e.g., databases, objects, files).

Four Architecture Types

Client-Server

• A server as a shared resource (e.g., printer, database, web server).
• Multiple clients use the shared resource.

Three-Tier

• Clients no longer need to be intelligent.
• Can rely on a middle tier to do processing and decision-making.
• Most first web applications fall under this category.

Multi-Tier (n-Tier)

• Enterprise web services created n-tier or multi-tier systems architectures.
• Interacts with data tiers and presentation tiers (e.g., google.com).

Peer-to-Peer

• No centralized or special machine that does the heavy lifting and intelligent work.
• All decision-making and responsibilities are split amongst the machines involved.
• Each machine can take on client or server roles (e.g., blockchain).