I use onActivate() to return an image for a heartbeat to an Ajax
dashboard. Using an image allows me to use the onLoad event to verify
connectivity. When I proposed that, I was warned that using
onActivate() to return an image can create performance issues. In my
case I'm returning a 1-pixel GIF so wasn't worried about performance but
you might want to be careful because you are doing a lot of back end
processing.
Chuck
On 12/9/2010 9:37 AM, Michael Gentry wrote:
I took a more conventional approach. I created a DatabaseImage page
that streams the image from the database.
In the TML of the page that wants to embed an image from the database:
<img src="${imageLink}"/>
In the Java:
@Inject
private PageRenderLinkSource pageRenderLinkSource;
public Link getImageLink()
{
String encryptedContext = DatabaseImage.encrypt(...);
return
pageRenderLinkSource.createPageRenderLinkWithContext(DatabaseImage.class,
encryptedContext);
}
The encrypt method basically encrypts everything I need (table names,
primary keys, etc) to go find the database image and stuffs it into
the link's context. At runtime, I end up with requests from the
browser like:
GET
/MyApp/databaseimage/$002faiNglawZWKGHKrl$002fgpKneotYRwaq9gMk3dPr5zQkW8KkoezyRBm0TutynHstG0$002fyn$002b6izoD$002f$002f9V$000a$002fqAXmUmgxQ$003d$003d
Ugly URL, but it works. In the DatabaseImage page itself I have:
public StreamResponse onActivate(String context)
{
...
}
that decrypts the encrypted context, finds the image blob stored in
the database, and streams it out as the response.
mrg
On Thu, Dec 9, 2010 at 7:22 AM, Igor Drobiazko<igor.drobia...@gmail.com> wrote:
There is no documentation for it as this is not an often use case. However,
just provide you own implementation of AsssetFactory, build it or bind it in
your module and make the contribution:
public void contributeAssetSource(MappedConfiguration<String,
AssetFactory> configuration, @InjectService("DbAssetFactory") AssetFactory
dbAssetFactory) {
configuration.add("db", dbAssetFactory);
}
Now it is up to you to implement the AssetFactory.
On Thu, Dec 9, 2010 at 11:53 AM, Gunnar Eketrapp
<gunnar.eketr...@gmail.com>wrote:
Hi!
I would like to store uploaded images in the database and then use them in
template files.
Are there any examples of how to do this? I.e. how to define a new
AssetFactory and contribute it to the AssetSource service configuration.
Thanks in advance,
Gunnar Eketrapp (from a very cold and snowy Stockholm)
==================================
The doc says ...
New Asset Domains
If you wish to create new domains for assets, for example to allow assets
to
be stored on the file system or in a database, you may define a new
AssetFactory and contribute it to the AssetSource service configuration.
===================================
--
Best regards,
Igor Drobiazko
http://tapestry5.de
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