API Strategy: Specifications

API specifications play a crucial role in executing a successful API strategy. They provide a standardized way of defining the structure and behavior of an API, making it easier for developers to understand and use the API. With an API specification, developers can quickly learn how to interact with the API, without having to read through extensive documentation. It also helps to ensure that the API is consistent and interoperable, which is important when working with multiple teams or third-party developers. API specifications can also help to reduce errors and improve security by defining the expected input and output formats, as well as any authentication or authorization requirements. Overall, API specifications are essential for designing, documenting, and testing APIs, and are critical to the success of any API strategy.

API Specifications Approach

Designing an API specification using OpenAPI specifications involves several best practices and tools.

Components of API Specification strategy

Below are some of the best practices and tools for designing an API specification:

• OpenAI Specifications
• Specification Editor/Designer
• Version Control
• Specification Catalog
• Endpoint Catalog
• Conventions/Standards
• Specification Validation
• Specification Conversion
• Specification to Code
• Specification Governance

OpenAI Specifications

The OpenAPI Specification, also known as Swagger, is a widely accepted industry standard for describing RESTful APIs, which offers various benefits when incorporated into your API strategy. Here are some benefits of using OpenAI specifications:

1. It improves the developer experience by providing a clear and consistent way for developers to understand how to interact with the API and integrate it into their applications.
2. It accelerates development by reducing the time and effort required to develop and test API integrations.
3. It simplifies testing by providing a clear definition of API endpoints, methods, and parameters, which makes it easier to write automated tests for the API, improving its reliability.
4. It encourages better collaboration between teams working on the API by providing a common language and format. ,
5. The OpenAPI Specification enhances the API’s interoperability with other systems and services, increasing its usefulness and flexibility. Overall, incorporating the OpenAPI Specification into the API strategy helps create a more developer-friendly, reliable, and scalable API that is easier to maintain.

Specification Editor/Designer

The Specification Editor is a critical tool in executing a successful API strategy in an enterprise. The editor allows developers to create, edit, and maintain OpenAPI specifications that describe their APIs, making it easier for others to understand and use them. With the help of the Specification Editor, developers can ensure that their APIs comply with industry standards and best practices, reducing the risk of errors and ensuring that the APIs are reliable and scalable. Furthermore, the Specification Editor can be used to document APIs, which is crucial for collaboration between teams, as it helps to ensure that everyone is on the same page when it comes to API functionality and requirements. Overall, the Specification Editor is an essential tool for enterprises that want to create developer-friendly, interoperable, and reliable APIs that can be easily maintained and scaled over time.

A custom built API specification design tool as shown in the below diagram as some benefits as it can be easily integrated with customized specification validation, model catalog and other enterprise and internal applications and APIs.

API Specification Design tool — Integration with other APIs and applications

Version Control

Version Control offers a centralized platform to manage changes to API specifications, source code, and related assets. By using a VCS, developers can track API version changes, monitor code changes made by team members, and revert changes if necessary. This ensures that everyone on the team is working with the same API version, reducing the chances of errors and improving code quality. Moreover, version control allows developers to collaborate effectively, without any conflicts while working on the same codebase. With a VCS, enterprises can organize and collaborate better, making it easier to maintain and scale the API over time. Overall, a VCS is an essential tool for enterprises aiming to guarantee their API strategy’s success.

Specification Catalog

The Specification Catalog system provides a centralized repository for storing and managing API specifications, making it easier to discover and reuse them across the organization. With a Specification Catalog system, enterprises can standardize their API design and documentation practices, reducing the risk of errors and inconsistencies. Additionally, the Specification Catalog system can be used to manage the lifecycle of API specifications, ensuring that they are kept up-to-date and retired when no longer needed. This helps to improve the maintainability and scalability of the APIs over time. Furthermore, the Specification Catalog system can be used to enforce governance policies, such as security and compliance requirements, ensuring that all APIs conform to enterprise standards. Overall, having a Specification Catalog system is crucial for enterprises that want to streamline their API development processes, improve collaboration between teams, and create a more consistent and reliable API landscape.

