Mapped resource reference and urlFor()
Hi, I am using resource references for the first time to implement fetching images from a DB. The URLs will be of the following form: /resources/dbImages/DB_ID.png where DB_ID is an identifier to retrieve the image from the DB. I'm using the article at http://wicketinaction.com/2011/07/wicket-1-5-mounting-resources/ as a guide and have a couple of questions. 1. What is the purpose of the equals() override in the class ImageResource? I don't understand the explanation given in the article... Also, I put a breakpoint in my own resource class' equals() method and it never hits! 2. Can I use part of the resources namespace or is that asking for trouble since Wicket can use it however it likes? 3. When using getRequestCycle().urlFor(new MyResourceReference(), imageParameters), the following happens: at line 216 in ResourceMapper#addCachingDecoration(Url, PageParameters) : final IResource resource = resourceReference.getResource(); with a comment right above that says // TODO is calling getResource() a potential performance bottleneck? I am concerned that each time a url to my image resource reference is created, the DB will be hit, simply for getting the Url! It will then maybe be hit a second time afterwards if the client doesn't have the image in cache. Am I completely off-base here? Is there another way to manage resources so this doesn't happen? Thanks, Bertrand - To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
Re: Mapped resource reference and urlFor()
HI, On Wed, Dec 14, 2011 at 7:59 PM, Bertrand Guay-Paquet ber...@step.polymtl.ca wrote: Hi, I am using resource references for the first time to implement fetching images from a DB. The URLs will be of the following form: /resources/dbImages/DB_ID.png where DB_ID is an identifier to retrieve the image from the DB. I'm using the article at http://wicketinaction.com/2011/07/wicket-1-5-mounting-resources/ as a guide and have a couple of questions. 1. What is the purpose of the equals() override in the class ImageResource? I don't understand the explanation given in the article... Also, I put a breakpoint in my own resource class' equals() method and it never hits! Until recently both ResRef's #equals() and IResource#equals() were needed to find the mapped ResRef. This was improved recently (1.5.3 or trunk, not sure) and now only ResRef#equals() is used. See ResourceMapper#mapRequest(). 2. Can I use part of the resources namespace or is that asking for trouble since Wicket can use it however it likes? Use it. /resources/... is for 1.4.x In 1.5 the special one is /wicket/resource/... See IMapperContext 3. When using getRequestCycle().urlFor(new MyResourceReference(), imageParameters), the following happens: at line 216 in ResourceMapper#addCachingDecoration(Url, PageParameters) : final IResource resource = resourceReference.getResource(); with a comment right above that says // TODO is calling getResource() a potential performance bottleneck? I am concerned that each time a url to my image resource reference is created, the DB will be hit, simply for getting the Url! It will then maybe be hit a second time afterwards if the client doesn't have the image in cache. Am I completely off-base here? Is there another way to manage resources so this doesn't happen? Thanks, Bertrand - To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org -- Martin Grigorov jWeekend Training, Consulting, Development http://jWeekend.com - To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
Re: Mapped resource reference and urlFor()
Try to do the real work in the IResource#respond() (accessing the database and retrieving the image) and make calling the constructor cheap, then you should not have any bottlenecks at all. Am 14.12.2011 um 18:59 schrieb Bertrand Guay-Paquet: Hi, I am using resource references for the first time to implement fetching images from a DB. The URLs will be of the following form: /resources/dbImages/DB_ID.png where DB_ID is an identifier to retrieve the image from the DB. I'm using the article at http://wicketinaction.com/2011/07/wicket-1-5-mounting-resources/ as a guide and have a couple of questions. 1. What is the purpose of the equals() override in the class ImageResource? I don't understand the explanation given in the article... Also, I put a breakpoint in my own resource class' equals() method and it never hits! 2. Can I use part of the resources namespace or is that asking for trouble since Wicket can use it however it likes? 3. When using getRequestCycle().urlFor(new MyResourceReference(), imageParameters), the following happens: at line 216 in ResourceMapper#addCachingDecoration(Url, PageParameters) : final IResource resource = resourceReference.getResource(); with a comment right above that says // TODO is calling getResource() a potential performance bottleneck? I am concerned that each time a url to my image resource reference is created, the DB will be hit, simply for getting the Url! It will then maybe be hit a second time afterwards if the client doesn't have the image in cache. Am I completely off-base here? Is there another way to manage resources so this doesn't happen? Thanks, Bertrand - To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org - To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
Re: Mapped resource reference and urlFor()
@Peter: This is actually what I was doing already via the
ByteArrayResource class! I just didn't notice that only the constructor
was called... Thanks for opening my eyes!
@Martin: In 1.5.3, I think the code you referenced is :
// see if request handler addresses the resource we serve
if (resourceReference.equals(handler.getResourceReference()) ==
false
resourceReference.getResource().equals(handler.getResource()) == false)
{
return null;
}
Indeed, it suffices for the ResourceReference to implement equals which
it already does by default using its key. Thanks for explaining!
Regards,
Bertrand
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