4:36 p.m.
Hi,
Basic questions on the facts that are created in Guvnor using New
Declaritive Model
I have the facts that are created in Guvnor which i dont have java classes
defined. I am refering to the tutorial provided on Chapter 5 The Fact Model
and in that it shows how to use the declarative facts from Java.
I am having hard time following the steps. So i am going to layout below to
see if my understanding is correct:
Step 1: // get a reference to a knowledge base with a declared type:
KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
Step 2:// get the declared FactType
FactType personType = kbase.getFactType( "PackageName", "FactName"
);
Step 3:// handle the type as necessary:
Not sure what this means
Step 4:// create instances:
Object bob = personType.newInstance();
Step5: // set attributes values
personType.set( bob,
"name",
"Bob" );
Step 6: // insert fact into a session
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
Step 7:ksession.insert( bob );
Step 8:ksession.fireAllRules();
I am able to understand Step 4 thru Step 8. I guess i am having trouble
understanding step 1 and Step 3.
Can someone please help me clarify or have example for me to refer.
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5:40 p.m.
The KnowledgeBuilder processes the declared types in a DRL file,
creating the bytecode on the fly.
When the knowledge package is added to a knowledge base, the newly
created class descriptor
(the FactType and its related components) become part of the KB and the
actual class is (re)loaded by
the KB's classloader.
Since the dynamic class is not available until runtime, the "Type"
descriptors give you a reflection-like
API to manipulate the instances. This said:
Step 1: I'd actually get **the** KB which is being used to spawn
sessions, to make sure you are using
the same classes, as loaded by the same classloader.
Step 2: The FactType also holds a reference to the loaded class, you can
get it using FactType.getDefinedClass(), if needed
Step 3: it's not really a step: it means that the next two steps (4+5)
are just an example of what you can
do now that you have the Type reference.
Best,
Davide
On 02/27/2013 03:36 PM, IPatel wrote:
Hi,
Basic questions on the facts that are created in Guvnor using New
Declaritive Model
I have the facts that are created in Guvnor which i dont have java classes
defined. I am refering to the tutorial provided on Chapter 5 The Fact Model
and in that it shows how to use the declarative facts from Java.
I am having hard time following the steps. So i am going to layout below to
see if my understanding is correct:
Step 1: // get a reference to a knowledge base with a declared type:
KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
Step 2:// get the declared FactType
FactType personType = kbase.getFactType( "PackageName", "FactName"
);
Step 3:// handle the type as necessary:
Not sure what this means
Step 4:// create instances:
Object bob = personType.newInstance();
Step5: // set attributes values
personType.set( bob,
"name",
"Bob" );
Step 6: // insert fact into a session
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
Step 7:ksession.insert( bob );
Step 8:ksession.fireAllRules();
I am able to understand Step 4 thru Step 8. I guess i am having trouble
understanding step 1 and Step 3.
Can someone please help me clarify or have example for me to refer.
--
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10:40 a.m.
Thank you for your response.
I was able to follow your instruction and created newInstance of the facts.
Quick question: I have 2 facts defined in Guvnor:
Conditions
Variable: Source (this variable is text/string)
Variable: SourceType (this variable is text/string)
Transcation
Variable: filter (this variable is boolean)
I have 2 rules as follows:
If source =ABC then filter = true
if source =ABC then hasIntegrated = true
In my main method
I created and inserted new instance of each Source as well as Transcation
I set the variables of the source instance so that i can fire above rules.
Source = ABC
Rule 1 fires fine. I get the expected result
However for Rule 2 the value of hasIntegrated is false instead of true. I
run the test in Guvnor and it passes. However in my main method it
fails/give me unexpected result.
Any idea why this is happening???
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3:39 p.m.
I was able to fix the problem but now I am with more questions then answers.
Here is what i had before defined in my DSL
[when] The transcation is zero dollar = trans:Transcation (Indicator == "N")
[when] System description one field is ABC= $trans1:Filter(Field1 == "ABC")
[then] Filter out the records = Transcation trans2 = new Transcation();
trans2.setFilterOutRecords( true );insert(trans2)
Now in the business rules i created following rules
Rule 1:
When
The transcation is zero dollar
Then
Filter out the records
Rule2:
When
System description one field is ABC
Then
Filter out the records
Both test cases are passing in guvnor
However when i fire these rules using Java, i was not able to get expected
results.
This is how i fixed it.
For each When defined in DSL i have appropriate Then.
So the question is can we not have a generic Then statement where i can set
a value of the field and then use that with When condition as appropriate.
Your help will be appreciated?
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3 comments
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participants (2)
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Davide Sottara -
IPatel