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55M model: approx. 15 minutes
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overhead pays off
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4store IncQuery-D Titan IncQuery-D 4store](https://image.slidesharecdn.com/danielvarroserene2014school-141120045708-conversion-gate01/85/SERENE-2014-School-Incremental-Model-Queries-over-the-Cloud-52-320.jpg)
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– Query from the Rete network’s indexer
– Propagation of modifications is fast
Model size [million elements]
4store IncQuery-D Titan IncQuery-D 4store](https://image.slidesharecdn.com/danielvarroserene2014school-141120045708-conversion-gate01/85/SERENE-2014-School-Incremental-Model-Queries-over-the-Cloud-53-320.jpg)
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Different characteristics
Sub-second response
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88M elements
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memory
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4store IncQuery-D Titan IncQuery-D 4store](https://image.slidesharecdn.com/danielvarroserene2014school-141120045708-conversion-gate01/85/SERENE-2014-School-Incremental-Model-Queries-over-the-Cloud-54-320.jpg)
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SERENE 2014 School: Incremental Model Queries over the Cloud
- 1. Distributed Incremental ModelQueries over the Cloud Budapest University of Technology and Economics Department of Measurement and Information Systems Dániel Varró Budapest University of Technology and Economics Fault Tolerant Systems Research Group
- 2. Outline of theTalk Motivation & Background: • Change detection in CPS •Design Space Exploration Incremental Model Queries: The EMF-IncQuery framework • Language - Execution Distributed Incremental Model Queries (IncQuery-D) •Architecture - Performance Benchmarks •Distributed model load • Incremental query evaluation Main Contributors o István Ráth (lead) o Ákos Horváth o Gábor Bergmann o Ábel Hegedüs o Zoltán Ujhelyi o Benedek Izsó o Gábor Szárnyas o Csaba Debreceni o Dénes Harmath o József Makai o Dániel Stein
- 3. Challenges for IoT/ CPS Cyber world Physical world Problem Solution scheme Deployment Service Solution pattern Component service offering Challenge: Detect changes • in system state • in environment Abstractions Design space exploration
- 4. CHANGE DETECTION BY INCREMENTAL QUERIES
- 5. Big Data Analyticsfor CPS Sensors / Services Data and Event sources Cloud based apps Data Store Data Store EvenCtlsoud based Computation Polling Events
- 6. Challenge: Change Detectionin CPS Sensors / Services Data and Event sources Cloud based apps Data Store Data Store EvenCtlsoud based Computation Polling Events ?
- 7. Change Detection inCPS by Incremental Queries Sensors / Services Data and Event sources Cloud based apps Polling Data Store Events Data Store UUnniiffiieedd CChhaannggee DDeetteeccttiioonn bbyy Distributed Incremental Queries Cloud based Computation
- 8. MOTIVATION FOR INCREMENTALMODEL QUERIES
- 9. Motivation: Early validationof design rules SystemSignalGroup design rule (from AUTOSAR) o A SystemSignal and its group must be in the same IPdu o Challenge: find violations quickly in large models o New difficulties • reverse navigation • complex manual solution AUTOSAR: • standardized SW architecture of the automotive industry • now supported by modern modeling tools Design Rule/Well-formedness constraint: • each valid car architecture needs to respect • designers are immediately notified if violated Challenge: • 500 design rules in AUTOSAR tools • 1 million elements in AUTOSAR models • models constantly evolve by designers
- 10. Domain-Specific Modeling Languages Abstract Meta-model Model «type»
- 11. Validation of Well-formednessConstraints Meta-model Model Query pattern switchWOSignal(sw) { Switch(sw); neg find switchHasSignal(sw); } pattern switchHasSignal(sw) { Switch(sw); Signal(sig); Signal.mountedTo(sig, sw); } Modify User Result
- 12. Model sizes inpractice Models with 10M+ elements are common: o Car industry o Avionics o Source code analysis Models evolve and change continuously Validation can take hours Application Model size System models 108 Sensor data 109 Geospatial models 1012 Source: Markus Scheidgen, How Big are Models – An Estimation, 2012.
