Logic Programming and the Internet - Revision history

John: /* Updating link to HTTPS */

2022-08-02T19:48:55Z

Updating link to HTTPS

← Older revision		Revision as of 15:48, 2 August 2022
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	==PiLLoW==		==PiLLoW==

	The [~~http~~://cliplab.org/miscdocs/pillow/pillow.html PiLLoW] library provides predicates for developing HTTP client and server applications.		The [https://cliplab.org/miscdocs/pillow/pillow.html PiLLoW] library provides predicates for developing HTTP client and server applications.

	For client applications, it provides mechanisms to retrieve HTML files and to parse HTML into useful Prolog terms.		For client applications, it provides mechanisms to retrieve HTML files and to parse HTML into useful Prolog terms.

John: XSLT Page problem resolved

2020-03-28T21:46:12Z

XSLT Page problem resolved

← Older revision		Revision as of 17:46, 28 March 2020
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	XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.		XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.

	Because Prolog is a very high-level language, it is more flexible and more powerful than [[#XSLT ~~Page Problem\|XSLT]~~]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.		Because Prolog is a very high-level language, it is more flexible and more powerful than [https://www.w3.org/TR/xslt/all/ XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.

	===xml.pl===		===xml.pl===
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	See also, [[Porting PiLLoW to Quintus Prolog]].		See also, [[Porting PiLLoW to Quintus Prolog]].

	~~===XSLT Page Problem===~~

	~~As of 2020-03-27, the W3C's [https://www.w3.org/TR/xslt/all/ XSLT] page is invalid.~~

	~~On Windows, it can be repaired with:~~

	~~<code>curl "https://www.w3.org/TR/xslt/all/" \| plxml - - \| plxml - xslt.html</code>~~

John: Temporarily diverting XSLT link.

2020-03-27T22:02:04Z

Temporarily diverting XSLT link.

← Older revision		Revision as of 18:02, 27 March 2020
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	XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.		XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.

	Because Prolog is a very high-level language, it is more flexible and more powerful than [~~https://www.w3.org/TR/xslt/all/~~ XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.		Because Prolog is a very high-level language, it is more flexible and more powerful than [[#XSLT Page Problem\|XSLT]]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.

	===xml.pl===		===xml.pl===
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	See also, [[Porting PiLLoW to Quintus Prolog]].		See also, [[Porting PiLLoW to Quintus Prolog]].

			===XSLT Page Problem===

			As of 2020-03-27, the W3C's [https://www.w3.org/TR/xslt/all/ XSLT] page is invalid.

			On Windows, it can be repaired with:

			<code>curl "https://www.w3.org/TR/xslt/all/" \| plxml - - \| plxml - xslt.html</code>

John: /* XML */

2018-05-15T21:38:41Z

XML

← Older revision		Revision as of 17:38, 15 May 2018
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	XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.		XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.

	Because Prolog is a very high-level language, it is more flexible and more powerful than [https://www.w3.org/TR/xslt/ XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.		Because Prolog is a very high-level language, it is more flexible and more powerful than [https://www.w3.org/TR/xslt/all/ XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.

	===xml.pl===		===xml.pl===

John: Updating the XSLT link.

2017-10-31T23:26:07Z

Updating the XSLT link.

← Older revision		Revision as of 19:26, 31 October 2017
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	XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.		XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.

	Because Prolog is a very high-level language, it is more flexible and more powerful than [~~http~~://www.w3.org/TR/xslt XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.		Because Prolog is a very high-level language, it is more flexible and more powerful than [https://www.w3.org/TR/xslt/ XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.

	===xml.pl===		===xml.pl===

John: Updated PiLLoW link

2016-05-22T00:33:19Z

Updated PiLLoW link

← Older revision		Revision as of 20:33, 21 May 2016
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	==PiLLoW==		==PiLLoW==

	The [http://~~clip~~.~~dia.fi.upm.es~~/miscdocs/pillow/pillow.html PiLLoW] library provides predicates for developing HTTP client and server applications.		The [http://cliplab.org/miscdocs/pillow/pillow.html PiLLoW] library provides predicates for developing HTTP client and server applications.

