Trema

Some background

This semester, I had a course on Advanced Computer Networks. One of the course assignments was to implement a simulation of an SDN. At that time, I had started learning Ruby, and wanted to try to build something with it. And that is how I stumbled across Trema. Trema didn’t work, and in the end I used os-ken instead.

Ruby-chan!

I don’t want to give up yet. I just started learning Ruby, so I thought it would be a nice experience to try and get Trema working. Ruby is such an awesome language. The syntax feels absolutely delightful! My first impression was that it felt somewhat similar to Scala, but I have only scratched the surface, so let’s see how this goes!

The problem

The last commit on the Trema repo’s develop branch was on June 14, 2018. That was not promising. I thought “Maybe it’s so good that it needs no more development?“. How wrong I was! When I installed Trema via gem and tried to run it, there were so many errors - version conflicts, missing libraries, deprecation warnings. I tried to install Ruby 2.0.0, but apparently rbenv no longer supports that version. I have yet to try rvm, but I have little hope.

The plan

I want to “update” Trema just enough so that it works. It seems like a great tool, and I think it would be a pity to let it go stale. Now, I know there are better contollers like OpenDaylight, and os-ken, and whatnot, but I suppose this little hobby project of mine is worth a try.

What I’ve done till now

I’ll update whatever I’ve tried here. This is my fork.

2025-10-15

Added copilot instructions, because, apparently that’s the “modern” way now.

2025-10-17

I have no idea what I’m doing, and I’ve lost track of what versions of the dependencies I have installed. I tried adding some dependencies to the Gemfile from the errors I got from running the bundler. I tried running the “updated” trema (I haven’t figured out the build system yet) on the hello_trema repo, and still got some weird errors.

$~: ../trema/bin/trema ./lib/hello_trema.rb -c trema.conf 
/home/ananth/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/bundler-1.13.2/lib/bundler/shared_helpers.rb:161:in 'Bundler::SharedHelpers#search_up': undefined method 'untaint' for an instance of String (NoMethodError)
 
      current  = File.expand_path(SharedHelpers.pwd).untaint
                                                    ^^^^^^^^
	from /home/ananth/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/bundler-1.13.2/lib/bundler/shared_helpers.rb:148:in 'Bundler::SharedHelpers#find_file'
	from /home/ananth/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/bundler-1.13.2/lib/bundler/shared_helpers.rb:144:in 'Bundler::SharedHelpers#find_gemfile'
	from /home/ananth/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/bundler-1.13.2/lib/bundler/shared_helpers.rb:49:in 'Bundler::SharedHelpers#in_bundle?'
	from /home/ananth/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/bundler-1.13.2/lib/bundler/setup.rb:5:in '<top (required)>'
	from <internal:/home/ananth/.rbenv/versions/3.4.6/lib/ruby/3.4.0/rubygems/core_ext/kernel_require.rb>:136:in 'Kernel#require'
	from <internal:/home/ananth/.rbenv/versions/3.4.6/lib/ruby/3.4.0/rubygems/core_ext/kernel_require.rb>:136:in 'Kernel#require'
	from ../trema/bin/trema:7:in '<main>'
 

I think I need to learn a bit more about Ruby before proceeding. I found this 10 year old repo that just says “An OpenFlow Parser/Serializer in Ruby”.

Am I missing something? Is everyone ditching Ruby controllers? And why?

2025-10-20

Yep, I’m taking a break. There’s still a lot about Ruby that I don’t know, and I’m not able to manage time effectively between learning something new, refreshing old knowledge, and studying for my exams. SO, I’ll be back by the end of the month (which is when my exams end). Still, get in touch if you have any ideas!

If you want to help

Get in touch with me via email (it’s here → index) or drop a comment below!