The Inbox: Help-Squeak-Project-it.4.mcz

> A new version of Help-Squeak-Project was added to project The Inbox:
> http://source.squeak.org/inbox/Help-Squeak-Project-it.4.mcz
>
> ==================== Summary ====================
>
> Name: Help-Squeak-Project-it.4
> Author: it
> Time: 4 May 2010, 10:31:33.929 am
> UUID: 1460ca93-adfa-0147-adbb-35447aa254ac
> Ancestors: Help-Squeak-Project-tbn.3
>
> Adding "Retrieving XML data" tutorial. A rewritten version from
> http://mecenia.blogspot.com/2010/05/using-squeak-with-blogger-export-files.html
>
> =============== Diff against Help-Squeak-Project-tbn.3 ===============
>
> Item was added:
> + ----- Method: SqueakTutorials classSide>>bookName (in category
> 'accessing') -----
> + bookName
> + ^'Tutorials'!
>
> Item was added:
> + ----- Method: SqueakTutorialsOnXML classSide>>pages (in category
> 'accessing') -----
> + pages
> + ^# (dataRetrieval)!
>
> Item was added:
> + SqueakTutorials subclass: #SqueakTutorialsOnXML
> + instanceVariableNames: ''
> + classVariableNames: ''
> + poolDictionaries: ''
> + category: 'Help-Squeak-Project'!
>
> Item was added:
> + ----- Method: SqueakTutorialsOnXML classSide>>dataRetrieval (in category
> 'pages') -----
> + dataRetrieval
> + ^HelpTopic
> + title: 'Retrieving XML data'
> + contents:
> + 'Retrieving data from XML documents is simple and easy. This tutorial
> demonstrates the fundamentals with a straightforward approach where code can
> be tested right away either here or in a Workspace window. The beauty of
> Squeak Smalltalk resides in the possibility to evaluate, inspect, print and
> debug code anywhere and this window is no different.
> +
> + This tutorial demonstrates how...
> +
> + * to retrieve an XML document from the World Wide Web
> + * to instance an XML document class
> + * to inspect and understand the content of an XML document
> + * to retrieve and display values from specific XML tags
> +
> + Retrieve an XML document from the World Wide Web
> +
> + There are many manners to retrieve data from the World Wide Web in Squeak
> Smalltalk. HTTPClient is among them and let you download files in all
> simplicity. Select the following code snippet and inspect it (press alt-i).
> An Inspect window will open with the document loaded in memory. The result
> is a MIMEDocument object.
> +
> + HTTPClient httpGetDocument: ''http://www.squeaksource.com/ss/feed.rss''.
> +
> + TIP: Select HTTPClient and browse it (press alt-b) to open a System
> Browser window on its class. HTTPClient does not have instance methods but
> it has class methods. Click on class to see class methods.
> +
> + Instantiate an XML Document
> +
> + An instance of MIMEDocument will not allow to retrieve XML data in a
> comprehensive manner because it does not understand the nature of XML. For
> this reason, it is necessary to parse the content of MIMEDocument using
> XMLDOMParser. XMLDOMParser>>parseDocumentFrom: requires a stream as a
> parameter and ReadStream will be used for this purpose. The following code
> snippet instantiates an XMLDocument using the content of the downloaded
> file.
> +
> + | doc |
> + doc := HTTPClient httpGetDocument:
> ''http://www.squeaksource.com/ss/feed.rss''.
> + XMLDOMParser parseDocumentFrom: (ReadStream on: (doc content)).
> +
> + Inspect and understand the content of an XML document
> +
> + XML is a flexible document format and it is necessary to understand how
> each given XML file is structured in order to properly search, retrieve and
> manipulate data. Inspecting values is critical in a dynamic programming
> language and environment, such as Squeak Smalltalk. Select the previous code
> snippet and inspect it (press alt-i).
> +
> + Unfortunately, the Inspect window does not reveal a lot about the XML
> structure of the downloaded file. Select the previous code snippet once
> again and explore it (press alt and the capital letter i). An Explorer
> window will open with a tree outline on the instance of XMLDocument.
