2009 Qing Li

Application of Object OrientationApplication of Object Orientation

2009 Qing Li

1.CAD/CAM (Design Engineering) applications1.CAD/CAM (Design Engineering) applications

2009 Qing Li

1.CAD/CAM (Design Engineering) applications(cont.)1.CAD/CAM (Design Engineering) applications(cont.)

Both versions can have the same interface corresponding to the same commands:pick up objectsstretch the arm rotate the hand……

OO representation and abstraction closely/directly model such complex, multi-version engineering objects only operations are relational algebra, using comparators from base types

2009 Qing Li

2.Office Information Systems2.Office Information Systems

Office information systems are inherently complex, dynamic, and goal-oriented (requiring knowledge-level processing and management)

OO Techniques are especially suited to OISs:(i) Office Objects: forms -> new forms

(inheritance between form types) documents => Chapters =>Sections => paragraphes

(part hierarchy: “part inheritance” between object structure) mailboxes Editors spreadsheets <= also potential for exploiting class inheritance …

2009 Qing Li

2.Office Information Systems(Cont.)2.Office Information Systems(Cont.)

(ii) Office Procedures:-- the routine sequences of operations that are used to manipulate office objects-- often ill-defined and exhibit large number of exceptions; furthermore, they expand in scope and evolve in time

=> can be supported by object methods!

(iii) Knowledge Management -- the organizational regulations, rules-- constraints, migrations, …

=> call for rule-level processing and management

2009 Qing Li

3. 3. Geographic Information SystemsGeographic Information Systems

Characterized by - mixture of traditional data with non-traditional data (maps, satellite pictures) How do we integrate them? Long fields for nonstandard data such as images:

>> Relation can get very large?>> Non-standard size for tuples?

- fractals: multiple representations (multi-resolution) due to cartographic generalization (ratio change): new details become apparent at the larger scale lines behave as if they have properties of phenomena whose

dimension is somewhere between that of a line and an area

2009 Qing Li

3. 3. Geographic Information Systems(cont.)Geographic Information Systems(cont.)

- spatial-temporal query processing: Queries about line segments

>> all segments that intersect a given point or set of points

>> all segments that have a given set of endpoints

>> segments that intersect a given line segment

>> …

Proximity queries

>> The nearest line segment to a given point

>> All segments within a given distance from a given point (“range/window query”)

>> …

2009 Qing Li

3. 3. Geographic Information Systems(cont.)Geographic Information Systems(cont.)

- spatial-temporal query processing: Queries about line segments

>> all segments that intersect a given point or set of points>> all segments that have a given set of endpoints>> segments that intersect a given line segment>> …

Proximity queries>> The nearest line segment to a given point>> All segments within a given distance from a given point

(“range/window query”)>> …

Queries involving attributes of line segments>> Given a point, find the closest line segment of a particular type>> Given a point, find all the polygons that are incident on it>> …

2009 Qing Li

3. 3. Geographic Information Systems(cont.)Geographic Information Systems(cont.)

-Special indexing techniques needed: Need an implicit rather than explicit index

>> Cannot foresee all possible queries in advance New indexing techniques such as:

>> Quadtree,

>> R-tree

>> Pyramid

>> …

2009 Qing Li

3. 3. Geographic Information Systems(cont.)Geographic Information Systems(cont.)

-Special operators needed: Operations on the special indices

>> E.g., set operations on Quadtrees (Union, Intersect, etc.) Operations on Maps

>> Spatial join (like map overlay)

>> Semi spatial join (“identity overlay”)

E.g. Find the soil type in the counties

(Impose partition of space induced by County Map on feature values in Soil Map ignoring portion of space induced by the Soil Map)

OO Techniques work better for GIS?!

2009 Qing Li

4. Multimedia Information Systems4. Multimedia Information Systems

Characterized by

- mixture of traditional data with media data (image, audio, video, free-text, animation, etc.)

How do we integrate them?

- MM objects are complex in structure: E.g., Video consists of audio and moving/continues

images; an MM document can contain everything! What data model to use?

2009 Qing Li

4. 4. Multimedia Information Systems(Cont.)Multimedia Information Systems(Cont.)

-spatial-temporal query processing: Similar to GIS, MM objects are of rich spatial-temporal

semantics (think of a video clip!) Impossible (too costly) to have static, explicit indices on

all possible features

Would OO Techniques be useful for MMIS

2009 Qing Li

4. 4. Multimedia Information Systems(Cont.)Multimedia Information Systems(Cont.)

Answer is YES!

Here, we look at MediaView – an object-oriented semantic model for MMIS

2009 Qing Li

““ Semantic Gap” Problem:Semantic Gap” Problem:

2009 Qing Li

Semantic modeling of multimedia Semantic modeling of multimedia -- Why hard?-- Why hard?

2009 Qing Li

Why hard? (cont.)Why hard? (cont.)

