Javascript API (I)-Basic Framework

Javascript API is a new API framework of ArcGIS Server 9.3. It provides a lightweight solution for creating a WebGIS application. On the client side, it uses the services provided by ags, map applications and geographic functions can be implemented.

Remember that in the ArcIMSBlueviewer sample framework, all operations in the Framework are implemented based on the client, and parameters are calculated in javascript scripts to return the results to the server to get the images we need, programmers who have rewritten Blueviewer can better grasp the basic process of webgis development and write beautiful webgis + ajax applications on this basis. This method is somewhat similar to the javascript api of ags93, however, the latter is based on the dojo library and encapsulates basic functions in an object-oriented manner.

Theoretically, we can extend the Javascript API without limit to implement all the server functions of Ags. Currently, it provides the following basic functions:

1. display interactive maps based on your own data
2. Execute a GIS model and display the result
3. display our data on ArcGIS online basic map
4. Search for attributes or ry and display the results
5. Search for the address and display the result

Javascript APIs contain the following resource components:

Maps-- Supports displaying cache and non-cache maps on Ags, specifying the projection Reference System
Graphics-- Drawing, and displaying property information or geographic operations through the mouse, keyboard, and other operations
Tasks-- It is similar to the ADF Tasks. It provides functions such as Querying, Finding addresses, Finding attributes, Identifying features, and Geoprocessing.
Based on Dojo and other librariesExtension-- For example, using the Dojo widgets, google maps api, and virtual earth api

Dojo is not as widely used as EXT and has some controversy. However, ESRI chooses dojo as the base library of Javascript APIs for the following reasons:

1. Dojo loose license
2. the Dojo function is comprehensive. The event design mode, vector graphics support, display effect, widgets, Ajax, JSON, and so on are all required for the development of the Ags client. In addition, the Dojo function is convenient for the Mashup application.
3. Support from companies such as IBM, Sun, and AOL

The efficiency of Dojo is a problem, but I have not encountered some sample code before. I will pay special attention to it in the future. I have not extended the widget myself, and I have not encountered any problems in this regard yet, in any case, client applications and Mashup will be a mainstream development direction for WebGIS in the future. ESRI development team should carefully consider the Dojo issue, regardless of whether it is GISer or not, ESRI Ags should be more confident in the Development of Dojo after using Dojo as the basic core of the Javascript API library.

Related Articles:

Talking about Ags REST API
Introduction to the object-oriented architecture of Dojo

Javascript API object model: http://files.cnblogs.com/flyingis/javascript_api_om_poster_v1.rar
Blog garden link: http://www.cnblogs.com/flyingis/archive/2008/07/18/1246178.html

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