To follow up; with some help from Konstantin and Stefan, we realized that this
particular problem should already be fixed.  While I was using the most recent version
of MIDAS, I hadn't rebuild the EPICS frontend programs when I was doing this test.  Once
I did that the error no longer occurred.  This is because the most recent version of
MIDAS includes a check that will resize these particular string variables before using
them (technically, this is included in db_get_record1()); this resizing only happens for
these couple strings that must have a fixed size.

We are still having a separate discussion about whether this treatment of string lengths
that need to have a fixed size can be further improved.  Will update once discussion
converges.


> I guess this might be related to the changes in the last elog conversation; but
> I'll break it out as a separate problem.
> 
> The new mhttpd ODB editor seems to resize all strings (not just strings that are
> greater than 256 characters).  So, when I change some string with the mhttpd ODB
> editor to 'ffffff', then I find that the string size is now ~7 characters.
> 
> This might be fine in general; but it seems to cause a problem when dealing with
> alarms.  In particular, I find that if I try to set (through mhttpd) the
> "execute command" for an alarm class or the "condition" for an alarm, then I get
> into lots of trouble.  For instance, I changed the "execute command" for my
> alarm class through mhttpd; when associated alarms were triggered, I got errors
> 
> 21:58:12 [feSourceEpics,ERROR] [odb.c:9133:db_get_record,ERROR] struct size
> mismatch for "/Alarms/Classes/Alarm" (expected size: 348, size in ODB: 100)
> 21:58:12 [feSourceEpics,ERROR] [alarm.c:379:al_trigger_class,ERROR] Cannot get
> alarm class record
> 
> This makes sense, since ALARM_CLASS has a fixed size
> 
> typedef struct {
>    BOOL write_system_message;
>    ...
>    char execute_command[256];
>    ...
>    char display_fgcolor[32];
> } ALARM_CLASS;
> 
> so problems will clearly occur when I change the size and try to grab it:
> 
>    ALARM_CLASS ac;
>    status = db_get_record1(hDB, hkeyclass, &ac, &size, 0, strcomb(alarm_class_str));
>  
> I guess that similar problems also occur if you edit the string for ALARM or
> PROGRAM_INFO instances.  These problems do not occur when I change my strings
> with odbedit, which doesn't resize strings below 256.
> 
> I'm not sure what the proper solution is.  A temporary solution is that the
> mhttpd ODB editor shouldn't resize strings if the new size is less than 256
> characters; in that case the size should be left as 256 characters.
> 
> This test was done with MIDAS git repository as of today:
> commit 45a90dc329554f528485da121501daf6ecde100d

Dear MIDAS users,

We have an approximately final agenda for the MIDAS workshop in two weeks.  The
workshop will be on July 26, from 1-6PM (Vancouver time).  The detailed agenda is
posted here:

https://indico.triumf.ca/conferenceDisplay.py?confId=2342

Next week I will provide details on how to remotely connect to the workshop.

Cheers,
Thomas

PS: as a reminder, the timetable and slides from the last MIDAS workshop can be
found here:

https://indico.psi.ch/conferenceTimeTable.py?confId=3793#20150715



> Dear MIDAS users,
> 
> We would like to announce another MIDAS workshop at TRIUMF on July 26, 2017. 
> This will be a follow-on to the successful workshop two years ago.  This
> workshop will again be during one of Stefan Ritt's visit to TRIUMF.
> 
> The goal of the workshop would be to have a general discussion on the state of
> MIDAS.  We would have presentations from MIDAS developers on new MIDAS features
> that are being implemented, with a particular focus on improvements to MIDAS web
> functionality and analyzers.  But equally important would be to hear the
> experiences of MIDAS users. What aspects of MIDAS work well?  Which aspects need
> improving?  What are the major trends in scientific computing that we should
> adapt to?  We always appreciate feedback and suggestions from the MIDAS
> community (even when we have trouble finding time to make the changes!)
> 
> We will naturally broadcast the workshop on the web, but it would also be great
> if anyone was interested in coming to TRIUMF in person to participate.
> 
> Thomas, on behalf of MIDAS developers

Dear MIDAS colleagues,

We will use Zoom for people making remote connections to the MIDAS workshop next week.  The connection details 
are shown below.  You will need to install a Zoom application, which should happen automatically when clicking on the 
first link below.  It seemed to work pretty easily for me.

