Last night, Herbert Van de Sompel announced the availability of the draft specifications and user guide for Object Reuse and Exchange (ORE). This effort, under the auspices of the Open Archives Initiative (OAI), seeks to define a standard for the description and exchange of aggregations of web resources.

If you stop to think about it, the world of the web is at once a simple and a complex place. It is simple in that it is made up of resources (this HTML page, the jester’s cap graphic in the upper right corner, the text-to-speech audio version of this posting, etc.) that are uniquely addressed by URLs.¹ It is complex in that there is a relationship between this HTML page, the jester’s cap graphic, and the audio version that is not explicitly stated — at least not stated in a way understandable by machines processing content on the web. Which is to say, how does a web crawler know that the linked audio file is an alternate version of the text of this posting rather than a link to some holiday music file that I am critiquing?

This is where OAI-ORE comes in. It offers a machine-parsable way to describe relationships between various web resources. In a manner of speaking, an “ORE file” is a new kind of web resource that encapsulates and describes the complexity of real-world compound documents that already exist on the web. The neat thing now, though, is that there is a formal specification for those compound documents that allows their nature to be understood by web crawlers, indexers, and content repositories.

There is lots more about OAI-ORE in the user’s guide and specifications. Keep in mind, though, that these are alpha specifications that represent the best thinking and compromises of a couple dozen people. ² There are undoubtedly issues and ideas that haven’t been considered yet, so don’t go too far in coding up an implementation that may change (in subtle or dramatic ways) as the public conversation gets going. An OAI-ORE Google Group has been set up to discuss these documents. Those working on ORE to date welcome your comments there, and to reinforce that, I’ve taken the until now unprecedented step of closing comments here on DLTJ — put your comments into the Google Groups area.

Also remember that there are two open meetings scheduled to focus on the specifications:

Download iCal file

March 3th, 2008 — OAI-ORE U.S. Open Meeting at Johns Hopkins University

On March 3, 2008 the Open Archives Initiative (OAI) will hold a public meeting at Johns Hopkins University in Baltimore, MD to introduce the Object Reuse and Exchange (ORE) specifications. Space is limited, please register. Supported by Microsoft.

Download iCal file

April 4th, 2008 — OAI-ORE European Open Meeting at University of Southampton

On April 4, 2008 the Open Archives Initiative (OAI) will hold a public meeting at the University of Southampton, in conjunction with the Open Repositories 2008 conference, to introduce the Object Reuse and Exchange (ORE) specifications. Supported by JISC.

We’re looking forward to your questions and comments on the OAI-ORE draft documents.

The text was modified to remove a link to http://www.talkr.com/app/fetch.app?feed_id=16975&perma_link=http://dltj.org/2007/12/ore-draft-specs/ on December 30th, 2010.

Footnotes

1. Technically called “URIs”, but let’s not go down that path for the sake of trying to speak the vernacular of the public web and not that of the technicalities of the underlying standards.
2. I’m honored to be among those serving on the ORE Technical Committee.

With the release of Microsoft’s Windows Media Player version 11, the Microsoft Media Server (MMS) protocol is officially no longer supported. (Except, of course, for the confusing/amusing footnote on that page that says ‘mms://’ URIs are “highly recommended” as a protocol rollover URL — only Microsoft can at the same time make something deprecated and highly recommended.) As Ryan Eby noted earlier this year, those generating ASX files for Windows Media Player need to adjust their scripts.

Last year I published an entry called Embedded Web Video in a Standards-Compliant, Accessible, and Successful Way on how to embed (without using the non-standard <EMBED> tag) video on an HTML page. It has been one of the most widely read articles on DLTJ.org, and so I wanted to publish an updated version of the script from that article to take into account this new wrinkle from Microsoft. The change is at line #41 below:

#!/usr/bin/perl -w
# Copyright (C) 2006-2007 OhioLINK
#
# This file is part of the OhioLINK Digital Resource Commons (DRC) Project.
#
# The OhioLINK DRC is free software; you can redistribute it and/or
# modify it under the terms of the Affero General Public License as
# published by Affero, Inc. -- either version 1 of the License, or
# (at your option) any later version.
#
# The OhioLINK DRC Project is distributed in the hope that it will be
# useful, but WITHOUT ANY WARRANTY -- without even the implied warranty
# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# Affero General Public License for more details.
#
# You should have received a copy of the Affero General Public
# License in the LICENSE.txt file that comes with the DRC project;
# if not, write to DRC Development Team, OhioLINK, 2455 North Star Rd,
# Suite 300, Columbus, OH 43221, USA.
 
