PackageDescription: NetResources


Net Resources

Last published: October 21, 2004 by 'michael'

Defines 15 Classes
Extends 24 Classes

NetResources provides a simple API for access content via URI's and transforming the content of the URI in to a relevant object. For example:

'http://www.w3.org' asURI asResource

This package does not provide HTTP behaviour, see NetResourcesHTTP to use the NetResources API with HTTP.

This package can use the following other packages:
a) GIFSupport - for viewing GIF images
b) WinGDIPlusInterface - for viewing many kinds of images. Windows only. needs gdi+.dll
c) LibTidy or Twoflower - for viewing badly formed XML and HTML and using HTML entities
d) PNGImageReader - for viewing PNG images

NetResources works off URI's. It currently works with File URL's, HTTP URL's and Resource URL's. It does not work with FTP URL's at present.

A new kind of URI is provided with NetResources called a 'resource' URI. It works like so:

resource://MyNamespace.MyClass/myClassMethod

Access will call the method named on the class. For a POST, the same method name is called except with a : on the end and an argument that contains the parameters of the post.

NetResources has an in-memory cache and on-disk cache mechanism for CacheItem's. If the directory './cache' exists then CacheItem's will write themselves to disk for later retrieval if the CacheItem is not already in memory. CacheItem's check their timestamp to ensure their data is not out of date.

More API's on URI's in NetResources are:

#asCacheItem
#asCacheItemUnreconciled
#asEncodedCacheItem
#asResourceInEncoding: anEncoding
#asResourceInMimeType: aMimeType
#asResourceInMimeType: aMimeType encoding: anEncoding
#binaryValueStream
#valueStream
#delete
#refresh
#post: contents
#post: contents encoding: anEncoding
#put: contents
#put: contents encoding: anEncoding
#isAvailable
#hasChanged

Converting a URL's contents in to a Resource object such as an XML DOM tree or an Image object is done using ResourceHandlers. All ResourcesHandlers are subclasses of ResourceHandler. A ResourceHandler is picked based on the MimeType of a URI.

For FILE URI's this is guessed from a file's filename extensionm. For HTTP the HTTP request itself gives the mime type, etc. Each ResourceHandler must implement #canHandle: on the class side to say whether that handler can handle a given mime type for a URI.

On the instance side, a ResourceHandler must implement #handle: contents for: aURI to return the object of interest for a URI's contents.

Preamble

The intent of this document is to state the conditions under which a Package may be copied, such that the Copyright Holder maintains some semblance of artistic control over the development of the package, while giving the users of the package the right to use and distribute the Package in a more-or-less customary fashion, plus the right to make reasonable modifications.

Definitions:

* "Package" refers to the collection of files distributed by the Copyright Holder, and derivatives of that collection of files created through textual modification.
* "Standard Version" refers to such a Package if it has not been modified, or has been modified in accordance with the wishes of the Copyright Holder.
* "Copyright Holder" is whoever is named in the copyright or copyrights for the package.
* "You" is you, if you're thinking about copying or distributing this Package.
* "Reasonable copying fee" is whatever you can justify on the basis of media cost, duplication charges, time of people involved, and so on. (You will not be required to justify it to the Copyright Holder, but only to the computing community at large as a market that must bear the fee.)
* "Freely Available" means that no fee is charged for the item itself, though there may be fees involved in handling the item. It also means that recipients of the item may redistribute it under the same conditions they received it.

1. You may make and give away verbatim copies of the source form of the Standard Version of this Package without restriction, provided that you duplicate all of the original copyright notices and associated disclaimers.

2. You may apply bug fixes, portability fixes and other modifications derived from the Public Domain or from the Copyright Holder. A Package modified in such a way shall still be considered the Standard Version.

3. You may otherwise modify your copy of this Package in any way, provided that you insert a prominent notice in each changed file stating how and when you changed that file, and provided that you do at least ONE of the following:

a) place your modifications in the Public Domain or otherwise make them Freely Available, such as by posting said modifications to Usenet or an equivalent medium, or placing the modifications on a major archive site such as ftp.uu.net, or by allowing the Copyright Holder to include your modifications in the Standard Version of the Package.

b) use the modified Package only within your corporation or organization.

c) rename any non-standard executables so the names do not conflict with standard executables, which must also be provided, and provide a separate manual page for each non-standard executable that clearly documents how it differs from the Standard Version.

d) make other distribution arrangements with the Copyright Holder.

4. You may distribute the programs of this Package in object code or executable form, provided that you do at least ONE of the following:

a) distribute a Standard Version of the executables and library files, together with instructions (in the manual page or equivalent) on where to get the Standard Version.

b) accompany the distribution with the machine-readable source of the Package with your modifications.

c) accompany any non-standard executables with their corresponding Standard Version executables, giving the non-standard executables non-standard names, and clearly documenting the differences in manual pages (or equivalent), together with instructions on where to get the Standard Version.

d) make other distribution arrangements with the Copyright Holder.

5. You may charge a reasonable copying fee for any distribution of this Package. You may charge any fee you choose for support of this Package. You may not charge a fee for this Package itself. However, you may distribute this Package in aggregate with other (possibly commercial) programs as part of a larger (possibly commercial) software distribution provided that you do not advertise this Package as a product of your own.

6. The scripts and library files supplied as input to or produced as output from the programs of this Package do not automatically fall under the copyright of this Package, but belong to whomever generated them, and may be sold commercially, and may be aggregated with this Package.

7. C or perl subroutines supplied by you and linked into this Package shall not be considered part of this Package.

8. The name of the Copyright Holder may not be used to endorse or promote products derived from this software without specific prior written permission.

9. THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

10. The user must assume all risk of using this package


The End

Copyright Holders: Software WithStyle, James Robertson