GNU MediaGoblin
+ + +Table of Contents
+ +1 About
++What is MediaGoblin? I'm shooting for: +
+-
+
- Initially, a place to store all your photos that's as awesome as, + more awesome than, existing proprietary solutions + +
- Later, a place for all sorts of media, such as video, music, etc + hosting. + +
- Federated, like statusnet/ostatus (we should use ostatus, in fact!) + +
- Customizable + +
- A place for people to collaborate and show off original and derived + creations + +
- Free, as in freedom. Under the GNU AGPL, v3 or later. Encourages + free formats and free licensing for content, too. + +
+Wow! That's pretty ambitious. Hopefully we're cool enough to do it. +I think we can. +
++It's also necessary, for multiple reasons. Centralization and +proprietization of media on the internet is a serious problem and +makes the web go from a system of extreme resilience to a system +of frightening fragility. People should be able to own their data. +Etc. If you're reading this, chances are you already agree though. :) +
+2 Milestones
++Excepting the first, not necessarily in this order. +
+ +2.1 Basic image hosting
+2.2 Multi-media hosting (including video and audio)
+2.3 API(s)
+2.4 Federation
++Maybe this is 0.2 :) +
+2.5 Plugin system
+3 Technology
++I have a pretty specific set of tools that I expect to use in this +project. Those are: +
+-
+
- Python: because I love, and know well, the language + +
- MongoDB: a "document database". Because it's extremely flexible + (and scales up well, but I guess not down well) + +
- MongoKit: a lightweight ORM for mongodb. Helps us define our + structures better, does schema validation, schema evolution, and + helps make things more fun and pythonic. + +
- Jinja2: for templating. Pretty much django templates++ (wow, I + can actually pass arguments into method calls instead of tediously + writing custom tags!) + +
- WTForms: for form handling, validation, abstraction. Almost just + like Django's templates, + +
- WebOb: gives nice request/response objects (also somewhat djangoish) + +
- Paste Deploy and Paste Script: as the default way of configuring + and launching the application. Since MediaGoblin will be fairly + wsgi minimalist though, you can probably use other ways to launch + it, though this will be the default. + +
- Routes: for URL routing. It works well enough. + +
- JQuery: for all sorts of things on the javascript end of things, + for all sorts of reasons. + +
- Beaker: for sessions, because that seems like it's generally + considered the way to go I guess. + +
- nose: for unit tests, because it makes testing a bit nicer. + +
- Celery: for task queueing (think resizing images, encoding + video) because some people like it, and even the people I know who + don't don't seem to know of anything better :) + +
- RabbitMQ: for sending tasks to celery, because I guess that's + what most people do. Might be optional, might also let people use + MongoDB for this if they want. + +
3.1 Why python
++Because I (Chris Webber) know Python, love Python, am capable of +actually making this thing happen in Python (I've worked on a lot of +large free software web applications before in Python, including +Miro Community, the Miro Guide, a large portion of +Creative Commons' site, and a whole bunch of things while working at +Imaginary Landscape). I know Python, I can make this happen in +Python, me starting a project like this makes sense if it's done in +Python. +
++You might say that PHP is way more deployable, that rails has way more +cool developers riding around on fixie bikes, and all of those things +are true, but I know Python, like Python, and think that Python is +pretty great. I do think that deployment in Python is not as good as +with PHP, but I think the days of shared hosting are (thankfully) +coming to an end, and will probably be replaced by cheap virtual +machines spun up on the fly for people who want that sort of stuff, +and Python will be a huge part of that future, maybe even more than +PHP will. The deployment tools are getting better. Maybe we can use +something like Silver Lining. Maybe we can just distribute as .debs +or .rpms. We'll figure it out. +
++But if I'm starting this project, which I am, it's gonna be in Python. +
+3.2 Why mongodb
++In case you were wondering, I am not a NOSQL fanboy, I do not go +around telling people that MongoDB is web scale. Actually my choice +for MongoDB isn't scalability, though scaling up really nicely is a +pretty good feature and sets us up well in case large volume sites +eventually do use MediaGoblin. But there's another side of +scalability, and that's scaling down, which is important for +federation, maybe even more important than scaling up in an ideal +universe where everyone ran servers out of their own housing. As a +memory-mapped database, MongoDB is pretty hungry, so actually I spent +a lot of time debating whether the inability to scale down as nicely +as something like SQL has with sqlite meant that it was out. +
++But I decided in the end that I really want MongoDB, not for +scalability, but for flexibility. Schema evolution pains in SQL are +almost enough reason for me to want MongoDB, but not quite. The real +reason is because I want the ability to eventually handle multiple +media types through MediaGoblin, and also allow for plugins, without +the rigidity of tables making that difficult. In other words, +something like: +
+ + + +{"title": "Me talking until you are bored",
+ "description": "blah blah blah",
+ "media_type": "audio",
+ "media_data": {
+ "length": "2:30",
+ "codec": "OGG Vorbis"},
+ "plugin_data": {
+ "licensing": {
+ "license": "http://creativecommons.org/licenses/by-sa/3.0/"}}}
+
+
+
+
++Being able to just dump media-specific information in a media_data +hashtable is pretty great, and even better is having a plugin system +where you can just let plugins have their own entire key-value space +cleanly inside the document that doesn't interfere with anyone else's +stuff. If we were to let plugins to deposit their own information +inside the database, either we'd let plugins create their own tables +which makes SQL migrations even harder than they already are, or we'd +probably end up creating a table with a column for key, a column for +value, and a column for type in one huge table called "plugin_data" or +something similar. (Yo dawg, I heard you liked plugins, so I put a +database in your database so you can query while you query.) Gross. +
++I also don't want things to be too lose so that we forget or lose the +structure of things, and that's one reason why I want to use MongoKit, +because we can cleanly define a much structure as we want and verify +that documents match that structure generally without adding too much +bloat or overhead (mongokit is a pretty lightweight wrapper and +doesn't inject extra mongokit-specific stuff into the database, which +is nice and nicer than many other ORMs in that way). +
+3.3 Why wsgi minimalism / Why not Django
++If you notice in the technology list above, I list a lot of components +that are very Django-like, but not actually Django components. What +can I say, I really like a lot of the ideas in Django! Which leads to +the question: why not just use Django? +
++While I really like Django's ideas and a lot of its components, I also +feel that most of the best ideas in Django I want have been +implemented as good or even better outside of Django. I could just +use Django and replace the templating system with Jinja2, and the form +system with wtforms, and the database with MongoDB and MongoKit, but +at that point, how much of Django is really left? +
++I also am sometimes saddened and irritated by how coupled all of +Django's components are. Loosely coupled yes, but still coupled. +WSGI has done a good job of providing a base layer for running +applications on and if you know how to do it yourself it's not hard or +many lines of code at all to bind them together without any framework +at all (not even say Pylons, Pyramid, or Flask which I think are still +great projects, especially for people who want this sort of thing but +have no idea how to get started). And even at this already really +early stage of writing MediaGoblin, that glue work is mostly done. +
++Not to say I don't think Django isn't great for a lot of things. For +a lot of stuff, it's still the best, but not for MediaGoblin, I think. +
++One thing that Django does super well though is documentation. It +still has some faults, but even with those considered I can hardly +think of any other project in Python that has as nice of documentation +as Django. It may be worth +learning some lessons on documentation from Django, on that note. +
++I'd really like to have a good, thorough hacking-howto and +deployment-howto, especially in the former making some notes on how to +make it easier for Django hackers to get started. +
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