Chapter.4 Version

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E.Bertino, L.MatinoObject-Oriented Database Systems

Chapter.4 Version

Seoul National University

Department of Computer Engineering

OOPSLA Lab.

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Table of Contents

Basic Concepts The Orion Model Proposed Models

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Basic Concepts

Design object Version Derivation and History Workspace Configurations Revisions

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Design Object

In database for design application Aggregation of design data as a coherent unit

usually a complex object consists of many component objects

• primitive

• complex object

Design database

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Version, Derivation, and History

Semantically, a snapshot of a design object In OODB engineering

different implementations of the same object revisions of an object

Derivation a version of a given object is derived from the previous

one by modification to the latter

History of version an outline of derivations starting with initial version

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History of Version

O[1]

O[0]

O[2] O[3]

Latest VersionCreated

(default version)

O[1.1] O[2.1] O[2.2]

O[1.1.1]Current Version

Alternatives

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Configuration

A link between a version of a complex object and a version of each of its component object

Static configuration Dynamic configuration

generic reference current version default version

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Example of Configuration

D[0]

D[1]

D[k]

L[0]

L[1]

L[j]

RT[0]

RT[1]

RT[i]

RPS[W]

RPS

Composed of

Derived from

StaticConfiguration

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Workspace

Workspace is named repository which constitutes work area that is shared by users access control unit

private workspace public workspace

read & append mode by check-in/check-out protocol

semi-public workspace an incomplete object combining the work of several

designers read & append mode by check-in/check-out protocol.

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Revision on Version

New version of an object can invalidate some of the objects which reference the given object notifying changes propagating changes

Problems in change propagation scope of change propagation in history path for change propagation in configuration

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RT[0]

RT[1]

RT[2]

RT[i]

D[0]

D[1]

D[2]

D[k]

L[0]

L[1]

L[2]

L[j]

RPS1[j]

RPS1

RPS[w]

RPS

Ambiguous Propagation of a Change

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Ways of Managing Ambiguities

Prevent any change propagation if there is a DAG Propagate the change to all the branches

the resulting version as alternatives of the root version

Propagate the change, interrupting it when ambiguity arises.

Provide operational mechanism whereby user can make their intention unambiguous

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Schema Version

Versions can be applied to classes and schema keep track of the objects created under each schema

version define rules both for updating and for deleting versions

of a class

Schema evolution in Chapter 5

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The ORION Model

Types of Version Transient Version Working Version Released Version

Generic Object Version Descriptor Notification of Changes Schema Versions

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Transient Version

In the private workspace Only the creator can update or delete it Can be created

from scratch by check-out a released version from a public database.

Can be derived from another transient version then the source is

promoted to a working version from a working version in a private database

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Working Version

In the private workspace Considered to be stable, thus can’t be updated

only deletion by the creator

Can be derived from transient version by implicit or explicit promoting the latter

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Released Version

In a public database Cannot be updated or deleted Can be created

by promoting the working version from the check-in of the working version

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CHECK-OUT

Promotes orCHECK-IN

PublicWorkspace

PrivateWorkspace

Createdfrom scratch

Promotes(implicit or explicit)

Release Version

Working Version

Transient Version

Types of Versions in ORION

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Generic Object

Distinction between versionable object and non-versionable object.

Generic (= versionable) object is an instance of a versionable class version-counter next-version-number default-version-number default-switch derivation-tree (a tree of version descriptors)

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An Example of Generic Object

OID O[0]

O[1]

O[2]

OID[0]

OID[1]

OID[2]

VersionInstances

Generic Object

default version

Generic Reference(Dynamic)

Specific Reference(Static)

A

B

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Version Descriptor

A version descriptor for each version instance Oi the version-number of Oi

the OID of Oi

a list of the references to version descriptors for all version instances which are derived directly from Oi

System attributes in each version instance version-number type-of-version OID of its generic object

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Messages for Creating Versionable Class and its Instances (define-class Classname :versionable TrueOrNil) Create message to a versionable class, then

creates a generic object and the first version instance Oi

Oi is a transient version and becomes the root of the derivation hierarchy for the generic object

(derive-version VersionedObject) if VersionedObject is a transient version

• promotes it to a working version

• makes a copy of it which becomes a new transient version

if VersionedObject is a generic object• the message is redirected to the default version.

