I made a few minor modifications to the ODB JSON encoder and implemented a javascript "ls" function to 
report full ODB directory information as available from odbedit "ls -l" and the mhttpd odb editor page.

Using the new ODBMLs(), the existing ODBMCreate(), ODBMDelete() & etc a complete ODB editor can be 
written in Javascript (or in any other AJAX-capable language).

While implementing this function, I found some problems in the ODB JSON encoder when handling 
symlinks, also some problems with handling symlinks in odbedit and in the mhttpd ODB editor - these are 
now fixed.

Changes to the ODB JSON encoder:
- added the missing information to the ODB KEY (access_mode, notify_count)
- added symlink target information ("link")
- changed encoding of simple variable (i.e. jcopy of /experiment/name) - when possible (i.e. ODB KEY 
information is omitted), they are encoded as bare values (before, they were always encoded as structures 
with variable names, etc). This change makes it possible to implement ODBGet() and ODBMGet() using the 
AJAX jcopy method with JSON data encoding. Bare value encoding in ODBMCopy()/AJAX jcopy is enabled by 
using the "json-nokeys-nolastwritten" encoding option.

All these changes are supposed to be backward compatible (encoding used by ODBMCopy() for simple 
values and "-nokeys-nolastwritten" was previously not documented).

Documentation was updated:
https://midas.triumf.ca/MidasWiki/index.php/Mhttpd.js

K.O.

> I am not sure what to do with the javascript snippet 

Just read elog:908, it tells you to put this into a file, name it header.html for example, and put into the ODB:

/Custom/Header [string32] = header.html

make sure that you put the file into the directory indicated by /Custom/Path.

Cheers,
Stefan

> On most Linux systems, doxygen is easy to install. Red Hat instructions are here: 
> http://www.triumf.info/wiki/DAQwiki/index.php/SLinstall#Install_packages_needed_for_QUARTUS.2C_ROOT.2C_EPICS_and_MIDAS_DAQ
> 
> On MacOS, doxygen is easy to install via macports: sudo port install doxygen
> 
> > Is there a web site where one can see the generated graphs?
> 
> http://ladd00.triumf.ca/~olchansk/midas/index.html
> 
> there is no cron job to update this, but I may update it infrequently.
> 
> K.O.

Great, thanks a lot!

-Stefan

> > The capability to generate doxygen documentation of MIDAS was restored.
> > 
> > Use "make dox" and "make cleandox",
> > find generated documentation in ./html,
> > look at it via "firefox html/index.html".
> > 
> 
> To generate the files, you need doxygen installed which not everybody has.

On most Linux systems, doxygen is easy to install. Red Hat instructions are here: 
http://www.triumf.info/wiki/DAQwiki/index.php/SLinstall#Install_packages_needed_for_QUARTUS.2C_ROOT.2C_EPICS_and_MIDAS_DAQ

On MacOS, doxygen is easy to install via macports: sudo port install doxygen

> Is there a web site where one can see the generated graphs?

http://ladd00.triumf.ca/~olchansk/midas/index.html

there is no cron job to update this, but I may update it infrequently.

K.O.

> I'm looking into using MIDAS for an experiment that creates one large event
> (20MB or more) every second.

Hi, there - 20 Mbyte event at 1/sec is not so large these days. (Well, depending on your hardware).

Using typical 1-2 year old PC hardware, 20 M/sec to local disk should work right away. Sending data from a 
remote front end (through the mserver), or writing to a remote disk (NFS, etc) - will of course requre a GigE 
network connection.

By default, MIDAS is configured for using about 1-2 Mbyte events, so for your case, you will need to:

- increase the event size limits in your frontend,
- increase /Experiment/MAX_EVENT_SIZE in ODB
- increase the size of the SYSTEM event buffer (/Experiment/Buffer sizes/SYSTEM in ODB)

I generally recommend sizing the SYSTEM event buffer to hold a few seconds worth of data (ot 
accommodate any delays in writing to local disk - competing  reads, internal delays of the disks, etc).

So for 20 M/s, the SYSTEM buffer size should be about 40-60 Mbytes.

For your case, you also want to buffer 3-5-10 events, so the SYSTEM buffer size would be between 100 and 
200 MBytes.

Assuming you have between 8-16-32 GBytes of RAM, this should not be a problem.

One the other hand, if you are running on a low-power ("green") ARM system with 1 Gbyte of RAM and a 
1GHz CPU, you should be able to handle the data rate of 20 Mbytes/sec, as long as your network and 
storage can handle it - I see GigE ethernet running at about 30-40 Mbytes/sec, so you should be okey,
but local storage to SD flash is only about 10 Mbytes/sec - too slow. You can try USB-attached HDD or SSD, 
this should run at up to 30-40 Mbytes/sec. I would expect no problems with this rate from MIDAS, as long 
as you can fit into your 1 GByte of RAM - obviously your SYSTEM buffer will have to be a little smaller than 
on a full-featured PC.

