Reactive Programming for Databases

by Val Huber (val@espressologic.com) CTO, Espresso Logic, Inc.

April 9, 2014

Topics

• Introduction

• Reactive: what, usage…

• Reactive for Database, using REST

• Demo

– Connecting to a database: create/test default RESTful API

– Reactive Logic: Define, Test and Debug

• Complex Examples

• Q&A

Page 3

Espresso Logic, Inc. Overview

• History– Previous iterations of technology deployed at over 500 Fortune 1000

companies

– Current version in development for 3 years; launched V1.0 in November 2013

• Investors– Inventus Capital, a VC firm founded by Kanwal Rekhi focusing on early stage

firms

– Angel investors include: Anurag Jain (Perot Systems), Gokul Rajaram (Square), Lee Nackman (IBM), Raju Reddy (Hitachi), Saeed Amidi (Plug and Play)

• What we do – Backend-as-a-service to accelerate web and mobile application

– Offered as a service hosted on Amazon, Azure and on premise

• Distribution – Direct and via resellers / integrators

Reactive Programming

What is it, how is it being used

Maintain State (dependencies) over change

Time Statement Imperative Reactive

t0 A = B+C

t1 B = 2 * Recompute A

Define

Watch referenced values

React to changes

Common Uses

• GUI: Change Model, reflect on View (Microsoft active here)

• Spreadsheet– CellA = sum (ColumnB)

• Challenging Problem– Language integration – where’s the model?– Simpler as domain-specific: database… ?

Reacts to inserts, updates and deletes to B

Reactive, RESTand Database

Reactive DB: Conceptual

• Schema is the Object Model

• Add– Derivation Expressions, bound to columns– Validation Expressions, bound to tables

– Imperative Integration

Bal = sum (unpaid order totals)

Bal <= creditLimit

Reactive DB: Architecture

• Triggers

• App Server (but model is fuzzy)

• RESTful DB

TechnologyIndependent

• Mobile• SOA• Public API

RESTful DB

• Perfect start– Tables are resources (find from schema)– GET, POST, PUT and DELETE… – HTTP Arguments for filter, sort

• But not quite enough– Rich Resources (views “business objects”)

Reactive, RESTful

DB

Reactive DB• Schema as Model• Derivation / Validation Expressions

RESTful DB• Schema as Resources• Get, Post, Put, Delete

Golden Spike

• Rich Resources• JavaScript Integration• Security• Test & Debug

Our Take

DEMO

You can sign up for Free Trial@

www.espressologic.com

Technology Evaluation

• Re-use– N clients 3 events 1 rule

• Conciseness– 5 lines of logic is hundreds of lines of triggers

• Maintainability– (Re) Ordering by dependency analysis

• Quality– Execution ensured (per middle tier)

• Performance– Well-known patterns ensured

Examples

• Simple

• Budget Rollup

• Payment Allocation

• Bill of Materials

Summary

• Reactive is like spreadsheet – Used appropriately it can offer you huge

savings in development cost

• JavaScript or some procedural language model needed to augment reactive

• RESTful API to your SQL data – Must have ability to customize, add security,

filtering, pagination, optimistic locking

• Check out video and more examples at http://www.espressologic.com

/resources/