- 13. MODEL QUERIES AND GRAPH PATTERN MATCHING
- 14. What is amodel query? For a programmer: o A piece of code that searches for parts of the model For the scientist: o Query = set of constraints that have to be satisfied by (parts of) the (graph) model o Result = set of model element tuples that satisfy the constraints of the query oMatch = bind constraint variables to model elements A query engine: Supports o the definitionexecution of model queries Query(A,B) ∧condi(Ai,Bi) • all tuples of model elements a,b • satisfying the query condition • along the match A=a and B=b • parameters A,B can be input/ output
- 15. Graph Pattern Matchingfor Queries route: Route sp: SwitchPosition routeDefinition sensor: Sensor switch: Switch Match: o m: L G (graph morphism) o CSP: • Variables: Nodes of L • Constraints: Edges of L • Domain values: G o Complexity: |G|^|L| L G straight left switchPosition switch sensor All sensors with a switch that belongs to a route must directly be linked to the same route.
- 16. Graph Pattern Matching(Local Search) switchPosition route: Route sp: SwitchPosition switch routeDefinition sensor sensor: Sensor switch: Switch Search Plan: o Select the first node to be matched o Define an ordering on graph pattern edges Search is restarted from scratch each time 1 2 0 3 4 straight left
- 17. Incremental Graph PatternMatching switchPosition route: Route sp: SwitchPosition switch routeDefinition sensor sensor: Sensor switch: Switch Main idea: More space to less time o Cache matches of patterns o Instantly retrieve match (if valid) o Update caches upon model changes o Notify about relevant changes Approaches: o TREAT, LEAPS, RETE, … o Tools: VIATRA, GROOVE, MoTE, TCore straight left route sp switch sensor r1 sp1 sw1
- 18. INCREMENTAL MODEL QUERIES: THE EMF-INCQUERY PROJECT
- 19. EMF-IncQuery: An OpenSource Eclipse Project • Declarative graph query language • Transitive closure, Negative cond., etc. • Compositional, reusable Definition • Incremental evaluation • Cache result set •Maintain incrementally upon model change Execution • Derived features, • On-the-fly validation • View generation, Notifications, Soft links, Databinding, Features http://eclipse.org/incquery
- 20. The IncQuery (IQ)Graph Query Language route: Route sp: SwitchPosition routeDefinition sensor: Sensor Switch: Switch IQ: declarative query language o Attribute constraints o Local + global queries o Compositionality+Reusabilility o Recursion, Negation, o Transitive Closure o Syntax: DATALOG style pattern routeSensor(sensor: Sensor) = { TrackElement.sensor(switch,sensor); Switch(switch); SwitchPosition. switch(sp, switch); SwitchPosition(sp); Route.switchPosition(route, sp); Route(route); neg find head(route, sensor); } pattern head(R, Sen) = { Route.routeDefinition(R, Sen); } ModelQuery(A,B): • tuples of model elements A, B • satisfying the query condition • enumerate 1 / all instances • A,B can be input or output switchPosition switch sensor
- 21. Incremental Query Evaluationby RETE AUTOSAR well-formedness validation rule Communication channel Logical signal Mapping Physical signal Instance model Invalid model fragment Valid model fragment
- 22. Incremental Query Evaluationby RETE Read the changes in the PFrFRioMlileplltoaahtddghea ietftwhyeineottphrrhkueeeetsm rucnhnlootaoddsndeeegeltsess result set (deltas) join join antijoin Result set Communication channel Logical signal Mapping Physical signal
- 23. Performance of EMF-INCQUERY Incremental graph queries based on Rete Built for the Eclipse Modeling Framework model size runtime batch queries incremental queries Runtime is proportional to the size of the modification.
