Active Object-oriented DBMS Case Study Using Ode

1
Active Object-oriented DBMS Case Study Using Ode

• Khanh Le
• Email khanhle_at_us.ibm.com

2
Topics

• Introduction to Ode.
• What is Ode?
• O Database Facilities
• Using Ode to implement a home security system.
• Requirement spec of a home security system
• Data design and implementation
• Behavior implementation example

3
What is Ode?

• An active, Object Database System and Environment
  based on object paradigm.
• Developed by Database System Research Department
  of ATT Bell Lab (in 1989?).
• Use a programming language called O.
• upward-compatible extension of C.
• offers a simple, elegant notion of persistence.
• Be able to query and modify the database.
• provide sophisticated trigger facilities (trigger
  is the basic ingredient of active database.)

4
What is Ode? (cont.)

• Version 4.2 currently run on SunOs 4.1.x, Solaris
  2.3, Windows NT, Windows 95.
• Product family
• OdeltEOSgt (aka Ode) disk-based version of Ode,
  using EOS storage manager. It is free to
  download.
• MM-OdeltDaligt (aka MM-Ode) main-memory based
  version of Ode, using the Dali main-memory
  storage manager, useful for time-critical
  applications.
• OdeFS file system interface to Ode object
  database, allow objects to be treated and
  manipulated like files.
• Ode/Oql an interpreter that execute select
  statement that query objects in Ode.

5
O language
6
O vs. C

• Has 35 new keywords.
• Database creation and manipulation.
• Capability to create objects persist beyond the
  lifetime of the program creating them.
• Provide iterator to manipulate set of objects
  similar to SQL
• Transaction support
• Capability to create access multiple versions
  of an object.
• Capability to attach to object the condition
  action that are triggered when condition is T.

7
Class database

• Open, close, remove. Example
• void main()
• database db
• if ((db databaseopen(security)) NULL)
  
• cout ltlt Cannot create database security ltlt
  endl
• exit(1)
• int i db-gtclose()
• cout ltlt close() ltlt i
• registerAction(..)
• int transCount 0
• void incrementCount () transCount
• databaseregisterAction(databaseAFTER_COMMIT,in
  crementCount)

8
Persistent Objects

• Volatile object vs. persistent object.
• Example
• persistent class Person
• public
• indexable char Name50
• int Age
• Person(char n, int a)
• persistent Person p
• p pnew Person(John Doe, 35)
• pdelete p

9
Clusters of Persistent Objects

• Cluster is a physical grouping of persistent
  objects
• By default, all persistent objects of the same
  type are grouped together in a cluster the name
  of a cluster is the same as that of the
  corresponding type
• Objects of class type can be accessed using the
  iterator.

10
Query

• All objects
• for (pe in Person)
• cout ltlt pe-gtName ltlt pe-gtAge
• Restrict the query by suchthat
• for (pe in Person) suchthat (pe-gtAge gt 20)
• cout ltlt pe-gtName ltlt pe-gtAge
• All object and its derived objects
• class Employee public Person
• for (pe in all Person)

11
Indexing a cluster

• You can build an index on a data member (declare
  with indexable) of a persistent class type
• databaseBuildIndex(Person,
  PersonName,DB, 1, HASH_TYPE)
• Index type can be Hash table or B-tree

12
Transaction in O

• All code interacting with DB (except open and
  close) or manipulate persistent obj must be
  within transaction block.
• Update transaction
• trans
• Read-only transaction
• readonly trans
• Hypothetical transaction
• hypothetical trans
• Transaction abort inside trans block tabort

13
Versions

• Updating an object does not create a new version.
  New versions must be created explicitly by
  invoking the function newvers
• Temporal relationship vs. Derived-from
  relationship
• Example
• persistent Part p, vp1, vp2, vp3, vtemp
• p pnew Part
• vp1 newvers(p)

14
(No Transcript)
15
Triggers - Example

• persistent class Person
• void Alert (persistent Person , const char , .
  . .)
• persistent class Stock
• char name40
• float price
• public
• void NewPrice(float price)
• . . .
• event after NewPrice
• . . .
• trigger AboveLimit(persistent Person p,
  float limit)
• after NewPrice (price gt limit)
• gt Alert(p, s currently trading at
  .2f, name, price)

16
Triggers

• Declare events all the basic events used in a
  trigger must be declared in the class containing
  the trigger.
• Declare trigger
• trigger trigger_name (parameter) trigger-body
• Trigger-body Event gt Action
• Activate trigger ps-gtAboveLimit(Joe, 500.0)
• Fire a trigger action is an independent
  transaction. If triggering trans aborted, then
  trigger action is aborted.

