Where OpenAPI tooling renders rich text it MUST support, at a minimum, markdown syntax as described by CommonMark 0.27. Tooling MAY choose to ignore some CommonMark features to address security concerns. Providing web requests in HTTP is the bare minimum for documentation. It’s usually assumed that devs will know how to send HTTP requests in their language of choice, but sometimes, API creators include requests in various languages. This can be done automatically via API spec tools and API management tools like Postman.
Unless specified otherwise, relative references are resolved using the URLs defined in the Server Object as a Base URL. Note that these themselves MAY be relative to the referring document. Each template expression in the path MUST correspond to a path parameter that is included in the Path Item itself and/or in each of the Path Item's Operations. An exception is if the path item is empty, for example due to ACL constraints, matching path parameters are not required. Swagger is another popular API development tool using OpenAPI specification. In fact, OpenAPI was part of Swagger until 2016, when the specification became the brand-agnostic standard for web services.
Versions
Their definition is the same as the one from JSON Schema, only where the original definition references the JSON Schema definition, the Schema Object definition is used instead. The default can be used as the default response object for all HTTP codes that are not covered individually by the specification. It is used by parameter definitions that are not located in "body".
It is not expected from the documentation to necessarily cover all possible HTTP response codes, since they may not be known in advance. However, it is expected from the documentation to cover a successful operation response and any known errors. This object is an extended subset of the JSON Schema Specification Wright Draft 00. To support polymorphism, the OpenAPI Specification adds the discriminator field. When used, the discriminator will be the name of the property that decides which schema definition validates the structure of the model. There are two ways to define the value of a discriminator for an inheriting instance.
What Is an API?
OAS provides the means to support this in an agnostic and portable way. It also provides the means to do this quickly and be able to socialize their ideas with other stakeholders with minimal set-up. Alternatively, any time a Schema Object can be used, a Reference Object can be used in its place.
Testing is therefore a stage in our conceptual API lifecycle that significantly benefits from leverage OAS. Using an OpenAPI document as an input both accelerates this activity and provides a deterministic mechanism for executing tests. The vast majority of organizations exposing APIs internally or externally use infrastructure to protect the API from malicious intent or provide standardized patterns of deployment. Technologists working on bringing those requirements need some means to convey them.
How to Write API Documentation: Best Practices and Examples
Authentication helps keep an API's data safe and secure, and it is the first hurdle that a developer must cross when using a new API. If an API's authentication process is too difficult or poorly documented, the developer might become frustrated and decide to try a different API. API-first is a development model in which applications are conceptualized and built by composing internal or external services that are delivered through APIs. An increasing number of organizations are therefore adopting the API-first strategy to help them systematically develop high-quality APIs that advance business objectives in myriad ways. Here, we'll start by discussing the role that API documentation plays in an API-first world. Then, we'll review the key components of API documentation, as well as some API documentation best practices.
- The default can be used as the default response object for all HTTP codes that are not covered individually by the specification.
- A metadata object that allows for more fine-tuned XML model definitions.
- An API definition is important in that it can be used to power automated tools that can ensure the success of your API like interactive documentation and SDKs.
The Reference Object is a JSON Reference that uses a JSON Pointer as its value. For this specification, only canonical dereferencing is supported. The metadata can be used by the clients if needed, and can be presented in the Swagger-UI for convenience.
Parameter Object
Parameter definitions can be referenced to the ones defined here. An object to hold data types that can be consumed and produced by operations. Further information about the properties can be found in JSON Schema Core and JSON Schema Validation. Unless stated otherwise, the property definitions follow the JSON Schema specification as referenced here. The container maps a HTTP response code to the expected response.
As it is programming-language agnostic you can quickly identify and understand service capabilities. You can also use OAS to configure infrastructure, generate client code and create test cases for your APIs. OAS can therefore support your endeavors throughout the API lifecycle, and help you communicate with developer communities both inside and outside your organization. The Link object represents a possible design-time link for a response.
Contact Object
API design and functionality are key factors when choosing to integrate an API with an application. Machine-readable API descriptions (including OpenAPI) were then invented to bring to remote APIs the same degree of robustness that method signatures brought to local APIs. Tools do exist now which check that requests are made in the correct format, or even ensure it by generating the request code themselves. To what is api in simple words begin with, documentation for humans including the list of available methods and their details can be easily generated from the API description file. Done as a step in the build process, this easily prevents out-of-sync docs. In these cases, to find the information they require developers might have to read source code (if available), debug programs or analyze network traffic, which are gigantic time sinks.
A metadata object that allows for more fine-tuned XML model definitions. Here the discriminator value of dog will map to the schema #/components/schemas/Dog, rather than the default (implicit) value of Dog. If the discriminator value does not match an implicit or explicit mapping, no schema can be determined and validation SHOULD fail.
Specification Extensions
Security Requirement Objects that contain multiple schemes require that all schemes MUST be satisfied for a request to be authorized. This enables support for scenarios where multiple query parameters or HTTP headers are required to convey security information. The following example shows a callback where the server is hard-coded, but the query string parameters are populated from the id and email property in the request body. This includes accessing any part of a body that a JSON Pointer RFC6901 can reference. For more complex scenarios, the content property can define the media type and schema of the parameter. A parameter MUST contain either a schema property, or a content property, but not both.
