最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
3.3.1. SOAP building module ¶
An SOAP message is a normal XML document that contains the following elements:
Required Envelope element to identify this XML document as an SOAP message
Optional Header element containing header information
Required Body elements that contain all call and response information
An optional Fault element that provides information about the error that occurred while processing this message
All of the above elements are declared in the default namespace for SOAP encapsulation:
http://www.w3.org/2001/12/soap-envelope
And the default namespace for SOAP encoding and data types:
3.3.2. rule of grammar ¶
Here are some important grammar rules:
SOAP messages must be encoded in XML
SOAP messages must use the SOAP Envelope namespace
SOAP messages must use the SOAP Encoding namespace
SOAP messages cannot contain DTD references
SOAP messages cannot contain XML processing instructions
3.3.3. The basic structure of SOAP messages ¶
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