Api

Comparing Swagger with Thrift or gRPC

I’ve been asked recently, what’s the difference between Swagger and Thrift (or gRPC)? Although they look similar, they solve fundamentally different problems. Let’s look at the differences. Swagger At the most basic level, Swagger is a REST API specification language. The great part is that there is an entire ecosystem of tools built around this specification language to support API design, client and server code generation, and interactive documentation. [Read More]

Checking for null in an API Gateway transform

Amazon’s API Gateway provides the ability to transform a response from an endpoint into a different format for return to the client. One thing I wished to accomplish with this was to return a value to the client, only if it was set in the response. Essentially, I wanted to check for the existence of a JSON property in the response, and react accordingly. The solution was not obvious to me, and this post serves to record that solution for posterity. [Read More]

Configuring REST-assured for Amazon API Gateway

As part of testing our Amazon API Gateway deployment, we set up JUnit tests to run automated Swagger/OpenAPI validation using Swagger Request Validator and REST-assured. This allows us to write simple tests in a fluent style, with automatic validation that requests and responses match the Swagger API specification deployed to API Gateway. given() .log().all() .filter(validationFilter) .when() .post("/oauth2/token") .then() .assertThat() .statusCode(200); Out of the box, REST-assured does not work with Amazon’s API Gateway endpoints using Java 8. [Read More]

Understanding API Gateway Payload Mappings

Amazon’s API Gateway provides the facilities to map an incoming request’s payload to match the required format of an integration backend. API Gateway Payload Mapping API Gateway uses the concept of “models” and “mapping templates” to specify the mapping between the client payload and the server payload. Models A model defines the structure of the incoming payload using JSON Schema. The model is an optional, but not required, piece of API Gateway. [Read More]

Securing a Swagger API with OAuth2

In our previous article on Swagger, we defined a Player API modelling GET access to a Player resource. In this article, I show how to use Swagger’s security models to to deploy this API using an OAuth2 configuration. Swagger handles authentication and authorization using a combination of a “Security Definitions” Object and a list of “Security Requirements” Objects. Each of these definitions are applied at the top-level of your Swagger specification. [Read More]

How to deploy a Swagger specification to Amazon API Gateway using CloudFormation

Full sample code for this article is available on Github. Aamazon’s API Gateway supports the direct importing of Swagger specification files using CloudFormation rules. To do this, you have two choices. Injecting the swagger.json or swagger.yaml file directly into the Body field of the CloudFormation template, or uploading the swagger.json or swagger.yaml file to an S3 location and setting that location as the BodyS3Location field of the CloudFormation template. [Read More]

Designing a Swagger API

The goal of Swagger is to define a standard interface for describing REST APIs. In an ideal world, a Swagger definition for your API will allow both humans and computers to discover and understand your API. At it’s core, Swagger is a formal specification of an API. Surrounding this specification are a wide swath of tools to support creating documentation, providing client libraries, and managing API deployments. One of Swagger’s original goal was to provide a way to document an API in both a human and machine readable way. [Read More]

Understanding JSON Patch

The typical update cycle for an API resource is to (1) GET the representation, (2) modify it and (3) PUT back the entire representation. This can waste bandwidth and processing time for large resources. An alternative is to use the HTTP PATCH extension method to only send the differences between two resources. HTTP PATCH applies a set of changes to the document referenced by the HTTP request.

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How to Version a REST API

API versioning is a fact of life. Even the most well designed API changes as new features and relationships are uncovered. Unfortunately, updating an API is seldom as simple as changing the behaviour of our existing URL endpoints on her he server. If we have existing clients we need to explicitly advertise breaking changes in a seamless way. This article explains a few methods of specifying breaking changes that offer a clear upgrade path for existing API clients.

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