More information on MIDAS event size limits is here (as already reported by Stefan)
https://midas.triumf.ca/MidasWiki/index.php/Event_Buffer

Let us know how it works out for you.

K.O.

I am not sure what to do with the javascript snippet - I understand it should be somehow connected to /Custom/Header, but if I create the /Custom/Header string, I cannot put this snippet 
into this string using odbedit - if I try to cut&paste it into odbedit, it is truncated to the first line - nor using the mhttpd odb editor - when I cut&paste it into the odb editor text entry box, it 
is truncated to the first 519 bytes (must be a hard limit somewhere). K.O.

> As reported in the bug tracker, the proposed header does not work if no specific (= different from the default 60 sec.) update period is specified, 
> since then no cookie is present. Here is the updated code which works for all cases:
> 
> 
> 
> <div id="footerDiv" class="footerDiv">
> <div style="display:inline; float:left;">MIDAS experiment "Test"</div>
> <div id="refr" style="display:inline; float:right;"></div>
> </div>
> <script type="text/javascript">
> var r = document.getElementById('refr');
> var now = new Date();
> var refr;
> if (document.cookie.search('midas_refr') == -1)
>    refr = 60;
> else {
>    var c = document.cookie.split('midas_refr=');
>    refr = c.pop().split(';').shift();
> }
> r.innerHTML = now.toString() + '&nbsp;&nbsp;&nbsp;' + 'Refr:' + refr;
> </script>
> 
> 
> 
> /Stefan

> Since several projects at PSI need MSCB but not MIDAS, I decided to separate the two repositories. So if you 
> need MIDAS with MSCB support inside mhttpd, you have to clone MIDAS, MXML and MSCB from bitbucket 
> (or the local clone at TRIUMF) as described in
> 
> https://midas.triumf.ca/MidasWiki/index.php/Main_Page#Download
> 
> I tried to fix all Makefiles to link to the new locations, but I'm not sure if I got all. So if something does not 
> compile please let me know.
> 
> -Stefan

After this split, Makefiles used to build experiment frontends need to be modified for the new location of the mscb tree:

replace
$(MIDASSYS)/mscb
with
$(MIDASSYS)/../mscb

K.O.

As reported in the bug tracker, the proposed header does not work if no specific (= different from the default 60 sec.) update period is specified, 
since then no cookie is present. Here is the updated code which works for all cases:



<div id="footerDiv" class="footerDiv">
<div style="display:inline; float:left;">MIDAS experiment "Test"</div>
<div id="refr" style="display:inline; float:right;"></div>
</div>
<script type="text/javascript">
var r = document.getElementById('refr');
var now = new Date();
var refr;
if (document.cookie.search('midas_refr') == -1)
   refr = 60;
else {
   var c = document.cookie.split('midas_refr=');
   refr = c.pop().split(';').shift();
}
r.innerHTML = now.toString() + '&nbsp;&nbsp;&nbsp;' + 'Refr:' + refr;
</script>



/Stefan

> I'm looking into using MIDAS for an experiment that creates one large event
> (20MB or more) every second.
> 
> Q1: It looks like I should use EQ_FRAGMENTED. Has this feature been in use
> recently? Is it known to work/not work?
> 
> More specifically, the computer should initiate a 1 second data taking, start to
> such the data out of the electronics (which may take a while), change some
> experimental parameters, and start over. 
> 
> Q2: What's the best way to do this? EQ_PERIODIC? 
> I cannot guarantee that the time required to read the hardware has an upper bound.
> In a standalone-prog I would simply use a big loop and let the machine execute
> it as fast as it can: 1.1s, 1.5s, 1.1s, 1.3s, 2.5s, ..... depending on the HW
> deadtimes.
> Will this work with EQ_PERIODIC?
> 
> (Sorry for these maybe stupid questions, but I have so far only used MIDAS for
> externally generated events, with <32kB event size).
> 
> 
> Thanks a lot,
> 
> Randolf

Hi Randolf,

EQ_FRAGMENTED is kind of historically, when computers had a few MB of memory and you have to play special tricks to get large data buffers through. Today I 
would just use EQ_PERIODIC and increase the midas maximal event size to your needs. For details look here:

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

The front-end scheduler is asynchronous, which means that your readout is called when the given period (1 second) is elapsed. If the readout takes longer 
than 1s, the schedule will (hopefully) call your readout immediately after the event has been sent. So you get automatically your maximal data rate. At MEG, we 
use 2 MB events with 10 Hz, so a 20 MB/sec data rate should not be a problem on decent computers.

Best,
Stefan

I'm looking into using MIDAS for an experiment that creates one large event
(20MB or more) every second.

Q1: It looks like I should use EQ_FRAGMENTED. Has this feature been in use
recently? Is it known to work/not work?

More specifically, the computer should initiate a 1 second data taking, start to
such the data out of the electronics (which may take a while), change some
experimental parameters, and start over. 

