Patterns

Partnership

The Partnership pattern defines a relationship between two or more independent entities (Partners) who collaborate to achieve a common goal through a shared state. Each Partner maintains its own autonomy but relies on the SharedState for synchronization and data exchange, effectively creating a bounded collaboration. …

Half-Sync/Half-Async

behavioral concurrency

The Half-Sync/Half-Async pattern addresses performance bottlenecks in request processing by decoupling time-consuming, non-essential tasks from the critical path. It allows a service to respond quickly to a client by handling essential parts of a request synchronously, then offloading less important, potentially …

Object Pool

creational performance

The Object Pool pattern is a creational design pattern that aims to improve performance by reusing objects that are expensive to create. Instead of creating a new object each time one is needed, the pool maintains a collection of pre-initialized objects. When an object is required, it’s borrowed from the pool; …

Blackboard

behavioral AI

The Blackboard pattern provides a central repository (the Blackboard) of information that multiple, independent Knowledge Sources can access, modify, and react to. A Controller selects which Knowledge Sources are relevant at any given time based on the current state of the Blackboard, and applies their expertise to …

Request-Reply

behavioral messaging

The Request-Reply pattern is a fundamental communication pattern where one party (the client) sends a request to another party (the service) and waits for a response (the reply). It’s a synchronous interaction style, meaning the client blocks until the reply is received. This pattern is commonly used in …

Front Controller

behavioral web application

The Front Controller pattern provides a centralized entry point for all requests coming into a web application. Instead of having each servlet or controller directly handle requests, all requests are initially dispatched to a single controller – the Front Controller. This controller then determines the appropriate …

Mediator

behavioral communication

The Mediator pattern defines an object that encapsulates how a set of objects interact. This mediator promotes loose coupling by preventing objects from referring to each other explicitly and lets the mediation logic vary independently of the interacting objects. Instead of components communicating directly, they …

Transactional Consumer

behavioral integration reliability

The Transactional Consumer pattern ensures that messages received from a message broker are processed reliably and atomically. It handles message consumption within a database transaction, allowing for either complete processing of a message batch or a full rollback in case of failure. This prevents partial updates and …

Idempotent Receiver

behavioral integration resilience

The Idempotent Receiver is a pattern used in distributed systems to ensure that a receiver can safely reprocess the same message multiple times without causing unintended side effects. This is crucial in scenarios where message delivery is not guaranteed – a message might be retried due to network issues or receiver …

Plug-in

behavioral extensibility

The Plug-in pattern defines a framework where software functionality can be extended without modifying the core application code. It achieves this by defining extension points—interfaces or abstract classes—that allow third-party developers or internal teams to add features dynamically. These extensions, known as …