> +
> + The Inspect and Explorer windows tell a lot about an XMLDocument. The
> sections are instance variables and their values are displayed aside. In the
> Explorer window, unfold elementsAndContents. Unfold other sections as deem
> necessary to understand the XML format and the data available.
> +
> + The gibberish coding is about to become clear. Open a Browser window from
> the world menu and right click in the first pane, select find class (press
> alt-f) and type XMLDocument to search for its class, or select the class
> name and browse it (press alt-b). However, it is suggested to read more
> about XMLParser and XMLParserTest first.
> +
> + Retrieve and display values from specific XML tags
> +
> + The downloaded XML file contains a list of items which are denoted by the
> tag name "item". The Explorer window revealed the content of interest is
> located at the array index 1 of the elementsAndContents.
> +
> + The following code snippet will display items in a Transcript window. Open
> a Transcript window using the world menu before selecting and executing the
> code. Select the code snippet and execute it (press alt-d).
> +
> + | doc xml |
> + doc := HTTPClient httpGetDocument:
> ''http://www.squeaksource.com/ss/feed.rss''.
> + xml := XMLDOMParser parseDocumentFrom: (ReadStream on: (doc content)).
> + (xml elements at: 1) tagsNamed: #item do: [:e |
> + Transcript show: (e asString); cr.
> + ].
> +
> + An XML item looks like this:
> +
> + <item>
> + <title>SqueakSource-lr.1039.mcz</title>
> + <link>http://www.squeaksource.com/ss.html</link>
> + <description>integrated new stylesheet</description>
> + <pubDate>Sat, 10 Apr 2010 11:30:38 +0100</pubDate>
> + <author>Lukas Renggli &lt;[hidden email]&gt;</author>
> + <category>SqueakSource, seaside, server</category>
> + <enclosure length="302570" type="application/x-monticello"
> url="http://www.squeaksource.com/ss/SqueakSource-lr.1039.mcz"/>
> + <guid isPermaLink="false"/> </item>
> +
> + The following code snippet uses information learned, retrieves each
> comment and displays them in a Transcript window. Notice an author can have
> a nil value and is handled accordingly.
> +
> + | doc xml |
> + doc := HTTPClient httpGetDocument:
> ''http://www.squeaksource.com/ss/feed.rss''.
> + xml := XMLDOMParser parseDocumentFrom: (ReadStream on: (doc content)).
> + (xml elements at: 1) tagsNamed: #item do: [:e |
> + Transcript
> + show: ''Date: '', ((e firstTagNamed: #pubDate) contentString); cr;
> + show: ''Title: '', ((e firstTagNamed: #title) contentString); cr;
> + show: ''Author: '',
> + (((e firstTagNamed: #author) notNil)
> + ifTrue: [(e firstTagNamed: #author) contentString]
> + ifFalse: ['''']); cr;
> + show: ''Description: '', ((e firstTagNamed: #description)
> contentString); cr; cr.
> + ].
> +
> + An item will now looks like:
> +
> + Date: Wed, 21 Apr 2010 22:33:18 +0100
> + Title: SqueakSource-lr.1060.mcz
> + Author: Lukas Renggli <[hidden email]>
> + Description: - ignore email errors
> + '!
>
> Item was added:
> + ----- Method: SqueakTutorialsOnXML classSide>>bookName (in category
> 'accessing') -----
> + bookName
> + ^'XML'!
>
> Item was added:
> + SqueakHelp subclass: #SqueakTutorials
> + instanceVariableNames: ''
> + classVariableNames: ''
> + poolDictionaries: ''
> + category: 'Help-Squeak-Project'!
>
>
>

> I have read through it and I like it. I will test it later.