if (!$ENV{PATH_INFO}) {
  print "Location: http://no-path-info-given/\\r\\n\\r\\n";
} else {
  ($format,$id) = $ENV{PATH_INFO} =~ q#^/+(.*?)/(.*)$#;
 
  if ($format =~ /Quicktime/i) {
    print "Location: http://video.ohiolink.edu/blah/Quicktime/$id\\r\\n\\r\\n";
  } elsif ($format =~ /Real/i) {
    print "Location: http://video.ohiolink.edu:8080/ramgen/blah/Real/$id\\r\\n\\r\\n";
  } elsif ($format =~ /Windows/i) {
    ($winType,$winFile) = $id =~ q#^(.*?)/(.*)$#;
    if ($winType =~ /asx/i) {
      $winFile =~ s/\\..*$//;
      print >> "EoMarkup";
Content-type: video/x-ms-asf
 
<asx version="3.0">
<copyright>(c) 2005 - xxx</copyright>
<entry>
<ref href="mms://video.ohiolink.edu/blah/Windows/$winFile.wmv?SAMI=http://rave.ohiolink.edu/dmc/blah/windows/smi/$winFile.smi">
<ref href="http://video.ohiolink.edu/blah/Windows/$winFile.wmv?SAMI=http://rave.ohiolink.edu/dmc/blah/windows/smi/$winFile.smi"/>
<copyright>(c) 2005 - xxx</copyright>
</ref></entry>
</asx>
EoMarkup
    } elsif ($winType =~ /wmv/i) {
      print "Location: mms://video.ohiolink.edu/blah/Windows/$winFile\\r\\n\\r\\n";
    } elsif ($winType =~ /smi/i) {
      use LWP::UserAgent;
      $ua = LWP::UserAgent->new;
      $ua->agent("$0-lwp/0.1 " . $ua->agent);
      $req = HTTP::Request->new(GET => "http://video.ohiolink.edu:8080/blah/Windows/$winFile");
      # send request
      $res = $ua->request($req);
      # check the outcome
      if ($res->is_success) {
        print "Content-type: application/smil\\r\\n\\r\\n";
        print $res->decoded_content;
      } else {
        print "Location: http://error-from-remote-server/$winType/$winFile/".$res->code."/".$res->message."\\r\\n\\r\\n";
      }
    } else {
      print "Location: http://invalid-Windows-format-given/$winType/$winFile\\r\\n\\r\\n";
    }
  } else {
    print "Location: http://invalid-format-given/$format/$id\\r\\n\\r\\n";
  }
}

Thanks to Neil Bennett at the University of Southern Maine for contacting OhioLINK about the problem, providing some very helpful diagnostics, and pointing us to the URL to the protocol table mentioned above. It is also worth noting that the A List Apart website posted a new article about sane ways of embedding Flash content that builds upon the same work in the original ‘Embedded Web Video…’ article. It might be time to update some of the techniques used in the original article, but that’ll need to wait for another time.

The text was modified to remove a link to http://blog.ryaneby.com/archives/windows-media-player-11-and-mms/ on January 19th, 2011.

As you may have noticed, the web has evolved a set of common principles that are a mix of ratified standards and ad hoc practices. The notion of a Web Architecture was codified in a W3C technical report called “Architecture of the World Wide Web” http://www.w3.org/TR/2004/REC-webarch-20041215/ or simply ‘Web Architecture.’ Those projects and protocols that align with the ‘Web Architecture’ are more likely to be picked up and used than those that do not. As a result, the OAI Object Reuse and Exchange (ORE) project seeks to provide an infrastructure for web-based information systems that exploit and enhance the Web Architecture, and therefore overlay cleanly on the existing web.

Given that we want to align closely with this ‘Web Architecture’ how far does the Web Architecture report go to define what is needed to make an ORE environment happen? The answer lies in the definition of three terms and the interaction of these three concepts.

• Resource: “A network data object or service that can be identified by a URI…. Resources may be available in multiple representations (e.g. multiple languages, data formats, size, and resolutions) or vary in other ways.” ¹
• Uniform Resource Identifier (URI): “A compact string of characters for identifying an abstract or physical resource.” ²
• Representation: “An entity included with a response that is subject to content negotiation…. There may exist multiple representations associated with a particular response status.” ¹

This is perhaps best explained by this graphic from the “Architecture of the World Wide Web” document. All three terms are included: a URI identifies a resource which is in turn expressed as one representation. The key part of how the web works, though, lies in the definition of “representation” — that there may exist multiple representations for a single URI. Believe it or not, you already know this. The representation of the resource identified by the URI ‘cnn.com‘ at noon today is different from the one that existed at noon yesterday. You might say, “well so what…it is a dynamic website,” and I would agree — what is important here is that the web architecture does not give you a way to identify with a URI that representation of the cnn.com resource at noon yesterday. Put another way, in the words of the Web Architecture technical report, “Agents [web browsers and the like] may use a URI to access the referenced resource; this is called dereferencing the URI.” ³ The representation comes into being as a result of a service request by an agent for a resource via a URI.

