Budapest University of Technology and EconomicsFault Tolerant Systems Research Group

TOOLS Europe 2012Prague, Czech Republic, 2012. 05. 30.

Integrating Efficient Model Queries in State-of-the-art EMF Tools

Gábor Bergmann, Ábel Hegedüs, Ákos Horváth, István Ráth, Zoltán Ujhelyi and

Dániel Varró

Overview Introduction EMF-INCQUERY overview Transparent query integration Performance considerations Conclusion

MDE today

REQ

SD

IMP

TST

Modeling techniques

IDE

Integrated model-driven tools

Model-based early

analysis Architecture modeling,

DSMLsCode

generation, model-assisted development

Model-based test generation

MDE today

REQ

SD

IMP

TST

Modeling techniques

IDE - Eclipse

Eclipse Modeling Framework

A key problem of MDE Scalability vs. modeling tools

o Issues encountered by several industrial partners using tools based on the Eclipse Modeling Framework (EMF)

o Modeling scenarios can get really complex really quickly• Instance models of size 1-2M and beyond• Performance issues with model transformations and code

generators have an adverse effect on everyday development tasks

Scalability?o Complex

(meta)modelso Large instance modelso Complex query and manipulation scenarios

Recognized e.g. by AUTOSAR tool vendorshttp://wiki.eclipse.org/Auto_IWG_WP2

Focus: model queries Model queries: “a piece of code that retrieves a given set of the

model” Queries are at the heart of MDE

o Every model access/read is a (simple) queryo More complex: Views, content providerso Most complex: Model transformations, code generators, …

Query performance (= the speed of content retrieval) is crucialo First vs. consecutive vs. throughputo Query result vs. query contents

Core problems1. Slow query engines 2. Considerable programming effort necessary to get complex

queries right

EMF-INCQUERY

Overview EMF-INCQUERY: a model query engine

o Supports batch querieso Optimized for incremental queries!

Incremental evaluationo Based on the RETE algorithmo Compute once, update afterwardso Gain: Instant re-evaluationo Price: Uses some more memory• Manageable with proper life cycles

Query engine

RETE networkInput nodes

Intermediate nodes

Outputnodes

Deltamonitor

EMF instance model

Generated query components

Input = Model contents + changes (EMF notifications)

Output = Query results + (subsequent) Query result deltas

Query definition

Benefits of EMF-INCQUERY Makes on-the-fly well-formedness validation, view

maintenance, … feasible over really large instance models

Simplifies writing really complex querieso Graph pattern languageo Highly reusable query libraries

Easy-to-integrate into existing appsoWorks with any EMF domain metamodelo Integrates through Eclipse standards works with

many EMF-based apps out-of-the-box

DEMO School metamodel in EMF

INCQUERY Pattern Language

INCQUERY Pattern Language

Expressive declarative query language by graph patterns

Capture local + global queriesCompositionality + Reusabilility „Arbitrary” Recursion, Negation

New features with version 0.6 Tools

o Xtext2-based language• Content assist (code completion), validation, outline, …

o Unique query language features• Unlimited recursion and transitive closure• Aggregate functions• Match/exceed the expressive power of OCL, while providing more

flexible re-use

Runtimeo Build and execute queries on-the-flyo Strong generative bindings to Javao Efficient incremental transitive closure

INCQUERY Development Tools

Query Explorer

Pattern Editor

Queries are applied & updates on-the-fly

• Works with most EMF-based editors out-of-the-box

• Reveals matches as selection

INCQUERY Model Validation

Markers in the Problems View

Standard Eclipse BPMN Editor

• Works with most EMF-based tools out-of-the-box

• Manages error-warning markers on-the-fly as the user is editing the model = Instantaneous feedback

TRANSPARENT QUERY INTEGRATION

… beyond the development tools

<<derived>>

<<derived>>

<<derived>>

Derived features in EMFDerived features:• Supported by auxiliary

mechanisms (e.g. Java, OCL)• Supported by EMF-based

tools out-of-the-box

Derived edges:• Binary relationships• Supported by binary

INCQUERY patterns

Derived attributes:• Typed scalar values• Supported by

INCQUERY derivatives

INCQUERY derivatives

Derived attribute “hasPrimeWeight”:

True iff pattern “coursePrimeWeight”

matches to host C

You can combine IQPL with (side-effect free, deterministic) Xbase

Key benefits:• Automatic

dependency-aware change notifications for derived features

• Instantaneous result retrieval

PERFORMANCE BENCHMARK

Instantaneous result retrieval?

Benchmarking scenario In-memory models

o Embedded railways control software system design domaino Instance models up to 2.7M elements

Scenario: well-formedness validationo 5 rules, from simple to very complexo Batch validation: loading models + executing querieso On-the-fly revalidation: modifying models + re-executing

queries instantaneously Tools

o Eclipse tools (OCL, INCQUERY, EMF-Java)o RDF/SPARQL engines (for comparison)

http://viatra.inf.mit.bme.hu/publications/trainbenchmark

Revalidation on-the-fly

• Incremental EMF engines typically 5-10x faster

• sub-100ms response times for up to 1.5M elements

SPARQL tools are generally 1-2 Orders-of-Magnitude (OM) slower

than top EMF tools

A closer look at the top

Performance advantage of OCL-IA over OCL is not significant with

complex queries

INCQUERY is 1-1.5 orders-of-magnitude

faster than OCL-IA

Memory usage

• Incremental engines impose a linear memory consumption overhead

• INCQUERY overhead is larger than OCL-IA

• Even the largest models fit into 1GB of RAM

Final points EMF-INCQUERY has been proposed as an

Eclipse.org project under EMFT http://www.eclipse.org/proposals/modeling.emf.incquery/

EMF-INCQUERY 0.6 preview release is available immediatelyo Pointers:

http://viatra.inf.mit.bme.hu/incquery http://viatra.inf.mit.bme.hu/incquery/getting_started http://viatra.inf.mit.bme.hu/performance

Release 0.6 is scheduled shortly after the Eclipse Juno Launch (beginning of July)

Acknowledgements Additional development team members

oMárk Czotter, Tamás Szabó Performance benchmarking

o Benedek Izsó, Zoltán Szatmári Testing, examples

o Attila Csicsely, Tamás Csurgó, Dániel Kávássy, Gábor Szárnyas, Tamás Tóth

Thank you very much!