There are a couple of ways to do this. The hivemind website documents using
properties, the list has some other methods.
My personal favorite it use a service with multiple contributed
implementations.
In this case you have a service that implements the interface and is
constructed with a configuration-point. The configuration-point is
contributions of implementation of the same interface that are ordered. The
service then chooses from the contributions the SPI it wants. Your default
out of the box jar provides a default implementation, your customer provides
a custom implementation and contributes it to your configuration, your core
service chooses the customers implementation over your standard
implementation.
I actually use a hivemind provided version of this called the ChainFactory.
The first method in the chain that returns something resembling true stops
the chain. In your case, you could document to your customers to return true
if they handle the search, or false if they want the default to handle the
search.
<service-point id="TextMiner" interface="TextExtractor">
<invoke-factory service-id="hivemind.lib.ChainFactory">
<construct configuration-id="TextExtractor" />
</invoke-factory>
</service-point>
<configuration-point id="TextExtractor"
schema-id="hivemind.lib.ChainContribution" />
<contribution configuration-id="TextExtractor">
<command id="Html"
object="instance:HtmlTextExtractor,pattern=(?i).*\.(htm|html)$" />
<command id="Pdf"
object="instance:PdfTextExtractor,pattern=(?i).*\.(pdf)$" />
</contribution>
Releavent documentation
http://jakarta.apache.org/hivemind/hivemind-lib/ChainFactory.html
Richard
-----Original Message-----
From: Glen Stampoultzis [mailto:[EMAIL PROTECTED]
Sent: Wednesday, June 15, 2005 4:53 PM
To: [email protected]
Subject: Overriding services
I was wondering whether it was possible to override service implementations?
For instance, say I have a Lucene indexer as a default implementation
for a search service and I would like to let my customer add a jar in
that would override this by copying in a hivemind-aware jar file
containing an alternative search implementation.
Would this be possible easily?
Regards,
Glen Stampoultzis
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