Software Architecture Patterns

The Circuit Breaker pattern is one in which an intermediary service is placed between a caller and a target. The purpose of the intermediary service is to observe conditions in the target. Should hazard occur, the circuit breaker process reroutes traffic to another service that has the logic to mitigate the hazardous condition. Analogically, the […]

In the client-server architecture patterns, there are two main components: The client, which is the service requester, and the server, which is the service provider. Although both client and server may be located within the same system, they often communicate over a network on separate hardware. The client component initiates certain interactions with the server to generate

The Command Query Responsibility Segregation (CQRS) pattern separates a service’s write tasks from its read tasks. While reading and writing to the same database is acceptable for small applications, distributed applications operating at web-scale require a segmented approach. Typically there’s more read activity than write activity. Also, read activity is immutable. Thus, replicas dedicated to reading data can be spread out over

This was often referred to as the master/slave architecture pattern, but because it is not a useful metaphor, some engineers and software companies have adopted replacement terms such as primary/secondary, primary/replica, parent/helper, master/replica or the controller/responder pattern. Most notably, the IEEE has adopted this as a better term for network technology. Like the client-server architecture pattern, this pattern consists

The Event Sourcing pattern involves sending a continuous stream of messages to an authoritative storage target. Each message describes an event in the system. Examples include: A write to the database, request to a web server, or logging activity from within an application. Services and applications then query the event store for interesting events in

The layered architecture pattern is the most common among developers. It is useful for programs that comprise several groups of subtasks, each of which is at a different level of abstraction. Each of these subtasks is represented by a layer in the software—a unit of modules that produces a cohesive set of services—and each layer

The model-view-controller (MVC) pattern divides an application into three components: A model, a view, and a controller. The model, which is the central component of the pattern, contains the application data and core functionality. It is the dynamic data structure of the software application, and it controls the data and logic of the application. However, it does not

The microservices pattern involves creating multiple applications—or microservices—that can work interdependently. Although each microservice can be developed and deployed independently, its functionality is interwoven with other microservices. A key concept in the microservices pattern is the separate deployment of units. This creates a streamlined delivery pipeline that allows for easy deployment of microservices and increases application

The Pub-Sub pattern is one in which a process sends a message into a message broker. Then, the message is forwarded to one or more parties listening for incoming messages according to a given queue or topic. Sending a message to the broker is called publishing. Binding to a particular topic and then listening for incoming

The database per service pattern creates a need for this pattern. The Saga pattern is one in which the steps of a transaction are chronicled according to a set of predefined actions. This chronicle is called a saga. As each step in a transaction is executed, a controller service compares the result of the step against the saga