UMLtoGraphDB: Mapping Conceptual Schemas to Graph Databases

UMLtoGraphDB: Mapping Conceptual Schemas to Graph Databases

Jordi CabotICREA-UOC

[email protected]

Gwendal DanielInria - Mines Nantes & Lina

[email protected]

Gerson SunyéInria - Mines Nantes & Lina

[email protected]

17/11/2016 UMLtoGraphDB: Mapping Conceptual Schemas to Graph Databases - G. Daniel 2

Introduction

● NoSQL– Scalability– Availability– Performance

● Graph Databases

– Store highly interconnected data● Vertices, edges, properties

– Expressive query language● Gremlin, Cypher

– Social networks, data provenance analysis


Introduction

● Schemaless

Flexible● Non-uniform data● Schema evolutions

Implicit schema defined by data● Need to acquire this knowledge● Specific to each database● Not formally described


Introduction

Hard to integrate in code-generation architectures

– Few options for mapping ER/UML to NoSQL

– Data consistency challenge

– Lack of support for integrity constraints

→ Goal: create a code generation framework

– Map conceptual schemas to graph databases

– Input: UML + OCL

– Output: graph database + graph queries


UMLtoGraphDB

● MDA methodology

– Platform Independent Model (PIM)

● Conceptual schema

– Platform Specific Model (PSM)

● Refines PIM for a specific implementation

– Code generation from PSM


UMLtoGraphDB – Starting Point

● Conceptual Schema

– UML class diagram

● Concepts

● Data structure

– OCL

● Business rules

● Invariants / Constraints


UMLtoGraphDB


UMLtoGraphDB


UMLtoGraphDB


Class2GraphDB Transformation


GraphDB Metamodel

GraphSpecification

+ baseDB : DBType

VertexDefinition

EdgeDefinition

PropertyDefinition

+ Key : String+ Type : PrimitiveType

GraphElement

+ label : String[*]

<<Enumeration>>

PrimitiveType

ObjectIntegerStringBoolean

<<Enumeration>>

DBType

Neo4jOrientDB

vertices *

inEdges *

head 1

outEdges *

tail 1

edges *

properties*


Class2GraphDB

● (Subset of) UML class diagram to GraphDB

– Non-abtract classes → VertexDefinition

– Attribute → PropertyDefinition

– Association (2 classes) → EdgeDefinition

– Association (n classes) → VertexDefinition + EdgeDefinitions

– Association class → VertexDefinition + EdgeDefinitions

– Support for generalization / specialization


Client

+ name : String+ address : String

Order

+ shipmentDate : Date+ deliveryDate : Date+ paid : Boolean

Product

+ name : String+ price : Integer+ description : String

OrderLine

+ quantity : Integer+ productPrice : Integer

PrivateCustomer

+ cardNumber : String

orders

*

1..**

Running Example

context Product inv validPrice:self.price > 0

context Order inv validOrder:self.shipmentData < self.deliveryDate

context Client inv maxUnpaidOrders:self.orders→select(o | not o.paid)

→size() < 3

Running Example - PIM


Class2GraphDB

Class mapping

Product

+ name : String+ price : Integer+ description : String

v1:VertexDefinition

+ label : String = "Product"

p1:PropertyDefinition

+ key : String = "name"+ type : PrimitiveType = String


+ key : String = "description"+ type : PrimitiveType = String


+ key : String = "price"+ type : PrimitiveType = Integer


Class2GraphDB

Association mapping

v3:VertexDefinition

+ label : String = "Order"

v1:VertexDefinition

+ label : String = "Client"

e1:EdgeDefinition

+ name : String = "orders"

tail

head

Client

Order

orders*


Class2GraphDB

Order

Product

OrderLine

+ quantity : Integer+ productPrice : Integer

1..*

*

AssociationClass mapping

v2:VertexDefinition

+ label : String = "Order"

v3:VertexDefinition

+ label : String = "Product"

v4:VertexDefinition

+ label : String = "OrderLine"

e2:EdgeDefinition

+ name : String = "orderLine"

e3:EdgeDefinition

+ name : String = "orderLine"


+ key : String = "quantity"+ type : PrimitiveType = Integer


+ key : String = "productPrice"+ type : PrimitiveType = Integer

tail

head

head

tail


UMLtoGraphDB


OCL2Gremlin Transformation


Gremlin Metamodel

● Gremlin language

– Graph traversal DSL

– Based on the Blueprints API

– Generic query language for graph databases


Gremlin Metamodel

GremlinScript

Instruction

TraversalElement

Step

OutEStep

+ label : String

InEStep

+ label : String

OutVStep

InVStep

FilterStep

. . .

EdgesStep

+ label : String

VerticesStep

+ id : String

instructions*

next

0..1


OCL2Gremlin

● Adaptation of the Mogwaï* query framework

– Gremlin metamodel definition

– Map OCL expressions to Gremlin steps

– Merge created steps into traversals

– Generate query code from Gremlin AST

* G. Daniel, G. Sunyé, and J. Cabot. Mogwaï: a Framework to Handle Complex Queries on Large Models. In RCIS 2016, Grenoble, FR,June 2016


OCL2Gremlin

context Product inv validPrice:self.price > 0

context Order inv validOrder:self.shipmentData

< self.deliveryDate

context Client inv maxUnpaidOrders:self.orders→select(o | not o.paid)

→size() < 3

// validPricev.property(''price'') > 0;

// validOrderv.property(''shipmentDate'') < v.property(''deliveryDate'')

// maxUnpaidOrdersv.outE(''orders'').inV

.filter{it.property(''paid'') == false}.count() < 3


UMLtoGraphDB


Graph2Code


Graph2Code

● Generate Java beans

– Adapter pattern

● Delegate to database objects

● Lightweight implementation

– Bean factory

● Create new elements

● Reifies database objects


Graph2Code – Client Classpublic class Client extends BlueprintsBean {

public Client(Vertex v, Graph graph, UMLModelFactory factory) {super(v,graph,factory);

}

public String getName() {return (String) this.vertex.property(''name'').value();

}

public void setName(String newName) {this.vertex.property(''name'', newName);

}

public List<Order> getOrders() {Iterator<Vertex> otherEnd = this.vertex.vertices(Direction.OUT,"orders");return new GremlinIterator<Order>(otherEnd, factory);

}

public void addOrder(Order newOrder) {this.vertex.addEdge(“orders”, newOrder.getVertex());

}


Graph2Code – Client Class

[...]

public boolean checkMaxUnpaidOrders() {return this.graph.traversal().V(this.vertex).out(''orders'').filter(

v -> v.get().<Boolean>property(''paid'').value()).count().is(P.lt(3)).hasNext();

}

}


Tooling

● Set of open-source eclipse plugins

– ATL: Model-to-model transformations● ~ 110 rules / helpers

– XTend: Code generation

● Full stack execution: less than 5 seconds


Conclusion

● Chain of model transformations

– UML (class diagram) to GraphDB

– OCL to Gremlin

– Graph to code transformation

● GraphDB metamodel

● Future Work

– Refactoring operations at the PSM level

– Cover multiple database types

– Reverse engineering


Questions?

Websites / Repositories

UMLtoGraphDB: https://github.com/atlanmod/UML2NoSQL

Mogwaï: https://github.com/atlanmod/Mogwai

https://github.com/atlanmod

Thank you for your attention!

https://github.com/SOM-Research

https://github.com/atlanmod/UML2NoSQL

https://github.com/atlanmod/Mogwai

https://github.com/atlanmod

https://github.com/SOM-Research

Presentations & Public Speaking

UMLtoGraphDB: Mapping Conceptual Schemas to Graph Databases