The Web Architecture technical report lists four factors that determine which representation(s) are retrieved as a result of a service request: ⁴

1. Whether the URI owner makes available any representations at all;
2. Whether the agent making the request has access privileges for those representations…;
3. If the URI owner has provided more than one representation (in different formats such as HTML, PNG, or RDF; in different languages such as English and Spanish; or transformed dynamically according to the hardware or software capabilities of the recipient), the resulting representation may depend on negotiation between the user agent and server.
4. The time of the request; the world changes over time, so representations of resources are also likely to change over time.

When a URI is accessed by a browser, one goes through a content negotiation to get a representation. Representations may vary by device or time or IP address or authorization or any number of factors. In a graph or type-based thinking, a resource is a first class object: it is linkable — one can cite a resource. Representations, on the other hand, are second class objects: identified only in the context of a resource. A representation is not linkable, there may be many representations per resource, and a representation only comes about as a result of an action.

Observations

Footnotes

1. “Hypertext Transfer Protocol — HTTP/1.1″ RFC 2616. Available from http://www.ietf.org/rfc/rfc2616 Accessed Feb 15 2007.
2. “Uniform Resource Identifiers (URI): Generic Syntax” RFC 2396. Available from http://www.rfc-editor.org/rfc/rfc2396.txt Accessed Feb 15 2007.
3. “Architecture of the World Wide Web, Volume One” paragraph #117. Available from http://www.w3.org/TR/2004/REC-webarch-20041215/#p117 Accessed Feb 15 2007.
4. “Architecture of the World Wide Web, Volume One” paragraph #122. http://www.w3.org/TR/2004/REC-webarch-20041215/#p117 Accessed Feb 15 2007.

The word “Successful” in the title, when juxtaposed with “Standards-Compliant” and “Accessible,” should be big, bold and flashing (except that the flashing style would then go against web accessibility best practice). The goal is to embed a video clip into a web page that validates as “XHTML4.01 Transitional”, includes a Closed Captioning text track to be displayed in the web page, and could be viewed in one of three flavors: Windows Media, QuickTime, and Real. And the content being presented is about using accessible technologies in the classroom, so it had to be “right.” This task was much harder than I thought, and I’ll offer much harder than it should have been. Piecing together sources too numerous to mention, I managed to make it happen … with just a few caveats. Here, documented for all time, or at least until dltj.org goes away or the next major browser/streaming-client revision (which ever comes first) is how it can be done.

The Content

Windows/

.wmv (the video) and .smi (the closed caption text track)

Real/

.rm (the video), .rt (the closed caption text track) and .smi (the container that pulls the first two together)

Quicktime/

.mov (the video)

Now right out of the gate we’re fudging things a little bit. For whatever reason the team developing the content decided to punt when it came to the text track in Quicktime. I don’t know if there was an insurmountable barrier or some other reason, but the practical upshot is that the Quicktime version of the video includes the text track an “open caption” encoded right into the video stream. That makes Quicktime, from my perspective, very easy to deal with.

Those with a keen eye will notice that both the Windows Media and the Real Media version have a .smi file. This is true, but they are not identical. Windows media wants to use a .asx file as its container object and only uses the .smi for the text stream. The Real Media version has the text stream in .rt files. Could these be combined? Perhaps, but I’ve got real-world problems to solve and this is what I was given. In any case, I don’t think it makes the end result any easier or harder than it would be otherwise.

