Streaming Digital Media for E-Learning 4: Delivering Content via HTTP Tunneling

The topic of today's post was preempted in a comment I received on Friday 10th July. In it, Digital Chalk's Tony McCune wrote:

...I think that the technology decision has to include consideration of the client capabilities of the audience you are serving as well as the network you will ultimately be streaming into and their openness to the ports and protocols. Most enterprise networks close the streaming ports.

Communications and collaboration using streaming media platforms only work if the client side has the facility to access the content. If you or your organization has a requirement to deliver content (on-demand courseware or a pre-sales demo, for example ) to a customer, you are probably familiar with the refrain " I can't see the content" from the prospective attendee or viewer. There are many reasons why this may occur, but all other things being equal, the probability is that the client cannot access the content because their firewall is blocking the data delivery.

According to Wikipedia, a firewall is

a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. It is a device or set of devices configured to permit, deny, encrypt, decrypt, or proxy all (in and out) computer traffic between different security domains based upon a set of rules and other criteria.

To control the flow of data, numbered ports in the firewall are either opened or closed to specific types of packets. The firewall reviews two pieces of information in each arriving or departing packet: the protocol through which the packet is being delivered and the port number to which it is being sent. If the firewall is configured to accept the specified protocol through the targeted port, the packet is allowed through. The most commonly-known example of this process is probably Port 80, the access point for TCP, UDP, and the Hypertext Transfer Protocol (HTTP).

Firewall policy management is beyond the remit of this blog, but suffice it to say that most organizations are understandably cautious about providing 'open house' access to their networks. The downside of this caution is that when a legitimate need arises to provide access via a rarely-used port, most organizations' IT departments have reservations (to say the least) about granting access.

Table 1 describes all of the ports needed to facilitate the delivery of unicast streaming via Microsoft Media Server 9.

Table 1 Delivering a Unicast Stream via MS Media Serve 9

Application Protocol	Protocol	Port	Description
RTSP	TCP	554 (In/Out)	Used for accepting incoming RTSP client connections and for delivering data packets to clients that are streaming by using RTSPT.
RTSP	UDP	5004 (Out)	Used for delivering data packets to clients that are streaming by using RTSPU.
RTSP	UDP	5005 (In/Out)	Used for receiving packet loss information from clients and providing synchronization information to clients that are streaming by using RTSPU.
MMS	TCP	1755 (In/Out)	Used for accepting incoming MMS client connections and for delivering data packets to clients that are streaming by using MMST.
MMS	UDP	1755 (In/Out)	Used for receiving packet loss information from clients and providing synchronization information to clients that are streaming by using MMSU.
MMS	UDP	1024-5000 (Out)	Used for delivering data packets to clients that are streaming by using MMSU. Open only the necessary number of ports.
HTTP	TCP	80 (In/Out)	Used for accepting incoming HTTP client connections and for delivering data packets to clients that are streaming by using HTTP.

Table 1 only represents a small portion of Windows Media Server 9’s requirements, the platform has separate port access requirements for:

• Delivering a multicast stream
• Streaming from an encoder
• Distributing content
• Administering the server remotely

Apple, on the other hand, provides proxy server software to get around firewalls, by the IT department maintaining the firewall must install the proxy software.

The Flash Streaming Server platform uses what Michael Topic (2002) calls a "drastic solution" to negotiate this problem: HTTP tunneling

Where [Real Time Protocol] RTP packets are wrapped inside ordinary HTTP packets so that they can pass through the firewall.

(p.99)

"Unfortunately" he notes, this approach adds "significant overhead to the stream" taking up more bandwidth. Adobe Systems solution to this issue (and the one implemented by Digital Chalk, as well as a broad range of e-learning vendors and other enterprises and institutions) is to implement the proprietary Real-Time Messaging Protocol for streaming audio, video and data over the Internet, between a Flash player and a server..

According to Adobe

The Real-Time Messaging Protocol (RTMP) was designed for high-performance transmission of audio, video, and data between Adobe Flash Platform technologies, including Adobe Flash Player and Adobe AIR. RTMP is now available as an open specification to create products and technology that enable delivery of video, audio, and data in the open AMF, SWF, FLV, and F4V formats compatible with Adobe Flash Player.

The protocol works by a client (such as the Flash Player) communicating with a Flash Communication Server (for example via a corporate Adobe Connect solution) using RTMP protocol over port 1935. If that fails, it will try again over ports 443 and 80 in an attempt to get around firewall policies within an organization, which prevent TCP/IP connections over non-standard ports.

According to Adobe this approach allows "approximately 96% of all users to access publicly accessible Flash Communication servers."

