XML parsers

[Mehmet Cevikce]

What is the difference between IBM and Sun XML parsers?

[Ajith Kallambella]

Except the fact that they are from two separate vendors, there shouldn't be any visible difference. It is like asking what is the difference between a PC from Compaq and a PC from Dell. As an user, both should deliver at least what is expected out of it. Any fancy feature would just be an added bonus.
Similarly all parsers should adhere to a common set of rules of XML parsing -like checking well-formedness, checking validity, resolving external entities, resolving namespaces etc. These requirements define the common denominator. Parser implementations from different vendors are often bundled with extra classes that offer value-added features.
In order to eliminate the pains of coping with idiosyncratic parser behaviors, Sun has provided the JAXP framework. Using JAXP you can achieve a higher level of abstraction and transparency while using different parsers.
Hope that helps!

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Ajith Kallambella M.
Sun Certified Programmer for the Java�2 Platform.
IBM Certified Developer - XML and Related Technologies, V1.

[Ajith Kallambella]

Just like automobiles, one parser might fair better than another under specific conditions - such as size of the XML file, complexity of structure, processor speed, memory and other OS resources, optimization features turned on etc..
When these conditions change the performance( or any measured entity ) matrix might change too.
Checkout a sample performance test statistics of different parsers. I suggest you take the figures with a pinch of salt since those parsers have later versions available now.
Cheers!
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Ajith Kallambella M.
Sun Certified Programmer for the Java�2 Platform.
IBM Certified Developer - XML and Related Technologies, V1.