9' Introduction to ArcObjects

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9. Introduction to ArcObjects

• Most GIS analysis carried out within a GIS
  consists of a labor-intensive sequence of steps.
• Automating a GIS makes it possible to do much
  more comprehensive modeling than manually going
  through these steps.
• It becomes possible to construct a dynamic model,
  then generate and evaluate a range of possible
  scenarios in a way that is very difficult when
  using the GIS interactively.
• ArcObjects allows you to automate most processes
  within ArcGIS in a flexible way, greatly
  expanding the available kinds of analyses.

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Introduction to ArcObjects

• The ESRI product nomenclature can be somewhat
  confusing. As background, here is is a list
• ArcGIS Desktop the collection of ESRI desktop
  applications.
• ArcView Provides comprehensive mapping and
  analysis tools along with simple editing and
  geoprocessing.
• ArcEditor Includes advanced editing
  capabilities for shapefiles and geodatabases in
  addition to the full functionality of ArcView.
• ArcInfo Builds on the functionality of
  ArcEditor with advanced geoprocessing. It also
  includes the legacy applications for ArcInfo
  Workstation.
• ArcMap ArcMap is the central application in
  ArcGIS Desktop. It is the GIS application used
  for all map-based tasks, including cartography,
  map analysis, and editing.
• ArcCatalog The ArcCatalog application helps you
  organize and manage all of your GIS information
  (maps, globes, datasets, models, metadata,
  services, and so on).
• ArcObjects ArcObjects provides an
  infrastructure for application development and
  customization, and is most of what we will be
  dealing with with programming usiing ESRIs
  tools.
• Spatial Analyist, Network Analyst, 3DAnalyst, and
  other toolbox extensions can also be accessed
  from within ArcObjects.

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Introduction to ArcObjects
ArcObjects is a set of classes and objects
designed for automating ArcGIS Desktop
applications. It is a set of building blocks,
and is also used by ArcMap and ArcCatalog. It is
part of a set of code libraries published by
ESRI. It works with C, VB, and other
Windows-based languages/environments. Basic
information about the ArcObjects Library is
available at http//edndoc.esri.com/arcobjects/9
.2/welcome.htm, under ArcObjects Library
Reference. For additional help and reference
material, go to http//edn.esri.com/.

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Introduction to ArcObjects

ArcGIS Engine Makes it possible to embed
ArcObjects into other Windows applications or
Developer Components.
ArcGIS Server Offers similar services, but is
run by remote clients, such as web browsers.
Built to run in a non-visual server environment.
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Introduction to ArcObjects

ArcGIS Desktop For applications that control
ArcGIS, or extensions to be included within
ArcGIS such as marcros or toolbox extensions.
Allows full interaction with ArcGIS user
interface. ArcGIS Desktop is what we will be
using in class.
Other ESRI development tools include Java
interfaces for ArcGIS Engine and ArcGIS Server
(not desktop) ArcWeb services, which let
applications use services provided by ESRI
remotely ArcSDE for database integration and
ArcIMS for web-server-based applications. More
information...
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Introduction to ArcObjects

ArcObjects was built in C using a technology
called COM, or Component Object Model. COM is a
predecessor to .NET, and is focused on allowing
applications to embed components or other
applications. On of the key features of .NET is
Managed Code, that is, code that is
garbage-collected by the .NET runtime
environment, and that interacts with the system
only through .NET interfaces. Unmanaged code
interacts with the system directly. ArcObjects
are build on Unmanaged code there is a layer
within the .NET libraries that manage
communication between these two
environments. That means that there is some
extra overhead to each call from C into the
ArcObjects library. More information...
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Introduction to ArcObjects

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Introduction to ArcObjects

• Within ArcObjects Desktop development
  environment, the main kinds of software you can
  develop are
• Custom simple commands that can be run from
  within ArcGIS.
• More complex toolbox plugins with their own user
  interfaces that can also be run from within
  ArcGIS.
• Applications that launch and control ArcGIS ,
  accessing ArcGIS functionality from an external
  process.
• Embedding ArcGIS functionality within a separate
  stand-alone application requires ArcEngine.

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Introduction to ArcObjects

Simple custom tool example
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Introduction to ArcObjects

More complex ArcMap Extension
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ArcObjects Library

The most direct way to use ArcObjects from within
C is to control ArcGIS from an external
application, which runs ArcGIS and controls it
using the ArcObjects interfaces. This is the
approach we will use in class. To get an initial
idea of the ArcObjects environment and
documentation, we can look at the now-familiar
Geometry classes. The next slide first displays
the ESRI diagramming conventions.
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ArcObjects Library

• The ArcObjects library is quite large, with
  hundreds of classes documented by pages and pages
  of class diagrams.
• Geometry objects are found within a more
  complicated context than Geotools. You have to
  go through a few layers to get to the actual
  geometry of a map.
• The main organizing objects are
• Application A representation of the running
  application
• Document A map document
• Map A map within a document
• Layer A layer within a map

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ArcObjects
Application

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ArcObjects
Document

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ArcObjects
Layer

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ArcObjects

Map
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ArcObjects

• The overall sequence of automating ArcMap from an
  external application is
• Launch ArcMap
• Open map document file
• Get a reference to the map within the document
• Retrieve the layers from the map
• . Read/write from the map layer .
• Close/save the document
• Quit ArcMap
• ArcObjects allows you to automate most processes
  within ArcMap.