More…
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References:

Adobe DevNet (2009). Real-Time Messaging Protocol (RTMP) specification. [Internet] Available from: http://www.adobe.com/devnet/rtmp/ Accessed 11th July 2009

Adobe TechNote (2009). HTTP Tunneling protocols [Internet] Available from: http://kb2.adobe.com/cps/166/tn_16631.html Accessed 11th July 2009

Nelson, D. (2007) Firewall Information for Windows Media Services 9 Series. [Internet] Available from: http://www.microsoft.com/windows/windowsmedia/forpros/serve/firewall.aspx Accessed 11th July 2009

Topic, M. (2002) Streaming Media Demystified. McGraw-Hill Professional. eBook, United States.

Wikipedia (2009) Firewall. [Internet] Available from: http://en.wikipedia.org/wiki/Firewall Accessed 11th July 2009

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Streaming Digital Media for E-Learning 3: Using a Dedicated Media Server

According to Adobe, organizations use streaming media for corporate communications, electronic learning, and sales & marketing.

In a learning context, streaming media technology is a central component of

• Delivering remote presentations to employees, customers, and partners
• Delivering asynchronous (on-demand) just-in-time training
  Providing delta training to upskill workers
• Enhancing professional development via VLEs/PLEs and mentoring programs
• Capturing tacit knowledge from experts for distribution to their colleagues
• Conducting pre-sales demos
• Providing customer service

According to the eLearning Guild (Marks, 2002) e-learning using streaming media can save you money, increase learner participation, and improve motivation and focus (p.2).

So let's take a closer look at content delivery via a streaming media server. When using a streaming media server approach, the initial production, post-production, and content encoding steps are undertaken in the same manner as for progressive downloading and HTTP streaming. However, at the distribution stage, the compressed media file is placed on a specialized streaming media server. A Web page with a reference to the media file is placed on a regular HTTP server 'front end' web page .

The rest of the streaming media server delivery process differs significantly from the web server approach. In contrast to the HTTP/TCP methodology used in web server streaming, the digital media file data is actively and intelligently sent to the client. This means that the media server delivers the content at the data rate associated with the compressed audio and video streams. The server and the client communicated during the content delivery process, and the streaming media server can respond to any feedback from the client (see Figure 1).

Figure 1 UDP and RTP/RTSP protocols

While streaming media servers can use the HTTP/TCP protocols used by Web servers, they can also use specialized protocols such as the User Datagram Protocol (UDP) and Real Time Streaming Protocol (RTSP) to greatly enhance the quality of the streamed content and ultimately the users' media access experience.

UDP is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages called datagrams to other hosts on an Internet Protocol (IP) network without requiring prior communications to set up special transmission channels or data paths.

Unlike TCP, UDP is a fast, lightweight protocol. This makes UDP an ideal protocol for transmitting real-time digital media data, which can tolerate some lost packets. Instead of the blind retransmission scheme employed by TCP, streaming media servers' resend feature ensures that the server only retransmits lost packets that can be sent to the client in time to get played.

Like UDP, the Real Time Streaming Protocol (RTSP) takes advantage of streaming by breaking data into many packets, sized according to the bandwidth available between client and server. When enough packets have been received by the client, the user's software can begin viewing the content: typically one packet is played, while subsequent packets are decompressed and downloaded. The advantage of RTSP is that it enables the user to start viewing multimedia content almost immediately. Both live data feeds and stored clips can be used as the sources of the content. The transmission of streaming data itself is not a task of the RTSP protocol; most RTSP servers use the Real-time Transport Protocol (RTP) for media stream delivery, though some vendors implement proprietary transport protocols. The RTSP server from adobe Systems, for example, also features their proprietary RTMP stream transport protocol.

RTSP has been called a "network remote control" for multimedia servers, in that the user can typically play, pause, rewind, scrub through (rewind and fast-forward), record, and stop playback via client interactions with the streaming server. Examples of media server products using this approach include:

• Flash Media Server family
• Microsoft Windows Media Services
• Apple Darwin Streaming Server
• RealMedia Helix Server

In a sense, RTSP is more of a framework than a protocol. It's meant to control multiple delivery sessions, provide a way to choose delivery channels such as UDP, TCP and IP-multicast. The delivery mechanisms are based solely on RTP. RTSP has been designed sit on top of RTP to facilitate both control and synchronous delivery of content.
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References:

Adobe Dynamics Group (2001). A Streaming Media Primer. [Internet] Available from: http://www.adobe.com/products/aftereffects/pdfs/AdobeStr.pdf Accessed 4 July 2009

Marks, R.B. (2002). Learning Styles and Streaming Media. The eLearning Developers Journal, October. [Internet] Available from: http://www.elearningguild.com/articles/abstracts/index.cfm?id=43&action=viewonly [Subscription Required). Accessed 3 July 2009.