Cheers,
Thomas
 
_________________________________________

Hi there,

Thomas Lindner is inviting you to a scheduled Zoom meeting.

Topic: MIDAS workshop
Time: Jul 26, 2017 12:30 PM Pacific Time (US and Canada)

Join from PC, Mac, Linux, iOS or Android: https://zoom.us/j/749477537?pwd=-TSKYSiS0_k
    Password: midas

Or iPhone one-tap (US Toll):  +16465588656,,749477537# or +14086380968,,749477537#

Or Telephone:
    Dial: +1 646 558 8656 (US Toll) or +1 408 638 0968 (US Toll)
    Meeting ID: 749 477 537
    International numbers available: https://zoom.us/zoomconference?m=0Bug-COhDHYndpVqRLnNST9H-uXrauWk




> Dear MIDAS users,
> 
> We have an approximately final agenda for the MIDAS workshop in two weeks.  The
> workshop will be on July 26, from 1-6PM (Vancouver time).  The detailed agenda is
> posted here:
> 
> https://indico.triumf.ca/conferenceDisplay.py?confId=2342
> 
> Next week I will provide details on how to remotely connect to the workshop.
> 
> Cheers,
> Thomas
> 
> PS: as a reminder, the timetable and slides from the last MIDAS workshop can be
> found here:
> 
> https://indico.psi.ch/conferenceTimeTable.py?confId=3793#20150715
> 
> 
> 
> > Dear MIDAS users,
> > 
> > We would like to announce another MIDAS workshop at TRIUMF on July 26, 2017. 
> > This will be a follow-on to the successful workshop two years ago.  This
> > workshop will again be during one of Stefan Ritt's visit to TRIUMF.
> > 
> > The goal of the workshop would be to have a general discussion on the state of
> > MIDAS.  We would have presentations from MIDAS developers on new MIDAS features
> > that are being implemented, with a particular focus on improvements to MIDAS web
> > functionality and analyzers.  But equally important would be to hear the
> > experiences of MIDAS users. What aspects of MIDAS work well?  Which aspects need
> > improving?  What are the major trends in scientific computing that we should
> > adapt to?  We always appreciate feedback and suggestions from the MIDAS
> > community (even when we have trouble finding time to make the changes!)
> > 
> > We will naturally broadcast the workshop on the web, but it would also be great
> > if anyone was interested in coming to TRIUMF in person to participate.
> > 
> > Thomas, on behalf of MIDAS developers

Hi Folks,

I just realized I never provided the location for the meeting (for those at TRIUMF).  It will be in the ISAC-II conference room.

Cheers,
Thomas

> Dear MIDAS colleagues,
> 
> We will use Zoom for people making remote connections to the MIDAS workshop next week.  The connection details 
> are shown below.  You will need to install a Zoom application, which should happen automatically when clicking on the 
> first link below.  It seemed to work pretty easily for me.
> 
> Cheers,
> Thomas
>  
> _________________________________________
> 
> Hi there,
> 
> Thomas Lindner is inviting you to a scheduled Zoom meeting.
> 
> Topic: MIDAS workshop
> Time: Jul 26, 2017 12:30 PM Pacific Time (US and Canada)
> 
> Join from PC, Mac, Linux, iOS or Android: https://zoom.us/j/749477537?pwd=-TSKYSiS0_k
>     Password: midas
> 
> Or iPhone one-tap (US Toll):  +16465588656,,749477537# or +14086380968,,749477537#
> 
> Or Telephone:
>     Dial: +1 646 558 8656 (US Toll) or +1 408 638 0968 (US Toll)
>     Meeting ID: 749 477 537
>     International numbers available: https://zoom.us/zoomconference?m=0Bug-COhDHYndpVqRLnNST9H-uXrauWk
> 
> 
> 
> 
> > Dear MIDAS users,
> > 
> > We have an approximately final agenda for the MIDAS workshop in two weeks.  The
> > workshop will be on July 26, from 1-6PM (Vancouver time).  The detailed agenda is
> > posted here:
> > 
> > https://indico.triumf.ca/conferenceDisplay.py?confId=2342
> > 
> > Next week I will provide details on how to remotely connect to the workshop.
> > 
> > Cheers,
> > Thomas
> > 
> > PS: as a reminder, the timetable and slides from the last MIDAS workshop can be
> > found here:
> > 
> > https://indico.psi.ch/conferenceTimeTable.py?confId=3793#20150715
> > 
> > 
> > 
> > > Dear MIDAS users,
> > > 
> > > We would like to announce another MIDAS workshop at TRIUMF on July 26, 2017. 
> > > This will be a follow-on to the successful workshop two years ago.  This
> > > workshop will again be during one of Stefan Ritt's visit to TRIUMF.
> > > 
> > > The goal of the workshop would be to have a general discussion on the state of
> > > MIDAS.  We would have presentations from MIDAS developers on new MIDAS features
> > > that are being implemented, with a particular focus on improvements to MIDAS web
> > > functionality and analyzers.  But equally important would be to hear the
> > > experiences of MIDAS users. What aspects of MIDAS work well?  Which aspects need
> > > improving?  What are the major trends in scientific computing that we should
> > > adapt to?  We always appreciate feedback and suggestions from the MIDAS
> > > community (even when we have trouble finding time to make the changes!)
> > > 
> > > We will naturally broadcast the workshop on the web, but it would also be great
> > > if anyone was interested in coming to TRIUMF in person to participate.
> > > 
> > > Thomas, on behalf of MIDAS developers