	For client applications, it provides mechanisms to retrieve HTML files and to parse HTML into useful Prolog terms.		For client applications, it provides mechanisms to retrieve HTML files and to parse HTML into useful Prolog terms.

John at 21:57, 10 June 2015

2015-06-10T21:57:09Z

← Older revision		Revision as of 17:57, 10 June 2015
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	== HTTP ==		== HTTP ==

	Consider that Prolog's default behaviour is query-solving - where a query is posed for which arbitrarily many answers (solutions) may be returned.		Consider that Prolog's default behaviour is query-solving – where a query is posed for which arbitrarily many answers (solutions) may be returned.

	This can be mapped to HTTP's request/response mechanism straightforwardly:		This can be mapped to HTTP's request/response mechanism straightforwardly:
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	=== HTTP GET ===		=== HTTP GET ===

	The HTTP GET verb has a clear correspondence with Prolog's notion of a query. In fact, Prolog can be used directly as part of a request-URI, acting as a lightweight data structuring mechanism.		The HTTP GET verb has a clear correspondence with Prolog's notion of a query. In fact, Prolog can be used directly as part of a request URI, acting as a lightweight data structuring mechanism.

	However, HTTP requires each request/response to be deterministic, which suggests that ''all'' the solutions for a non-deterministic query should be returned. The solutions can be formatted as an XHTML list or table, for example.		However, HTTP requires each request/response to be deterministic, which suggests that ''all'' the solutions for a non-deterministic query should be returned. The solutions can be formatted as an XHTML list or table, for example.
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	=== Caching ===		=== Caching ===

	Prolog programming allows for the 'caching' of expensive results using ~~"~~lemmas~~"~~, a technique used in the solution of the [[Mister X#Lemmas\|Mister X]] puzzle, for example.		Prolog programming allows for the 'caching' of expensive results using lemmas, a technique used in the solution of the [[Mister X#Lemmas\|Mister X]] puzzle, for example.

	HTTP's 'HEAD' verb~~, (~~and GET with &~~quot~~;If-Modified-Since&~~quot~~;) support caching mechanisms, primarily to save communications bandwidth.		HTTP's 'HEAD' verb and GET with “If-Modified-Since” support caching mechanisms, primarily to save communications bandwidth.

	The integration of Prolog ~~"~~lemmas~~"~~ with HTTP's caching methods can save both bandwidth and recomputation through a single mechanism, enabling the creation of robust distributed applications with a minimum of fuss.		The integration of Prolog lemmas with HTTP's caching methods can save both bandwidth and recomputation through a single mechanism, enabling the creation of robust distributed applications with a minimum of fuss.

	=== HTTP POST ===		=== HTTP POST ===

	When using Prolog with HTTP, the POST verb should be reserved for passing ''clauses'' from the client to the server, to update the server, not for queries.		When using Prolog with HTTP, the POST verb should be reserved for passing clauses from the client to the server, to update the server, not for queries.

	The fact that Prolog is a good format for including structured (composite) data items as part of a URI can obviate some inappropriate uses of HTTP's POST verb, by allowing more complex terms in GET requests.		The fact that Prolog is a good format for including structured (composite) data items as part of a URI can obviate some inappropriate uses of HTTP's POST verb, by allowing more complex terms in GET requests.
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	XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.		XML data is represented easily in Prolog, and vice versa, because both use tree-structured data exclusively.

	Because Prolog is a very high-level language, it is more flexible and more powerful than [http://www.w3.org/TR/xslt XSLT]. In particular, it seems to be very much easier to create robust, reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.		Because Prolog is a very high-level language, it is more flexible and more powerful than [http://www.w3.org/TR/xslt XSLT]. In particular, it seems to be very much easier to create robust and reliable transformations with Prolog, i.e. ones that produce only valid output for any valid input.