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Streaming Digital Media for E-Learning 2: Delivering Content via a Web Server

Deploying streaming media content with the web server approach is very similar to the download-and-play model I described in yesterday's post: it's a pull technology.

Using this paradigm, the initial request for data originates from the client, and then is responded to by the server. When using digital media, uncompressed audio and video is first compressed into a single, muxed (multiplexed) media file for delivery over the Internet or a network at a specific bit rate. The media file is then placed on a regular web server. A web page containing the media file's URL is also created and placed on the same web server. When the link on the web page is clicked on, a client-side player (such a Windows Media Player or QuickTime Player) downloads and plays the requested media file.

In the context of e-learning, it's pretty standard for a video demo (for example) to be stored and progressively streamed from a Moodle LMS running on an Apache such as Apache server (see Figure 1)

Figure 1. Demonstration: Uploading a WMV file to Moodle, and playback via HTTP streaming in Windows Media Player
[Click to play the demo]

From a user's perspective, this process looks and feels identical a download-and-play case use case. From a technical point of view, the difference lies in how the client functions.

Unlike the download-and-play model, the client player starts actually starts playing the streamed digital media file while it's being downloaded. This is possible because the content is cached: a process of collecting the first part of a media file before playing. This small 'buffer' of information allows the content to continue playing even during periods of high network congestion. With this delivery method, the client retrieves data as fast as the Web server, network and client will allow, regardless of the quality of the compressed stream. Only certain media file formats support this type of progressive playback including Microsoft's Windows Media format (WMV) and Apple's QuickTime (MOV).

Web server streaming uses the Hyper Text Transport Protocol (HTTP), the standard Web protocol used by all Web servers and Web browsers for communication between the server and the client. HTTP operates on top of the Transmission Control Protocol (TCP), which handles all the data transfers.

It's useful to remember that HTTP/TCP is optimized for asynchronous, static applications, such as displaying static Web pages, and file transfer; this can affect the distribution and delivery of motion-based, asynchronous ('on-demand') content. Users may experience interruptions, 'glitches,' and temporary loss of playback because to the limitations of the HTTP and TCP protocols when handling multimedia content.

More...

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Streaming Media for E-Learning: A Primer

I'm preparing a series of blog articles on the topic E-Learning Using Collaboration Platforms. In the series I will discuss:

• Collaboration Platform Technology
• Synchronous Delivery
• Asynchronous Delivery
  
• Overview of Products on the Market
  
• Production Considerations
  
• What works (and what doesn't work)
  
• The Online Instructor
  
• Mentoring
• Integrating Collaboration Solutions and Other E-Learning Channels

This is an area of technology in education that I'm especially interested in, so I'm really looking forward to bringing this set of blog posts to you here on the E-Learning Curve Blog. As the series is still under development, there's an opportunity to request an article on an aspect of this topic that you might like to see covered: let me know and I'll see what I can do.

In the meantime, I thought I'd give you a 'heads up' by discussing some of the fundamentals surrounding using collaboration solutions: streaming media.

Until about five years ago, Web-based audio and video - or digital - media was primarily a download-and-play technology. Users had to download an entire media file before it could be played back. If you're over 30, you'll remember those postage stamp-sized video clips (usually in ASF or MOV format) that took forever to load over your dial-up connection (and were hardly worth the wait). Because digital media files are usually very large and take a long time to download, the only content found on the Web was short, low motion clips. Even these files could take 20 minutes or longer to download.

How video used to look and sound – Marc J. Rosenberg discusses personalized learning
[Click to play video]

With the increasing availability of high-speed internet access, streaming digital media has become more prevalent. In the consumer market, this has led to the rise in popularity of services like YouTube, and the current emergence of video-on-demand (VOD) solutions like Hulu, as well as ustream and for lifecasting and live video streaming of events online.

Streaming media works almost instantaneously: other than a short delay before the requested file starts to play, you don't have to wait to start watching, no matter if the file lasts thirty seconds or thirty minutes in duration.

Broadly speaking, there are two way of delivering streaming digital media content over the Web. The first method uses a standard HTTP Web server to deliver the audio and video data to a media player. The second approach uses a separate streaming media server designed specifically to stream digital media. Using a streaming server is more efficient and flexible, provides a better user experience, and is more secure than HTTP streaming.

Both approaches have their advantages and disadvantages, and I will begin to look at these tomorrow.

