his article discusses distributed systems’ basics, types, concepts, communication methods, challenges, and real-world examples that we encounter daily.
Distributed systems are ubiquitous today, powering everything from the internet and cloud computing to social networks, gaming, e-commerce, and streaming services. A distributed system comprises independent components in different locations that communicate to achieve a common goal. These components can be computers, servers, devices, sensors, etc., that process data and exchange messages. Distributed systems enable various services and tasks through improved scalability, availability, performance, and cost-effectiveness over centralized systems. However, they also introduce complexities that designers and developers must address. This article discusses distributed systems’ basics, types, concepts, communication methods, challenges, and real-world examples that we encounter daily.Basics of Distributed Systems
Before diving into distributed systems details, let’s review key components and principles of it.Components
Distributed systems comprise nodes and links. Nodes are processing units that execute computations, store data, or send/receive messages. Nodes can be physical machines or logical entities with different capabilities like processing power and memory. Links are communication channels between nodes enabling message exchange. Links can be physical or logical connections with various properties like reliability and bandwidth.Principles
Distributed computing principles come from seminal works by Leslie Lamport and Andrew Tanenbaum.
Lamport introduced concepts like logical clocks and consensus, proposing four requirements for distributed systems: reliability, security, maintainability, and efficiency.
Tanenbaum suggested eight design goals: transparency, openness, scalability, concurrency, fault tolerance, consistency, replication, and distribution awareness. Specifically, the system should hide complexity, use standard interfaces, accommodate growing demands, allow simultaneous execution, recover from failures, ensure data coherence, create redundant components, and adapt to the network.
Overall, components and principles provide the fundamental building blocks and assumptions underpinning distributed systems. Nodes and links enable computation and communication, while principles guide system design to meet functional and quality requirements.Types of Distributed Systems
Distributed systems can be categorized by architecture, functionality, or application domain. Major types include:
Cluster computing: Nodes are homogeneous machines connected by high-speed networks acting as a unified resource for computationally intensive tasks like scientific computing and machine learning, such as Hadoop, Spark, and Kubernetes.
Grid computing: Heterogeneous nodes geographically dispersed and connected over wide-area networks acting as a virtual supercomputer for large-scale computations like simulations and bioinformatics. Well-known grid computing systems include BOINC, Globus Toolkit, and Open Science Grid.
Cloud computing: Virtualized nodes hosted by providers and accessed via the internet to provide on-demand services and resources like computing, storage, and analytics, with leading examples being AWS, Azure, and GCP.
Peer-to-peer computing: Autonomous nodes communicate directly without centralized control for decentralized tasks like file sharing, content distribution, and cryptocurrency transactions, evident in systems like BitTorrent, Skype, and Bitcoin.