>
> One minor thing
> instead of
>
>     * to instance an XML document class
> I would say
> either
>     * to create and instance of the XMLDocument class
> or
>     * to instantiate an XML document class object (however I'm not
> sure about this)
>
> --Hannes
>
>
>
> On Tue, 4 May 2010 14:31:38.375 0000, [hidden email]
> <[hidden email]> wrote:
>> A new version of Help-Squeak-Project was added to project The Inbox:
>> http://source.squeak.org/inbox/Help-Squeak-Project-it.4.mcz
>>
>> ==================== Summary ====================
>>
>> Name: Help-Squeak-Project-it.4
>> Author: it
>> Time: 4 May 2010, 10:31:33.929 am
>> UUID: 1460ca93-adfa-0147-adbb-35447aa254ac
>> Ancestors: Help-Squeak-Project-tbn.3
>>
>> Adding "Retrieving XML data" tutorial. A rewritten version from
>> http://mecenia.blogspot.com/2010/05/using-squeak-with-blogger-export-files.html
>>
>> =============== Diff against Help-Squeak-Project-tbn.3 ===============
>>
>> Item was added:
>> + ----- Method: SqueakTutorials classSide>>bookName (in category
>> 'accessing') -----
>> + bookName
>> + ^'Tutorials'!
>>
>> Item was added:
>> + ----- Method: SqueakTutorialsOnXML classSide>>pages (in category
>> 'accessing') -----
>> + pages
>> + ^# (dataRetrieval)!
>>
>> Item was added:
>> + SqueakTutorials subclass: #SqueakTutorialsOnXML
>> + instanceVariableNames: ''
>> + classVariableNames: ''
>> + poolDictionaries: ''
>> + category: 'Help-Squeak-Project'!
>>
>> Item was added:
>> + ----- Method: SqueakTutorialsOnXML classSide>>dataRetrieval (in
>> category
>> 'pages') -----
>> + dataRetrieval
>> + ^HelpTopic
>> + title: 'Retrieving XML data'
>> + contents:
>> + 'Retrieving data from XML documents is simple and easy. This tutorial
>> demonstrates the fundamentals with a straightforward approach where code
>> can
>> be tested right away either here or in a Workspace window. The beauty of
>> Squeak Smalltalk resides in the possibility to evaluate, inspect, print
>> and
>> debug code anywhere and this window is no different.
>> +
>> + This tutorial demonstrates how...
>> +
>> + * to retrieve an XML document from the World Wide Web
>> + * to instance an XML document class
>> + * to inspect and understand the content of an XML document
>> + * to retrieve and display values from specific XML tags
>> +
>> + Retrieve an XML document from the World Wide Web
>> +
>> + There are many manners to retrieve data from the World Wide Web in
>> Squeak
>> Smalltalk. HTTPClient is among them and let you download files in all
>> simplicity. Select the following code snippet and inspect it (press
>> alt-i).
>> An Inspect window will open with the document loaded in memory. The
>> result
>> is a MIMEDocument object.
>> +
>> + HTTPClient httpGetDocument:
>> ''http://www.squeaksource.com/ss/feed.rss''.
>> +
>> + TIP: Select HTTPClient and browse it (press alt-b) to open a System
>> Browser window on its class. HTTPClient does not have instance methods
>> but
>> it has class methods. Click on class to see class methods.
>> +
>> + Instantiate an XML Document
>> +
>> + An instance of MIMEDocument will not allow to retrieve XML data in a
>> comprehensive manner because it does not understand the nature of XML.
>> For
>> this reason, it is necessary to parse the content of MIMEDocument using
>> XMLDOMParser. XMLDOMParser>>parseDocumentFrom: requires a stream as a
>> parameter and ReadStream will be used for this purpose. The following
>> code
>> snippet instantiates an XMLDocument using the content of the downloaded
>> file.
>> +
>> + | doc |
>> + doc := HTTPClient httpGetDocument:
>> ''http://www.squeaksource.com/ss/feed.rss''.
>> + XMLDOMParser parseDocumentFrom: (ReadStream on: (doc content)).
>> +
>> + Inspect and understand the content of an XML document
>> +
>> + XML is a flexible document format and it is necessary to understand how
>> each given XML file is structured in order to properly search, retrieve
>> and
>> manipulate data. Inspecting values is critical in a dynamic programming
>> language and environment, such as Squeak Smalltalk. Select the previous
>> code
>> snippet and inspect it (press alt-i).