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Moodle Flies High

When I was an undergraduate, I worked for a summer in the Phillips assembly plant in Eindhoven in The Netherlands. Life as a "gluer and screwer" or line assembly worker is quite repetitive, and repetitive, and repetitive, and repetitive, so my college friends and I tried to get to visit the cultural amenities of nearby Amsterdam as often as possible: yes, there are many galleries and museums to broaden a young man's mind in one of the jewels in Europe's crown - I recommend it.

After one particularly "cultural" weekend, my friends and I found ourselves in Centraal Station waiting for our train back to Eindhoven, and across the platform I saw an odd thing: a group of skiers! My initial thought was that I had hit the culture a little too hard, what would skiers be doing in the Low Countries (which after all, is famed for its plains, lack of topographical relief, and general flatness), and in the Summer, no less?

Holland: notably bereft of the conditions for skiing

Eventually the answer seeped into my culture-addled brain: of course! They were going to the Alps! As a young lad from a small island nation on the western margin of Europe (the island without the Eurotunnel) it had simply never occurred to me that you could hop on a train in one country, and a few hours later be on the piste in Switzerland, Austria or Italy.

Living in Ireland, the only way I can travel off the island is by sea and by air. As a result of this situation, most Irish people have quite the soft spot for Aer Lingus, the Irish national airline. Until the emergence of Ryanair and other low-cost carriers, flying Aer Lingus was the only way to travel to foreign lands quickly and comfortably: it's how I travelled to go on the piste (as it were) in Holland after all.

So I'm pleased to see that Aer Lingus have decided to use Moodle (another organization I have a much admiration for) for their Online Pilot Training courses. The aviation industry has been involved with e-learning for over twenty years - indeed, the first generally-used e-learning specification AICC was an aviation industry initiative, developing guidelines for the development, delivery, and evaluation of computer-based, and Web-based Training (and related training technologies).

AICC specifications are usually designed to be general purpose (and not necessarily aviation specific) so that learning technology vendors can spread their costs across multiple markets and thus provide products at a lower cost. This strategy has resulted in AICC specifications having broad acceptance and relevance to non-aviation and aviation users alike. Even today, AICC PENS (Package Exchange Notification Services) is a broadly-used standard implemented in many e-learning authoring packages, such as Adobe Captivate.

Aer Ling chose Enovation, an Irish Moodle Partner, to undertake on the consultancy in the project. Using Moodle, Enovation provided the following services in line with Aer Lingus’s technical requirements:

• Hosting – Provided secure solution hosting for Aer Lingus courseware.
• Training – Provided hands-on training to all administration staff at Aer Lingus.
• Reporting – To comply with industry regulations, Aer Lingus has to produce a report to show that users view and complete all tasks within Moodle. As part of this, Enovation integrated the third-party reporting solution, Jaspersoft, with Moodle to allow administrators to report on user activity.
• Branding – Enovation customized Moodle to match the Aer Lingus branding.
• Support – Enovation implemented a Web-based issue reporting and tracking system for Aer Lingus.
• Courseware – Enovation worked with Aer Lingus to transform their original course content into the Moodle environment.

According to Conor Rock, Training Captain at Aer Lingus,

Moodle has been universally well received by the pilots and we have reduced our training costs, what can I say - the project has been a huge success.

Captain Rock continued that Moodle could be used in other domains within Aer Lingus:

Moodle has obvious potential in other areas. I see Aer Lingus expanding Moodle to the wider employee base for cabin crew and technical training.

Next time: back to ISD

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Camtasia Lab – create a short learning object

I’m on leave for a few weeks, so I decided that I better leave you some homework to keep you occupied in my absence.

Objective
The objective of this assignment is to create a short e-learning module based upon a PowerPoint presentation. Your mission (should you choose to accept it) is to convert a PowerPoint presentation into a Web-deliverable format.

The demo must contain slides, animation, graphics, transport controls and a progress bar. In the ‘Things to Try Yourself’ section of the tutorial, there are some guidelines about how to add audio narration to your learning object.

Format
The published learning object must be a Flash movie (FLV or SWF) file, and the file must be able to play back in a standard Web browser such as Internet Explorer, Opera or Mozilla Firefox.

Lab Structure

• Task Breakdown 1
• Task Breakdown 2
• Recording your presentation
• Edit your content
• Publishing your content
• Some things to try yourself
• Conclusion
• References / Sources

Click here to download the PDF of the tutorial.

Hopefully this assignment will keep you occupied in my absence, so I would like to wish you a happy Easter / Spring break, and I’ll talk you in May.

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