支持版本演进的高兼容性OGC客户端关键技术研究——以WMS客户端为例

在分析了OGC网络服务的不同版本标准和不同服务器实现的差异基础上,提出了一种结合“面向对象思想”和“工厂设计模式”的兼容性解决方案.该方案通过继承抽象的OGC解析器,实现了不同版本标准的WMS解析器,然后结合“工厂设计模式”以实现对不同版本标准的支持；设计了提供扁平化功能的多叉树结构以结合树形图层和一般GIS软件的列表式图层的优势；设计了标准键关键字库以实现对基地址的识别和URL的修正.实现了通过选择高效的序列化器以支持XML文本的高效解析；封装高性能的网络传输工具以支持对服务的高效访问.笔者根据以上设计思路,实现了一个WMS客户端,可支持不同版本、不同厂商开发的WMS服务.

The Study of Key Techniques of High Compatibility OGC Client Supporting Version Evolution——Taking WMS Client as a Case Study

Based on the analysis of different versions of OGC Web service standards and their implementation on different servers,the authors put forward a solution combining the object-oriented thinking and factory design pattern,which implements some WMS parsers under different versions of the standards by inheriting from Abstract OGC parser class,and uses factory design pattern in order to support different versions of standards.They design a multi-tree structure which can be squeezed to a flat list and have the advantages of nested layers and list layers of normal GIS software,and standard Key words:library in order to realize the base address recognition and URL modification.By using efficient serialized library to support efficient parsing of XML text and developing high performance network transmission tools,the client achieved high-performance access to OWS services.With an in-depth research of WMS standards and the proposal above,the author implemented a WMS client that can support different versions and services implemented by different GIS manufacturers.