![]() ![]() “Any organization that designs a system will produce a design whose structure is a copy of the organization’s communication structure.” Inverting Conway’s Law allows for the organizational structure to align with the bounded contexts. Whatever the choice of deployment, these services will speak the same language and belong to the same bounded context. Inter-service communication is performed via gRPC through Axon Server, an infrastructure component capable of routing these messages to interested services. ![]() The logical boundary of the Shipping context is represented as a set of messages we choose to consume (commands, queries) or publish (events). This generally means that if the events/commands/queries are published as JSON, or perhaps a more economical object format, the consumer can consume the messages by parsing them to obtain their data attributes. These diagrams show the Hexagonal (Ports & Adapters) architecture of three different options, with the service contracts (API) published as a schema. This has enormous benefits for operational teams allowing them to update one component without making other components unavailable. Location transparency allows for additional extraction of REST/HTTP adapters as services and deploys them individually. Shipping-Query, Shipping-Command, and Adapters as services These projections are optimized for querying, and the Shipping-Query service exposes 'queries' as an API. The Shipping-Query service is subscribed to these domain events, and it creates projections (materialized views) of the system’s aggregates. The commands are handled by the business logic (aggregates), and domain events are published. The Shipping-Command service consumes commands only. Shipping-Query and Shipping-Command servicesīy applying CQRS architectural pattern, the system can be further decoupled by separating the command component from the query component of the Shipping service and deploying them individually as two services: ) maps the 'user-friendly' API to the core messaging API of the service. A layer of adapters (REST, WebSockets, gRPC. The API of this service is represented as a set of commands and queries it consumes and events it publishes. The core of the service is its business logic, which is surrounded by adapters that communicate with other services and applications. deploy command and query components as two independent services (CQRS), and extract their HTTP/REST adapters/controllers to services as well (location transparency).deploy command and query components separately ( CQRS), as two independent services.deploy all components within one service. ![]() This design enables different deployment strategies with different scalability options, for example: It’s simply a matter of configuration whether the system runs on a single node or is distributed on several nodes. These components aren’t interested in the actual destination of a message. Additionally, these components communicate via messages (commands, events, queries) transparently. In Axon applications, the CQRS architectural pattern decouples command components from the query side components. Let’s introduce a sample subdomain of Shipping management responsible for managing courier information and contains a courier view of an order ( shipping) for managing the delivery of orders. Bounded Contexts are a strategic concept in Domain Driven Design, and it is important to know how it is reflected in the architecture and organizational/team structure. In Axon applications, the contract (API) is represented as a set of messages (commands, events, and queries) that the application publishes and consumes. As the model starts to take on a deeper meaning and clarity, Bounded Contexts will transition to the 'solution space', with the software model being reflected in project source code.īounded Contexts represent logical boundaries from a run-time perspective, defined by contracts within software artifacts where the model is implemented. In this phase, the task is to find the actual boundaries of specific contexts and then visualize the relationships between these contexts. When starting with software modeling, Bounded Contexts are conceptual and are part of the 'problem space'. The domain model expresses a Ubiquitous Language as a software model. "A Context is the setting in which a word or statement appears, and that determines its meaning".Ī Bounded Context is an explicit boundary within which a domain model exists.
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