Hi Folks,

In last year's updates to MIDAS, the MIDAS sequencer has been broken out as a
separate program (rather than running as part of mhttpd).  We hope that this
change will make the sequencer operation more stable.

Before anyone gets too used to using the new sequencer program, I would like to
rename it.  Currently the program is called 'sequencer'; I would like to rename
it 'msequencer', to make it consistent with most other MIDAS programs.  If you
object to making this change, please say so in the next two weeks.

Documentation on the MIDAS sequencer can be found on the wiki:

https://midas.triumf.ca/MidasWiki/index.php/Sequencer

Note that there are still some tweaks that need to be made to the sequencer
webpage and mhttpd in order to handle this new sequencer program.

Cheers,
Thomas

Pierre Gorel identified a problem with the 'start program' button on the new version of MIDAS that uses the 
mjsonrpc functions for building the webpages.  In particular, he tracked the problem down to some 
questionable std::string / char* handling.  

Interestingly, the particular 'start program' problem was seen on Pierre's Ubuntu 16.04.3 LTS machine, but 
could not be reproduced on RHEL-7 or Macos 10.13 machines.  So the manifestation of the code error 
seemed to depend on the compiler.

The problem should now be fixed in the HEAD version of MIDAS.  If you are using the newer MIDAS (since last 
summer), particularly on Ubuntu, then you may want to update your installation. 

Details of the problem are on the bitbucket issue tracker:

https://bitbucket.org/tmidas/midas/issues/132/corruption-of-char-in-mjsonrpccxx

Hearing no objections I changed the name of the program to msequencer.  Wiki
documentation updated.

> Hi Folks,
> 
> In last year's updates to MIDAS, the MIDAS sequencer has been broken out as a
> separate program (rather than running as part of mhttpd).  We hope that this
> change will make the sequencer operation more stable.
> 
> Before anyone gets too used to using the new sequencer program, I would like to
> rename it.  Currently the program is called 'sequencer'; I would like to rename
> it 'msequencer', to make it consistent with most other MIDAS programs.  If you
> object to making this change, please say so in the next two weeks.
> 
> Documentation on the MIDAS sequencer can be found on the wiki:
> 
> https://midas.triumf.ca/MidasWiki/index.php/Sequencer
> 
> Note that there are still some tweaks that need to be made to the sequencer
> webpage and mhttpd in order to handle this new sequencer program.
> 
> Cheers,
> Thomas

Hi Amy,

Let me start by explaining the reasoning for the default behavior of db_get_values.  I think it was mentioned elsewhere, but is worth repeating.

The ODB is case-insensitive.  So the ODB key name /Equipment/dcrc01 is equivalent to /equipment/Dcrc01; you could rename the variable like that and your 
frontend programs would still work fine.  Javascript, of course, is case sensitive.  However, we want our default MIDAS webpages to work no matter what the 
capitalization is for a particular ODB; so, for instance, the main status.html page should work whether the ODB key is called /Runinfo or /rUnInFo, since both 
of these are equivalent from the point of the ODB (and the rest of MIDAS).

The solution was to have the db_get_values method convert all key names to lower case and consistently use the lower case spelling when writing the main 
MIDAS webpages; this makes us insensitive to ODB capitalization (and hence makes the MIDAS pages behaviour match the previous mhttpd behaviour).

