1:26 a.m.
updated Drools docs content from SOA 4.2.CP03 Rules Guide
---------------------------------------------------------
Key: JBRULES-1908
URL: https://jira.jboss.org/jira/browse/JBRULES-1908
Project: JBoss Drools
Issue Type: Task
Security Level: Public (Everyone can see)
Components: drools-docs-expert
Reporter: Darrin Mison
Assignee: Mark Proctor
I revised the language of the "Insertion" section while fixing a couple of
reported grammatical errors for the 4.2.CP03 SOA Rules Guide.
The original language is the same in:
http://anonsvn.jboss.org/repos/labs/labs/jbossrules/soa_tags/4.3.0.FP01_B...
, so these changes would also apply to the most recent docs.
Updated content below, the section ids are different but you get the idea ;-)
<section
id="sect-JBoss_Rules_Reference_Manual-WorkingMemory_and_StatefulStateless_Sessions-Insertion">
<title>Insertion</title>
<para>
<firstterm>Insertion</firstterm> is the act of telling the WorkingMemory
about the facts.
</para>
<important>
<para>
In many Expert Systems the term used for this concept is
<firstterm>assert</firstterm> or
<firstterm>assertion</firstterm>.
However as the keyword <methodname>assert</methodname> is already
used
in many languages, Drools uses the keyword & term
<methodname>insert</methodname>.
You will often encounter these terms used interchangably in discussion of
Rules Engines.
</para>
</important>
<para>
When inserted, the rule is examined for matches against the rules. The work
of determining what rules to fire is done during insertion, but no rules are
executed at this time. The rules are executed when
<methodname>fireAllRules()</methodname> is called, and it should only be
called
after you have inserted all your facts.
</para>
<para>
It is a common misconception that rule matching occurs when
<methodname>fireAllRules()</methodname> is called.
</para>
<para>
When an Object is inserted it returns a FactHandle. This FactHandle is the
token used to represent your inserted Object inside the WorkingMemory, it is
also how you will interact with the Working Memory when you wish to retract
or modify an object.
</para>
<programlisting language="java">Cheese stilton = new
Cheese("stilton");
FactHandle stiltonHandle = session.insert( stilton );</programlisting>
<para>
As mentioned in
<xref
linkend="sect-JBoss_Rules_Reference_Manual-The_Drools_Rule_Engine-RuleBase"
/>
a Working Memory can operate in two assertions modes:
<firstterm>equality</firstterm>
and <firstterm>identity</firstterm>. Identity is the default mode. The
assertion
mode determines how the Working Memory stores the facts and how it compares the
newly inserted fact to previously inserted ones. If the Working Memory
determines the fact to "be the same" as an already inserted one it will
ignore
the new fact and return the FactHandle for the previously inserted one.
</para>
<variablelist>
<varlistentry>
<term>Identity</term>
<listitem>
<para>
Identity Mode uses an <classname>IdentityHashMap</classname>to
store all
asserted Objects. New facts being inserted are compared to existing facts
"by reference". A new FactHandle will be returned if the object
being
inserted is not a reference to an object that has been inserted previously.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Equality</term>
<listitem>
<para>
Equality Mode uses a <classname>HashMap</classname> to store all
asserted
Objects. New facts being inserted are compared to existing facts "by
value".
A new FactHandle will be returned if the content of the object is not
identical to that of a previously inserted object.
</para>
</listitem>
</varlistentry>
</variablelist>
</section>
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