Classifier Noun Annotation in Vietnamese Treebank

DEVELOPING A TOOL TO VERIFY TRIGGERS IN DBMS Supervisor : Assoc Prof Dr Truong Ninh Thuan Co-supervisor : MSc Le Hong Anh Student : Dang Minh Dung Outline Motivation Background S2B tool Conclusion and future works Motivation No table employee yet Example Some SQL statements are only checked when they execute  How we can verify the correctness of database systems with triggers in early design phase? Infinite loop Example Motivation  In a previous work [1], a new method was introduced by using Event-B formal method to solve above issue  Our contribution is building a tool (called S2B) which can automatic translate form database systems to event-b models and partly supports modelling process with the Rodin platform [1] Hong Anh Le, and Ninh Thuan Truong "Modeling and verifying DML triggers using event-B." Intelligent Information and Database Systems Springer Berlin Heidelberg, 2013 539-548 Database systems  Tables (T)  Constraints (C)  Triggers (G)  ECA (Event – Condition – Action) form TRIGGER Event Condition Generalize Actions WHEN BEGIN END; Event-B Event-B is a formal method for system-level modelling and analysis Key features: • using set theory as modelling notation • using refinement to represent systems at different level • Using mathematical proof to verify consistency  Context A context describes the static part of a Event-B model  Machine A machine describes the dynamic behaviour of a Event-B model o Event Event describe when and how machine state changes over the time Event also has the form of an EAC  Rodin The Rodin Platform is an Eclipse-based IDE for Event-B 7 S2B Tool  Main function: translate from database system to event-b model  Other function: Detect some compilation errors S2B tool architecture Database Adapter  Functionality: connect to database and dump its schema  Input: database URL for example: E:\SQL-to-EventB\res\test\db\demo.db  Output: database schema in SQL statements form  Currently, our tool only support SQLite  Using JDBC to connect to database  Use following statement to get schema: SELECT sql FROM (SELECT * FROM sqlite_master UNION ALL SELECT * FROM sqlite_temp_master) WHERE type!='meta' ORDER BY tbl_name, type DESC, name SQL Extractor  Functionality: eliminate redundant information and transform schema into a standard form  steps: o Parsing SQL statements o Normalizing database models  Step 1: Parsing SQL statements o Using ANTLR library o Define SQLite grammar then ANTLR generate lexer and parser o Output: Abstract Syntax Tree (AST) Abstract Syntax Tree 10 SQL Extractor  Step 2: normalizing database models o Reasons for normalizing database models  AST is sequential access  Exists opposite statements as CREATE, ALTER, DROP in schema  Unnecessary statements as DML statements (INSERT, UPDATE, DELETE)  We want to create a unified format across DBMS schema o Use visitor design pattern to travel AST  Extend default visitor  Use symbol table to manager identifiers o Output: database models – a unified form of schema o After SQL extractor module, we can detect some compilation errors… S2B Translator 11  Functionality: translate form database model to event-b model  Base on bellow translation rules[1]: Database definitions Event-B concepts Rule 𝑑𝑏 = 𝑇, 𝐶, 𝐺 Rule Table 𝑡 ∈ 𝑇 𝑇𝑎𝑏𝑙𝑒 = 𝑇𝑦𝑝𝑒1 × 𝑇𝑦𝑝𝑒2 × ⋯ × 𝑇𝑦𝑝𝑒𝑛 Rule Primary key constraint Invariant 𝑝𝑘: 𝑑𝑜𝑚(Type1 × ⋯ × 𝑇𝑦𝑝𝑒𝑖 ) ⤖ 𝑟𝑎𝑛(Typei+1 × ⋯ × 𝑇𝑦𝑝𝑒𝑛 ) Rule Constraint 𝑐 ∈ 𝐶 Invariant 𝑖 Rule Trigger 𝑔 ∈ 𝐺 Event 𝑒 𝑑𝑏𝐶𝑜𝑛𝑡𝑒𝑥𝑡, 𝑑𝑏𝑀𝑎𝑐ℎ𝑖𝑛𝑒 [1] Hong Anh Le, and Ninh Thuan Truong "Modeling and verifying DML triggers using event-B." Intelligent Information and Database Systems Springer Berlin Heidelberg, 2013 539-548 12 S2B Translator MACHINE dbMachine SEES dbContext VARIABLES t1_rec t2_rec t1_pk t2_pk INVARIANTS inv1 : t1_rec ∈ P(table1) inv2 : t2_rec ∈ P(table2) inv3 : t1_pk ∈ TYPE1 ⤖ TYPE2 inv4 : t1_pk ∈ TYPE3 ⤖ TYPE4 inv5 : I EVENTS Event G1 = Event G2 = END A part of Event-B specification of database system 13 S2B Translator  Trigger and event both have the form of an ECA (EventCondition-Action)  A trigger is translated to an Event-B event: TRIGGER EVENT WHEN WHEN BEGIN THEN END; END 14 S2B Translator  Translation of trigger actions: SQL EVENT-B INSERT INTO T VALUES (value1, value2, … valuen) ANY r WHEN r ∈ T ∧ e ∧ c THEN T := T ∪ r END DELETE FROM T WHERE (column1 = some_value) ANY v WHEN v ∈ TYPE ∧ e ∧ c THEN T := {v} ⩤ T END UPDATE T SET column1 = value1, column2 = value2,… WHERE (column1 = some_value) ANY u WHEN u ∈ T ∧ e ∧ c THEN T := T ◁ u END ⩤ : is domain subtraction operator ◁ : is relational override operator S2B Translator 15  In order to • decouple translation implementations form database model • Create a common API for all database elements We apply visitor design pattern  Translation rules are implemented directly 16 S2B Translator // S2BTranslator.java public void translateSchema(Schema database){  Translating algorithm rodinPrj = new RodinProject(database.getName()); preTranslate(); for (Table tbl : database.getTables()) { Translate each table translate(tbl); } for (Trigger trg : database.getTriggers()) { translate(trg); Translate each trigger } postTranslate(); } public void translateTable(Table table){ Implementation of table translation } public void translateTrigger(Trigger trigger){ Implementation of trigger translation } 17 Event-B Builder  Functionality: export event-b models into a Rodin project  Rodin files are XML-base files  Using a template engine call StringTemplate to help generating Rodin files 18 Experiments  Experiments Generated Event-B project after imported into Rodin S2B tool Parse GUI Tree Inspector Packages in S2B tool 19 Conclusion and future works  Conclusion o First step building successfully S2B tool o Partly support modelling database systems  Future works o Expends translations rule o Decouple rules into separated files o Support other DBMSs 20 Thanks for listening  ... modelling process with the Rodin platform [1] Hong Anh Le, and Ninh Thuan Truong "Modeling and verifying DML triggers using event-B." Intelligent Information and Database Systems Springer Berlin... Rule Constraint