• API architecture provides the framework for API design and determines how an application programming interface (API) is structured and constructed, including the rules and protocols for data exchange.
• Different architectures and protocols are suitable for different areas of application and applications, depending on which properties (e.g. speed, security, flexibility) are required.
• In this article, you will learn which API architectures and protocols are commonly used, how they differ, and what advantages and disadvantages they offer for different application scenarios.

Understand API architectures

What is an API Architecture?

An API architecture is a structured framework for the development and integration (connection) of application programming interfaces (APIs) that enable different software applications to communicate with each other and exchange data.The architecture of an API determines how this communication is structured, including the rules and protocols for exchanging data.

Different interface architectures are suitable for different areas of application depending on the requirements, depending on whether, for example, the security and accuracy of the data (bank transfer), the speed of data transmission (streaming) or the timeliness of the data (chat) play a more important role. This allows developers to work more efficiently because they can access existing features and reuse them in new applications without having to start from scratch each time.

The elements of an API

APIs consist of multiple components that work together to enable smooth interactions between different software applications. These components are crucial to the functionality and effectiveness of an interface.

• Endpoints: API endpoints are specific paths or URLs through which API requests are sent. Each endpoint is responsible for a specific function or data type. For example, one endpoint could be used to retrieve user data while another creates new records.
• Methods: APIs use various methods such as GET, POST, PUT and DELETE to identify different types of operations. For example, GET is used to retrieve data while POST is used to create new records.
• Request and response formats: Interfaces define specific formats for requests and responses. Formats such as JSON (JavaScript Object Notation) or XML (Extensible Markup Language) are often used to structure data and facilitate exchange between client and server.
• Parameters: Parameters are additional information passed in an API call. They can be used to specify or filter the request, such as returning data for a specific time period or for a specific user.
• Header: The header of an API request conveys additional information, such as authentication data, content type or other metadata. This information is often critical to the security and efficiency of API communications.
• Status Codes: APIs use HTTP status codes to communicate the result of a request. For example, status code 200 indicates a successful operation, while 404 means the requested endpoint was not found.

JSON and XML: The languages of the APIs

JSON (JavaScript Object Notation) and XML (Extensible Markup Language) are two of the most commonly used formats for exchanging data in APIs. They play a critical role in defining how data is structured and communicated.

JSON:

• Simple and Efficient: JSON is known for its simple syntax that makes reading and writing data easier. It uses a key-value based structure that makes it easy to parse and generate data.
• Flexible: JSON is language independent and can be used with many programming languages. Its flexibility makes it ideal for web applications and services that require fast and efficient data transfer.

Example:

{
“name”: “John Doe”,
“age”: 30,
“interests”: [“Reading”, “Hiking”, “Programming”]
}

XML:

• Strict structuring: XML provides a very detailed and strict structure for data. This makes it easier to validate and interpret data, especially in complex systems.
• Extensibility: XML is extensible and allows you to define your own tags and structures, offering high adaptability to different needs.

Example:

<person>
<name>Max Mustermann</name>
<age>30</age>
<interests>
<interest>Reading</interest>
<interest>Hiking</interest>
<interest>Crafts</interest>
</interests>
</person>

While JSON is preferred for its efficiency and simplicity. Although preferred, particularly in web-based applications, XML is used in more complex or regulated environments due to its precise structuring and extensibility. The choice between JSON and XML depends largely on the specific requirements of the project and the preferred way of working of the development team.

Advantages and disadvantages of common API architectures and protocols

Each API architecture has its own advantages that make it suitable for different areas of use and applications. However, the architecture should not be confused with the protocol used: While API architectures define the conceptual framework and principles for how APIs are designed and used, the protocols used determine the rules and standards of API communication.

REST APIs: simple and flexible

Advantages

• Simply
• Flexible
• Scalable
• Caching capable

Areas of application

• Web APIs and services
• Mobile and web app development
• Microservice architectures

REST (Representational State Transfer) is an architectural style for designing network-based applications such as web apps or mobile apps. It establishes a framework for communication between client and server and is based on the principle that everything is viewed as a resource. These resources are identifiable by unique URIs (Uniform Resource Identifiers) and can be manipulated via the HTTP protocol. A REST API uses standardized HTTP methods such as GET, POST, PUT and DELETE to perform operations such as reading, creating, updating or deleting specific resources.