- 24. Performance of EMF-INCQUERY Storing partial memory results consumption incremental queries batch queries memory limit model size
- 25. Selected Applications (EMF-IncQuery) • Complex traceability • Query driven views • Abstract models by derived objects Toolchain for IMA configs • Connect to Matlab Simulink model • Export: Matlab2EMF • Change model in EMF • Re-import: EMF2Matlab MATLAB-EMF Bridge • Live models (refreshed 25 frame/s) • Complex event processing Gesture recognition • Experiments on open source Java projects • Local search vs. Incremental vs. Native Java code Detection of bad code smells • Rules for operations • Complex structural constraints (as GP) • Hints and guidance • Potentially infinite state space Design Space Exploration • Itemis (developer) • Embraer • Thales • ThyssenKrupp • CERN Known Users
- 26. INCQUERY-D: DISTRIBUTED INCREMENTALMODEL QUERIES
- 27. Goals of INCQUERY-D Objectives o Distributed incremental pattern matching o Adaptation of EMF-INCQUERY’s tooling to graph DBs o Executed over cloud infrastructure (COTS hardware) Achieve scalability by avoiding memory bottleneck o Sharding separately • Data • Indexers • Query network o In memory: • Index + Query Assumptions • All Rete nodes fit on a server node • Indexers can be filled efficiently • Modification size ≪ model size • The application requires the complete result set of the query (opposed to just one match)
- 28. Dimensions of Scalability Infrastructure o Number of machines o Available memory / CPU o Network performance o Number of concurrent users Model o Model size o Model characteristics Queries o Number of queries o Query complexity Metrics
- 29. INCQUERY-D Architecture EMF-INCQUERYINCQUERY-D Join Database shard 1 Server 1 Join Database shard 2 Server 2 Triple store (4store), Document DB (Mongo), RDF over Column family Database shard 3 Server 3 Transaction Database shard 0 In-memory EMF model Server 0 Antijoin Rete net Indexer layer Akka Distributed query evaluation network Distributed indexer Model access adapter Indexing Indexer Indexer Indexer Indexer In-memory storage Distributed indexing, notification Production network • Stores intermediate query results • Propagates changes Distributed persistent storage Distributed production network • Each intermediate node can be allocated to a different host • Remote internode (Cumulus) communication
- 30. Termination Protocol inINCQUERY-D Database shard 0 When a production node reached an ACK message is sent back Stack added to each update msg Database shard 1 Server 1 • Registers the Rete nodes the message passes through Database shard 2 Server 2 User retrieves query result Database shard 3 Server 3 Transaction Server 0 INCQUERY-D Join Join Antijoin Indexer Indexer Indexer Indexer
- 31. IncQuery-D Architectural Layers • Gremlin, Cypher • SPARQL • IQPL (IncQuery) High-Level Query Lang • Distributed Indexers (MONDIX) • SPARQL Low-Level Query Lang • Cayley • Titan • 4store Distributed Graph DB • MongoDB • Cassandra • 4store Native Storage • RDF • XMI / Ecore • Property Graphs Storage Format • Global queries • Complex navigations • Efficient element access by indices • Local queries • Can be transparent (via indexers) • Integrates popular graph storages • Efficient NoSQL storages • Triple stores • Standardized data formats • Popular interchange formats
- 32. Summary: Key Componentsof IncQuery-D Distributed Model Storage • Adaptable to different back-end storages • Agnostic to graph repres. • TripleStores (RDF), EMF, Property graph Model Access Adapter • Surrogate key to identify distibuted elements • Graph manip. API • Change notifications Distributed Indexer • Type-instance indices, etc. • Stored on multiple servers • Protects exceeding memory limits Distributed Query Evaluator • Distributed RETE network • Distributed termination protocol • Constructed and deployed by coordinator node Decouple and separately distribute Storage, Indexer and Query layers
- 33.
- 34. Load Model (1)Loading a Query Update Model Request Result Deploy RETE RETE Network Allocate RETE Cloud Infra-structure Construct RETE Load Query Construct RETE • From EMF-IncQuery specs • Should incorporate infrastructure constraints Deploy RETE • Managed by a coordinator node • Intelligent sharding of RETE nodes
- 35. Load Model (2)Loading a Model Update Model Request Result Model shards Deploy RETE RETE Network Allocate RETE Maintain Result Set Cloud Infra-structure Construct RETE Model Access Adapter Load Query Load model • Model traversal • Init indexers • Network communication
