Hi,
On Feb, 22th this year I tried to start a thread ("Open issues in Hessian
protocol")
on this subscription list, which never appeared. But I'm glad to see that some
of my
concerns have been addressed for Hessian 2.0 in the most recent discussion.
Nevertheless, here are some of my remaining issues:
1) One of basic flaws in the original spec 1.0.x is that objects types
are represented as potentially unordered (hash) maps which are restricted to
single-keys. This conflicts with class definitions in nearly all languages,
where
data members are sequentially ordered and where the same member name can occur
multiple times in the same class (at least in class hierachies). This is not an
hypothetical issue: I stumbled across this when I tried to read an object of
type
org.springframework.core.NestedRuntimeException
which derives from java.lang.RuntimeException as result of a failed request.
The derived class NestedRuntimeException legally (according to language rules
of Java)
contains two data members "cause" (Throwable):
- One from the derived class NestedRuntimeException
- The second one from it's base class java.lang.Throwable.
While the caucho implementation persisted the object map of
NestedRuntimeException
loss-free (with two occurrences of the key "cause"), the HessianInput(2)
classes
did simply override any multiple occurrence of keys, which is a natural result
of
the single-key model.
Now that the reworked Hessian 2.0 seems to address the object-representation
problem
by introducing new object types, I strongly encourage to change the current
fault
result map to a proper object model in Hessian 2.0!
2) Date (for Hessian 2.0 x4a/x4b) has been provided as an individual type, but
at least the most recent gaucho implementations actually wrap this date
*additionally*
as a class map [of java.util.Date]. This is very annoying, because it breaks
the normal
symmetry of type representations. If you write your own Hessian reader for
another language (as I did) it is an awful hack to expect that Dates are
actually
a Hessian date inside a Hessian map (if coming from a Java-based server) and
makes
language-neutral Hessian usage nearly impossible!
Greetings from Bremen,
Daniel Krügler
Bruker Daltonik GmbH
--------------------------------------------------------
Fahrenheitstrasse 4
28359 Bremen
Germany
Permoserstrasse 15
04318 Leipzig
Germany
Geschäftsführer
Frank Laukien, Ph. D.
Gerd Hülso
Sebastian Meyer-Plath
Stefan Ruge
Ian Sanders, Ph. D.
Dr. Michael Schubert
Sitz der Gesellschaft
Bremen
Handelsregister
Amtsgericht Bremen
HRB 8150
www.bdal.de
--------------------------------------------------------
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Bruker Daltonik GmbH------------------------------Fahrenheitstrasse 428359
Bremen, Germany Permoserstrasse 1504318 Leipzig, Germany Geschäftsführer: Frank
Laukien, Ph. D., Gerd Hülso, Sebastian Meyer-Plath, Stefan Ruge, Ian
Sanders, Ph. D., Dr. Michael Schubert Sitz der Gesellschaft: Bremen
Handelsregister Amtsgericht Bremen: HRB 8150 www.bdal.de
------------------------------------------------------------Haftungsausschluss:
Die Bruker Daltonik GmbH ist nicht verantwortlich für die ordnungsgemäße,
vollständige und verzögerungsfreie Übertragung der Nachricht. Der Inhalt der
E-Mail ist nur rechtsverbindlich, wenn er unsererseits durch einen Brief oder
ein Fax entsprechend bestätigt wird.Exclusion from liability: Any liability of
Bruker Daltonik GmbH referring to the correct, complete and immediate
transmission of the message shall be excluded. The content of the e-mail
including its attachments is only legally binding if confirmed by Bruker
Daltonik GmbH by letter or fax.
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