2009 Qing Li

MediaView – A “Semantic Bridge”MediaView – A “Semantic Bridge”

2009 Qing Li

ArchitectureArchitecture

2009 Qing Li

Fundamentals of MediaViewFundamentals of MediaView

Basic concepts – class vs. MV View operators – basic functions of MV View algebra – derivations of MV Comparison – other “dynamic” object

models

2009 Qing Li

Basic ConceptsBasic Concepts

Definition 1: Set C as the set of base classes. A base class Ci C has a unique class name, a type description, and a set of objects associated with it. The type of Ci is referred to as type(Ci), which defines a set of properties as the common interface of all the instances of Ci. The set of properties are referred to as properties(Ci), and each property in it can be a value of a simple type, an instance of a certain class, or a method. The set of objects associated with Ci is defined as extent(Ci)= {o | oCi}.

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

Definition 2: A media view MVi is a virtual class that has a unique view name, a type description, and a set of objects associated with it. The type of MVi is referred to as type(MVi), which defines a set of properties properties (MVi) as the common interface of all its instances. Similarly, a property can be a value of a simple type, an instance of a media view, or a method. The set of objects associated with MVi is defined as extent(MVi)= {o | oMVi}.

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

So, a media view MVi can be represented as a tuple of 4 elements:

MVi= <Mi, Piv, Pim, Ri,>

Where:

Mi - a set of objects that are included into MVi as its members. Each object o∈Mi belongs to a certain source class, and different members of MVi may belong to different source classes.

Piv - a set of view-level properties (attributes and methods) applied on MVi itself.

Pim - a set of member-level properties (attributes and methods), which are applied on all the members of MVi.

Ri - a set of relationships, and each r∈Ri is in the form of <oj, ok, t>, which denotes a relationship of type t between member oj and ok in MVi.

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

Definition 3: A base class Ci is defined as a subclass of another base class Cj if and only if the following two conditions hold: (1) properties(Cj) properties(Ci), and (2) extent(Ci) extent(Cj). If Ci is the subclass of Cj, we also say that there is an is-a relationship from Ci to Cj. A base schema (BS) is a directed acylic graph G=(V, E), where V is a finite set of vertices and E is a finite set of edges as a binary relation defined on V×V. Each element in V corresponds to a base class Ci. Each edge in the form of e=<Ci, Cj>E represents an is-a relationship from

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

Definition 4: A media view MVi is a subview of another media view MVj (or there is an is-a relationship from MVi to MVj) if and only if properties(MVj) properties(MVi) and extent(MVi) extent(MVj). A view schema (VS) is a directed acylic graph G={V, E}, where a vertex in V corresponds to a media view MVi, and an edge e=<MVi,MVj>E represents an is-a relationship from MVi to MVj (or MVi is a subview of MVj).

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

An example…

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

Semantics-based data reorganization via media views

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

Definition 5: The semantic graph (SG) is an undirected graph G={V, E}, where V is a finite set of vertices and E is a finite set of edges. Each element ViV corresponds to a multimedia object Oi in the database. E is a ternary relation defined on V×V×N. Each e=<Vi,Vj, n>E represents a semantic link of degree n between object Oi and Oj, where n is the number of media views to which both objects belong. We define n as the correlation factor between Oi and Oj.

Definition 6: The correlation matrix M=[Mij] is an adjacency matrix of the semantic graph. Specifically, each element Mij contains the correlation factor between Oi and Oj, with all the diagonal elements set to zero.

2009 Qing Li

Basic Concepts (cont’d)Basic Concepts (cont’d)

Semantic Graph Model

2009 Qing Li

View OperatorsView Operators

A set of operators that take media views and view instances as operands.

Our intension is not to come up with a complete set of operators, but to focus on those that are indispensable in supporting queries and navigation over multimedia objects.

2009 Qing Li

View OperatorsView Operators

2009 Qing Li

View Operators (cont’d)View Operators (cont’d)

2009 Qing Li

View AlgebraView Algebra

Functions

-- derivation of new MVs from existing MVs

Heuristic Enumeration Blind enumeration Content-based enumeration Semantics-based enumeration

2009 Qing Li

View AlgebraView Algebra

2009 Qing Li

View AlgebraView Algebra

2009 Qing Li

Comparison (vs. class)Comparison (vs. class)

2009 Qing Li

Comparison (vs. class)Comparison (vs. class)

2009 Qing Li

Comparison (vs. class)Comparison (vs. class)

2009 Qing Li

5. Internet/Web Databases5. Internet/Web Databases Sometime also called as “Virtual Databases (VDBs)” VDBs can make the WWW behave as an extension of an enterprise’s

existing DBMSs

VDB information can be characterized by: all the requirements imposed by MISs, plus extra…

Large numbers of data sources which are autonomous (without centralized control)

Data sources can have a mixture of structured data and semi-structured data (e.g., HTML pages)

Dynamism in almost every aspect: Content Structure Links Formats …

2009 Qing Li

5. Internet/Web Databases(Cont’)5. Internet/Web Databases(Cont’)

An increasingly hot-area, with a lot of commercial potentials from the E-commerce application’s point of view

But, is OO the best technology for VDBs?