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. ...

The web supports a global network of billions of devices and users, and a key component of this support is effectively caching frequently accessed data along the request-response path. One of the key benefits in adopting a REST architectural style for your system is being able to leverage this existing infrastructure, taking advantage of the billions of dollars of investment already made in the web, and promoting loose coupling, performance and scalability. ...

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. Attempting to use it results in a handshake error when connecting to the API Gateway endpoint. ...

Title and Author of Paper Robust Query Processing through Progressive Optimization. Markl et al. Summary Traditional query optimizers choose an execution plan for a query by using estimates of current database statistics. However, these estimates may be inaccurate, leading to overly expensive query plans being chosen and executed. This paper presents progressive query optimization, allowing query execution to detect and recover from estimation errors during processing. During each execution step, progressive query optimization (POP) detects differences between the cardinality of the currently processed tuple and compares that to the estimated cardinality that was used to define the original execution plan. If those cardinalities differ enough, POP will re-optimize the query using updated estimates of cardinality. Any materialized views already computed can be reused during the re-execution step. ...

The decision to build products using a service-oriented (or microservice) architecture has enormous technical and organizational impact that is reflected in everything from how teams write code, to how they communicate, to how the organization itself is structured. Given the breadth and depth of impact this decision has, it pays to reflect on why an organization chooses a service oriented architecture, how an organization can support such an architecture, and how teams and individuals can support the organization in successfully adopting a service oriented platform. ...

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. By providing a model, you make it easier to define the upcoming mapping template that actually does the transformation between the client and server. ...

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. ...

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. A minimal YAML template is listed below: ...

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. Swagger provides such a documentation format for RESTful APIs. By augmenting this documentation format with tools for API clients and developers, Swagger grew into an ecosystem providing for API developers and consumers. ...

As someone who is being recently re-introduced to the Java platform, there are a lot of components and pieces to become familiar with. One of those pieces is OSGi, a service registry and deployment specification for Java apps. The OSGi specification describes a complete environment for running Java applications as components. Each component is a bundle that can be remotely installed, started, stopped, updated or uninstalled. In addition, OSGi provides a service registry that allows existing services to detect the addition or removal of other services and adapt accordingly. ...