1. Key object concepts (1 of 2 ) polymorphism –behaviors of an object class can adapt to variations of object Encapsulation –object is accessed only through a well defined set of software methods –this masks the internal complexity of the object from the application OBJECTOBJECT APIs

2. Key object concepts (2 of 2) Inheritance –one object class can be defined to include the behaviors of another class and to have additional behaviors of its own makes creation of complex objects much easier makes sure that important shared properties are not overlooked –inheritance can “derive” from an abstract class or form a “real” one abstract class line –has various properties –class primary line has all of line’s properties and some of its own

3. Classes and objects abstract class –a “template” for subclasses –cannot be used to create new objects but is a specification for a subclass line abstract class for primary line, secondary line creatable class –has objects that you can directly create pole, river instantiable class –cannot directly create new objects but objects of this class can BE created as a property of another class (pole objects create transformer objects)

4. Relationships (1 of 3) associations –relationships between classes –multiplicity constraints 1 = one only 0.. 1 = zero to one M.. N = from M to N * OR 0.. * = from zero to any positive integer 1.. * = from 1 to any positive number –number reads from the box to the other box A can have zero to one Bs B has 3 or 4 As A B 0..1 3..4

5. Relationships (2 of 3) type inheritance –specialized classes that share properties and methods with the superclass and also have additional properties and methods –inheritance can be from a abstract class or from a createable class ROW Feature Network feature Complex junction Simple junction Junction feature Edge feature transformer meter

6. Relationships (3 of 3) Instantiation –object in one class has a method that creates an object from another class pole creates transformer Aggregation –asymmetric relationship in which an object from one class is considered to be a “whole” and objects from another class are considered “parts” Composition –stronger form of aggregation in which objects from the whole class control the lifetime of objects from the part class poletrans

7. Componentization creation of small blocks of reusable computer code –in Microsoft use Component Object Model (COM) –in UNIX use Common Object Request Broker Architecture (CORBA) –multiple platforms use Java Remote Method Invocation (RMI) numerous advantages - some disadvantages concept has been extended to spatial entities

8. Geodatabase ESRI’s new objet model –geodatabase is top level –feature dataset collection of feature classes, network graphs, relationships simple feature classes may be within or outside a feature dataset but network features must be in a feature dataset –feature class(es) –relationships –TINs –rasters

9. Feature class may be within a feature dataset (must if network type) or outside –point feature class –line feature class –polygon feature class –object class –junction feature class –edge feature class –geometric network feature class –relationship class

10. Workspace old Arc data structure –coverages within a workspace there can be many coverages the georelational data model stores geometries AND topological relationships key types of coverages –point (attributes in PATs) –arcs (attributes in AATs) »network elements and polygon boundaries –polygons (attributes in PATs) –regions - groups of polys –labels (polygon markers) –nodes (attributes in NATs) –annotation (text on map)

11. Shapefiles and CAD files simple form no topology –shapefiles point line polygon dBase tables with attributes –CAD point line polygon annotation drawing - representation of CAD data for drawing only

12. Comparisons (1 of 6)

13. Comparisons (2 of 6)

14. Comparisons (3 of 6)

15. Comparisons (4 of 6)

16. Comparisons (5 of 6)

17. Comparisons (6 of 6)

18. Feature in a geodatabase feature class = DBMS table properties –shape (geometry) point, multipoint, polylines (include straight, circular arc, elleptical arc, bezier curve), rings (closed, non-intersecting polylines) special column in DBMS can be X, Y or X, Y, Z both single and multipart geometries can be in same feature class –e.g. in Arc 7 multiple part polygons were kept in a region class while simple polygons were in a polygon class

19. Spatial reference shapes are stored in Cartesian X and Y (as integers) but with a spatial reference to world system converted (as needed) to map units spatial domain –max X and Y and min X and Y scale –defines how many integers correspond to a map unit –example scale = 100 then each value in the coordinate corresponds to one one- hundredth of a map unit. –in effect scale defines the “precision” of the coordinates that are stored scale and domain are inversely related –if difference between max X and min X ( or y) is large than scale is limited –product of the scale and the maximum X (or Y) difference cannot exceed more than two billion

20. Subtypes –a little like inheritance but doesn’t require the creation of a new object class examples – building subtypes could be residential, commercial, industrial –highway subtypes could be asphalt, concrete and grave –why to use subtypes if you can use subtypes rather than new feature classes you will improve performance –when to use subtypes different groups of related features have distinct custom behaviors –repair options and periods are different for gravel and asphalt roads set of attributes are different –gravel road has gravel size, asphalt road has hot mix type and number of lanes

21. Relationships both spatial and non-spatial –house is “on” parcel –house “has” owner spatial = topological managed by Arc general relationships created by user –stored in a relationship table –origination class and destination class forward path label backward path label –a single object class can participate in one or many relationships simple relationship –“peer to peer” between two classes composite –“one to many” –composite object from origin class –part object from destination class –delete origin object and the destination parts are deleted –delete a part or replace with another part is ok –parts can be created independently of composite

22. Notifications associated with relationship classes used to propagate actions when a “significant” event occurs –like a trigger in older DBMS four different notification “directions” or types –no notification –notification issued to destination object when the origin object is changed “pole has been moved - reset location of associated transformer to new coordinates of pole” –notification is issued to the origin object when the destination object is changed “valve has been upgraded in size - total capacity of gas line can be increased” –notification is issued when either is changed

23. Attribute constraints domains –max or min values –coded value = selected list (farm, commercial, residential, industrial) default values –most common option default land use is residential essential –to reduce errors in entry –to insure consistency in reporting requires consideration BEFORE data entry begins

24. Rule validation Somewhat like domains particularly important at object creation can take many forms rules for both splitting and merging examples –when un-improved lot is split divide current value by the proportion of area of each lot and load into new value and apply current zoning class to new records –when power_line feature class is connected to building feature class a junction feature of transformer must be inserted –when merging two lots add the individual valuation for combined valuation

25. Client - server architecture original computer model = mainframes –all powerful, text terminals on desks mini-computer and mainframes –some independent smaller computers and mainframe PC revolution –everything that could be on machine on desktop –good - power to people –bad - duplication of data, lack of synchronization, complicated Client - server –mix of PC, “terminals” (sometimes) and server

26. Client - server in Arc Arc 8 desktop –ArcCatalogue, ArcMap, ArcToolbox –familiar Windows look and feel –friendly, interactive Arc 8 workstation (actually Arc 7.x) –on server or on local machine (w/ Workstation NT) –major complex operations ArcToolbox is a windows front-end to workstation operations –with mouse interact with windows –a set of commands are created and run (possibly) remotely) ArcSED –vehicle to connect to spatial data –operates as personal and on “data server”

27. Implications of client server architecture Good –large data can be on server better control large horsepower less duplication, etc. –graphic interface easily to design in windows –faster development of capable user –database isolated from application Bad –complexity of implementation –increased network requirements –performance issues