48
11.2.1.1.4 Conclusion
EXI with post compression offers very interesting performance in terms of compaction, always better than post compression only and Fast Infoset, though the latter offers quite
good performances overall. Adding the schema to EXI with post compression will improve the performance even more for the following types of data:
Taxiways Airspaces
Runway elements Geo borders
11.2.1.2 CPU consumption
The following graphs show both the CPU time needed by the algorithms and the compaction ratio associated, to get an idea of the CPU price of compaction.
11.2.1.2.1 First family – D-Notams
Figure 12 - Compaction Speed Results D-Notams
We can see that Fast Infoset without post compression is faster than any other algorithms even the basic SAX parser. This charts also points out the great complexity of EXI post
compression, where the CPU time sky rockets. Here EXI with Schema but no post compression performs very well in terms of both compaction and CPU time. However,
Fast Infoset remains the most interesting when it comes to the ration compactiontime.
49
11.2.1.2.2 Second family – medium size files
Figure 13 - Compaction Speed Results Medium Sized Files
As the file size gets bigger, EXI clearly shows its limits, with CPU times form 3 seconds to almost 15 seconds 100 times more that SAX, making it completely unusable in a
real-time or even close to real-time environment. Without post compression, Fast Infoset proves to be very fast, up to 4 times faster than the basic SAX parser.
11.2.1.2.3 Third family – bigger files
The results for the third family are basically confirming the trend observed with the second family
Figure 14 - Compaction Speed Results Large Sized Files
50 Fast Infoset still proves to be faster that SAX 2 to 3 times faster. Fast Infoset with post
compression and EXI with Schema perform approximately the same. Fast Infoset with post compression is only around 2 times slower than SAX, while its compaction
performance is greatly improved.
11.2.1.2.4 Conclusion
Fast Infoset is clearly the best option when it comes to compactiontime ratio. The very important throughput it allows makes it an adapted solution for very fast communication
networks. While offering very acceptable compaction performance in terms of compaction compared to EXI, it clearly demonstrate its lower complexity in terms of
CPU time. EXI with Schema knowledge but no post compression is still in the race, offering decent compression ratio with CPU comparable to Fast Infoset
11.2.1.3 Gzip compaction time analysis