Asynchronous

What Does Asynchronous Mean?

Asynchronous refers to events or operations that happen independently, without a shared clock or strict timing coordination. 

In computer science, asynchrony means operations can occur at different times and speeds, rather than in lockstep with a central timing signal.

In an asynchronous system, each component responds to events as they occur. This approach allows systems to continue functioning even when individual parts experience delays, making asynchronous designs useful in distributed systems where network conditions can vary.

How Do Asynchronous Systems Work?

Asynchronous systems are often built with a modular framework. 

Each module can operate independently and communicate with other modules as needed. These interconnected modules form a working system without requiring all parts to be synchronized at all times.

Asynchronous communication is a common example. Data can be transmitted irregularly, rather than in a steady stream. This can be seen in email and online forums: participants send and receive messages at different times, without requiring both parties to be available simultaneously.

How Do Asynchronous Blockchains Work?

Semi-synchronous networks aim to ensure that the network maintains a consistent global state. If the network becomes partitioned, consensus among nodes slows down until connectivity is restored.

Asynchronous and semi-synchronous blockchain networks can be designed to prioritize either consistency or availability. This is part of the Consistency, Availability, and Partition tolerance (CAP) theorem that states a distributed system can only guarantee two of these three properties. 

Since network failures make partition tolerance non-negotiable, blockchains must choose between consistency and availability when partitions occur. If availability is prioritized, all transactions are added without downtime. If consistency is prioritized, some transactions may be paused until prior transactions are confirmed. Rather than achieving immediate consistency, many blockchain designs rely on eventual consistency, where nodes converge on the same ledger state over time through confirmations.