Serving Up the Content

For the purposes of this project, these RAVE URLs were defined as this (the http protocol prefix is omitted so over-anxious RSS readers will not attempt to turn them into hyperlinks; “blah” is a placeholder for the project name; and [id] represents the identifier for the video segment):

rave.ohiolink.edu/dmc/blah/quicktime/[id]

Redirects to the location of the Quicktime file (a hinted .mov file, so it starts playing in the browser right away)

rave.ohiolink.edu/dmc/blah/real/[id]

Redirects to the location of the .smi container file via the mms protocol through the Helix streaming server

rave.ohiolink.edu/dmc/blah/windows/wmv/[id]

Redirects to the location of the wmv video file via the mms protocol through the Helix streaming server

rave.ohiolink.edu/dmc/blah/windows/smi/[id]

Pulls the .smi file off of the streaming server and sends it back to the browser with the appropriate MIME type

rave.ohiolink.edu/dmc/blah/windows/asx/[id]

Dynamically creates a .asx container that pulls together the windows/smi and the windows/wmv files

Here are the first of the tricky bits. First, it seems like Windows Media Player can’t cope with a 302 redirect message in response to its request for a .smi file. “Can’t cope” can be restated as “ignores”; it doesn’t throw an error, it just plays the file as if there was no closed captioning text. To get around this, the RAVE script has a bit of PERL where it asks like a web client to pull the .smi file off of the video server and send it back out to the media player.

Second — again for those with eagle eyes — is the dynamic generation of an .asx file. As it turns out, one can relate a .smi text-track file with a .wmv video file by including it as a SAMI parameter on the URL. By far the best practice for doing this seems to be to relate the .smi and the .wmv files in a .asx container file. So we create one on-the-fly. The PERL code looks like this:

#!/usr/bin/perl -w
# Copyright (C) 2006 OhioLINK
#
# This file is part of the OhioLINK Digital Resource Commons (DRC) Project.
#
# The OhioLINK DRC is free software; you can redistribute it and/or
# modify it under the terms of the Affero General Public License as
# published by Affero, Inc. -- either version 1 of the License, or
# (at your option) any later version.
#
# The OhioLINK DRC Project is distributed in the hope that it will be
# useful, but WITHOUT ANY WARRANTY -- without even the implied warranty
# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# Affero General Public License for more details.
#
# You should have received a copy of the Affero General Public
# License in the LICENSE.txt file that comes with the DRC project;
# if not, write to DRC Development Team, OhioLINK, 2455 North Star Rd, 
# Suite 300, Columbus, OH 43221, USA.
 
if (!$ENV{PATH_INFO}) {
  print "Location: http://no-path-info-given/\r\n\r\n";
} else {
  ($format,$id) = $ENV{PATH_INFO} =~ q#^/+(.*?)/(.*)$#;
 
  if ($format =~ /Quicktime/i) {
    print "Location: http://video.ohiolink.edu/blah/Quicktime/$id\r\n\r\n";
  } elsif ($format =~ /Real/i) {
    print "Location: http://video.ohiolink.edu:8080/ramgen/blah/Real/$id\r\n\r\n"; 
  } elsif ($format =~ /Windows/i) {
    ($winType,$winFile) = $id =~ q#^(.*?)/(.*)$#;
    if ($winType =~ /asx/i) {
      $winFile =~ s/\..*$//;
      print >> "EoMarkup";
Content-type: video/x-ms-asf
 
<asx version="3.0">
<copyright>(c) 2005 - xxx</copyright>
<entry>
<ref href="mms://video.ohiolink.edu/blah/Windows/$winFile.wmv?SAMI=http://rave.ohiolink.edu/dmc/blah/windows/smi/$winFile.smi">
<copyright>(c) 2005 - xxx</copyright>
</ref></entry>
</asx> 
EoMarkup
    } elsif ($winType =~ /wmv/i) {
      print "Location: mms://video.ohiolink.edu/blah/Windows/$winFile\r\n\r\n";
    } elsif ($winType =~ /smi/i) {
      use LWP::UserAgent;
      $ua = LWP::UserAgent->new;
      $ua->agent("$0-lwp/0.1 " . $ua->agent);
      $req = HTTP::Request->new(GET => "http://video.ohiolink.edu:8080/blah/Windows/$winFile");
      # send request
      $res = $ua->request($req);
      # check the outcome
      if ($res->is_success) {
        print "Content-type: application/smil\r\n\r\n";
        print $res->decoded_content;
      } else {
        print "Location: http://error-from-remote-server/$winType/$winFile/".$res->code."/".$res->message."\r\n\r\n";
      }
    } else {
      print "Location: http://invalid-Windows-format-given/$winType/$winFile\r\n\r\n";
    }
  } else {
    print "Location: http://invalid-format-given/$format/$id\r\n\r\n";
  }
}

The first part of the script parses the PATH_INFO variable — everything left over from the blah script name — and if what is requested is the Real Media or the Quicktime version of the video it sends the redirect back to the client (in the form of the “Location:” header with Apache HTTP daemon handling the 302 response code). If what is requested is the Windows variety, it further parses the PATH_INFO piece for the file type and acts according to that: for wmv, it redirects; for asx, it generates the .asx file; and for .smi, it pulls the content off the video server and returns it to the client.

