Copyright © 2011 Open Geospatial Consortium
34 As results showed, the compaction performance is we believe similar, but maybe some
tests could be made regarding CPU and memory consumption where the AgileDelta product seems to perform better.
As we face some slight bugs on the processing of list of floats and integers, we submitted a bug report to the Exificient team, and got a fast fix thanks Daniel. So the version we
used is a patch on release 0.7 and corresponds to the revision 361 from the sourceforge svn repository so it’s not a strait 0.7
5.3.1.3.1 Without previous schema knowledge and “deflate” post-compression
Like FIS and its default PER encoding, EXI uses a bit stream and not a byte stream. On this configuration without previous schema knowledge nor post-compression, the
compaction is mainly brought by XML parsing and structure recognition. It is not so different from FIS in this mode.
This configuration is in:
exi-ttfmsconfigdriverssaxexificient-neither.xml …
param name=japex.driverClass value=org.w3c.exi.ttf.candidate.exificient.ExificientSAXDriver
param name=org.w3c.exi.ttf.driver.candidateName value=Exificient 0.7 Siemens EXI Java open source impl.
driver name=ExificientNeitherSAX param name=description value=EXI without document analysis
or schema optimizations param name=org.w3c.exi.ttf.applicationClass
value=neither driver
…
5.3.1.3.2 Without previous schema knowledge but with “deflate” post-compression
As for FIS, the post-compression needs to output byte aligned symbols, and this choice is made by the candidate when it sees the “document” application-class parameter activated.
But, contrary to FIS or JAXP, EXI manages its own “deflate” algorithm and does not use zlib’s API. That’s why the GZIP parameter is not set in the config file.
This configuration is in:
exi-ttfmsconfigdriverssaxexificient-document.xml …
param name=japex.driverClass value=org.w3c.exi.ttf.candidate.exificient.ExificientSAXDriver
param name=org.w3c.exi.ttf.driver.candidateName value=Exificient 0.7 Siemens EXI Java open source impl.
Copyright © 2011 Open Geospatial Consortium
35
driver name=ExificientDocumentSAX param name=description value=EXI with deflate
param name=org.w3c.exi.ttf.applicationClass value=document
driver …
5.3.1.3.3 With previous schema knowledge but without “deflate” post-compression
This mode is very close to the first one, except that we give the location of schema the first xsd including others to the algorithm. In the preparation phase, EXI will parse .xsd
files beginning by AIXM_BasicMessage.xsd, then will compute its grammar to apply for encoding or decoding. The output is bit aligned.
The configuration is in:
exi-ttfmsconfigdriverssaxexificient-schema.xml …
param name=japex.driverClass value=org.w3c.exi.ttf.candidate.exificient.ExificientSAXDriver
param name=org.w3c.exi.ttf.driver.candidateName value=Exificient 0.7 Siemens EXI Java open source impl.
driver name=ExificientSchemaSAX param name=description value=EXI with schema optimizations
but without deflate param name=org.w3c.exi.ttf.applicationClass value=schema
driver …
5.3.1.3.4 With previous schema knowledge and “deflate” post-compression
