CHAPTER 11: MODEL TRANSFORMATION Transformation Definition - PowerPoint PPT Presentation

Architecture and Modelling of Information Systems (D0I71A) Prof. dr. Monique Snoeck CHAPTER 11: MODEL TRANSFORMATION Transformation Definition Transformation Tool

2 Agenda  Model Transformations  General approach  Transformation Rule Examples  General Architecture  The Enterprise Layer  The Event Handling Layer  Transformation Technology Example Transformation Definition Transformation Tool 18:12

3 General Approach transformation engine models models or code transformation definition Transformation Definition Transformation Tool 18:12

4 General approach to transformations  Develop software manually  Look for patterns that are best practices  Define Transformations based on patterns  = Pushing patterns "below the water line" Transformation Definition Transformation Tool 18:12

5 Pushing Best Practices “below the line”  DATABASE MGT SYSTEM (20xx)  FLAT FILE (198x)  Application  Application  Record insertion  record insertion  record deletion  record deletion  record search  record search  sorting  sorting  indexing  indexing  storage  storage Transformation Definition Transformation Tool 18:12

6 Pushing Best Practices “below the line”  Traditional  MDA Specifications Specifications Object Other Interaction Object Architectural Pattern Other Interaction Pattern Architectural Pattern OO –relational Pattern Storage Pattern OO –relational Storage Pattern Code Code Transformation Definition Transformation Tool 18:12

7 Agenda  Model Transformations  General approach  Transformation Rule Examples  General Architecture  The Enterprise Layer  The Event Handling Layer  Transformation Technology Example Transformation Definition Transformation Tool 18:12

8 General Transformation Architecture Business Process Business Process Engine Models User Interface Information Transactions System Services Queries Domain Event Handling Model Layer Enterprise Layer Persistence + Business Logic Transformation Definition Transformation Tool 18:12

9 Agenda  Model Transformations  General approach  Transformation Rule Examples  General Architecture  The Enterprise Layer  The Event Handling Layer  Transformation Technology Example Transformation Definition Transformation Tool 18:12

10 The Enterprise Layer  The Database Schema Domain Model Enterprise Layer Persistence + Business Logic  Associations  Navigability: one way or both ways ?  Cardinality of ‘one’  transform to ‘many’ ?  Optimisations  Merge classes for ‘mandatory-one’ dependencies ? Transformation Definition  Merge classes for ‘optional-one’ dependencies ? Transformation Tool 18:12

11 The Enterprise Layer  The Database Schema = PSM for the EDG (=PIM) Class Project  Foreign Key from Dependent to Master private Department owningDept Class Department  Navigation from master to dependent too ? private SET(Project) projects Class Employee  Transform cardinality of ‘one’ to ‘many ‘? private SET(DeptAssignment) assmtHistory Class Employee Transformation  Merge Employee and DeptAssignment into Definition private Department mydepartement one database class ? Transformation Tool 18:12

12 The Enterprise Layer  The Business Logic Domain Enterprise Layer Model Persistence + Business Logic Transformation Definition Transformation Tool 18:12

13 The Enterprise Layer (Business Logic) Business Logic Database Layer Abstract Class Object Type Implementation Class Factory 1 method per event type the object type participates in + 1 method for checking the corresponding preconditions Attribute of Attribute in Object Type Implementation Class Association Association Attribute Object Type Transformation in Implementation Class Definition participates in Transformation Tool 18:12

14 The Enterprise Layer (Business Logic) Business Logic Database Layer Abstract state class (associated with mapped class) Object Type's For each State of the FSM, a State subclass of FSM the mapped Abstract state class Per mapped State subclass, methods for checking state con- ditions for each event in of the mapped Abstract state class Transformation Definition Transformation Tool 18:12