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Messages Related to Version (1)

( promote VersionedObject ) promote a transient version to a working version no action on a working version

( demote VersionedObject ) demote a working version to a transient version no action on a transient version and a working version from

which other versions have been derived

( change-default-version VersionedObject [NewdefaultVersionNumber] ) by default, version number of the most recent version

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Messages Related to Version (2)

( delete-object [GenericObject | VersionInstance]) in case of a generic object, the whole derivation

hierarchy is removed in case that the version instance is the only instance of

the generic object, the latter is also removed. in case of a working version from which other versions

have been derived, the descriptor of it is not removed message parent-version message child-version message generic-object message default-version

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Version and Query

Version-number can be used in predicate Queries related with version

to find all of the version instances of a versionable class to find the user-defined default version to find the most recent version instance

Generic object should be accessed in some queries implementation and performance problem unsupported in ORION

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Notification of Changes

Two main approaches immediate notification by messages deferred notification using flags

Flag-based change notification in ORION change-notification-timestamp (CN) change-approval-timestamp (CA) set of events which generate a notification of change

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Concepts related to Notification of Changes

Notification sensitive attributes the attributes referencing the changed object

Reference consistent object, V if V.CA >= CN of all the referenced objects by V reference inconsistent system keeps CA and CN for all version instances user has the responsibility for making the instance

reference-consistent

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Schema Versions

Approaches to modeling schema versions schema versions class versions dynamic views of the schema

Not yet implemented, but model identifies operations which can result in new schema versions types with only transient and working version

Problems in schema versions keeping track of objects created under a schema version controlling access of applications to those objects

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Creator Schema Version

In a given object O, identifies the schema version(SV) in which O was created the access scope of SV the direct access scope of SV

• identifies the set of objects created from SV

Schema Version

Access Scope

Direct Access Scope

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Proposed Models

Time-oriented Data Model Dittrich and Lorie Klahold, Schlageter and Wilkes Landis Batory and Kim Ketabachi and Berzins Beech and Mahbod Vines, Vines and King SUN NSE Apollo DSEE

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Time-oriented data model

Data includes additional properties creation time of a certain object time at which an object is replaced by a new instance

Operations such as temporal series analysis ex) rate of sales increase as a function of time

No consideration of operational aspects such as inheritance, propagation of changes, workspaces, etc

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Version Model by Dittrich and Lorie

Design object set of versions with a specific current version reference other objects hierarchical aggregation direct reference & generic reference

Generic references resolved by environment mechanism which is a link

• between design objects and their specific versions• between design objects and another environment

Clusters of logic versions User can further structure versions such as grouping

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Model by Klahold, Schlageter and Wilkes

Version graph similar to the concept of history

partitions groups together a set of versions a level of consistencey

Views of subsets of a version’s graph

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Model by Landis

Non-linear history consists of several derivation branches the current version and the default branch.

Version references supports dynamic configuration

Change propagation a new version creation, schema change, value change

Additional mechanism to control changes delta sets which are similar to the log pended version creation is similar to checking-in in semi-

public workspace

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Model by Batory and Kim

Extension of the E-R model by inheritance Molecular objects

to define complex objects all versions are the instances of a molecular object

Type-version generalization to model the version history of a molecular object

Parameterized versions to use any version of a component object as the a component

of a molecular object provide support for the dynamic configuration

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Model by Ketabachi and Berzins Refinements for different descriptions of a object.

template refinement to describe aspects of an object explosion refinement to list the versions of the component

objects instance refinement to describe the revisions and alternatives of a

given object Incremental refinements

to describe the evolution of an object Graphs to represent the history of a version

refinement graph to derivation relationship IRG(incremental refinement graph) to stores differences between

a version and the father version.

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Model by Beech and Mahbod

IRIS project Version instances are organized into version sets

associated to a single generic instance Version graph

functions - first, last, next version, preceding version Messages to create new versions

mutation or propagation References can be generic or specific

generic references are resolved by contexts mechanism which consists of a trigger and a user-defined rule

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Model by Vines, Vines and King

Change control and versions model of GAIA Versions are identified with timestamps Version is related to the event which generated it

version sensitive relations change sensitive relations

Specific objects for managing changes change request object change notification object configuration object

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SUN NSU Model

System for software development environment Types of object

FILE, TARGET, COMPONENT, LINKDB

Versions are stored in the form of interleaved deltas inside an object

Access paradigm is based on acquire, modify and reconcile operations

Change notification support

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Apollo DSEE Model

System for software development environment Components

history manager - reserve and replace operation

configuration manager to define module composition • configuration thread and bound configuration thread(BCT)

task manager monitor manager advice manager

Versions of program modules are stored by using interleaved deltas

Release = a software system + BCT + a keyword.