[rules-dev] Spring support for drools-api
Mark Proctor
mproctor at codehaus.org
Mon Nov 24 00:42:23 EST 2008
I'm updating drools-api as we speak, based on the spring Resource idea.
the following Factory will provide a set of ready to go Resources, that
should satisfy most people's needs. So drools-api will be spimplied to
kbuilder.addResource( Resource, KnowledgeType )
kbuilder.addResource( Resource, KnowledgeType, ResourceConfiguration )
And the Resources available, and ofcourse people can implement the
interface themselves is:
public class ResourceFactory {
public static Resource newURLResource(URL url) {
return null;
}
public static Resource newURLResource(URI uri) {
return null;
}
public static Resource newURLResource(String url) {
return null;
}
public static Resource newFileResource(File file) {
return null;
}
public static Resource newFileResource(String file) {
return null;
}
public static Resource newByteArrayResource(byte[] bytes) {
return null;
}
public static Resource newInputStreamResource(InputStream stream) {
return null;
}
public static Resource newReaderResource(Reader reader) {
return null;
}
public static Resource newReaderResource(Reader reader, String encoding) {
return null;
}
public static Resource newClassPathResource(String path) {
return null;
}
public static Resource newClassPathResource(String path, ClassLoader classLoader) {
return null;
}
}
It can take a Reader, which underneath will open an InputStream, it'll use default encoding unless the encoding is
specified as otherwise in the alternative param.
So typically it'll be
kbuilder.addResource( ResourceFactory.newClassPathResource( "some path" ), KnowledgeType.DRL );
don't forget you can import static methods, so it can actually be:
kbuilder.addResource( newClassPathResource( "some path" ), KnowledgeType.DRL );
Mark
Greg Barton wrote:
> Well, if you look at String.getBytes() it uses the default encoding, then ISO-8859-1 if that fails. (Default is UTF-8 unless otherwise specified in the "file.encoding" property.) As long as that's documented I guess it's not a problem, unless someone wants to specify their own charset for a particular file. Java 1.6 has String.getBytes(Charset) and that could allow someone to use an alternate charset.
>
> I figure for the vast majority of cases it won't be a problem.
>
> --- On Sun, 11/23/08, Mark Proctor <mproctor at codehaus.org> wrote:
>
>
>> From: Mark Proctor <mproctor at codehaus.org>
>> Subject: Re: [rules-dev] Spring support for drools-api
>> To: "Rules Dev List" <rules-dev at lists.jboss.org>
>> Date: Sunday, November 23, 2008, 9:09 PM
>> I'm thinking of adopting the Spring approach to
>> Resources for
>> drools-api, obviously not tieing drools-api to spring -
>> just copying the
>> concept. Resource however doesn't seem to work with
>> Readers. Readers in
>> general are only needed for in memory generation , using
>> StringReader,
>> otherwise file/url/classpath resources suffice. So it seems
>> to do the
>> Spring way you would do a ByteArrayResource( "this is
>> my drl
>> file".getBytes() ). I'm wondering what people
>> think of that, and what
>> about encoding issues? Compared to the way at the moment
>> that we just
>> take a Reader, and that's it.
>>
>> Mark
>>
>> Mark Proctor wrote:
>>
>>> now my spring skills are improving, I'm looking to
>>>
>> improve the xml and
>>
>>> leverage spring Resource framework - so that we can
>>>
>> get complete
>>
>>> scripting of the entire KnowlegeBuilder api. I've
>>>
>> come up with the two
>>
>>> xmls so far:
>>> <property name="drls">
>>> <list>
>>>
>>>
>>>
>> <value>file:src/main/java/org/drools/ioc/spring/testSpring.drl</value>
>>
>>> </list> </property>
>>> <property name="dtables">
>>> <list>
>>> <bean
>>>
>>>
>> class="org.drools.ioc.spring.DtableResourceFactoryBean">
>>
>>> <property
>>>
>> name="resource"
>>
>> value="file:src/main/java/org/drools/ioc/spring/dt.xls"
>> />
>>
>>> <property
>>>
>> name="inputType" value="XLS" />
>>
>>>
>>> </bean>
>>>
>>
>>
>>> </list> </property>
>>> This one has a property per knowledge type, the
>>>
>> advantage is on
>>
>>> knowledge types which are just string, we can use a
>>>
>> simple <value>.
>>
>>> Although knowlege tyep that require additional
>>>
>> information, like the
>>
>>> DT input type, will need a bean.
>>>
>>> <property name="resources">
>>> <list>
>>> <bean
>>>
>>>
>> class="org.drools.ioc.spring.KnowledgeResourceBeanFactory">
>>
>>> <property
>>>
>> name="knowledgeType" value="DRL" />
>>
>>> <property
>>>
>> name="resource"
>>
>> value="file:src/main/java/org/drools/ioc/spring/testSpring.drl"
>>
>>
>>> /> </bean>
>>>
>>> <bean
>>>
>>>
>> class="org.drools.ioc.spring.KnowledgeResourceBeanFactory">
>>
>>> <property
>>>
>> name="knowledgeType" value="DTABLE"
>> />
>>
>>> <property
>>>
>> name="resource"
>>
>> value="file:src/main/java/org/drools/ioc/spring/dt.xls"
>> />
>>
>>> <property
>>>
>> name="resourceConfiguration">
>>
>>> <bean
>>>
>>>
>> class="org.drools.ioc.spring.DtableResourceFactoryBean">
>>
>>> <property
>>>
>> name="inputType" value="XLS" />
>>
>>> </bean>
>>>
>> </property>
>>
>>> </bean>
>>>
>> </list>
>>
>>> </property>
>>> This approach more closely resembles the kbuilder api.