15 The Enterprise Layer (Business Logic)  Preconditions  Code can be injected in different places  In a check-event method in business layer or in the event handling layer  Example:  checking a precondition for a returnDate to be later than today Public boolean isValidReturnDate (Date d){ return d.compareTo(today) > 0 } … if isValidReturnDate(input_returnDate) { this .returnDate = input_returnDate; } else { throw new RuntimeException("return date is not valid.");} Transformation Definition Transformation Tool 18:12

16 Agenda  Model Transformations  General approach  Transformation Rule Examples  General Architecture  The Enterprise Layer  The Event Handling Layer  Transformation Technology Example Domain Event Handling Model Layer Transformation Definition Transformation Tool 18:12

17 (Recap) A Business Event is ...  A request to perform an activity to register something that happens or that you would like to happen in the real world. Transformation Definition Transformation Tool 18:12

18 (Recap)The Object Event Table  identifies Business Event Types  identifies Object Types  models participation of Object Types to Business Event Types with an Object-Event-table  (Decide on notification & coordination pattern later at implementation time) Transformation Definition Transformation Tool 18:12

19 (Recap)The Object Event Table  In Merode, a business event is a request + an activity  request can be refused   When filled, a cell specifies what preconditions are imposed on a business event by a business object type  Activity is distributed across participants  (assuming that the request has been accepted)   when filled, cell specifies what the effect is of that business event on the participating business object type (modified attributes, operation to call), Transformation Definition Transformation Tool 18:12

20 Transforming the OET to code OET-table ( PIM )   No immediate transformation to code ... Transform to UML- PSM   Define collaboration diagram  Transform Collaboration Diagram to code MERODE OET UML PSM/ Collaboration Code Diagram Messaging Pattern ?  1 pattern, applicable to all event types !   Transparent  Maintenance easier Transformation tot non-OO platforms possible as well  Transformation Definition Transformation Tool 18:12

21 Business Event Handling 1. Tasks Event Dispatcher Check Preconditions of all participants  By Event Dispatcher  By rule engine  By Objects/Components  Notify Event (broadcast) to participants  Co-ordinate answers  Check first – do then  Do & compensate  2. How many Event Dispatchers ? Centralised versus Distributed  one event handler for all events (maximally centralised)  one event handler per event (maximally distributed)  Transformation Definition Transformation Tool 18:12

22 Mapping Platform Independent Model Business Event Object Object/Event  Involvement Mapping Platform Specific Model Mapping Rules for - Event Triggering - Precondition verification - Event Notification - Coordination of Event Execution Platform Choice - Programming Languages -EAI Middleware -Web Service Technology Transformation Definition -- ... Transformation Tool 18:12

23 Sample Event Handling Patterns Messaging Pattern should take care of:   Event Notification to participants, precondition checking, Coordination of Event Execution Scheme 1: Forwarding  1  Not standardised ⇒ Must be designed for each event type separately  More difficult to maintain  E.g. take inspiration from OO-SSADM (UK)  co-ordination of method invocation starts at home-entity  Merode  Forwarding can start in event owner Scheme 2: Broadcasting  2  one event handler per event (event class)  (option chosen in code-generator)  one event handler for all events of one type (C/M/E event dispatchers)  (option chosen in JMermaid) Transformation Definition Transformation Tool 18:12

24 Event Forwarding  In MERODE all receiving objects are connected with ED-relationship  Initiate forwarding in Owner of Event  Forward to Masters Questions  How to ensure atomicity ?  What if more than one Owner for an Event ?  What with Event-preconditions ? (= preconditions for event in general, not for a method in a class) Transformation Definition Transformation Tool 18:12

25 Event Forwarding: example scheme  General outline: PRODUCT TYPE Check first Do then (4) Checkmodify_quantity OK (4) modify_quantity Done PRODUCT ORDER OK (3) Check modify_quantity Done OK (3) modify_quantity (2) Check modify_quantity Done (2) modify_quantity ORDER LINE (1) Check modify_quantity Transformation Definition (1) modify_quantity Done Transformation Tool 18:12