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. ...

Title and Author of Paper The Volcano Optimizer Generator: Extensibility and Efficient Search. Goetz Graefe and William J. McKenna. Summary The query optimizer’s job is to take user input in the form of SQL and generate a cost-efficient plan for satisfying that query using the underlying physical layout of the database. This paper describes Volcano, a system for taking a data model, logical algebra, physical algebra, and optimization rules and translating them into optimizer source code. ...

Title and Author of Paper Dynamo: Amazon’s Highly Available Key-value Store, DeCandia et al. Summary Dynamo, as the title of the paper suggests, is Amazon’s highly available key-value storage system. Dynamo only supports primary-key access to data, which is useful for services such as shopping carts and session management. Dynamo’s use case for these services is providing a highly-available system that always accepts writes. This requirement forces the complexity of conflict resolution to data readers. Writes are never rejected. ...

Amazon Simple Queue Service (SQS) is a message queue service that allows applications to reliably queue messages from one system component to be consumed by another component. Adding a queue between application components allows them to run independently, effectively decoupling applications by providing a buffer between producers of data and their consumers. Up and Running This section provides a guide to getting up and running with SQS using a fictional music store as an example. This music store has the ability to notify clients of any upcoming events via SQS. ...

Title and Author of Paper Cap Twelve Years Later: How the “Rules” Have Changed. Eric Brewer. Summary This article provides an exploration of the CAP Theorem and how it relates to database system design. The author argues that, since partitions are likely to happen, the system designer can introduce methods for safely recovering from partitions to compensate. This strategy allows the database to continue to provide availability during a partition, and enforce consistency once the partition is resolved. ...

When integrating two independent services you have two options: making a remote procedure call (RPC), or sending a message. Which should you choose? What is a Remote Procedure Call? An organization often needs to share data and processes between multiple independent processes in a responsive way. For example, updating a user’s name in a shipping system may trigger updates in a billing system. The shipping system could update the billing system’s data directly by modifying a shared database, but this approach requires the shipping system to know far too much about the internal processes of the billing system. Instead, the business system can encapsulate the update operation behind an interface in the form of a remote procedure call, or RPC. ...