17
A Case Study

• A Home Security System

18
Requirement Specification

• Center controller monitors detectors, alarms, and
  notifies emergency personnel according to a
  protocol specified in a schedule.
• When a detector is tripped, controller records
  that event, sound the alarms. The resident has a
  certain amount of time to abort the protocol. If
  not, notify emergency personnel.

19
Requirement Spec (cont.)

• Control panel is an interface that allows user to
  initialize system, reset alarms, setup, change,
  delete schedule.
• Schedule has start, stop time and a choice of
  mode (Immediate, Short Delay, Long Delay)

20
(No Transcript)
21
OBM of Active Objects

• Control Panel
• Center Controller
• Detector
• Alarm
• Emergency Notifier

22
OBM of Control Panel Object
23
OBM of Center Controller Obj
24
OBM of Detector
25
OBM of Alarm
26
OBM of Emergency Notifyer
27
Database Schemes

• Emergency Notifier(Emergency Phone Number)
• Detection Event(Detector ID, Timestamp)
• Center Controller(State, (Detection Event))
• Schedule(Schedule ID, Start Hour, Start Minute,
  Stop Hour, Stop Minute, Mode, Short Delay Time,
  Long Delay Time)

28
Database Schemes (cont)

• Control Panel(Active Schedule ID, (Schedule))
• Detector(Detector ID, State)
• Alarm(AlarmID, State)

29
Ode Schemes EmergencyNofitier

• persistent class EmergencyNotifier
• private
• char phoneNumberMAX
• public
• void changeNumber(char NMAX)
• void notify()

30
Ode Schemes DetectionEvent

• persistent class DetectionEvent
• public
• indexable int detectorID
• indexable char timestampMAX

31
Ode Schemes CenterController

• persistent class CenterController
• private
• int state
• persistent DetectionEvent detectionEvents
• public
• void reset()
• void detection(int detectorID)
• void addDetector(int detectorID)
• void deleteDetector(int detectorID)
• void addAlarm(int alarmID)
• void deleteAlarm(int alarmID)

32
Ode Schemes Schedule

• persistent class Schedule
• public
• indexable int scheduleID
• int startH, startM, stopH, stopM
• int mode
• int shortDelay
• int longDelay

33
Ode Schemes ControlPanel

• persistent class ControlPanel
• private
• indexable int activeScheduleID
• persistent Schedule schedules
• public
• void reset()
• void changeSchedule(int schedID)
• void addSchedule(int schedID)
• void deleteSchedule(int schedID)
• void activateSchedule(int schedID)

34
Ode Schemes Detector

• persistent class Detector
• private
• indexable int detectorID
• int state
• public
• void reset()
• void trip()

35
Ode Schemes Alarm

• persistent class Alarm
• private
• indexable int alarmID
• int state
• public
• void reset()
• void activate()

36
Behavior Implementation Example

• persistent EmergencyNotifier emergencyNotifier
• persistent CenterController centerController
• persistent ControlPanel controlPanel
•  
• void CenterControllerdetection(int detectorID)
  
• . . .
• for (alarms in Alarm)
• alarms-gtactivate()
•  
• detectionEvents pnew DetectionEvent(detectorID,
  makeTimeStamp())
• wait FALSE

37
Behavior Implementation (cont)

• if (controlPanel-gtgetActiveMode()
  MODE_IMMEDIATE)
• state ACTIVE
• else
• wait TRUE
• if (wait)
• if (controlPanel-gtgetActiveMode()
  MODE_SHORT)
• delaytime controlPanel-gtgetShortDelay()
• else
• delaytime controlPanel-gtgetLongDelay()
•  
• targetTime gettime() delaytime
• delaying TRUE

38
Behavior Implementation (cont)

• while (delaying)
• if (timeEqual(targetTime))
• emergencyNotifier-gtnotify()
• state ACTIVE
• delaying FALSE
• else if (userAbortButtonPressed())
• reset()
• state READY
• delaying FALSE

39
Credit

• This home security system case study is extracted
  from Chapter 17 from Object Database Development
  Concepts and Principles by David W. Embley
• Code for this case study is extracted from
  security.c file, developed by Matthew Lundgreen,
  Brian Bouck, and Michael Martin