GSPress:一个GML流压缩器

GSPress:a GML Stream Compressor

GML已成为地理数据存储和交换的标准.在实际应用中,GML数据通常以数据流的形式在网络上传输.由于GML文档含有大量重复标签和高精度浮点数,使得GML文档通常比较大.因此如何有效地压缩GML数据流来减少网络传输的代价就显得越来越重要.本文提出一种GML数据流压缩算法,它只需扫描GML文档一次,将GML文档的结构和数据分离后分别进行压缩.对GML文档中的结构部分采用自适应方法进行压缩;对坐标数据则利用增量压缩的方法压缩.实验结果表明GSPress是一种高效的GML流压缩算法.

GML has become the standard for geographical data representation and exchange. In real applications, GML data is always transmitted via network in the form of stream. However, GML documents are usually very large in size because of the verbose tags and large amount of text-encoded coordinate data in the documents. Thus, it is necessary to compress GML stream so as to reduce the transmission cost. In this paper, we propose a GML stream compressor GSPress. It separates spatial data from structural information and compresses them individually. It employs an adaptive method to compress the structural information and the delta compression method to compress the spatial coordinate data. Experimental results show that GSPress can achieve satisfactory compression performance and good tradeoff between compression efficiency and compression effectiveness.