The bulk of the MIDAS AJAX and Javascript functions is now documented on the MIDAS Wiki:

https://midas.triumf.ca/MidasWiki/index.php/Mhttpd.js
https://midas.triumf.ca/MidasWiki/index.php/AJAX

Enjoy,
K.O.

> The bulk of the MIDAS AJAX and Javascript functions is now documented on the MIDAS Wiki:
> 
> https://midas.triumf.ca/MidasWiki/index.php/Mhttpd.js
> https://midas.triumf.ca/MidasWiki/index.php/AJAX
> 

The documentation was updated again.

All functions and AJAX methods except jset, jget, jrpc (ODBGet, ODBSet, ODBRpc) and inline edit are now fully 
documented. AJAX methods jset/jget and their javascript wrappers ODBSet/ODBGet/ODBMGet/ODBGetRecord() are 
partially documented. Inline edit will have to be documented by Stefan.

When using these functions please read the "BUG" sections carefully.

When using the Javascript functions (ODBGet, ODBSet, ODBMCopy, etc) please pay special attention to the rules for URI-
encoding function arguments - some functions require that some arguments be pre-encoded by 
"encodeURIComponent()", some functions require some arguments to NOT be pre-encoded. The examples in 
examples/javascript1/example.html are mostly correct.

Special confusion is created by special handling in mhttpd of URI-encoding of parameters named "format".

Special confusion is created by ODBSet(path, value), where "path" should be pre-encoded, while "value" is now encoded 
internally, which is a recent change introduced with the inline edit function. Older versions of mhttpd.js still require that 
"value" be URI-encoded.

Going forward, I hope to resolve most of the confusion by providing a cleaner interface for reading ODB
- ODBMCopy() already looks good with full async JSON/JSONP support (already implemented)
- ODBMKey() to read just the keys, with async JSON/JSONP support (to be added)
- ODBMCreate() to create ODB keys (RPC for db_create()) (to be added)
- ODBMSet() to write into ODB. (to be added)

K.O.

> > The bulk of the MIDAS AJAX and Javascript functions is now documented on the MIDAS Wiki:
> > 
> > https://midas.triumf.ca/MidasWiki/index.php/Mhttpd.js
> > https://midas.triumf.ca/MidasWiki/index.php/AJAX
> > 
> 
> The documentation was updated again.
> 

Newly documented are the additional Javascript and AJAX functions present in the GIT branch "feature/ajax":

ODBMCreate(paths, types);
ODBMCreate(paths, types, arraylengths, stringlengths, callback);  
ODBMResize(paths, arraylengths, stringlengths, callback);  
ODBMRename(paths, names, callback);  
ODBMLink(paths, links, callback);  
ODBMReorder(paths, indices, callback);
ODBMKey(paths, callback);
ODBMDelete(paths, callback);

All these functions permit asynchronous use (with callback on completion) and the underlying AJAX functions permit JSON-P encoding.

ODBSetUrl("http://mhttpd.somewhere.com:8080") : this new function removes the restriction that custom scripts had to be loaded from the same mhttpd that they will 
access. Together with the newly added CORS support in mhttpd, allows loading custom scripts from any web server, including local file, and having then access any one (or 
any several) mhttpd data sources.

I think these new functions are now stable (I still had to make some changes to ODBMCreate() recently) and after some more testing this branch will be merged into 
"develop".

To use this branch, do either:
a) git clone midas; git pull; git checkout feature/ajax
b) git clone midas; git checkout develop; git pull; git checkout -b ajaxtest; git merge feature/ajax;

(Option (b) creates a local branch with the latest "develop" and "feature/ajax" merged together).

K.O.

I find that new mhttpd has strange behaviour for ODB strings.

- I create a new STRING variable in ODB through mhttpd.  It defaults to size 32.

- I then edit the STRING variable through mhttpd, writing a new string larger
than 32 characters.

- Initially everything looks fine; it seems as if the new string value has been
accepted.

- But if you reload the page, or navigate back to the page, you realize that
mhttpd has silently truncated the string back to 32 characters.

You can reproduce this problem on a test page here:

http://midptf01.triumf.ca:8081/AnnMessage

Older versions of mhttpd (I'm testing one from 2 years ago) don't have this
'feature'.  For older mhttpd the string variable would get resized when a larger
string was inputted.  That definitely seems like the right behavior to me.

I am using fresh copy of midas from bitbucket as of this morning. (How do I get
a particular tag/hash of the version of midas that I am using?)

I can confirm part of the problem - the new inline-edit function - after you finish editing - shows you what you 
have typed, not what's actually in ODB - at the very end it should do an ODBGet() to load the actual ODB 
contents and show *that* to the user.

The truncation to 32 characters - most likely it is a failure to resize the ODB string - is probably in mhttpd and 
I can take a quick look into it.

There is a 3rd problem - the mhttpd ODB editor "create" function does not ask for the string length to create.

Actually, in ODB, "create" and "set string size" are two separate functions - db_create_key(TID_STRING) creates 
a string of length zero, then db_set_data() creates an empty string of desired length.

In the new AJAX interface these two functions are separate (ODBCreate just calls db_create_key()).

In the present ODBSet() function the two are mixed together - and the ODB inline edit function uses ODBSet().

K.O.