That being said, I agree that it is sometimes counter-intuitive to use lower case key names with db_get_values, particularly if you are directly creating ODB 
keys and writing the javascript at the same time.  So we have added the option 'preserve_case' to db_get_values, which preserves the ODB key name 
capitalization (the default behaviour is still to make key names lower case).

This option should not be used for writing any standard MIDAS webpages (ie, webpages that will be used across multiple experiments), since standard MIDAS 
webpages should not break when ODB key name capitalization changes.  For the same reason you should use caution with this option for custom pages as 
well.

With regards to your second question: the db_save method is not deprecated and you could use that method instead.  The use-case for the db_save method 
is different; db_save is used to make dumps of the ODB.  In that case it seems best that key name capitalization is preserved.  Otherwise if you dumped your 
whole ODB and then reloaded it from the dump the new ODB would be different (in key capitalization) from the old ODB; different in a way that shouldn't 
matter but still probably not the behaviour that people expect.

Admittedly this means that the mjsonrpc API is not always intuitive; but I think is the best we can do, given the underlying case-insensitivity of the ODB.

Thomas


> It appears I needed to read the documentation more closely - the method db_save
> does respect key-name capitalization and solves my problem.
> 
> Is db_save considered a deprecated method?  If so, I'd reiterate my suggestion for
> a capitalize-preserve option for db_get_values.
> 
> Otherwise, I'll plan on using db_save.
> 
> > I'd like to use the mjsonrpc db_get_values method, but (as indicated in the
> > documentation) it returns all ODB keys as lowercase.
> > 
> > This breaks quite a lot of my code - it was written with the old AJAX commands,
> > and these did respect the capitalization of the ODB keys.
> > 
> > Would it be possible to add a capitalization-preserve option to db_get_values? 

> Is there a simple way from the javascript side to check if a fontend is running?
> Currently one would need to go through the /System/Client list to find out if a
> frontend/client is running. Wouldn't it be nice to have this centralized, either
> in the mhttpd.cxx or mhttpd.js part? 

Hi,

I think that this option already exists with the cm_exist method for the mjsonrpc calls.  For instance, you can use a 
call like 

curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","id":null,"method":"cm_exist","params":
{"name":"Logger"}}' 'http://localhost:8081?mjsonrpc'

to get the status of the logger program.  There is a description of the cm_exist parameters on this page:

https://midas.triumf.ca/MidasWiki/index.php/Mjsonrpc

I wanted to try to summarize the current situation with regards to the handling of strings through the MIDAS web interface.

During the last year, we started the switch-over to using the new mjson-rpc functions in the MIDAS webpages.  As part of this work, changes were made that allowed for 
resizing strings through the MIDAS web interface (specifically through the MJSON-RPC calls). This reflected desires from some users that strings could be allowed to 
grow larger than the default 256 size that is usually used for MIDAS strings (for instance, see [1]).  In this first set of changes the ODB strings would always be resized to 
the exact size of the string that it was set to.

The problem with this change was that it breaks the behaviour of db_get_record(), which typically expects strings to be a fixed length of 32 or 256 (for instance, see 
[2,3]).  Konstantin notes that we can work around this problem by using db_get_record1() function, which automatically resizes strings to expected values; this method 
has already been used in the MIDAS core code.  But the problem would still remain for some user code that uses db_get_record.

As a short-term compromise solution, Stefan implemented a change where the MJSON-RPC string setting will now expand the size of strings, but not truncate them; ie a 
string that is size 256 will stay 256 bytes, unless you set it to something larger.  So this should fix most cases of user code that call db_get_record() and hence expects 
fixed string lengths. Users who call that db_get_record with strings that exceed the expected length will still have problems; but now you will at least get an explicit 
MIDAS error message, rather than just silent string truncation (as was the case before).

In the longer run we still want to develop a new set of ODB methods that more naturally support C++-style variable-length strings. But that's a discussion for the longer 
term.

[1] https://midas.triumf.ca/elog/Midas/1150
[2] https://bitbucket.org/tmidas/midas/issues/121/odb-inline-editor-truncates-stings
[3] https://midas.triumf.ca/elog/Midas/1343

> > I apologise for miss using the word refresh. The re-appearing sidebar was also seen with the automatic
> > reload, I have implemented your fix here and it now works great!
> 
> Still did not get your point. Why is there "automatic reload"? The status page should not "completely reload" any more. 
> Instead, all data is fetched in the background using AJAX calls, and only the data on the page is updated once per second. 
If 
> there is a "complete reload", something is wrong.