- 36. Load Model (3)Updating a Model Update Model Request Result Model shards Deploy RETE RETE Network Allocate RETE Maintain Result Set Cloud Infra-structure Construct RETE Model Access Adapter Load Query Model manipulation • Update messages • Create / Delete
- 37. (4) Requesting QueryResult Load Model Update Model Request Result Model shards Deploy RETE RETE Network Allocate RETE Evaluate Query Maintain Result Set Cloud Infra-structure Construct RETE Model Access Adapter Load Query Evaluate query • Process incoming messages • Propagate along RETE network Retrieve results • instantly
- 38. (5) Monitoring andReconfiguration Load Model Update Model Request Result Model shards Deploy RETE RETE Network Allocate RETE Evaluate Query Maintain Result Set Cloud Infra-structure Monitor Manage Construct RETE Model Access Adapter Load Query Visualized on a web-based dashboard OS metrics JVM metrics Akka metrics Rete metrics
- 39. DEPLOYMENT PROCESS FOR DISTRIBUTED RETE
- 40. RETE Deployment Process Query Language Query Predicates RETE Structure route: Route sp: SwitchPosition routeDefinition sensor: Sensor Switch: Switch Platform Description Allocation / Mapping Deployment Descriptor pattern routeSensor(sensor: Sensor) = { TrackElement.sensor(switch,sensor); Switch(switch); SwitchPosition. switch(sp, switch); SwitchPosition(sp); Route.switchPosition(route, sp); Route(route); neg find head(route, sensor); } pattern head(R, Sen) = { Route.routeDefinition(R, Sen); } switchPosition switch sensor
- 41. Tooling: RDF PatternLanguage import http://www.semanticweb.org/ontologies/2011/1/TrainRequirementOntology.owl pattern posLength(Segment, SegmentLength) { Segment(Segment); Segment.Segment_length(Segment, SegmentLength); check(SegmentLength = 0); } EMF-IncQuery syntax Vocabulary railway.rdf base http://www.semanticweb.org/ontologies/2011/1/TrainRequirementOntology.owl# pattern posLength(Segment, SegmentLength) { Segment(Segment); Segment_length(Segment, SegmentLength); check(SegmentLength = 0); } segment: Segment segment.length 0 RDF-IncQuery syntax Xbase (compiles to Java) Javascript
- 42. RETE Deployment Process Construct language-independent constraints Resolution of o syntactic sugar o type information Query Language Query Predicates RETE Structure Platform Description Allocation / Mapping Deployment Descriptor Variables rroouuttee sspp sswwiittcchh PPaarraammeetteerr sensor Edge: SwitchPosition.switch Edge: TrackElement.sensor Edge: Route.switchPosition Negation: head Constraints
- 43. RETE Deployment Process Construct RETE structure (platform independently) Optimizations: o Model statistics o Expected usage profile Query Language Query Predicates RETE Structure Platform Description Allocation / Mapping Deployment Descriptor join join join
- 44. RETE Deployment Process Architecture model (Cloud infrastructure) o Virtual Machines • Memory limits • CPU speed • Storage capacity o Communication Channels • Bandwidth Specified by a textual DSL (Xtext) Query Language Query Predicates RETE Structure 1 2 3 4 Platform Description Allocation / Mapping Deployment Descriptor
- 45. RETE Deployment Process Machine Allocated Nodes 1 In1, In2, Join2 2 In3 3 In4 4 Join1, Join3 Query Language Query Predicates RETE Structure 1 2 3 4 Platform Description Allocation / Mapping Deployment Descriptor Join1 Join3 Join2 In1 In2 In3 In4
- 46. RETE Deployment Process Configuration scripts for o Deployment o Communication middleware Derived by automated code generation o Using Eclipse technology: EMF-IncQuery + Xtend Query Language Query Predicates RETE Structure Platform Description Allocation / Mapping Deployment Descriptor
- 47.
- 48. The Train Benchmark Model validation workload: o User edits the model o Instant validation of well-formedness constraints o Model is repaired accordingly Scenario: o Load o Check o Edit o Re-Check Models: o Randomly generated o Close to real world instances o Following different metrics o Customized distributions o Low number of violations Queries: o Two simple queries (2 objects, attributes) o Two complex queries (4-7 joins, negation, etc.) o Validated match sets Incremental Batch validation validation Instance model Read Check ! Edit ReCheck 100x
- 49. Evaluation of distributedscalability Extensions to previous work (single workstation) o Generation of large instance models o Distributed, parallel loading of models o Distributed transformation and validation Benchmark Distributed benchmark Model size 1K – 13M 1K – 88M Load method Batch Distributed, parallel Transformation and validation Single workstation Multiple servers
