Now it is time for Magic. Ever hear the term "PodCasting?" Well it originally came from the Apple IPod and that little device that has swept the world allowing everyone to hook into their favorite music (and now video etc.) The RSS specifications grew with the world around it and therefore the little XML "enclosure" command came to be found within the files.
What does this mean? Well at first RSS was limited to the text format. What RSS first generation files were doing were spreading the news of the world in small little text headline files. Of course the human desire for ever more and more is impossible to stop. What if we wanted to send picture? Well there is the [!Cdata command which we will discuss in the next article. But what if I wanted to send some type of information that was not text? That is where the enclosure does its magic.
Within enclosure I can actually place any audio, mpg, jpeg..whatever into that little element. And what this means to the aggregator is, "Hey, my RSS file also has a few small additions that come with it. Grab those as well." And as part of this element the RSS file also says, "Hey, this is the format and this is the size of the file. Because I am being courteous and nice, and I want you the aggregator to know just how much you have to grab."
For those quick thinkers out there, what one can actually do in an RSS file is this. Take Janis Joplin and her album "Ball & Chain". Well we would create an item for each of the songs, (I will show you how to do this in another article), describe each one of them in the "description" element and put an mp3 of the song defined in the item in the enclosure command. And then anyone who wanted to get my RSS feed on Janis would be able to read a description of the songs and listen to them.
Or say I wanted to release a few short-shorts on Shakespeare's Sonnets. I would read them, record them, and then put the text of each into the description and my mp3 recording into the enclosure. Voila! An RSS on Shakespeare.
One critical caveat. Remember these are not text files and therefore they can get large. The larger they are the more the aggregator has to grab, the more bandwidth etc. Remember that when you release your songs on the Net in an RSS file for those IPod-ers out there!
Just to remind you. The enclosure command consists of three parts:
1. url - The URL of the actual enclosure.
2. length - The size in bytes and not an estimate but a total size
3. type - A standard MIME type, e.g. Audio, Video, Text etc. A list and explanation of standard MIME types can be found here - http://www.fileformat.info/info/mimetype/standard.htm
Lets see how this would be done, without too much coding. We will begin with the Item Element, so this is just a part of the RSS file. (I left out the guid here.)
There you have it. An RSS PodCast. One item of the song Summertime. Of course your RSS will have every song on the album. Anyone who applies to the feed will be able to listen to all of Janis's songs in their RSS feed - Their Podcast. And you can do the same with a video, pictures etc. For all the "current" terminology take a look at Wikipedia.