In REST architecture, every interaction is stateless, meaning that every request must contain all the information the server needs to understand and process it. This increases the scalability and reliability of the service because the server does not have to manage the state of each client session.

Another feature of REST is the use of Hypermedia (HATEOAS: Hypermedia as the Engine of Application State), which allows clients to dynamically navigate through the available actions and resources by following hyperlinks in the server’s responses. This promotes decoupling between client and server because the client does not need to know about fixed endpoints, but instead uses the hyperlinks provided by the server to navigate through the application.

RESTful APIs that follow this architectural style are easy to understand and simple to use, which explains their popularity for developing web services and applications.

SOAP APIs: secure and reliable

Advantages

• secure
• Reliable and consistent transaction management
• Strictly standardized

Areas of application

• Applications and services that require high security and reliability (e.g. banking transactions)
• Enterprise applications
• Legacy system integration

SOAP stands for Simple Object Access Protocol and is a protocol standard used for exchanging message data between network applications. It relies on XML (Extensible Markup Language) to structure messages and typically relies on HTTP or SMTP (Simple Mail Transfer Protocol) to transmit these messages, although it can also operate over other network protocols. SOAP APIs are particularly well known for use in decentralized IT environments and in combination with web services.

An important feature of SOAP is its strict specification and strong extensibility and neutrality towards transport protocols. This allows complex messages to be transmitted securely and reliably using WS specifications (Web Services Specifications).

SOAP defines the structure of messages so that they can be processed independently of the programming language used by an application and the underlying transport system, enabling interoperability between applications in different environments and using different technologies.

Despite its high flexibility, SOAP tends to be viewed as more cumbersome than, for example, REST, especially for simple use cases. This is due to the complex structure of SOAP messages and the overhead caused by the XML format. Nevertheless, SOAP remains a popular choice for enterprise-level applications where the needs for security and data reliability justify the complexity.

GraphQL: modern REST alternative

Advantages

• Efficient data queries
• Flexible
• Self-descriptive
• Strong typing

Areas of application

• Web and mobile apps
• Complex systems and microservices
• Real-time data updates

GraphQL is an API query language developed by Facebook and is a modern alternative to traditional REST and SOAP APIs. GraphQL was originally designed to overcome the complexities and inefficiencies of querying data via traditional REST APIs.

The powerful query language provides efficient and flexible data query, improves developer productivity through a self-describing schema, and provides strong typing.

At its core, GraphQL allows clients to specify exactly what data they need, avoiding over- and under-queries that are common with REST APIs. Instead of creating multiple endpoints for different data needs, GraphQL provides a single endpoint that supports flexible and efficient queries.

A key advantage of GraphQL is the ability to query and merge multiple resources with one request, reducing the number of network requests. This is particularly useful in networks with high latency or limited bandwidth, such as mobile networks.

GraphQL also provides strong typing and a self-describing schema. This means that the API schema is defined in GraphQL, including types and relationships between types. This makes development easier because both frontend and backend developers can understand exactly what data is available and how to query it.

HTTP: The web standard

Advantages

• Universally usable
• Simple and flexible
• Stateless (each request is independent)
• Expandable

Areas of application

• Website views
• RESTful APIs
• Data transfer

HTTP (Hypertext Transfer Protocol) is the Internet’s protocol par excellence and serves as the basis for communication between clients (e.g. web browsers) and servers, which is why REST APIs also communicate via this protocol.

HTTP defines a set of methods (such as GET, POST, PUT, DELETE) that specify the type of actions to be performed on the resources.

• GET  to retrieve data
• POST  to create new data
• PUT  to update existing data
• DELETE  to delete data

These HTTP methods allow developers to perform standardized operations over the Internet using HTTP as the transport mechanism. Whether the API communication was successful or not is recorded using status codes (e.g. 200 OK, 404 Not Found, 500 Internal Server Error). The transmission of metadata (such as content type or authentication information) is also supported using HTTP headers.

