Hi, Giorgio - you are asking excellent questions. I will try to answer them, but as ever, there are no 
easy answers.

In general, the top of the midas "develop" branch is "the best midas there is".

So for a new experiment, it is a reasonable place to start. Of course you can see
that there is quite a bit of commit activity going on, however, most substantial
changes are done on separate branches, where we try the new code, debug
it and test it. Only when the new code is "ready", we commit it to the "develop"
branch. Then, most often, we find some more last minute post-merge bugs,
and fix them right then and there on the head of the "develop" branch. Eventually
the dust settles and we have stable code that stays stable for a long time.

For example, right now we are waiting for the dust to settle on the change
of the MIDAS URL scheme, which was necessitated by needs of several experiments
that have more-complex-then-usual https proxy configurations. Unusual today,
but more common as we move forward, I think.

So if the head of the "develop" branch does not work for you, we encourage
that you file a bug report (here on this forum or on the bitbucket issue tracker).

While we try to sort out your problem, you can fall back to a previous version
of midas:

a) go back to one of the older "midas-YYYY-MM-X" tags
b) go back to one of the release candidate branches "feature/midas-YYYY-MM".

But if you have an already running system and you already have a working
instance of MIDAS, you do not have to update it to the latest version
unless you need some newest feature or you suffer from a bug
that has been fixed in a newer version.

In general, I find that it is fairly safe to update a working instance of MIDAS to
the latest code. But do keep your old working copy, if there is trouble, you can
always go back to something that works.

Now to your questions:

> For a running experiment that needs software stability what branch of the MIDAS 
> repository is better suited?

easy to answer. the most stable is the version you are using right now (doh!). each time
you upgrade, there is a risk that something will go wrong.

if you start from scratch, use the head of the "develop" branch (the latest and greatest),
if you run into trouble, report the trouble and update to a newer version with your
trouble fixed, or go back in time to previous tags and release candidate branches (as I described 
above).

> The master branch or the develop branch?

the "develop" branch.

> Moreover, what point in time do you think is more stable?

I find that it is impossible to have a stable-stable-stable version of midas
because the rest of the world flows forward in time. Old versions of midas
stop compiling because of OS and compiler changes; they stop running
because of OS or web browser or hardware changes. Then somebody
always asks for new features and new or old bugs surface constantly.

But we try to mark some "good" spots using git tags and release branches,
however the more far you go back in time, the more likely the code will
not even compile anymore.


K.O.



> Hello!
> My name is Giorgio Pintaudi and I am a Ph.D. student at Yokohama National 
> University (Japan). I also happen to be a T2K collaborator.
> I am currently developing the DAQ software for a T2K near detector called WAGASCI 
> (different from ND280) and we recently decided to adopt MIDAS as a user 
> interface.
> Now I am using the "develop" branch of the MIDAS BitBucket repository: I merge 
> the remote repository every now and then with my local copy and that is fine ... 
> but on the 25th of April our experiment is officially starting and I was 
> wondering which version of MIDAS should I use for "production".
> So my question is:
> For a running experiment that needs software stability what branch of the MIDAS 
> repository is better suited? The master branch or the develop branch? Moreover, 
> what point in time do you think is more stable?
> Best regards
> Giorgio