More Information on ArcGIS As Used by the Mapplet

This section provides some more technical background information on how the mapplet project will use the underlying technology. It’s quite specific to ArcGIS, so if you’re not expressly interested in ArcGIS, it probably wouldn’t do any harm to skip this section.

Tip 

You can find a lot of useful information on developing with ArcGIS at the ArcGIS Developer Online website at http://arcgisdeveloperonline.esri.com.

ArcGIS Software Developer Kit

The ArcGIS SDK is geared toward helping developers implement custom ArcGIS functionality. It consists of the following:

• Developer tools: These are executables provided by ESRI for developing applications that use ArcObjects. For example, the Component Category Manager tool (Categories.exe) registers components in different component categories, and the Library Locator tool identifies an object library containing a specified interface. The developer tools are installed under the DeveloperKit\tools folder. There is one exception to this: the Component Category Manager tool is located in the ArcGIS\bin folder.

• Add-ins: These add-ins plug into the integrated development environment (IDE) that you use for developing on top of ArcGIS (e.g., there are add-ins for Visual Basic 6 and Visual Studio .NET).

• Help system: The help system provides a gateway to all the SDK documentation, including help for all the add-ins, developer tools, and samples. The help system organizes samples by functionality (e.g., all the Geodatabase samples are grouped under Samples\Geodatabase).

• Code samples: There are over 600 code samples to try out.

ArcGIS Server Terminology

The following list provides an overview of the terms and concepts you’ll encounter during ArcGIS development. We also use some of these terms in the next few chapters to describe the mapplet project.^[11.]

• GIS server: The GIS server is responsible for hosting and managing server objects. The GIS server is the set of objects, applications, and services that make it possible to run ArcObjects components on a server. The GIS server consists of the Server Object Manager and one or more Server Object Containers.

• Server Object Manager (SOM): The SOM is a Windows service or a UNIX daemon that manages the set of server objects distributed across one or more container machines. When an application makes a connection to an ArcGIS Server over a LAN, it is making a connection to the SOM.

• Server Object Container (SOC): An SOC is a process in which one or more server objects are running. SOC processes are started up and shut down by the SOM. The SOC processes run on the GIS server’s container machines. Each container machine is capable of hosting multiple SOC processes.

• Server object: A server object is a coarse-grained ArcObjects component—that is, it’s a high-level object that simplifies the programming model for doing certain operations and hides the fine-grained ArcObjects that do the work. Server objects support coarse-grained interfaces that have methods that do large units of work, such as “draw a map” or “geocode a set of addresses.” Server objects also have SOAP interfaces, which make it possible to expose server objects as web services that can be consumed by clients across the Internet.

• Web server: The web server hosts web applications and web services written using the ArcGIS Server API.

• Pooled server object: ArcGIS Server allows you to pool instances of server objects such that they can be shared between multiple application sessions at the per-request level. This allows you to support more users with fewer resources. Pooled server objects should be used by applications that make stateless use of the GIS server.

• Nonpooled server object: Nonpooled server objects are created for exclusive use by an application session and are destroyed when returned by the application to the server. The creation of each object includes creating the object and loading up any initialization data (e.g., the map document associated with a Map Server object). Users of a server application that makes use of a nonpooled server object require an instance of that object dedicated to their session. Nonpooled server objects are for applications that make stateful use of the GIS server.

• Application Developer Framework (ADF): The ADF is a collection of web controls, convenience classes and data objects, and application templates that make it easy to build and deploy .NET or Java web applications that use ArcObjects running within the GIS server. The ADF includes an SDK with web controls, web application templates, developer help, and code samples. It also includes a web application runtime that allows you to deploy applications without having to install ArcObjects on your web server.

^[11.]Thanks again to ESRI for allowing us to reproduce this material.