Endpoint Catalog

Having a system in place to propose, review, and catalog API endpoints can be extremely beneficial during the early stages of API development or as a supplement to the continuous API specifications management process. This process allows API development teams to streamline, optimize, and reuse API endpoints across various applications and domains. Additionally, endpoint cataloging provides a quick and efficient method for maintaining existing APIs and their corresponding specification documentation. The endpoint review process, whether done manually or automatically, can enforce API endpoint naming standards and ensure compliance with enterprise-level regulations. In the context of Banking APIs, it is important to ensure that API endpoints adhere to BIAN-recommended business and service domains.

Conventions/Standards

API conventions and standards play a crucial role in enabling the creation of high-quality, interoperable APIs that can be easily adopted and used by developers. There are several types of standards that can be applied as part of the API strategy:

1. Naming conventions: Using consistent and clear naming conventions for API endpoints and parameters can make it easier for developers to understand and use the API.
2. Data formats: Standardizing data formats, such as using JSON or XML for response payloads, can help ensure consistency and interoperability across different applications and platforms.
3. Authentication and authorization: Applying standards for authentication and authorization mechanisms can help ensure that only authorized users or applications can access the API and its endpoints.
4. Error handling: Standardizing error responses and error codes can help developers understand and troubleshoot issues with the API.
5. Versioning: Implementing versioning standards for APIs can help manage changes and updates to the API over time, while minimizing disruption to existing API users.
6. Security: Applying security standards such as encryption, tokenization, and SSL/TLS can help protect the API and its endpoints from unauthorized access and attacks.
7. Documentation: Creating comprehensive and well-organized documentation for the API can help developers understand how to use the API and its endpoints, as well as provide guidance on best practices and troubleshooting.

Specification Validation

The API Specification validation is important to enforce standards and best practices. It is recommended to have some specification validation system which can be easily integrated with specification design tool, CI/CD pipeline, and systems for on-demand validation (via APIs or CLs). There can be various types and levels of specification validation rules including:

• OpenAPI Specification validation rules
• Enterprise-level validation rules
• Department/Group-level validation rules
• Team level validation rules.
• Application/Component-level validation rules.

The validation system should be able to support various types and levels of validations rules in terms of evaluation them and storing and communication to stakeholders including API development teams.

Validation Rules

The impost important validation rule is that API specification document must pass the OpenAPI specifications standard (like 3x). Some enterprises and teams like to have custom rules which are around having some additional directives/attributes in the specification document. Below is an example:

{
  "openapi": "3.0.0",
  "info": {
    "title": "example title",
    "description": "example description",
    "contact-name": "first last"
    "contact-email": "teamxyz@mycompany.com"
    "version": "x.x.x",
    "version-description": "example version description",
    "tags":"tag1, tag2, ..."
    "api-type":"system"
  },
  "servers": [
   {
  "url": "https://api.example.com"
 },
  ]
}

Specification Conversion

It is recommended to use a tool that can convert API specification documents from older versions of the API Specifications (like 2.x) to the new OpenAPI Specification 3.x or later. This tool should be able to convert the contents with minimal or no loss of information, and may also add the required fields/attributes to the target specification document.

Specification to Code

The “Specification to Code” system can be a CLI, plugin, API, or UI. It aims to help API development teams generate compliant and enterprise-ready code from the API Specifications document (Swagger). The generated code can also be used to modify the model classes of an existing application to reflect changes in the input specifications document.

Specification Governance

Effective governance plays a critical role in enforcing standards for API specification strategies by ensuring that all stakeholders are on the same page and complying with established rules and guidelines. In the absence of governance, maintaining consistency and quality in API specification development becomes challenging, and this may lead to various issues such as security vulnerabilities, compatibility problems, and ineffective communication between systems. Below diagram depicts how governance can be implemented as pat of the development process.

API Specifications Governance

With clear governance policies and procedures, organizations can ensure that all API developers adhere to best practices, industry standards, and regulatory requirements. This ultimately results in APIs that are more reliable, interoperable, and user-friendly, leading to improved customer experiences and increased business success.