Hi,
Before I open a jira for this I have devised an coded example to illustrate it,
and hopefully get some comments:
//Example: The shell of an eagerloaded service
public class ImageService {
/** Cache to hold thumbnail images */
private static ConcurrentHashMap<Integer, Thumbnail> imageCache_ = new
ConcurrentHashMap<Integer, Thumbnail>();
public void preloadImageCache() {
DbConnection connection = null;
try {
//Sometimes this turns into a Null Pointer Exception as
another eagerloaded service sets up the connection pool etc.
//this service should start up after that one, but this
is not always the case in practice??
connection = DatabaseConnection.getReadConnection();
//database query
} catch (Exception e) {
//handle exception
}
}
public static ImageService build() {
return new ImageService();
}
public ImageService() {
preloadImageCache();
}
}
//Workaround: adding a dependency on the other eagerloaded service solves it,
but this is not a practical solution if there are many of these services
public class ImageService {
/** Cache to hold thumbnail images */
private static ConcurrentHashMap<Integer, Thumbnail> imageCache_ = new
ConcurrentHashMap<Integer, Thumbnail>();
public void preloadImageCache() {
DbConnection connection = null;
try {
connection = DatabaseConnection.getReadConnection();
//database query
} catch (Exception e) {
//handle exception
}
}
public static ImageService build(SiteInitialise siteInitialise) {
return new ImageService(siteInitialise);
}
public ImageService(SiteInitialise siteInitialise) {
if(siteInitialise.isConnectionOk())
preloadImageCache();
}
}
If there is a way to ensure the ordering of eagerloaded services, then this is
not an issue, perhaps this is a regression from the fix to
http://issues.apache.org/jira/browse/TAPESTRY-2267 ? otherwise I am surprised
that others have not come across this, perhaps I have missed something?
Cheers,
Peter
----- Original Message -----
From: "Peter Stavrinides" <p.stavrini...@albourne.com>
To: "Tapestry Mailing List" <users@tapestry.apache.org>
Sent: Friday, 24 July, 2009 15:59:20 GMT +02:00 Athens, Beirut, Bucharest,
Istanbul
Subject: Tapestry 5 IoC Eagerloading and ordering of services
Hi everyone,
Is it possible to control the ordering of eagerloaded IoC services, especially
if the services exist is separate but dependent IoC modules.
I found an issue http://issues.apache.org/jira/browse/TAPESTRY-2267 that states
these service proxies are claimed and loaded collectively, however no mention
is made of how to ensure the correct ordering of these claimed services?
Any help with this would be greatly appreciated.
Kind regards,
Peter
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