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。
3.8.1. HTTP protocol ¶
HTTP communicates over TCP/IP. The HTTP client connects to the HTTP server using TCP. After the connection is established, the client can send a HTTP request message to the server:
POST /item HTTP/1.1 Host: 189.123.255.239 Content-Type: text/plain Content-Length: 200 The server then processes the request and sends a HTTP response to the client. This response contains a status code that indicates the status of the request:
200 OK Content-Type: text/plain Content-Length: 200 In the above example, the server returns a status code of 200. This is the standard success code for HTTP.
If the server cannot decode the request, it may return information like this:
400 Bad Request Content-Length: 0 3.8.2. SOAP HTTP Binding ¶
The SOAP method refers to a HTTP request / response that complies with the SOAP coding rules. The SOAP request may be a HTTP POST or HTTP GET request. The HTTP POST request specifies at least two HTTP headers: HTTP + XML = SOAP ¶
Content-Type and Content-Length .
3.8.3. Content-Type ¶
Request and response of SOAP Content-Type header can define the message’s MIME type, and for the request or response XML the character encoding of the body (optional).Grammar ¶
Content-Type: MIMEType; charset=character-encoding
Example ¶
POST /item HTTP/1.1 Content-Type: application/soap+xml; charset=utf-8
3.8.4. Content-Length ¶
Request and response of SOAP Content-Length the header specifies the number of bytes for the request or response body.Grammar ¶
Content-Length: bytes
Example ¶
POST /item HTTP/1.1 Content-Type: application/soap+xml; charset=utf-8 Content-Length: 250