>> +
>> + Unfortunately, the Inspect window does not reveal a lot about the XML
>> structure of the downloaded file. Select the previous code snippet once
>> again and explore it (press alt and the capital letter i). An Explorer
>> window will open with a tree outline on the instance of XMLDocument.
>> +
>> + The Inspect and Explorer windows tell a lot about an XMLDocument. The
>> sections are instance variables and their values are displayed aside. In
>> the
>> Explorer window, unfold elementsAndContents. Unfold other sections as
>> deem
>> necessary to understand the XML format and the data available.
>> +
>> + The gibberish coding is about to become clear. Open a Browser window
>> from
>> the world menu and right click in the first pane, select find class
>> (press
>> alt-f) and type XMLDocument to search for its class, or select the class
>> name and browse it (press alt-b). However, it is suggested to read more
>> about XMLParser and XMLParserTest first.
>> +
>> + Retrieve and display values from specific XML tags
>> +
>> + The downloaded XML file contains a list of items which are denoted by
>> the
>> tag name "item". The Explorer window revealed the content of interest is
>> located at the array index 1 of the elementsAndContents.
>> +
>> + The following code snippet will display items in a Transcript window.
>> Open
>> a Transcript window using the world menu before selecting and executing
>> the
>> code. Select the code snippet and execute it (press alt-d).
>> +
>> + | doc xml |
>> + doc := HTTPClient httpGetDocument:
>> ''http://www.squeaksource.com/ss/feed.rss''.
>> + xml := XMLDOMParser parseDocumentFrom: (ReadStream on: (doc content)).
>> + (xml elements at: 1) tagsNamed: #item do: [:e |
>> + Transcript show: (e asString); cr.
>> + ].
>> +
>> + An XML item looks like this:
>> +
>> + <item>
>> + <title>SqueakSource-lr.1039.mcz</title>
>> + <link>http://www.squeaksource.com/ss.html</link>
>> + <description>integrated new stylesheet</description>
>> + <pubDate>Sat, 10 Apr 2010 11:30:38 +0100</pubDate>
>> + <author>Lukas Renggli &lt;[hidden email]&gt;</author>
>> + <category>SqueakSource, seaside, server</category>
>> + <enclosure length="302570" type="application/x-monticello"
>> url="http://www.squeaksource.com/ss/SqueakSource-lr.1039.mcz"/>
>> + <guid isPermaLink="false"/> </item>
>> +
>> + The following code snippet uses information learned, retrieves each
>> comment and displays them in a Transcript window. Notice an author can
>> have
>> a nil value and is handled accordingly.
>> +
>> + | doc xml |
>> + doc := HTTPClient httpGetDocument:
>> ''http://www.squeaksource.com/ss/feed.rss''.
>> + xml := XMLDOMParser parseDocumentFrom: (ReadStream on: (doc content)).
>> + (xml elements at: 1) tagsNamed: #item do: [:e |
>> + Transcript
>> + show: ''Date: '', ((e firstTagNamed: #pubDate) contentString); cr;
>> + show: ''Title: '', ((e firstTagNamed: #title) contentString); cr;
>> + show: ''Author: '',
>> + (((e firstTagNamed: #author) notNil)
>> + ifTrue: [(e firstTagNamed: #author) contentString]
>> + ifFalse: ['''']); cr;
>> + show: ''Description: '', ((e firstTagNamed: #description)
>> contentString); cr; cr.
>> + ].
>> +
>> + An item will now looks like:
>> +
>> + Date: Wed, 21 Apr 2010 22:33:18 +0100
>> + Title: SqueakSource-lr.1060.mcz
>> + Author: Lukas Renggli <[hidden email]>
>> + Description: - ignore email errors
>> + '!
>>
>> Item was added:
>> + ----- Method: SqueakTutorialsOnXML classSide>>bookName (in category
>> 'accessing') -----
>> + bookName
>> + ^'XML'!
>>
>> Item was added:
>> + SqueakHelp subclass: #SqueakTutorials
>> + instanceVariableNames: ''
>> + classVariableNames: ''
>> + poolDictionaries: ''
>> + category: 'Help-Squeak-Project'!
>>
>>
>>
>