Joseph's original message says that the problem is with the standard MIDAS history page, which currently use a complete reload 
when refreshing.  Of course we are planning to update this history pages to only grab what it needs (as well as changing the 
plotting to use newer HTML plotting). But until that upgrade happens your fix is helpful for the history page.

> A new tag has been implemented to display history panels in custom pages, integrated in the 
> new custom page design from 2017. The full documentation can be found at 
> 

As part of consolidating/cleaning the MIDAS Wiki documentation, the "New Custom Pages" was folded into the main "Custom Page".  So to see a
description of Stefan's new functionality please go to 

https://midas.triumf.ca/MidasWiki/index.php/Custom_Page#mhistory

Hi Stefan and Konstantin,

I think that this proposal sounds fairly reasonable.  I agree that we might as well move to a secure final solution at this point.  

One comment: since this change would break almost every experiment I have worked on for the last 4 years, it would be nice to add a command-line option to mhttpd that preserves the old /Custom/Path behavior.  This would allow experiments a transition 
period, so that they didn't immediately need to fix their setup.  The command-line option could be clearly marked as obsolete behaviour and could be removed within a year.

Cheers,
Thomas



> Parsing all URL in mhttpd to prevent /etc/passwd etc. to be returned is tricky, because people can use escape sequences etc. Therefore I think it is much better to restrict file access 
> on the file system level when opening a file. The only escape there one could have is "..", which can be tested easily. 
> 
> Therefore, I propose to restrict file access to two well-defined directories, which is one system directory and one user directory. The system directory should be defined via 
> $MIDASSYS/resources, and the user directory should be the experiment directory (as defined in exptab) followed by "resources". So if MIDASSYS equals to /usr/local/midas and the 
> experiment directory equals to /home/users/exp for example, we would only have these two directories (and of course the subdirectories within these) served by mhttpd:
> 
> $MIDASSYS/resource -> /usr/local/midas/resources
> <exptab>/resources -> /home/users/exp/resources
> 
> These directories should be hard-wired into mhttpd, and not go through and ODB entry, since otherwise one could manipulate the ODB entries (knowingly or unknowingly) and open a 
> back-door. 
> 
> If users need a more complex structure, they can put soft links into these directories.
> 
> The code which opens a resource file should then first evaluate $MIDASSYS, then add "/resources/", then add the requested file name, make sure that there is no ".." in the file name, 
> then open the file. If not existing, do the same for the <exptab>/resources/ directory.
> 
> This change will break most experiments, and forces people to move their custom pages to different directories, but I think it's the only clean solution and we just have to bite the 
> bullet.
> 
> Comments are welcome.
> 
> Stefan

> First, I did not propose to give up the /Custom tree in the ODB, sorry for the misunderstanding. We still need it in order to display the menu with the custom pages at the left side navigation bar. In principle all can stay like it is, except we remove /Custom/Path and rewrite the file server to restrict it only 
> to the two mentioned directories.
> 
> Second, to keep the compatibility with running experiments, we have to make the move over as simply as possible. Thomas proposed a "deprecated" mhttpd command line option. As an alternative, I propose to make a symbolic link from <exptab>/resources to where the old /Custom/Path was pointing 
> to. This should work as well, and we don't have to implement a parameter in mhttpd.

That sounds fine, as long as it is clearly documented.

> Third, the /Custom/Path should really go away. We are all concerned that people can read security critical files from the whole file system. To read those files, people have to access to mhttpd, so they have to know at least the authentication credentials to pass the Apache firewall in front of mhttpd or 
> whatever. This means they have access to the ODB, and then they can simply change /Custom/Path to "/" and voila - they have again access to /etc/passwd. This is why I propose symbolic links on the file system. This area is much better protected than the ODB, since people have to physically log into 
> a machine to change it.

Yes, I agree that /Custom/Path should go away.

Cheers,
Thomas

Dear MIDAS users,

We would like to announce a third MIDAS workshop at TRIUMF on Aug 7, 2019.
Stefan Ritt will again be visiting TRIUMF at this time.

The overall goal of the workshop is to present new features in MIDAS, to discuss
future changes and to hear experiences from different experiments.

We expect that some participants will connect remotely to the workshop; we will
setup a video-conferencing option.  The exact time of the workshop will be
decided later and will be optimized based on the geographic distribution of
remote attendees. So please let us know if you want to attend remotely.  We are
also happy for people to come in person to TRIUMF.  

