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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: A more fundamental concept than functions: units of code t
 without going into the RDF vs XML debate, i must admit the capability of a rule engine to enhance its original data set with business rules has definitely made me a description-logic and inference engine fanatic. On Tue, May 18, 2010 at 1:26 PM, Costello, Roger L. <costello@mitre.org> wrote: > Hi Olivier, > > I was hoping someone would bring up rule engines. That is very exciting about a rule adding more data to the input, thus triggering other rules to fire. Wow! > > /Roger > > -----Original Message----- > From: Olivier Rossel [mailto:olivier.rossel@gmail.com] > Sent: Tuesday, May 18, 2010 4:28 AM > To: Hermann Stamm-Wilbrandt > Cc: xml-dev@lists.xml.org > Subject: Re: A more fundamental concept than functions: units of code that self-select > > self-selecting units of code are the fundament of all (forward) rules engines. > such as drools, euler, cwm, fuxi, etc. > > the differences between these rules engines and xslt is the concept of > working memory. > the working memory is the set of data that are processed by the rule > engine to decide which > rules to trigger. > > in xslt, the working memory could be seen as the input document(s). > with the limitation > that the running stylesheet cannot alter its working memory (i.e the > input document(s)). > > on the contrary, in rules engines, the working memory is accessible to > the rules also in write mode. > so rules can add data to the working memory, and these data will > trigger other rules that add > other data to the working memory, and so on. > > > On Tue, May 18, 2010 at 10:05 AM, Hermann Stamm-Wilbrandt > <STAMMW@de.ibm.com> wrote: >>> Are there other programming languages that support self-selecting units >> of code? >> David already pointed to C++ and Java. >> >> Add perl, awk and even sed to that list (/regexp/ selectors). >> >> >> Mit besten Gruessen / Best wishes, >> >> Hermann Stamm-Wilbrandt >> Developer, XML Compiler, L3 >> WebSphere DataPower SOA Appliances >> ---------------------------------------------------------------------- >> IBM Deutschland Research & Development GmbH >> Vorsitzender des Aufsichtsrats: Martin Jetter >> Geschaeftsfuehrung: Dirk Wittkopp >> Sitz der Gesellschaft: Boeblingen >> Registergericht: Amtsgericht Stuttgart, HRB 243294 >> >> >> >> "Costello, Roger >> L." >> <costello@m... To >> rg> "xml-dev@lists.xml.org" >> <xml-dev@lists.xml.org> >> 05/18/2010 12:27 cc >> AM >> Subject >> A more fundamental >> concept than functions: units of >> code that self-select >> >> >> >> >> >> >> >> >> >> >> Hi Folks, >> >> XSLT has xsl:template and xsl:function. On the surface they appear to be >> the same: you invoke a template rule using xsl:apply-templates and you >> invoke a function by dereferencing its name; you can pass parameters to >> both; both return values. >> >> Clearly the idea of "function" is a fundamental concept in Computer >> Science. >> >> It occurs to me that the functionality provided by template rules represent >> an even more fundamental concept. In fact, functions are merely a subset of >> the functionality provided by template rules. >> >> Allow me to explain. >> >> Consider these three template rules: >> >> <xsl:template match="Book[Publisher lt 1970]"> >> >> <xsl:template match="Book[Publisher eq 1970]"> >> >> <xsl:template match="Book[Publisher gt 1970]"> >> >> Suppose that Book is the context node and it has a Publisher child element >> with value 1970. With this apply-templates: >> >> <xsl:apply-templates select="." /> >> >> the second xsl:template rule will fire. Of the three template rules, the >> second one self-selected ("I meet the requisite conditions; I will now >> activate myself"). >> >> Template rules have the ability to self-select. Functions never >> self-select. They must always be explicitly called out. >> >> Template rules can also be explicitly called out. Consider these revised >> templates: >> >> <xsl:template match="*" mode="pre-1970"> >> <param name="Book" /> >> >> <xsl:template match="*" mode="eq-1970> >> <param name="Book" /> >> >> <xsl:template match="*" mode="post-1970"> >> <param name="Book" /> >> >> The second template can be explicitly called out: >> >> <xsl:template select="." mode="eq="1970"> >> <xsl:with-param name="Book" select="." /> >> >> Each template rule is "named" using mode. Effectively the mode is used as >> the name of the template rule. >> >> So template rules are units of code that can be either explicitly called >> out, or can self-select. >> >> Functions are units of code that can only be explicitly called out. >> >> The ability to create self-selecting units of code is very powerful. It >> resounds of decentralization, local-control, Complex Systems. Wow! >> >> Are there other programming languages that support self-selecting units of >> code? >> >> Do you agree that self-selecting units of code represents a more >> fundamental concept than functions? >> >> /Roger >> >> >> >> _______________________________________________________________________ >> >> XML-DEV is a publicly archived, unmoderated list hosted by OASIS >> to support XML implementation and development. To minimize >> spam in the archives, you must subscribe before posting. >> >> [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ >> Or unsubscribe: xml-dev-unsubscribe@lists.xml.org >> subscribe: xml-dev-subscribe@lists.xml.org >> List archive: http://lists.xml.org/archives/xml-dev/ >> List Guidelines: http://www.oasis-open.org/maillists/guidelines.php >> >> >> >> >> _______________________________________________________________________ >> >> XML-DEV is a publicly archived, unmoderated list hosted by OASIS >> to support XML implementation and development. To minimize >> spam in the archives, you must subscribe before posting. >> >> [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ >> Or unsubscribe: xml-dev-unsubscribe@lists.xml.org >> subscribe: xml-dev-subscribe@lists.xml.org >> List archive: http://lists.xml.org/archives/xml-dev/ >> List Guidelines: http://www.oasis-open.org/maillists/guidelines.php >> >> > > _______________________________________________________________________ > > XML-DEV is a publicly archived, unmoderated list hosted by OASIS > to support XML implementation and development. To minimize > spam in the archives, you must subscribe before posting. > > [Un]Subscribe/change address: http://www.oasis-open.org/mlmanage/ > Or unsubscribe: xml-dev-unsubscribe@lists.xml.org > subscribe: xml-dev-subscribe@lists.xml.org > List archive: http://lists.xml.org/archives/xml-dev/ > List Guidelines: http://www.oasis-open.org/maillists/guidelines.php > > 
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