- 50. IncremBenattcahl sgcreanpahr isoce–nIanrciQouery-D Load and first validation: load the graph to the databases and execute initialize the the Rete query net and retrieve the results Transformation: query the incrementally graph query and the delete graph some and delete elements some elements, propagate the changes Revalidation: execute retrieve the query results from the Rete net Load and first validation GraphML Transformation Revalidation DB shards Result set Rete net DB shards Result set Rete net
- 51. Benchmark environment Private cloud Different DBMSs Query o The DBMS’s own query language o IncQuery-D SPARQL Gremlin
- 52. 4096 1024 256 64 16 4 1 Runtime [s] Load and first validation 55M model: approx. 15 minutes Rete network’s initialization overhead pays off Model size [million elements] 4store IncQuery-D Titan IncQuery-D 4store
- 53. 256 128 64 32 16 8 4 2 1 Runtime [s] Model modification 1. Elementary model query 2. Model modification 2 orders of magnitude – Query from the Rete network’s indexer – Propagation of modifications is fast Model size [million elements] 4store IncQuery-D Titan IncQuery-D 4store
- 54. 128,00 32,00 8,00 2,00 0,50 0,13 0,03 0,01 Runtime [s] Revalidation Different characteristics Sub-second response time for models with 88M elements Model size [million elements] memory limit 4store IncQuery-D Titan IncQuery-D 4store
- 55. Benchmarking Conclusions Memory consumption o Single workstation: 13M model, 4 GB o Cloud of four servers: 55M model, 4×8 GB Runtime o Same order of magnitude and similar characteristics to the single workstation tool INCQUERY-D is scalable and significantly more efficient for query evaluation than the native query engines in 4store, Titan and Neo4j
- 56. Applications of DistributedIncremental Queries • Query based optimistic locking • Queries for Attribute Based Access Control Collaborative Modeling (MONDO) • Events vs. Changes • Handle compound changes as events Complex Event Processing w/ compound changes • System evolves along operations • Cost / Objectives associated to • States + Environment + Trajectory Rule-based Design Space Exploration
- 57. CONFIGURATION SYNTHESIS BY DESIGN SPACE EXPLORATION
- 58. TRANS-IMA Project (Avionics) Goal: Allocate SW components to ARINC653 compliant IMA platform 58 Functional Architecture Component database Platform description Allocation Integrated System Model Inputs: • Platform Independent Model (PIM) (functional + nonfunc. reqs; Simulink) • Platform Description Model (PDM) for ARINC 653 (DSL) Output: • Integrated system model • Ready for simulation • End-to-end traceability
- 59. Designing ARINC653 configurations (critical + non-critical) Supply fresh air Supply hot air Monitor temperature Set temperature SW functionality Pack Controller Zone Controller 3 System Display AirCond Panel 3 Redundancy requirement
- 60. Job instances, Partitions,Modules SW functionality (critical + non-critical) Pack Controller Zone Controller 3 System Display AirCond Panel 3 Job instances 1 2 3 4 5 6 7 8 Partitions Modules Constraints 2 5 3 4 8 8 8 8 Memory needs + constraints Do not mix critical and non-crit. jobs Do not mix instances of the same critical job Additional constraints • WCET, • scheduling, etc. • interfaces • datatypes
- 61. Allocating communication channels SW functionality Pack Controller Zone Controller 3 System Display AirCond Panel 3 1 2 3 7 4 5 6 8 Communication channels Humidity Pressure Temperature
- 62. Design Space Exploration Design Space Exploration 62 Design Alternative 1 Design Alternative 2 Design Alternative 3 Design Alternative 4 Objectives Global Constraints Initial Design Solvers • CLP solvers (Choco) • model finders (Alloy) • meta-heuristics + multi-objective optimization
- 63. Design Space Exploration(Example) 63 Consistency Analysis Design Alternative 1 Design Alternative 2 Design Alternative 3 Design Alternative 4 Objectives Global Constraints Initial Design A B x=2 C A A A B x=? C I1 I2
- 64. Design Space Exploration(Example) 64 + Filled Attributes Consistency Analysis Design Alternative 1 Design Alternative 2 Design Alternative 3 Design Alternative 4 Objectives Global Constraints Initial Design A B x=2 C x=? A B x=5 C C C A C O C1 C2 + Objects I1 I2 + Relations
- 65. Rule Based DesignSpace Exploration Design Space Exploration 65 Design Alternative 1 Design Alternative 2 Design Alternative 3 Design Alternative 4 Objectives Global Constraints Operations Initial Design Special state space exploration • potentially infinite state space • „dense” solution space
- 66. Rule-Based Guided DesignSpace Exploration Design Space Exploration 66 Seq of Transf. Rules 1 Seq of Transf. Rules 2 Seq of Transf. Rules 3 Seq of Transf. Rules 4 Model queries as Objectives Model queries as Constraints Transf. Rules as Operations Initial Model Guidance for exploration: Hints • designer / end user • formal analysis
- 67.