A (very) preliminary agenda includes

- New default mhttpd pages and new APIs for custom pages
- Conversion of MIDAS to C++
- new C++ based frontend framework (tmfe and mvodb from ALPHA-g)
- MySQL/Postgres database for storing ODB configurations
- Plans for updating history plotting
- Using MIDAS with an online trigger farm
- new C++ multithreaded flow analyzer (manalyzer from ALPHA-g)

But please suggest other topics; we also hope to hear reports from particular
experiments.

Sincerely,
Thomas (on behalf of MIDAS developers)

Dear MIDAS users,

Here's further information on the third MIDAS workshop:

1) Workshop will take place from 1PM-5PM (Vancouver time) on Aug 7.

2) A mostly finalized agenda for the workshop is posted here:

https://indico.triumf.ca/conferenceDisplay.py?confId=2438

People are still welcome to email me if they want to present something.  We should be able to add it to the schedule.

3) For those who want to participate remotely, we will be using bluejeans.  The webpage for the bluejeans meeting is here:

https://bluejeans.com/462865444

4) For those at TRIUMF I will confirm the meeting room closer to the date.

Thomas


> Dear MIDAS users,
> 
> We would like to announce a third MIDAS workshop at TRIUMF on Aug 7, 2019.
> Stefan Ritt will again be visiting TRIUMF at this time.
> 
> The overall goal of the workshop is to present new features in MIDAS, to discuss
> future changes and to hear experiences from different experiments.
> 
> We expect that some participants will connect remotely to the workshop; we will
> setup a video-conferencing option.  The exact time of the workshop will be
> decided later and will be optimized based on the geographic distribution of
> remote attendees. So please let us know if you want to attend remotely.  We are
> also happy for people to come in person to TRIUMF.  
> 
> A (very) preliminary agenda includes
> 
> - New default mhttpd pages and new APIs for custom pages
> - Conversion of MIDAS to C++
> - new C++ based frontend framework (tmfe and mvodb from ALPHA-g)
> - MySQL/Postgres database for storing ODB configurations
> - Plans for updating history plotting
> - Using MIDAS with an online trigger farm
> - new C++ multithreaded flow analyzer (manalyzer from ALPHA-g)
> 
> But please suggest other topics; we also hope to hear reports from particular
> experiments.
> 
> Sincerely,
> Thomas (on behalf of MIDAS developers)

Dear MIDAS users,

A final reminder about the MIDAS workshop tomorrow.  A couple reminders/notes: 

1) Workshop will take place from 1PM-5:30PM (Vancouver time) on Aug 7.

2) A finalized agenda for the workshop is posted here:

https://indico.triumf.ca/conferenceDisplay.py?confId=2438

Speakers should email me their talks beforehand and I will post them.

3) For those who want to participate remotely, we will be using bluejeans.  The webpage for the bluejeans meeting is here:
 
https://bluejeans.com/462865444

I will start the connection ~20min before the start of the session; people calling in remotely might want to call early, so we can test the sound quality.

4) For those at TRIUMF, the meeting will be in the ISAC-II conference room.

Thomas
 

> Dear MIDAS users,
> 
> Here's further information on the third MIDAS workshop:
> 
> 1) Workshop will take place from 1PM-5PM (Vancouver time) on Aug 7.
> 
> 2) A mostly finalized agenda for the workshop is posted here:
> 
> https://indico.triumf.ca/conferenceDisplay.py?confId=2438
> 
> People are still welcome to email me if they want to present something.  We should be able to add it to the schedule.
> 
> 3) For those who want to participate remotely, we will be using bluejeans.  The webpage for the bluejeans meeting is here:
> 
> https://bluejeans.com/462865444
> 
> 4) For those at TRIUMF I will confirm the meeting room closer to the date.
> 
> Thomas
> 
> 
> > Dear MIDAS users,
> > 
> > We would like to announce a third MIDAS workshop at TRIUMF on Aug 7, 2019.
> > Stefan Ritt will again be visiting TRIUMF at this time.
> > 
> > The overall goal of the workshop is to present new features in MIDAS, to discuss
> > future changes and to hear experiences from different experiments.
> > 
> > We expect that some participants will connect remotely to the workshop; we will
> > setup a video-conferencing option.  The exact time of the workshop will be
> > decided later and will be optimized based on the geographic distribution of
> > remote attendees. So please let us know if you want to attend remotely.  We are
> > also happy for people to come in person to TRIUMF.  
> > 
> > A (very) preliminary agenda includes
> > 
> > - New default mhttpd pages and new APIs for custom pages
> > - Conversion of MIDAS to C++
> > - new C++ based frontend framework (tmfe and mvodb from ALPHA-g)
> > - MySQL/Postgres database for storing ODB configurations
> > - Plans for updating history plotting
> > - Using MIDAS with an online trigger farm
> > - new C++ multithreaded flow analyzer (manalyzer from ALPHA-g)
> > 
> > But please suggest other topics; we also hope to hear reports from particular
> > experiments.
> > 
> > Sincerely,
> > Thomas (on behalf of MIDAS developers)

