So unlike Jess, Drools can or cannot use asserted facts from a data structure
and can only use data wrapped in a bean?
/* Assert ordered or unordered facts from the session's document. A deftemplate
with matching
* id and slots for each "fact" element should already exist for
unordered facts.
*/
public void assertDocument(Document document, Rete engine) throws
JessException {
Iterator facts =
(document.getRootElement().getChildren("fact")).iterator();
while (facts.hasNext() == true) {
Element factElement = (Element)facts.next();
String id = factElement.getAttributeValue("id");
Fact fact = new Fact(id, engine);
Iterator slots =
(factElement.getChildren("slot")).iterator();
while (slots.hasNext() == true) {
Element slotElement = (Element)slots.next();
String name =
slotElement.getAttributeValue("name");
String type =
slotElement.getAttributeValue("type");
if (slotElement.getChildren("value").size() ==
1) {
String value =
slotElement.getChild("value").getText();
fact.setSlotValue(name, getValue(type,
value));
}
else {
ValueVector valueVector = new
ValueVector();
Iterator values =
(slotElement.getChildren("value")).iterator();
while (values.hasNext() == true) {
String value =
((Element)values.next()).getText();
valueVector.add(getValue(type,
value));
}
fact.setSlotValue(name, new
Value(valueVector, RU.LIST));
}
} //while slots
engine.assertFact(fact);
} //while facts
}
/*
* Output the fact base to the response output stream.
* Intended for debugging. Override to do your own processing.
*/
public String processResults(HttpServletRequest request,
HttpServletResponse response,
Rete engine) throws IOException {
PrintWriter writer = response.getWriter();
writer.println("<html><head><title>Jess
Results</title></head>");
writer.println("<body><h1>PrettyPrint listFacts()</h1>");
writer.println("<pre>");
Iterator facts = engine.listFacts();
while (facts.hasNext() == true) {
Fact fact = (Fact)facts.next();
writer.println(new PrettyPrinter(fact));
}
writer.println("</pre>");
writer.println("</body></html>");
return null;
}
private Value getValue(String type, String value) throws JessException {
if ("STRING".equals(type) == true)
return new Value(value, RU.STRING);
else if ("INTEGER".equals(type) == true)
return new Value(Integer.parseInt(value), RU.INTEGER);
else if ("FLOAT".equals(type) == true)
return new Value(Float.parseFloat(value), RU.FLOAT);
else if ("SYMBOL".equals(type) == true)
return new Value(value, RU.SYMBOL);
else if ("LONG".equals(type) == true)
return new Value(Long.parseLong(value), RU.LONG);
else
return new Value(value, RU.ANY);
}
On Sep 10, 2010, at 11:18 AM, Wolfgang Laun wrote:
> So everthing is String or list of String? (What if your data contains
> numbers, where you'd like to use > in patterns?)
>
> Is there a stable relationship between key/slot and its type, i.e., scalar
> String or list of String?
>
> You realize that a record of untyped fields (slots) is fundamentally
> different from an approach where data is bound to be stored in (necessarily)
> strongly typed fields of an object. There's no difficulty with writing
> similar code for storing values from a Map into an object of some class, but
> class fields must have fixed types.
>
> -W
>
>
> 2010/9/10 Donald Winston <[email protected]>
> This is what I'm doing:
>
> /* Assert unordered facts from the request parameter map. A deftemplate with
> matching id and
> * slots should already exist.
> */
> public void assertParameterMap(String id, Map map, Rete engine) throws
> JessException {
> Fact fact = new Fact(id, engine);
> Iterator keys = map.keySet().iterator();
> while (keys.hasNext() == true) {
> String key = (String)keys.next();
> if (ID.equals(key) == true) continue;
> String[] paramValues = (String[])map.get(key);
> if (paramValues.length > 1) {
> ValueVector values = new ValueVector();
> for(String value : paramValues)
> values.add(new Value(value, RU.STRING));
> fact.setSlotValue(key, new Value(values,
> RU.LIST));
> }
> else
> fact.setSlotValue(key, new
> Value(paramValues[0], RU.STRING));
> }
> engine.assertFact(fact);
> }
>
> I'm working on something similar for a jdom document object. I'm not using
> POJOs. I'm using a data structure. (technically they're objects because java
> is object oriented, but they're not "problem domain objects").
>
> On Sep 10, 2010, at 10:12 AM, Wolfgang Laun wrote:
>
>> If you insert POJOs as facts in Jess, you'll have to write a
>> (deftemplace X (declare (from-class X)))
>> and the fields available for pattern matching in rules rely on the JavaBeans
>> convention.
>>
>> I have (quite successfully) used POJOs resulting from unmarshalling an XML
>> document (via JAXB) as facts, both in Drools and in Jess; most certainly
>> without writing any "copycat" fact classes and tedious transformations.
>>
>> As for globals: They play the same role in Drools as in Jess; in neither
>> system are they part of the working memory.
>>
>> I don't know what you could mean by a "standard fact class".
>>
>> As for iterating over all fact objects in Drools' WM, Drools provides
>> getObjects() in WorkingMemory; or you could set up a query and run this.
>>
>> -W
>>
>>
>> On 10 September 2010 14:54, Donald Winston <[email protected]> wrote:
>> I'm reviewing JBoss Rules (Drools) for an application I'm starting to build.
>> It appears that the only way to assert facts is to use the insert(Object)
>> method where the object is a bean using the proper naming conventions for
>> it's properties. There also appears to be a way to use arbitrary objects
>> using globals but do these end up in the fact base? It's disturbing to me
>> that I have to create a bunch of classes whose sole purpose in life is to
>> support the rule base. This is similar to using java server pages and having
>> to create a bunch of classes just to support each page. That's why I don't
>> use java server pages and use xsl transformations instead. I want to use my
>> xml jdom document to represent my data and not have to create a bunch of
>> beans. I can't seem to find anything in the api where I can assert facts
>> without creating my own custom classes. There's no standard Fact class?
>>
>> I've been also experimenting with Jess and it provides an easy way for me to
>> do this. I just iterate through my jdom document and create Fact objects and
>> assert them. I can then execute the rules and then iterate through the
>> updated fact base using engine.listFacts() and update my jdom document. It
>> couldn't be easier or more natural. Is there an analogous way to do this in
>> Drools?
>>
>>
>> Thank you very much.
>> _______________________________________________
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>> [email protected]
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>> _______________________________________________
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>
>
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