>>>
>> We have simple
>>
>>> resources list. Everything is a bean, so it's very
>>>
>> flexible, but we
>>
>>> lose the shortcut approach of the first one where we
>>>
>> can just give a
>>
>>> list of strings. As each one must be a bean, so that
>>>
>> it can contain
>>
>>> atleast the knowledge type, as well as the resource
>>>
>> string.
>>
>>> My preference currently is for the second one, as I
>>>
>> don't tink it's
>>
>>> too verbose, and it provides better consistency than
>>>
>> the first.
>>
>>> Mark
>>>
>>>
>>> Geoffrey De Smet wrote:
>>>
>>>> It doesn't indeed sound overkill to me to
>>>>
>> create a FactoryBean for
>>
>>>> the Builder.
>>>> Though I would probably reuse the Builder inside
>>>>
>> the
>>
>>>> KnowlegdeBaseFactory to build the Knowlegde base.
>>>>
>>>> The real issue is concurrency.
>>>> Spring promotes the idea of stateless beans which
>>>>
>> do have global
>>
>>>> variables, but those global variables are either
>>>>
>> synchronised
>>
>>>> thread-safe or also follow the stateless bean
>>>>
>> pattern.
>>
>>>> This in fact makes the stateless beans thread
>>>>
>> safe, without any need
>>
>>>> for synchronization/locking.
>>>>
>>>> So the question is: is your KnowlegdeBase
>>>>
>> thread-safe?
>>
>>>> Thread safe objects are usually put into global
>>>>
>> variables,
>>
>>>> while not thread unsafe objects are always put
>>>>
>> into local variables.
>>
>>>> class A {
>>>> private B b; // thread-safe by synchronization
>>>>
>> (JDBCConnection, ...)
>>
>>>> private C c; // thread-safe by the stateless
>>>>
>> pattern:
>>
>>>> // both b and c are set during initialization
>>>>
>> (constr. or setter),
>>
>>>> before A is exposed to other threads
>>>>
>>>> public void metho(D d) { // d is not thread-safe
>>>> E e = ...; // e is not thread-safe
>>>> }
>>>>
>>>> }
>>>>
>>>> In drools 4. B is the RuleBase, while E is the
>>>>
>> working memory instance.
>>
>>>> With kind regards,
>>>> Geoffrey De Smet
>>>>
>>>>
>>>> Mark Proctor schreef:
>>>>
>>>>> Geoffrey De Smet wrote:
>>>>>
>>>>>> With kind regards,
>>>>>> Geoffrey De Smet
>>>>>>
>>>>>>
>>>>>> Mark Proctor schreef:
>>>>>>
>>>>>>
>>>>>>>> I'd also maybe consider
>>>>>>>>
>> dropping the Spring prefix, as it's in a
>>
>>>>>>>> package called spring?
>>>>>>>> =>
>>>>>>>>
>> org.drools.spring.KnowledgeAgentFactoryBean
>>
>>>>>>> My worry here is it might be a
>>>>>>>
>> duplicate of the same name used in
>>
>>>>>>> the future - although it'll be in
>>>>>>>
>> a different package namespace,
>>
>>>>>>> it's still not good practice.
>>>>>>>
>> Anyone else have any opinions on this?
>>
>>>>>> Good point, prefixing it with Spring
>>>>>>
>> can't hurt :)
>>
>>>>> I'm just wondering about
>>>>>
>> KnowledgeBuilderFactory and
>>
>>>>> KnowledgeBaseFactory. While it makes sense to
>>>>>
>> put the
>>
>>>>> KnowledgeAgentFactory into spring, does it
>>>>>
>> make sense for those
>>
>>>>> other factories? What are they gonna do other
>>>>>
>> than return
>>
>>>>> KnowledgeBuilder or a KnowledgeBase, only
>>>>>
>> possible advantage is that
>>
>>>>> it would allow spring to inject the
>>>>>
>> KnowledgeBuilderConfiguration
>>
>>>>> and KnowledgeBaseConfiguration. And ideas?
>>>>>
>>>>>
>> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-api/src/main/java/org/drools/builder/KnowledgeBuilderFactory.java
>>
>>
>>>>>
>> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-api/src/main/java/org/drools/builder/KnowledgeBuilder.java
>>
>>
>>>>>
>>>>>
>> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-api/src/main/java/org/drools/KnowledgeBaseFactory.java
>>
>>
>>>>>
>> http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-api/src/main/java/org/drools/KnowledgeBase.java
>>
>>
>>>>> This is typically how those two factories are
>>>>>
>> used:
>>
>>>>> KnowledgeBuilder kbuilder =
>>>>> KnowledgeBuilderFactory.newKnowledgeBuilder();
>>>>> kbuilder.addResource( new URL(
>>>>>
>> "file://myrules.drl" ),
>>
>>>>>
>>>>>
>> KnowledgeType.DRL);
>>
>>>>> KnowledgeBase kbase =
>>>>>
>> KnowledgeBaseFactory.newKnowledgeBase();
>>
>>>>> If we use spring to automate the adding of
>>>>>
>> resources, that's pretty
>>
>>>>> much what the agent is doing anyway, so
>>>>>
>> wouldn't that be pointless?
>>
>>>>> Mark
>>>>>
>>>>>
>>>>>
>>>>>>
>> _______________________________________________
>>
>>>>>> rules-dev mailing list
>>>>>> rules-dev at lists.jboss.org
>>>>>>
>>>>>>
>> https://lists.jboss.org/mailman/listinfo/rules-dev
>>
>>>>>>
>>>>>
>>>>>
>> _______________________________________________
>>
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>>>>> rules-dev at lists.jboss.org
>>>>>
>>>>>
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>>
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>
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