Tramline
========

This presentation is based on a lightning talk at the Plone Conference
2005 in Vienna by Martijn Faassen. It has since been updated.

Introduction
------------

* Upload and download accelerator for Zope (2 or 3)

* Plugs into the Apache HTTP server.

* Large file data not stored in the ZODB

* Railroad's little sister

Why tramline?
-------------

* railroad powerful repository

* WebDAV, metadata, multi-CMS, search

* but complicated integration with applications

Tramline Goals
--------------

* Deliberately limited goals

* Fast uploads and downloads of files

* Store large file data in filesystem, not ZODB

* Easy to integrate with any application

* No need to cut down forests for a tramline

Design
------

* Plugs into Apache with mod_python

* Simple setup in Apache

* Works with any form that uploads files

* Need two one-liners in your applications to make it work

Upload one-liner
----------------

In response header to upload form, send out 'tramline_ok' header (no
contents)::

  response.addHeader('tramline_ok', '')

If that's not sent, tramline throws away the file. So, if application
raises error, user is unauthored, etc, file is thrown away.

Upload continued
----------------

* File received by the server is just an id string, very
  short, ZODB can scale to store these easily. :)

* Can store this just as any other file

Download
--------

* serve up file (the id) by returning the content, just
  like any other file

* Add a response header 'tramline_file' (another oneliner)

Performance
-----------

* Tested with chandler tarball, 26 megs of file

* This is really fast

Drawbacks
---------

* Needs latest stable Apache (2.0.55) (mod_proxy inputfilter bugfixes
  needed)

* Needs 1 line patch to mod_python

* Reported inputfilter problem to mod_python developers

Interesting benefit
-------------------

* You can now do ridiculously unscalable things, scalably

* Can stuff files in sessions!

* Can base64 encode files on page!

* hurry.file makes use of this property of tramline

Conclusion
----------

* Tramline is fast and easy

* Use it when you need fast upload and download and filesystem storage
  of large files