On Tue, Oct 4, 2011 at 11:45 AM, Srinath Perera <[email protected]> wrote:
> +1 .. if we can replace all with one mediator .. that is great! but we
> have to carefully design the syntax to make sure final result is
> natural for all cases.
>
I think there are two ends for this. One is making it general. Other think
is make common case simple.
Current filter (it actually does some thing like if) mediator configurations
can be as follows.
<filter xpath="//ns1:foo/ns1:bar/text() == 'test'">
<then />
<else />
</filter>
<filter source="//ns1:foo/ns2:bar/text()" regex="test">
<then />
<else />
</filter>
former 'xpath' is referred to an xpath returning a boolean while the
'source' attribute refer to an xpath returning a text value. Here it has
tried to cover different specific scenarios which make that particular
occasion to use it easily.
But we if follow an method like BPEL by using another copy mediator (in fact
I think these are not mediators but some language constructs). It would have
written like this.
<variable name='foo' >
<copy>
<from source='soapbody' xpath="//ns1:foo/ns1:bar/text()"/>
<to source='$foo' />
</copy>
<if condition="$foo =='test'">
<then/>
<else/>
</if>
then it is more generic. And no need to repeat the xpath, source veriables
with each mediator. But for a simple xpath based filter need to use another
copy mediator etc ..
thanks,
Amila.
> --Srinath
>
> On Fri, Sep 30, 2011 at 3:03 PM, Kasun Indrasiri <[email protected]> wrote:
> > Hi all,
> > In the current ESB implementation we have couple of mediators for message
> > routing. While 'Filter' and 'Switch' mediators provide basic level of
> > message filtering, router mediator is also doing very similar to what
> > filter/switch mediators do. The usage of Router mediator is rare and
> often
> > got replaced by filter/switch mediators. So, IMO, Router Mediator is
> > redundant, unless it provides some advance/complex routing logic support.
> > In the ESB 4.0.0 release, we introduces 'Conditional Router', which is
> > intended to route messages based on HTTP headers, query parameters and
> url.
> > However, this doesn't support routing based on message payload. But
> unlike
> > 'Router', the 'Conditional Router' introduces uses the concepts of
> > 'Evaluators' (And, Or, Match, Equal, Not) that can be utilize to
> construct
> > complex routing logics.
> > eg:
> > <conditionalRouter continueAfter="false">
> > <conditionalRoute breakRoute="false">
> > <condition>
> > <and xmlns="">
> > <match type="header"
> > source="my_custom_header1" regex="foo.*"/>
> > <match type="url"
> > regex="/services/StockQuoteProxy.*"/>
> > </and>
> > </condition>
> > <target sequence="cnd2_seq"/>
> > </conditionalRoute>
> > <conditionalRoute breakRoute="false">
> > <condition>
> > <and xmlns="">
> > <match type="header"
> > source="my_custom_header2" regex="bar.*"/>
> > <equal type="param" source="qparam1"
> > value="qpv_foo"/>
> > <or>
> > <match type="url"
> > regex="/services/StockQuoteProxy.*"/>
> > <match type="header"
> > source="my_custom_header3" regex="foo.*"/>
> > </or>
> > <not>
> > <equal type="param" source="qparam2"
> > value="qpv_bar"/>
> > </not>
> > </and>
> > </condition>
> > <target sequence="cnd3_seq"/>
> > </conditionalRoute>
> > </conditionalRouter>
> > So, we can easily add message level routing capability(so that we can
> drop
> > Router mediator) to Conditional Router and with that we'll get the power
> of
> > using evaluators for message level routing as well. Having bunch of
> > mediators that's doing the similar thing, cause a negative effect on
> ESB's
> > usability.
> > (Most of the pointed listed here, were discussed during last code-review
> of
> > Group-D.)
> >
> >
> > [1] http://wso2.org/project/esb/java/4.0.0/docs/mediator_guide.html
> >
> > Thanks,
> > --
> > Kasun Indrasiri
> > Associate Technical Lead
> > WSO2, Inc.; http://wso2.com
> > lean.enterprise.middleware
> >
> > cell: +94 71 536 4128
> > Blog : http://kasunpanorama.blogspot.com/
> >
>
>
>
> --
> ============================
> Srinath Perera, Ph.D.
> Senior Software Architect, WSO2 Inc.
> Visiting Faculty, University of Moratuwa
> Member, Apache Software Foundation
> Research Scientist, Lanka Software Foundation
> Blog: http://srinathsview.blogspot.com/
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>
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