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Posted to dev@tomcat.apache.org by bu...@apache.org on 2013/09/20 23:14:32 UTC
[Bug 55576] New: Order of ServletRequest parameters is not preserved
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
Bug ID: 55576
Summary: Order of ServletRequest parameters is not preserved
Product: Tomcat 7
Version: 7.0.35
Hardware: PC
Status: NEW
Severity: major
Priority: P2
Component: Servlet & JSP API
Assignee: dev@tomcat.apache.org
Reporter: corythearchitect@outlook.com
The ServletRequest interface provides two methods to iterate through request
parameters:
Enumeration<String> getParameterNames(), and
Map<String, String[]> getParameterMap()
Unfortunately, the underlying implementation in Tomcat is a HashMap, which
fails to preserve the order of parameters as they are specified in the request.
An alternate implementation should be used to preserve request order.
LinkedHashMap, for example, is capable of preserving insertion order.
The Servlet Specification (v3.0) speaks only to the relative ordering of query
string data and post body data. However, section 17.13.3 of the HTML
specification (v4.01) titled "Processing form data", clearly states that
"control names/values are listed in the order they appear in the document."
Therefore, I do not see a valid interpretation of either specification to
rationalize Tomcat's implementation. To receive a request with an ordered list
of parameters and represent them in an implementation that is guaranteed not to
preserve this order is difficult to rationalize.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
--- Comment #3 from corythearchitect@outlook.com ---
Thomas, thank you for your rapid evaluation and response on this matter.
The general use case is the servicing of a request in which the order of
parameter evaluation is significant.
http://host/resource?country=CA&postalcode=N7T5R4
Let's assume this is in context of a general infrastructure that evaluates each
parameter in the order received (field validation being just one example of
potential triggers). postalcode validation is dependent on the value of
country.
The specific scenario I am currently dealing with is porting a web service
implementation from ASP/IIS to Java/Tomcat. The Microsoft
IRequestDictionary.QueryString implementation respects order of insertion,
while Tomcat scrambles the order as a result of the backing HashMap collection.
I respect your position that there is no explicit specification of the
server-side evaluation of HTML parameters. However, I also see no significance
to the client-side specification of parameter order beyond the implication that
the ordering is also significant to the processing server that consumes it.
What other purpose could such an ordering possibly serve?
Assuming equivalent performance, what portability issues could arise from a
MORE determinate collection implementation? If anyone is currently relying on
the iteration order of the existing HashMap implementation,
a) they are in for a surprise anyhow, and
b) the ServletRequest interface, unfortunately, provides no guarantees, relying
on the generic Map and Enumeration interfaces, both of which defer to the
implementation for behaviour in this regard.
This decision could only be interpreted as an improvement in compliance (with
the HTML specification).
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
--- Comment #6 from mgrigorov <mg...@apache.org> ---
In my opinion this requirement and the use case are weak.
In the best case I'd try to avoid depending on any ordering in the application.
But if ordering is really required then I would encode the parameter values and
parse them myself and not rely on some container specific feature.
E.g.: ?ops=op1|op2|op3&something=else, or any other encoding that will work for
my use case. With URL encoded value the syntax could be quite rich.
On the other hand replacing HashMap with LinkedHashMap will not cause
performance degradation so I don't mind such change.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |NEW
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
--- Comment #5 from corythearchitect@outlook.com ---
"Or are you building a system where the order of the parameters in the request
dictates the way validation is performed?"
Essentially, yes.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
--- Comment #4 from Christopher Schultz <ch...@christopherschultz.net> ---
(In reply to corythearchitect from comment #3)
> The general use case is the servicing of a request in which the order of
> parameter evaluation is significant.
>
> http://host/resource?country=CA&postalcode=N7T5R4
>
> Let's assume this is in context of a general infrastructure that evaluates
> each parameter in the order received (field validation being just one
> example of potential triggers). postalcode validation is dependent on the
> value of country.
Isn't "postalcode validation is dependens on the value of country" part of your
business logic? If so, you should always be fetching the country first, then
the postalcode. Or are you building a system where the order of the parameters
in the request dictates the way validation is performed?
In any case, I am +1 for changing HashMap->LinkedHashMap to preserve parameter
ordering.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
--- Comment #2 from Christopher Schultz <ch...@christopherschultz.net> ---
(In reply to Mark Thomas from comment #1)
> I am curious as to the use case that supports it. Can you elaborate on why
> it might be important for the parameters to be returned in the same order as
> they appear on the form.
Somewhat related:
http://host/resource?op=add&op=update&op=delete
If the application expects left-to-right ordering when fetching "op" (which IMO
is reasonable) then the ordering of the values is quite important.
It seems like extending the above use case to parameters with different names
would be reasonable, though I can't really envision a use case where the order
of unknown request parameter names would be important.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
OS| |All
--- Comment #1 from Mark Thomas <ma...@apache.org> ---
The Servlet specification does defer to W3C for all HTML matters.
The text quoted above regarding ordering only applies when
application/x-www-form-urlencoded is being used. Strictly, it applies only to
the order that the client provides the data. It could be argued that if the
client is required to provide the parameters in order in this case then the
getParamererXXX() methods should respect that order. Further, if the order
needs to be maintained for this one case, it is easier to maintain it for all.
However, there is nothing that I can see in either the Servlet or HTML
specifications that strcitly requires the Servlet API to present the parameters
in the same order as they were received.
There is no major performance difference (I am aware of) between HashMap and
LinkedHahsMap so I am not against making this change but neither (at this
point) do I really see the need for it. One concern I do have is that given
that there is not a requirement for this, other containers may not implement it
and that could cause portability issues.
I am curious as to the use case that supports it. Can you elaborate on why it
might be important for the parameters to be returned in the same order as they
appear on the form.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #7 from Mark Thomas <ma...@apache.org> ---
Fixed in 8.0.x for 8.0.0-RC4 and 7.0.x for 7.0.45.
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[Bug 55576] Order of ServletRequest parameters is not preserved
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=55576
Violeta Georgieva <vi...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |zhouyanming@gmail.com
--- Comment #8 from Violeta Georgieva <vi...@apache.org> ---
*** Bug 55686 has been marked as a duplicate of this bug. ***
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