Kaiso: Modeling Complex Class Hierarchies with Neo4j - David Szotten @ GraphConnect London 2013

© Lifealike Limited, 2013.

Kaiso -‐ an object persistence framework for Python and Neo4j

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David Szo>enonefinestay

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@szo;en github.com/davidszo;en


Overview

• About onefinestay

• We care about homes

• How we track our homes using Neo4j

• Kaiso demo

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© Lifealike Limited, 2013.�3

onefinestay -‐ the unhotel


onefinestay -‐ the unhotel

• Guests live like a local – but with services and ameniNes of a hotel

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• Members with disNncNve homes earn hassle-‐free income

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• From just a handful of homes in 2010 to over 1000 homes in 4 ciNes in 2013

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How do we do it?

• Provision: Home ⇒ Unhotel

– Clean – Pack away certain items • Make wardrobe space

• Deprovision: Unhotel ⇒ Home

– Clean – Put everything back

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We care about our homes. A lot.

• Every home is different

• We require inNmate knowledge

!• For guests: “I can’t walk up stairs”, “Where is the iron?”

• For members: “Please put my fragile vase away before

the guests arrive”

• For us: “How much bed linen do I need to take to this

home for this booking?”

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Previous system

• Custom storage soluNon

• Dates back to when we were much smaller

• Problems:

– Siloed

– Hard to query ⇒ denormalised copies

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New system

• Want to model our homes – both layout and contents !

• Need flexibility – Our needs are likely to grow and change !

• Track not only objects, but their classes – Ideally treat the taxonomy itself as data

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Enter Neo4j

• Handle complex data structures

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• Ensure extensibility for future needs

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• Easy to create powerful queries

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• Makes for a nice conceptual model of our data

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Flexibility requirements

• We want to associate informaNon with classes as well as objects – This dishwasher is of make Electropool

– (All) appliances need PAT tesNng !

• Unlike convenNonal object mappers, the taxonomy/class hierarchy needs to be editable by users, and so should be part of the data

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Kaiso -‐ an object persistence framework

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# (import some stuff)!!class Animal(Entity):! id = Uuid(unique=True)! name = String()! friend_of = Outgoing(FriendOf)!!class Carnivore(Animal): pass!class Herbivore(Animal): pass!!class Penguin(Herbivore):! favourite_ice_cream = String()!!class Lion(Carnivore):! n_siblings = Integer()!


Kaiso: Create some instances

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# import types, connect to db!!manager = Manager("http://localhost:7474/db/data/")!!manager.save(Lion)!manager.save(Penguin)!!# create some instances!fred = Penguin(name="Fred")!tom = Lion(name="Tom")!!relation = FriendOf(fred, tom)!!manager.save(fred)!manager.save(tom)!manager.save(relation)


Instances are saved in the graph...

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[7] Lion: TomFRIENDOF

[6] Penguin: Fred


... and so is the class hierarchy

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FRIENDOF

[1] Type: Animal

[7] Lion: Tom[6] Penguin: Fred

[5] Type: Penguin

[4] Type: Herbivore [2] Type: Carnivore

[3] Type: Lion

ISA ISA

ISAISA

INSTANCEOF INSTANCEOF


Kaiso: Queries based on the type hierarchy

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START! Herbivore=node:persistabletype(id="Herbivore"),! Carnivore=node:persistabletype(id="Carnivore")!!MATCH! Carnivore <-[:ISA*]-()<-[:INSTANCEOF]-(carnivore),! Herbivore <-[:ISA*]-()<-[:INSTANCEOF]-(herbivore),!! (herbivore)-[:FRIENDOF]->(carnivore)!!RETURN! "The herbivore",! herbivore.name,! “is a friend of the carnivore",! carnivore.name;!!=> +--------------------------------------------------------------------+!=> | "The herbivore" | "Fred" | "is a friend of the carnivore" | “Tom" | => +--------------------------------------------------------------------+


Thank you

QuesNons?

!

!

Kaiso

github.com/onefinestay/kaiso

!github.com/davidszo;en

@davidszo;en

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Technology

Kaiso: Modeling Complex Class Hierarchies with Neo4j - David Szotten @ GraphConnect London 2013