Article:		Binary Killed the XML Star?
Subject:		Performance
Date:		2003-11-28 04:18:55
From:		Tim Jansen
Most of the discussion seems to be centered around the size of the XML representation. gzip is hard to beat at that. But the more interesting point in a binary encoding is performance. If XML should not be used for communication between systems, but also for internal communication inside the system (e.g. for SOAP IPC), performance is becoming much more important. And the performance difference between a good binary encoding and text XML is pretty large. CWXML, which is a pretty fast parser that supports both BXML and XML, is at least 3x faster when reading BXML compared to text XML, and it is 30x faster than reading gzip'd XML (http://www.cubewerx.com/main/cwxml/). Beside that, I don't think it matters which serialization format is used for the XML data model. The data model is the important part, not the text. The text serialization is quite useful because text happens to be a widespread data format, so you can use existing tools to view and edit XML. I agree with the microsoft position that having to support more than one serialization format would be a bad thing. Every XML processor needs to support the text format. But that doesnt mean that there can't be an alternative in environments where the producer and consumer are able to negotiate the format, like with SOAP over HTTP. For these cases it makes sense to have a single binary format, because otherwise each vendor will have its own format. This would create a situation where a product may be able to interoperate with those of other vendors, but it will be slower.

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• Performance
  2003-12-04 10:52:22 Toni Uusitalo [Reply]
  
  It might be worth mentioning that CWXML supports only Latin1 encoding. Exerpt from http://www.cubewerx.com/main/HTML/Binary_XML_Encoding.html:

  
  "The implementation presently uses ISO-8859-1 string encoding internally..."

  
  I don't try to say that binary XML isn't worth closer look and discussion, but comparing performance of CWXML to for example libxml2 (which is parser with full unicode support) is simply stupid.

  
  Note that if XML parser isn't unicode aware it means that it doesn't check for example qualified names that XML spesification requires any conformant parser to do.

  
  When we see CWXML parser (or any binary xml parser) tested against OASIS xml testsuite - with all tests successfully passed of course - then we should take this speed comparition seriously.
  
  

  • Performance
    2003-12-04 11:11:17 Toni Uusitalo [Reply]
    
    Addition: Of course OASIS XML testsuite should be modified to work as binary XML testsuite somehow.
    
    

• Performance
  2003-11-28 04:29:55 Tim Jansen [Reply]
  
  BTW another problem with gzip'd XML is the lack of random access. You won't see a XML-based format for storing images, sound or video with text-encoded or gzip'd serialization format. It would be simply to slow. A binary XML serialization with support for blobs (like BXML) would make it possible to store even these 'classic' binary formats as XML. The raw bitmap would not be split into elements, of course, but the meta data, allowing XQuery and XPath queries. Unless you want to have at least one other data model beside XML in the future, the use of a binary serialization format is compelling.