Hi Stefan,

This change does not sound like a good idea to me.  I think that this change will cause just as much confusion as before; probably more since you are changing established behaviour.

It is common that MIDAS frontends usually have a Settings directory in the ODB where details about the frontend behaviour are set.  The Settings directory might get initialized from strings in the frontend code, but after initialization the Settings in the ODB have precedence and define how the frontend will behave.  Indeed, most of my custom webpages are designed to control my frontend programs through their Settings ODB tree.

So you have created a situation where Frontend/Settings in the ODB has precedence and is the main place for changing frontend behaviour; but Frontend/Common in the ODB is essentially meaningless and will get overwritten the next time the frontend restarts.  That seems likely to confuse people. 

If you really want to make this change I suggest that you delete the Frontend/Common directory entirely; or make it read-only so that people aren't fooled into changing it.

Thomas 



> Today I fixed a long-annoying problem. We have in each front-end an equipment structure 
> which defined the event id, event type, readout frequency etc. This is mapped to the ODB 
> subtree
> 
> /Equipment/<name>/Common
> 
> In the past, the ODB setting took precedence over the frontend structure. We defined this 
> like 25 years ago and I forgot what the exact reason was. It causes however many people 
> (including myself) to fall into this trap: You change something in the front-end EQUIPMENT 
> structure, you restart the front-end, but the new setting does not take effect since the 
> (old) ODB value took precedence. After some debugging you find out that you have to both 
> change the EQUIPMENT structure (which defines the default value for a fresh ODB) and the 
> ODB value itself.
> 
> So I changed it in the current develop tree that the front-end structure takes precedence. 
> You still have a hot-link, so if you want to change anything while the front-end is running 
> (like the readout period), you can do that in the ODB and it takes effect immediately. But 
> when you start the front-end the next time, the value from the EQUIPMENT structure is 
> taken again. So please be aware of this new feature.
> 
> Happy BC day,
> Stefan

Hi Paolo,

Sorry for the slow response.  We were discussing this with Konstantin yesterday.  He is aware of the problem now and will be working on a solution soon.

In the short term I found that it works if you just comment out the offending line:

indnerlt:rootana lindner$ git diff libMidasInterface/TMidasOnline.cxx
diff --git a/libMidasInterface/TMidasOnline.cxx b/libMidasInterface/TMidasOnline.cxx
index 92eb3e9..67da613 100644
--- a/libMidasInterface/TMidasOnline.cxx
+++ b/libMidasInterface/TMidasOnline.cxx
@@ -191,7 +191,7 @@ bool TMidasOnline::sleep(int mdelay)
   #ifdef CH_IPC
   ss_suspend_set_dispatch(CH_IPC, 0, NULL);
   #else
-  ss_suspend_set_dispatch_ipc(NULL);
+  //  ss_suspend_set_dispatch_ipc(NULL);
   #endif
  int status = ss_suspend(mdelay, 0);
   if (status == SS_SUCCESS)

This compiles and at least runs for me; so maybe that is helpful for you.  But Konstantin will provide a longer term solution.



> Hi,
> 
> I posted on the ROOTANA elog but there seems to be little activity there...
> 
> Could someone confirm if this is a bug?
> https://midas.triumf.ca/elog/Rootana/14
> 
> Another user replied that they are encountering the same issue, so I think it is unlikely it is just our installation.
> 
> While ROOTANA is unusable for us, I tried to use the example Frontend and Analyzer (under the Experiment source folder). The analyzer does not seem to do much though. A root file is produced but nothing is placed into it. Is that normal?
> 
> Any help would be welcome.