DevSummit’06

Easy ArcObjects

Turbocharging Brian GoldinErik Hoel

Easy

DevSummit’06

Purpose of this talk

• How to get things done quick while your boss thinks it’s hard agonizing work– Save time– Be efficient– Write less code– Separate the model

builders from the coders

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IDEs

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Visual Studio IDE• Visual Studio IDE integration makes life easy

– Implements that boiler plate code for you• Licensing• Implement common interfaces• Base classes• Adding references over and over again

– Preconfigured templates• All applications start in the same place – use this as your

foundation• Prototype code not typing boiler plate code

– If you like to hack things the framework is very extensible – check it out…

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JAVA IDE

• Lots of templates• Very slick help system• Code snippets• Lots of wizards

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Configure your app with ArcMap

• Author maps its fun and easy• Use layer files

– Create a FeatureLayer or use a layer file– Some layers can be excessively complicated

• Work with symbols– Roll your own use one that you’ve configured

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Geoprocessing

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Geoprocessing

• Geoprocessing has many benefits– Lots of functionality is encapsulated into a

single tool– Tool implementation is robust and efficient– Great opportunity to delete code and simplify

implementation

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4 Ways to Leverage Geoprocessing

• Use Existing Tools• Build Models• Write Scripts• Create new tools

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Execute, Execute, Execute

• Tools are grouped into logical collections– Analysis - extract, overlay, proximity etc.– Data Management - create and manage data– Conversion - load data– Network Analysis– Spatial Analysis– Cartography– And the list goes on….

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Geoprocessing Example – Buffer• Fine grain ArcObjects call to Buffer Features

– Huge learning curve– Painful– Error Prone– Appropriate when you need to fine control but not

unnecessary• Using Geoprocessing to Buffer Features

– Simpler– Easier to debug and understand– Bullet proof code

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Execute more than just tools

• Build workflow with model

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Execute More than Tools cont.

• There’s Logic in using scripts

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Create your own geoprocessing tools

• It’s easy to extend geoprocessing with your own tools– Script Tool– Model Tool– Custom Tool

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How do you get started

• Read the desktop help for a conceptual understanding

• API Reference

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Cursors

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Cursors• Used when searching a table• Cursor is returned as result of applying a

QueryFilter to a Table• Client then iterates through the returned

rows in the cursor• Cursors come in different flavors

– Search, update, and insert• Update cursors take an argument

– Recycling or non-recycling

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Cursors• Search cursors return rows as specified by

the QueryFilter• Update cursors used to update or delete

rows specified in the QueryFilter• Insert cursors used to insert new rows into

a table– Good for bulk loading simple data– Slower for non-simple data– Consider object loader

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Recycling vs. Non-recycling• Recycling

– Allocate a single row object (re-load on each fetch)

– Should only be used for reading data– Performance advantages– Recycling Update Cursor can be faster then

calling Store() on rows from a Search Cursor• Non-Recycling

– Different row object on each fetch– Always has full set of fields

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Cursors vs. get_Feature

• In ArcObjects, there are often several ways to accomplish the same task– some are much faster than others

• Retrieving features given a set of ObjectIDs

• Significant performance differences

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QueryDefs vs. OpenTable• IFW::OpenTable()

– Acquires schema lock on data source – costly serialized process; many SQL statements

– Serialization kills scalability, can create queues with many (e.g., 100s) users

• QueryDefs– No schema locks– Fast creation of rowset

• Pabst vs. Heineken

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Component Burn

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Component Burn

• Easy to consume the ArcObjects fine grained components in an unoptimizedmanner

• Many ways to do the same task• Unnecessarily cocreating small

components can whack performance• Use coarse grained components when

possible

DevSummit’06

Data Models

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Data Models

• Data model structure is critical• Minimize the number of feature classes

– Cursors are expensive– Utilize subtypes– Subtypes not for you? Consider fat classes

• handle unpopulated attributes

• Avoid classes containing small number of large features– Nation or state polygon

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Data Models

• Model only those relationships that are important

• Event notification can have impact– relationship classes– feature linked annotation– workspace and class extensions– editor events

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Data Models

• Dense features (high vertex count) impact– E.g., 8 million vertex polygons– Display pipeline, geoprocessing, updating,

etc.• Extremely large features (extent) impact

– Nation or state polygon– Topology, networks

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Prototyping

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Prototyping• Largest mistake made with the geodatabase• Structure is critical – data quantity is not• Prototype as soon as a first pass model is

available– general structure; small details unimportant– load a modest amount of data (on versioned SDE)– empty classes are OK

• Try editing, observe system performance• Repeat this process as necessary

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Extensibility and Customization

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Levels of GDB Customization

Subtypes& defaults

Domains& validation

Connectivity& topo rules

Class & workspaceextensions

Built-in

Functionality

Custom

Applications

VBA

Programming

starts here

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Levels of GDB Customization

• Application level– Pros

• Business Logic is stored within application• Can access data without customization

– Cons• Only available when application is running• Users do not always interact with application

customization

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Levels of GDB Customization

• Database level– Pros

• Business Logic is stored with data• Always available, regardless of application

– Cons• One class extension per feature class• All users require dll to even view data• Database is unusable if code fails• Impacts on performance

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GDB Extensibility

• Five mechanisms– Workspace extensions

• Filtering, edit events, version events– Class extensions

• Drawing, split policies, property inspector, related object creation notification

– Plug-in data sources– OLE DB providers– Custom features

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Class extension uses• Schema generation • Custom drawing• Custom property inspection and validation• Custom split policies• Related object creation notification• PlugIn Data Sources

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Miscellaneous Stuff

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Workflows

• Workflow is critical with versioning• Recommended workflow:

– Load data– Define the dataset (e.g., topology, GN)– Build or process the entire dataset (e.g.,

validate entire topology, build the GN)– Register the dataset as versioned

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Caching

• Spatial cache– Features– E.g., network editing

• Schema cache– GDB schema tables– E.g., creating a checkout version

programmatically

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GP Tools

• Consider periodic GP tools for QA/QC– Not everything has to be in the data model or

in code– Avoidance of large polygons (e.g., nation or

state• Run Integrate to ensure data planarity and

cluster your vertices– Not necessary to create a topology

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Is your PC worth > $10 on eBay?

• Would people buy it only to create a novelty fishtank?

• Run on a decent PC– e.g., spend $500

at Walmart

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Questions?

DevSummit’06Best Villain?

Emilio Largo

Ernst Blofeld 1 Ernst Blofeld 2 Ernst Blofeld 3

Rosa Klebb Auric Goldfinger

DevSummit’06

Emilio Largo

Ernst Blofeld 1 Ernst Blofeld 2 Ernst Blofeld 3

Rosa Klebb

No, Mr. Bond. I expect you

to die.

Auric Goldfinger

Best Villain?

DevSummit’06

Emilio Largo

Ernst Blofeld 1 Ernst Blofeld 2 Ernst Blofeld 3

Best Villain

Rosa Klebb

Best Villain? Goldfinger

No, Mr. Bond. I expect you

to die.