As with all complex systems, the blockchain API architecture consists of key components that work together to form a robust and efficient system. These components include API gateways, API design and contracts, and data management and integration. 
API gateway
Think of API gateways as gatekeepers to the blockchain API ecosystem. It performs the following functions:
Route the request to the appropriate microservice based on the URL and content
Enables clients to retrieve data from multiple services in a single round trip
Reduce overhead by minimizing the number of requests
It also facilitates caching by storing and serving endpoint responses within a defined time to live (TTL), which improves response speed and reduces network overhead. API gateways are typically available through API management platforms that allow users to easily enhance the API through enhanced security or through automatic load balancing to achieve scale. API gateways are necessary for organizations that want to implement a robust API architecture.
API design and contracts
Think of the API design and contract as a blueprint for the API. They are critical to defining the structure, behavior, and interaction of the API. Well-thought-out design and API contracts ensure developers have consistency and ease of use when using the API. When designing apis, developers should consider user expectations by carefully planning and collaborating with potential API consumers.
Data management and integration
Data management and integration are key cogs in ensuring the smooth running of the blockchain API machine. They relate to:
Handle data flow, storage, and processing in an API architecture
Manage data access, security, and governance
Maintain data integrity and consistency across various systems and applications.
For apis that handle reading or writing data of any kind, you need to make sure that the underlying infrastructure doesn't run into concurrency issues. You should also ensure that you can take advantage of the authentication and authorization used in the API layer when controlling and managing data access. These factors are key to maintaining data integrity and security.
Popular API architectural style
When it comes to API architecture styles, there is no one size fits all. Different architectural styles offer different advantages and are suitable for different use cases. When it comes to web apis, many people automatically think of REST apis. Although they are the most popular types, some other popular API architecture styles include:
Each style has its unique characteristics and advantages that are suitable for specific use cases. Some styles apply more broadly, while others are more professional. Let's look at each one in more detail.
RESTful blockchain API
In the API architecture style, the REST API can be compared to the Swiss Army knife. The REST API is simple, stateless, and extensible, making it suitable for many web and mobile applications. A key feature of RESTful apis is that they rely on the HTTP standard, which enables them to be form-agnostic and allows data to be exchanged using XML, JSON, or HTML. In general, RESTful apis are the favorite of most developers to build apis because they are widely supported and there is plenty of technical support to build them.
GraphQL API
GraphQL is a relatively new area in the API field, growing in popularity due to its flexibility and efficiency in fetching data. It allows the client to request only the data it needs, thereby reducing over-extraction and under-extraction of the requested data. This makes it an excellent choice for applications where efficiency and performance are key considerations. Since the technology is still relatively new, its adoption has been slowly rising, as have the frameworks and technologies that support it.
SOAP API
For organizations that existed before RESTful apis were popular, the SOAP blockchain API is a tried and tested architectural style that has been widely adopted. SOAP, one of the most popular styles before REST became king, provided a standardized protocol for exchanging structured information in web service applications. It is particularly beneficial for applications that require structured communication and the management of complex data structures and transactions. Although SOAP services have slowly become less common, many traditional companies still build and maintain SOAP services.