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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] How much run-time validation do you do?
 Hi
Folks,
Suppose that you
have an application which exchanges XML instance documents (instance data) with
trading partners. I'd like to get a feel for how people are addressing
these issues:
1. Do you validate
outgoing instance data? Do you validate incoming instance
data?
2. What criteria do
you use for deciding whether or not to do run-time
validation?
Note: By "validate" I am referring to
"XML validation", that is, validate an XML instance document against a schema
(DTD, XML Schema, RelaxNG, of Schematron).
Also note that I am talking about
"run-time validation". That is, dynamic validation of XML instance data
while a system is operational.
RUN-TIME VALIDATION
SPECTRUM
There are two
ends of the spectrum with respect to run-time validation:
a. Never validate:
neither outgoing nor incoming instance data is validated.
b. Always validate:
every outgoing and incoming instance is validated.
Let's consider each
of these:
NEVER
VALIDATE
Suppose that you and
your trading partners have agreed to a schema. And suppose that you tune
your application so that it flawlessly generates instance data conforming
to the schema. In this scenario it seems reasonable to skip
validating outgoing instance data. And if your trading partners have
similarly tuned their applications then it seems reasonable to skip validating
incoming instance data. (In other words, one-time static XML validation is
good enough)
>>>
MOTIVATION: The motivation for skipping validation is to avoid the performance
hit incurred by doing validation. In scenarios where there are a lot of
instances being exchanged then avoiding validation could provide a
substantial savings in processing.
Question: Does
anyone have performance statistics on validators?
ALWAYS
VALIDATE
Suppose that you are
receiving instance data from a variety of trading partners and some of them
cannot be trusted to send you conforming data. In this scenario it seems
reasonable to always validate incoming instance data. And if your
application is assembling dynamically created data then it seems reasonable to
always validate outgoing instance data.
>>> MOTIVATION: The motivation for
always validating is to prevent bad data from entering your application, and
prevent your application from sending out bad data.
Questions:
Where does your
company stand with respect to run-time validation:
-
Do you validate every outgoing instance?
-
Do you validate every incoming instance?
-
Do you validate only certain outgoing instances? What criteria do you use
for determining which outgoing instances are validated?
-
Do you validate only some of the incoming instances? What
criteria do you use for determining which incoming instances are
validated?
/Roger 
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