Q2: What's the best way to do this? EQ_PERIODIC? 
I cannot guarantee that the time required to read the hardware has an upper bound.
In a standalone-prog I would simply use a big loop and let the machine execute
it as fast as it can: 1.1s, 1.5s, 1.1s, 1.3s, 2.5s, ..... depending on the HW
deadtimes.
Will this work with EQ_PERIODIC?

(Sorry for these maybe stupid questions, but I have so far only used MIDAS for
externally generated events, with <32kB event size).


Thanks a lot,

Randolf

> If you follow the MIDAS documentation for setting up password protection, you will get strange messages:

This is interesting. When I used it last time (some years ago...) it worked fine. I did not touch this, and now it's broken. Must be related to some modifications of the semaphore system. 
Well, anyhow, the problem seems to me the db_close_all_databses() and the re-opening of the ODB. Apparently the db_close_database() call does not clean up the semaphores properly. 
Actually there is absolutely no need to close and re-open the ODB upon a wrong password, so I just removed that code and now it works again.

/Stefan

> The MIDAS Web password function is broken - with the web password enabled, I am not prompted for a 
> password when editing ODB. The password still partially works - I am prompted for the web password 
> when starting a run. K.O.
> 
> P.S. https://midas.triumf.ca/MidasWiki/index.php/Security says "web password" needed for "write access", 
> but does not specify if this includes editing odb. (I would think so, and I think I remember that it used to).

Didn't we agree to put those issues into the bitbucket issue tracker?

This functionality got broken when implementing the new inline edit functionality. Actually one has to "manually" check for the password. The old way 
was that there web page asking for the web password, but if we do ODBSet via Ajax there is nobody who could fill out that form. So I added a 
"manual" checking into ODBCheckWebPassword(). This will not work for custom pages, but they have their own way to define passwords.

/Stefan

Since several projects at PSI need MSCB but not MIDAS, I decided to separate the two repositories. So if you 
need MIDAS with MSCB support inside mhttpd, you have to clone MIDAS, MXML and MSCB from bitbucket 
(or the local clone at TRIUMF) as described in

https://midas.triumf.ca/MidasWiki/index.php/Main_Page#Download

I tried to fix all Makefiles to link to the new locations, but I'm not sure if I got all. So if something does not 
compile please let me know.

-Stefan

> The capability to generate doxygen documentation of MIDAS was restored.
> 
> Use "make dox" and "make cleandox",
> find generated documentation in ./html,
> look at it via "firefox html/index.html".
> 
> The documentation is not generated by default - it takes quite a long time to build all the call graphs.
> 
> And the call graphs is what makes this documentation useful - without some visual graphical 
> representation it is quite difficult to understand some parts of MIDAS. Both caller and callee graphs are 
> generated.
> 
> Note that doxygen documentation for the javascript functions in mhttpd.js is also generated, making a 
> handy reference in addition to the full documentation on the MIDAS Wiki.
> 
> K.O.

To generate the files, you need doxygen installed which not everybody has. Is there a web site where one can see the generated graphs?

/Stefan

The capability to generate doxygen documentation of MIDAS was restored.

Use "make dox" and "make cleandox",
find generated documentation in ./html,
look at it via "firefox html/index.html".

The documentation is not generated by default - it takes quite a long time to build all the call graphs.

And the call graphs is what makes this documentation useful - without some visual graphical 
representation it is quite difficult to understand some parts of MIDAS. Both caller and callee graphs are 
generated.

Note that doxygen documentation for the javascript functions in mhttpd.js is also generated, making a 
handy reference in addition to the full documentation on the MIDAS Wiki.

K.O.

I made some tests of MIDAS support for "international characters" and we seem to be in a reasonable 
shape.

The standard standard is UTF-8 encoding of Unicode and the MIDAS core is believed to be UTF-8 clean - 
one can use "international characters" in ODB names, in ODB values, in filenames, etc.

The web interface had some problems with percent-encoding of ODB URLs, but as of current git version, 
everything seems to work okey, as long as the web browser is in the UTF-8 encoding mode. The default 
mode is "Western ISO-8859-1" and javascript encodeURIComponent() is mangling some stuff making the 
ODB editor not work. Switching to UTF-8 mode seems to fix that.

Perhaps we should make the UTF-8 encoding the default for mhttpd-generated web pages. This should be 
okey for TRIUMF - we use English language almost exclusively, but need to check with other labs before 
making such a change. I especially worry about PSI because I am not sure if and how they any of the special 
German-language characters.

On the minus side, odbedit does not seem to accept non-English characters at all. Maybe it is easy to fix.

K.O.

In some experiments (i.e. DEAP), we see spurious symlinks to midas.log scattered just about everywhere. I 
now traced this to an uninitialized variable in cm_msg_log() and it should be fixed now. K.O.

> I through to improve this by fixing a bug in cm_msg_log() (where the messages are coming from)

The periodic messages about broken semaphore actually come from al_check(). I put some whining there, too.

K.O.