Hi,
as you know we have a WFS 3.0 prototype implementation in community land.
Right now it's implemented
mostly as an internal proxy to WFS 2.0:
https://github.com/geoserver/geoserver/blob/master/src/community/wfs3/src/main/java/org/geoserver/wfs3/WFS3Filter.java
https://github.com/geoserver/geoserver/blob/master/src/community/wfs3/src/main/java/org/geoserver/wfs3/DefaultWebFeatureService30.java
The other possible alternative for implementation would have been to use
Spring MVC... however that would have come
with a very high cost, as it would have broken solid all usage of
DispatcherCallback, making WFS3 problematic to use
in the GeoServer ecosystem.
Here is a small recap of supported functionalities that would be broken by
a WFS implemnetation not going go through the Dispatcher and does
not invoke DispatcherCallback:
- Version negotiation
- Workspace specific services
- Monitor extension
- Service security
And then add to that whatever extra callback is present in vendor
implementations of GeoServer (in my experience it's one
of the most used callbacks).
Now, not going throught the Dispatcher does not equate with not calling
DispatcherCallback, but it's pretty close.
The main issue is that not all callbacks are read only, and each method
allows implementors to alter the call in many ways:
- *init* allows to fiddle with kvp maps, allowing to alter them, or
redefine them from scratch
- *serviceDispatcher* allows to re-route to another service (we do that,
for example, in the ncwms module, and I believe in the WFS NSG modules too)
- *operationDispatched* allows to change the parsed request parameters,
or to re-route to an entirely different call (done multiple times in
vendor extensions, e.g., to bypass GeoServer completely and call other
services in the infrastructure that could compute some GetMap responses
with higher efficiency)
- *operationExecuted* allows to rewrite the response object (e..g, to
enrich/decorate/filter the response)
- *responseDispatched* allows to change the response object that will
encode the response (allows for alternate encoding implementation)
- *finished*... is just finished, no changes allowed here :-)
In Spring MVC I see none of this flexibility, yes one can add interceptors,
but they are working at low level HTTP and would end up being shared with
the configuration API, and believe one can build proxies around
controllers, but their support of the above would seem rather limited
compared to the above (change http kvp, change single method request and
response objects). So even adding a proxy around the controller, the
support for callback would be severely limited and would not fit the
existing architecture, breaking them in case WFS 3 is used.
The above makes me believe MVC is not actually viable to implement OGC
resource oriented services, as a result, I'll probably continue
to work on the current proxy based approach, and see how deep the rabbit
hole is.
But... I'd like to hear from others, that surely have more MVC famliarity
than me, and see if there is any viable alternative
Cheers
Andrea
==
GeoServer Professional Services from the experts! Visit http://goo.gl/it488V
for more information.
==
Ing. Andrea Aime
@geowolf
Technical Lead
GeoSolutions S.A.S.
Via di Montramito 3/A
55054 Massarosa (LU)
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39 339 8844549
http://www.geo-solutions.it
http://twitter.com/geosolutions_it
AVVERTENZE AI SENSI DEL D.Lgs. 196/2003
Le informazioni contenute in questo messaggio di posta elettronica e/o
nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il
loro utilizzo è consentito esclusivamente al destinatario del messaggio,
per le finalità indicate nel messaggio stesso. Qualora riceviate questo
messaggio senza esserne il destinatario, Vi preghiamo cortesemente di
darcene notizia via e-mail e di procedere alla distruzione del messaggio
stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso,
divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od
utilizzarlo per finalità diverse, costituisce comportamento contrario ai
principi dettati dal D.Lgs. 196/2003.
The information in this message and/or attachments, is intended solely for
the attention and use of the named addressee(s) and may be confidential or
proprietary in nature or covered by the provisions of privacy act
(Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
Code).Any use not in accord with its purpose, any disclosure, reproduction,
copying, distribution, or either dissemination, either whole or partial, is
strictly forbidden except previous formal approval of the named
addressee(s). If you are not the intended recipient, please contact
immediately the sender by telephone, fax or e-mail and delete the
information in this message that has been received in error. The sender
does not give any warranty or accept liability as the content, accuracy or
completeness of sent messages and accepts no responsibility for changes
made after they were sent or for other risks which arise as a result of
e-mail transmission, viruses, etc.
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Geoserver-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/geoserver-devel
