Hefoki Database Module

Currently, the Hefoki application is written with the intent of being deployed using AWS DynamoDB for a database, but also to have an intermediate class which hides the particulars of that implementation from the application. This allows other persistent storage mediums or communication protocols to be added, and to better isolate application components for testing.

This document describes each data structure's persistent storage model, but this is not intended to directly translate to particular schema design choices for a given data storage medium. Sections with Data Structure in their name are intentionally non-specific. For example, in storing headlines and their metadata, whether a row or document handled by an implementation interface stores one or more headline/metadata entry can vary between implementations: a document store may group multiple headlines into one date with child objects containing metadata; but a future tabular store may have a row for each story, and additional tables for metadata, or encode metadata into JSON stored on a given columns. These details can vary between data store implementations.

Headlines

Headline Data Structure:

A given headline is represented with these fields:

• Date (YYYY-MM-DD string or calendar date, non-unique primary key)
• ExternalLinks (array of URL strings)
• Tags (array of strings)
• Text (String: UTF-8, Natural language, summarizing the story)

The adapter is written to be agnostic regarding whether a single row or document contains one or more headlines.

HeadlinesInterface: Abstract in-memory object interface

HeadlinesInterfaceDynamoDB: DynamoDB interface