What are the most common software architecture patterns for blockchain applications?

Layered architecture is a widely adopted pattern in blockchain applications, characterized by organizing the system into distinct layers, each with a specific role and responsibility. This modular approach allows for separation of concerns, where each layer performs a function independent of the others. Commonly, the architecture consists of layers like the data layer (handling the ledger and storage), the network layer (managing peer-to-peer communication), the consensus layer (ensuring agreement on the state of the blockchain), the application layer (for smart contracts and application logic), and sometimes a presentation layer for user interfaces.

Layered Architecture: This architecture divides the blockchain application into different layers, such as the presentation layer, application layer, business logic layer, and data layer. Each layer has its responsibility and interacts with the layers above and below it. This separation of concerns helps in managing complexity and promoting maintainability.

While smart contracts are enabled by blockchain technology and would certainly interact with the blockchain layer, I would rather have them in the business logic layer. This is one great benefit of the layered architecture pattern; it allows you to group the components of a system according to their common functionalities and objectives. For systems that include different technologies, you could also include your A.I/M.L, oracles, API's and Tokens in the business logic layer. The layered pattern is always a good starting point in software architecture because it is easy to visualize for both technical and non-technical audiences.

In a recent experience from designing a software protocol that included a blockchain protocol, smart contracts, and a few other technologies, I used the microservices architecture pattern because it allowed me to decompose the system into smaller components. This approach is great for the security and resilience of the system. It is also great because it allows you to modify and scale each independent service without needing to significantly modify the entire system at once. In this example, each service includes a few subdomains ranging from a marketplace to digital wallets and portfolio’s for asset management.

Microservices architecture is a software design approach where a single application is divided into a set of small, independent services, each running in its process and communicating with other services via lightweight mechanisms like HTTP/REST or messaging protocols. Here are several benefits. Scalability: Flexibility and Agility: Isolation and Fault Tolerance: Modularity and Maintainability: Team Autonomy: Continuous Deployment and DevOps: However, implementing microservices architecture also introduces challenges such as increased complexity in deployment and orchestration, inter-service communication overhead, and potential consistency issues in distributed systems.

EDA event represents a significant occurrence or change in the system, and event-driven architecture enables components to react to these events in real-time. Here are several benefits: Decoupling of Components: Real-time Responsiveness: Asynchronous Communication: Scalability: Flexibility and Extensibility: Event Sourcing and CQRS: Overall, event-driven architecture offers a flexible and scalable approach to designing blockchain applications, enabling real-time responsiveness, decoupling of components, and improved system reliability. However, it also introduces complexities related to event handling, event routing, and event consistency, which need to be carefully addressed during the design and implementation phase.

One major benefit of server less architecture is excellent scalability, able to spin up new instances in seconds to handle fluctuating loads

In a serverless architecture, the cloud provider manages the infrastructure, dynamically allocating resources to run the functions in response to events or requests. It includes reduced operational overhead, improved scalability, cost efficiency, and faster time-to-market. However, it also comes with challenges related to cold start latency, resource constraints, debugging, monitoring, and managing dependencies. Despite these challenges, serverless architecture has gained popularity for building a wide range of applications, including web and mobile backends, IoT applications, event-driven pipelines, and data processing tasks.

In the context of software development, hybrid architecture often involves integrating on-premises infrastructure with cloud-based services or combining multiple cloud providers' offerings. Overall, hybrid architecture offers organizations the flexibility to leverage the benefits of both on-premises and cloud environments while addressing specific requirements related to scalability, security, compliance, and resilience. By adopting a hybrid architecture approach, organizations can achieve a balance between on-premises control and cloud agility, enabling them to innovate, scale, and adapt to changing business needs effectively.

A helpful distinction to make is the difference between architecture patterns vs architecture view models. Architecture patterns describe the different approaches that you could use in building a system. Architecture view models like the 4+1 view model describe how the system would work from different perspectives. The patterns are “layered”, “microservices”, “event-driven”, “serverless”, “hybrid”. The 4+1 view model is “logical/conceptual” (providing the overall logic of the system through modeled objects), “process view” (describes the activities carried out by the system), “physical view” (maps the systems components unto hardware), “development view” (shows development requirements), + “use-case view” (describing possible scenarios).