Some responses below...<br><br><div><span class="gmail_quote">On 4/13/07, <b class="gmail_sendername">Arjun Dhar</b> <<a href="mailto:dhar_ar@yahoo.com">dhar_ar@yahoo.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br> I'm aware that you are working on 'From', to pull external data and use it in<br>the Rule conditions for comparison with that external data.<br><br>Three Questions:<br>Q1. I could define my own business object that fetches in the data? Cant I?
<br>What additional benifit does 'From' give me?</blockquote><div><br>"from" means you can call some/any logic only when needed - and only once the "from" node is checked - so its as lazy as possible. You could kind of do the same with eval() for very simple cases I guess, but also, with from you can reason over it as if the data was in working memory.
<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Q2. I use Decision Tables extensively; how do I use 'From' in a decision table?
<br>is it like a Keyword,.. but I cant imagine how it would be used? Could you<br>please give an example.</blockquote><div><br>No thoughts on how it would integrate there, off the top of my head I can't see how it would be used there. Open to any ideas.
<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Q3. When executing PL/SQL logic, the data is at the database itself and so is<br>
the logic.</blockquote><div><br>yes, although it would generally be a SQL query.<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
3.1. If we decide to abstract the logic to rules and fetch data from the<br>database, in theory wouldnt pure PL/SQL be faster inspite of Rete running the<br>logic?</blockquote><div><br>Possibly - in some cases sure. In other cases, it may be easier to use the rete engine, and then use the database to filter large amount of data that aren't facts.
<br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">3.2. Since most mainstream applications use external data, when we talk about<br>
SPEED how significant can the rule engine be? If my conditions depend on<br>external data, does the speed of the rule engine really count? Unless the rule<br>engine is sitting inside the database I have my doubts.</blockquote>
<div><br>I guess you would need to try out in specific cases. Sometimes it may be a tradeoff for speed versus flexability and expressability. <br></div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
... The above are pratical issues that am sure everyone would ask.<br><br>Thanks,<br>Arjun<br><br><br><br><br><br><br>_______________________________________________<br>rules-dev mailing list<br><a href="mailto:rules-dev@lists.jboss.org">
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