Voyage NoSQL Object Database Damien Cassou, Stphane Ducasse and Luc - - PowerPoint PPT Presentation

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Mar 21, 2024 492 likes •783 views

Voyage NoSQL Object Database Damien Cassou, Stphane Ducasse and Luc Fabresse W4S11 http://www.pharo.org Goal To let you build a real little application Show you a nice way to store objects W4S11 2 / 27 MongoDB Document

SLIDE 1

Voyage

NoSQL Object Database

Damien Cassou, Stéphane Ducasse and Luc Fabresse

W4S11

http://www.pharo.org

SLIDE 2

Goal

To let you build a real little application Show you a nice way to store objects W4S11 2 / 27

SLIDE 3

MongoDB

Document oriented, open-source NoSQL database Powerful query language Most popular document database so far W4S11 3 / 27

SLIDE 4

What is Voyage?

Object-Document Mapper for MongoDB Think on Hibernate for MongoDB For Pharo, obviously ;) W4S11 4 / 27

SLIDE 5

Voyage Feature

Simple Ensure object identity Provide error-handling Implement a connection pool W4S11 5 / 27

SLIDE 6

Setting a Connexion

| repository | repository := VOMongoRepository host: 'localhost' database: 'demo'. repository enableSingleton.

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SLIDE 7

Setting a In Memory Connexion

| repository | repository := VOMemoryRepository new. repository enableSingleton.

Really nice to prototype Then can easily switch to a MongoDB W4S11 7 / 27

SLIDE 8

A Simple Model

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SLIDE 9

A Simpler Model

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SLIDE 10

A Simpler Model

Object subclass: #Hero instanceVariableNames: 'name level powers' classVariableNames: '' package: 'SuperHeroes' Hero >> name ^ name Hero >> name: aString name := aString Hero >> level ^ level Hero >> level: anObject level := anObject Hero >> powers ^ powers ifNil: [ powers := Set new ] Hero >> addPower: aPower self powers add: aPower

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SLIDE 11

A Simpler Model

Object subclass: #Power instanceVariableNames: 'name' classVariableNames: '' package: 'SuperHeroes'. Power>>name ^ name Power>>name: aString name := aString

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SLIDE 12

Root Classes

Entry-point for our database Can be any class in the system Marked as root by isVoyageRoot class method W4S11 12 / 27

SLIDE 13

Root Classes

Hero class >> isVoyageRoot ^ true

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SLIDE 14

Some Heroes

Hero new name: 'Spiderman'; level: #epic; addPower: (Power new name: 'Super−strength'); addPower: (Power new name: 'Wall−climbing'); addPower: (Power new name: 'Spider instinct'); save. Hero new name: 'Wolverine'; level: #epic; addPower: (Power new name: 'Regeneration'); addPower: (Power new name: 'Adamantium claws'); save.

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SLIDE 15

In DB

> db.Hero.find()[0] { "_id" : ObjectId("d847065c56d0ad09b4000001"), "#version" : 688076276, "#instanceOf" : "Hero", "level" : "epic", "name" : "Spiderman", "powers" : [ { "#instanceOf" : "Power", "name" : "Spider instinct" }, { "#instanceOf" : "Power", "name" : "Super−strength" }, { "#instanceOf" : "Power", "name" : "Wall−climbing"

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SLIDE 16

Querying

Hero selectAll. > an OrderedCollection(a Hero, a Hero) Hero selectOne: [ :each | each name = 'Spiderman' ]. > a Hero Hero selectMany: [ :each | each level = #epic ]. > an OrderedCollection(a Hero, a Hero)

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SLIDE 17

Querying 2

Hero selectOne: { #name −> 'Spiderman' } asDictionary. > a Hero Hero selectMany: { #level −> #epic } asDictionary. > an OrderedCollection(a Hero, a Hero)

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SLIDE 18

Querying 3

Hero selectMany: { #level −> #epic } asDictionary sortBy: { #name −> VOOrder ascending } limit: 10

ffset: 0.

> an OrderedCollection(a Hero, a Hero)

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SLIDE 19

Some Operations

Hero count. > 2 Hero count: [ :each | each name = 'Spiderman' ] > 1. Hero removeAll. "Beware of this!" > Hero class hero := Hero selectAll anyOne. hero remove. > a Hero

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SLIDE 20

Defining Document Roots

If you want to query them If you want to share objects between roots W4S11 20 / 27

SLIDE 21

Defining Document Roots

Yes, Hero is a root on the example Power can be a root too (you can “share” powers between

heroes)

Any class can be declared as root, Voyage will manage it

automatically

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SLIDE 22

Defining Document Roots

Power class >> isVoyageRoot ^ true Power new name: 'Fly'; save. Power new name: 'Super−strength'; save. fly := Power selectOne: [ :each | each name = 'Fly']. superStrength := Power selectOne: [ :each | each name = 'Super

−strength'].

Hero new name: 'Superman'; level: #epic; addPower: fly; addPower: superStrength; save.

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SLIDE 23

Important

Reset repository when changing the schema VORepository current reset.

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SLIDE 24

In DB

> db.Hero.find()[0] { "_id" : ObjectId("d8474983421aa909b4000008"), "#version" : NumberLong("3874503784"), "#instanceOf" : "Hero", "level" : "epic", "name" : "Superman", "powers" : [ { "#collection" : "Power", "#instanceOf" : "Power", "__id" : ObjectId("d84745dd421aa909b4000005") }, { "#collection" : "Power", "#instanceOf" : "Power", "__id" : ObjectId("d84745dd421aa909b4000006") } ]

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SLIDE 25

Relationships

Root references (kind of “foreign keys”) Voyage handles cyclic references of root objects Beware, Voyage does not support cyclic references of

embedded objects (yet)

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SLIDE 26

Conclusion

We can easily save objects in MongoDB More information in Entreprise Pharo: a Web

Perspective

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SLIDE 27

A course by and in collaboration with

Inria 2016 Except where otherwise noted, this work is licensed under CC BY-NC-ND 3.0 France https://creativecommons.org/licenses/by-nc-nd/3.0/fr/