	===xml.pl===		===xml.pl===

John at 23:39, 1 June 2015

2015-06-01T23:39:57Z

← Older revision		Revision as of 19:39, 1 June 2015
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	=== HTTP GET ===		=== HTTP GET ===

	The HTTP GET verb has a clear correspondence with Prolog's notion of a query. In fact, Prolog can be used directly as part of a request URI, acting as a lightweight data-structuring mechanism.		The HTTP GET verb has a clear correspondence with Prolog's notion of a query. In fact, Prolog can be used directly as part of a request-URI, acting as a lightweight data structuring mechanism.

	However, HTTP requires each request/response to be deterministic, which suggests that ''all'' the solutions for a non-deterministic query should be returned. The solutions can be formatted as an XHTML list or table, for example.		However, HTTP requires each request/response to be deterministic, which suggests that ''all'' the solutions for a non-deterministic query should be returned. The solutions can be formatted as an XHTML list or table, for example.
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	For client applications, it provides mechanisms to retrieve HTML files and to parse HTML into useful Prolog terms.		For client applications, it provides mechanisms to retrieve HTML files and to parse HTML into useful Prolog terms.

	For server applications it provides a predicate to access CGI query parameters, so that a Prolog application can be used to handle form input directly i.e. without additional scripting. Additionally, HTML parsing supports the reverse translation of terms into HTML, so that forms can be generated.		For server applications, it provides a predicate to access CGI query parameters so that a Prolog application can be used to handle form input directly i.e. without additional scripting. Additionally, HTML parsing supports the reverse translation of terms into HTML so that forms can be generated.

	See also, [[Porting PiLLoW to Quintus Prolog]].		See also, [[Porting PiLLoW to Quintus Prolog]].

John: /* Prolog for the Worldwide Web */

2015-05-13T09:26:14Z

Prolog for the Worldwide Web

← Older revision		Revision as of 05:26, 13 May 2015
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	== Prolog for the Worldwide Web ==		== Prolog for the Worldwide Web ==

	For a Prolog programmer, to suggest that Prolog is an ideal language for web-based applications is to invite the comment that, &~~quot~~;if you have only a hammer, everything looks like a nail&~~quot~~;.		For a Prolog programmer, to suggest that Prolog is an ideal language for web-based applications is to invite the comment that, “if you have only a hammer, everything looks like a nail”.

	However, the correspondences between Prolog behaviour and HTTP, and Prolog data-structures and XML are so strong that it's fair to say that ''if Prolog is a hand, the Worldwide Web is a glove.''		However, the correspondences between Prolog behaviour and HTTP, and Prolog data-structures and XML are so strong that it's fair to say that ''if Prolog is a hand, the Worldwide Web is a glove.''

John: /* HTTP */

2015-05-13T09:25:08Z

HTTP

← Older revision		Revision as of 05:25, 13 May 2015
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	== HTTP ==		== HTTP ==

	Consider that Prolog's default behaviour is ~~"~~query-solving~~"~~ - where a query is posed for which arbitrarily many ~~"~~answers~~"~~ (solutions) may be returned.		Consider that Prolog's default behaviour is query-solving - where a query is posed for which arbitrarily many answers (solutions) may be returned.

	This can be mapped to HTTP's request/response mechanism straightforwardly:		This can be mapped to HTTP's request/response mechanism straightforwardly:
Line 14:		Line 14:
	=== HTTP GET ===		=== HTTP GET ===

	The HTTP GET verb has a clear correspondence with Prolog's notion of a ~~"~~query~~"~~. In fact, Prolog can be used directly as part of a request URI, acting as a lightweight data-structuring mechanism.		The HTTP GET verb has a clear correspondence with Prolog's notion of a query. In fact, Prolog can be used directly as part of a request URI, acting as a lightweight data-structuring mechanism.

	However, HTTP requires each request/response to be deterministic, which suggests that ''all'' the solutions for a non-deterministic query should be returned. The solutions can be formatted as an XHTML list or table, for example.		However, HTTP requires each request/response to be deterministic, which suggests that ''all'' the solutions for a non-deterministic query should be returned. The solutions can be formatted as an XHTML list or table, for example.