RPC – Interprocess Communication

Advantages

• Powerful
• Language independent
• Streaming capable
• Microservices
• Real-time applications

RPC stands for Remote Procedure Call and is a communications protocol that allows functions or operations to be performed on a physically remote system as if they were running locally on the calling system. This reduces complexity and makes implementation easier for developers.

When using RPC, the client defines a request to execute a specific function or process on the server with the required parameters. This request is sent over the network, received by the server and the result is sent back to the client.

Different formats can be used to serialize data, such as XML (as XML-RPC) or JSON (as JSON-RPC), which promotes interoperability between different systems and programming languages. It supports both synchronous and asynchronous API calls, meaning the client can wait for a response (synchronous) or continue with other tasks until the response arrives (asynchronous).

RPC is widely used in physically dispersed systems, microservice architectures, and in the development of network applications such as web services or cloud-based services, where it is important to reduce the complexity of direct network communication and enable efficient, seamless interaction between components.

Instead of RPC, the gRPC framework extended by Google is often used, which is known for its high performance and low latencies and is therefore particularly suitable for microservices and highly scalable applications. gRPC uses the faster and more secure HTTP/2 as a transport protocol, the also faster serialization format Protobuf (Protocol Buffers) and masters the API interaction models Unary (simple request-response), server streaming, client streaming and bidirectional streaming. While gRPC is specifically designed to meet the needs of modern, decoupled systems and microservices architectures, traditional RPC systems are somewhat more flexible and suitable for more application areas.

OData: open and standardized

Advantages

• Standardized data access
• Flexible for data queries
• Self-describing messages

Areas of application

• Data publication and exchange
• Development and integration of enterprise applications
• Mobile and web app development

OData (Open Data Protocol) is an open protocol based on REST architecture and designed for the creation and consumption of standardized, interoperable REST APIs.

It enables easy publishing, editing and querying of data over the Internet. The protocol aims to make access to data sets as easy as the web makes access to documents easier. It uses well-known web technologies such as HTTP, Atom Publishing Protocol (AtomPub) and JSON to unify and standardize access to information from different data sources.

OData is capable of processing complex queries over URLs, which includes operations such as filtering, sorting, pagination, associations between records and the ability to create complex queries tailored to client needs. Developers can use OData to create RESTful services that allow clients to flexibly interact with data.

By standardizing access to data sources of various types (such as relational databases, file systems, content management systems, and traditional web services), OData facilitates the development of platform and device independent applications. This makes it a valuable tool for developers to create data-driven applications that can be customized and integrated with various data sources with minimal effort.

WebSocket: everything via a single connection

Advantages

• Real-time communication
• Reduced overhead
• Persistent connection

Areas of application

• Interactive web applications
• Live streaming and real-time notifications
• Collaborative platforms

WebSocket is a protocol that enables persistent, two-way communication between a client, such as a web browser, and a server over a single, long-lasting connection. It is designed to overcome the limitations of traditional HTTP communication, particularly in relation to real-time data transfers. Unlike HTTP, which uses request-response-based communication and requires opening a new connection for each new request, WebSocket allows an open connection after the initial handshake, through which data can be sent quickly and at any time in both directions without multiple requests need to be made or responses need to be waited for.

A major advantage of WebSocket is its ability to transmit real-time information efficiently, making it ideal for applications that require real-time data such as online gaming, chat applications, live sports scores and financial market platforms. By reducing the overhead associated with traditional HTTP requests and providing full-duplex communication, WebSocket significantly improves the performance and user experience of interactive web applications.

No-Code: Easily manage interfaces and API integrations

A well-thought-out API architecture is an important element for the digitalization of business processes. It not only enables the efficient integration of a wide variety of systems and technologies, but also the secure and scalable management of data streams. Choosing the right data format and using appropriate protocols play an important role.

In this context, Lobster_data offers a comprehensive solution to overcome the challenges of modern data integration. The no-code platform Lobster_data simplifies both the management of your APIs and the integration of different systems and platforms. By supporting all common industry standards and providing a wide range of connectors for your API management, Lobster_data enables seamless and secure data transfer, regardless of the formats and standards used.

Mapping complex business logic is also particularly practical, which opens the door to further automation and data-driven decision-making processes. If you would like to use the potential of Lobster_data for your company, contact us today for a free demo or a non-binding consultation with one of our specialists.