The Markup

Also note that many of the recommendations out there start off with something like “if you have media to show, don’t embed it into your web page; but if you must, here is one way to do it.” The reason for this is pretty simple, if not obvious after a little thought: folks using alternate browsing/computing techniques (e.g. keyboard only for limited mobility, auditory only for sight impaired, visual only for the hearing impaired, etc.) lose much of their ability to control the flow of information because it is tied up in the functionally-limited browser rather than the native media player. These same recommendations go on to say that if you do embed the media into the web page, provide a link for the user to access it using the native media player.

So based on the URLs to the media objects described above, this is what the HTML markup looks like:

Quicktime

<object classid="clsid:02BF25D5-8C17-4B23-BC80-D3488ABDDC6B" codebase="http://www.apple.com/qtactivex/qtplugin.cab" width="320" height="380">
  <param name="src" value="http://rave.ohiolink.edu/dmc/blah/quicktime/[id].mov" />
  <param name="controller" value="true" />
  <param name="autoplay" value="true" />
  <!--[if !IE]>-->
    </object><object type="video/quicktime" data="http://rave.ohiolink.edu/dmc/blah/quicktime/[id].mov" width="320" height="380">
     <param name="autoplay" value="true" />
     <param name="controller" value="true" />
    </object>
   <!--<![endif]-->
 
&lt;br /&gt;
<a href="http://rave.ohiolink.edu/dmc/blah/quicktime/[id].mov" title="View in Native Player">View Video with External Player</a>

Windows Media

<object classid="clsid:6bf52a52-394a-11d3-b153-00c04f79faa6" type="application/x-oleobject" width="320" height="304" id="Player1">
  <param name="url" value="http://rave.ohiolink.edu/dmc/blah/windows/asx/[id].asx" />
  <param name="src" value="http://rave.ohiolink.edu/dmc/blah/windows/asx/[id].asx" />
  <param name="autostart" value="true" />
  <param name="showcontrols" value="true" />
  <param name="uimode" value="mini" />
  <param name="captioningID" value="CapText" />
  <param name="SAMIFileName" value="http://rave.ohiolink.edu/dmc/blah/windows/smi/scott.smi" />
    <!--[if !IE]>-->
     </object><object type="video/x-ms-wmv" data="http://rave.ohiolink.edu/dmc/blah/windows/asx/[id].asx" width="320" height="304" id="Player2">
     <param name="src" value="http://rave.ohiolink.edu/dmc/blah/windows/asx/[id].asx" />
     <param name="autostart" value="true" />
     <param name="showcontrols" value="true" />
     <param name="uimode" value="mini" />
     <param name="captioningID" value="CapText" />
     <param name="SAMIFileName" value="http://rave.ohiolink.edu/dmc/blah/Windows/smi/[id].smi" />
    </object>
   <!--!<[endif]-->
 
&lt;br /&gt;
<a href="http://rave.ohiolink.edu/dmc/blah/windows/asx/[id].asx" title="View in Native Player">View Video with External Player (including captions)</a>

Real Media

<script language="JavaScript" type="text/javascript">
  AC_RunRealContent( 
	"id", "player",  
	"width", "320",  
	"height", "280",  
	"CONTROLS", "imagewindow",  
	"CONSOLE", "radio",  
	"AUTOSTART", "TRUE",  
	"type", "audio/x-pn-realaudio-plugin",  
	"SRC", "http://rave.ohiolink.edu/dmc/blah/real/[id].smi"
  );
  window.document.write('&lt;br /&gt;');
  AC_RunRealContent( 
	"id", "controls",  
	"width", "320",  
	"height", "36",  
	"CONTROLS", "ControlPanel",  
	"CONSOLE", "radio", 
	"type", "audio/x-pn-realaudio-plugin",  
	"SRC", "http://rave.ohiolink.edu/dmc/blah/real/[id].smi"
  );
</script>
&lt;br /&gt;
<a href="http://rave.ohiolink.edu/dmc/fame/Real/scott.smi" title="View with Native Player">View Video with External Player (including captions)</a>

Conclusion

1. It seems to work for me and the machines I test with; your mileage may vary.
2. If you know of a better way to do it, please let me know!

Resources Consulted

• “Bye Bye Embed” by Elizabeth Castro on A List Apart
• “Web Captioning” in the Web Accessibility In Mind project