> I find that new mhttpd has strange behaviour for ODB strings.
> 
> - I create a new STRING variable in ODB through mhttpd.  It defaults to size 32.
> 
> - I then edit the STRING variable through mhttpd, writing a new string larger
> than 32 characters.
> 
> - Initially everything looks fine; it seems as if the new string value has been
> accepted.
> 
> - But if you reload the page, or navigate back to the page, you realize that
> mhttpd has silently truncated the string back to 32 characters.
> 
> You can reproduce this problem on a test page here:
> 
> http://midptf01.triumf.ca:8081/AnnMessage
> 
> Older versions of mhttpd (I'm testing one from 2 years ago) don't have this
> 'feature'.  For older mhttpd the string variable would get resized when a larger
> string was inputted.  That definitely seems like the right behavior to me.
> 
> I am using fresh copy of midas from bitbucket as of this morning. (How do I get
> a particular tag/hash of the version of midas that I am using?)

I confirm the second part of the problem.

Inline edit uses ODBSet(), which uses the "jset" AJAX call to mhttpd which does not extend string variables.

This is the jset code. The best I can tell it truncates string variables to the existing size in ODB:

db_find_key(hDB, 0, str, &hkey)
db_get_key(hDB, hkey, &key);
memset(data, 0, sizeof(data));
size = sizeof(data);
db_sscanf(getparam("value"), data, &size, 0, key.type);
db_set_data_index(hDB, hkey, data, key.item_size, index, key.type);

These original jset/jget functions are a little bit too complicated and there is no documentation (what exists is done by me trying to read the existing code).

We now have a jcopy/ODBMCopy() as a sane replacement for jget, but nothing comparable for jset, yet.

I think this quirk of inline edit cannot be fixed in javascript - the mhttpd code for "jset" has to change.

K.O.


> 
> I can confirm part of the problem - the new inline-edit function - after you finish editing - shows you what you 
> have typed, not what's actually in ODB - at the very end it should do an ODBGet() to load the actual ODB 
> contents and show *that* to the user.
> 
> The truncation to 32 characters - most likely it is a failure to resize the ODB string - is probably in mhttpd and 
> I can take a quick look into it.
> 
> There is a 3rd problem - the mhttpd ODB editor "create" function does not ask for the string length to create.
> 
> Actually, in ODB, "create" and "set string size" are two separate functions - db_create_key(TID_STRING) creates 
> a string of length zero, then db_set_data() creates an empty string of desired length.
> 
> In the new AJAX interface these two functions are separate (ODBCreate just calls db_create_key()).
> 
> In the present ODBSet() function the two are mixed together - and the ODB inline edit function uses ODBSet().
> 
> K.O.
> 
> 
> 
> > I find that new mhttpd has strange behaviour for ODB strings.
> > 
> > - I create a new STRING variable in ODB through mhttpd.  It defaults to size 32.
> > 
> > - I then edit the STRING variable through mhttpd, writing a new string larger
> > than 32 characters.
> > 
> > - Initially everything looks fine; it seems as if the new string value has been
> > accepted.
> > 
> > - But if you reload the page, or navigate back to the page, you realize that
> > mhttpd has silently truncated the string back to 32 characters.
> > 
> > You can reproduce this problem on a test page here:
> > 
> > http://midptf01.triumf.ca:8081/AnnMessage
> > 
> > Older versions of mhttpd (I'm testing one from 2 years ago) don't have this
> > 'feature'.  For older mhttpd the string variable would get resized when a larger
> > string was inputted.  That definitely seems like the right behavior to me.
> > 
> > I am using fresh copy of midas from bitbucket as of this morning. (How do I get
> > a particular tag/hash of the version of midas that I am using?)

> This is the jset code. The best I can tell it truncates string variables to the existing size in ODB:
> 
> db_find_key(hDB, 0, str, &hkey)
> db_get_key(hDB, hkey, &key);
> memset(data, 0, sizeof(data));
> size = sizeof(data);
> db_sscanf(getparam("value"), data, &size, 0, key.type);
> db_set_data_index(hDB, hkey, data, key.item_size, index, key.type);


Correct. So I added some code which extends strings if necessary (NOT string arrays, they are more complicated to handle).

Actually this was no bug, but a missing feature. Strings were never meant to be extended via the web interface. 
Now I added that feature to the current version. Please check it.

/Stefan

I would like to share with you a silly problem with mktime() and daylight savings time (Summer 
time/Winter time) that I have run into while working on the mhttpd history query page.

I am implementing 1 hour granularity for the queries (was 1 day granularity) and somehow all my queries 
were off by 1 hour.

It turns out that the mktime() and localtime() functions for converting between time_t and normal time 
units (days, hours) are not exact inverses of each other.

Daylight savings time (DST) is to blame.

While localtime() always applies the current DST,  mktime() will return the wrong answer unless tm_isdst is 
set correctly.

For tm_isdst, the default value 0 is wrong 50% of the time in most locations as it means "DST off" (whether 
that's Summer time or Winter time depends on your location).

Today in Vancouver, BC, DST is in effect, and localtime(mktime()) is off by 1 hour.

If I were doing this in January, I would not see this problem.

"man mktime" talks about "tm_isdst" special value "-1" that is supposed to fix this. But the wording of 
"man mktime" on Linux and on MacOS is different (I am amused by the talk about "attempting to divine 
the DST setting"). Wording at http://pubs.opengroup.org/onlinepubs/007908799/xsh/mktime.html is 
different again. MS Windows (Visual Studio) documentation says different things for different versions.

So for mhttpd I use the following code. First mktime() gets the approximate time, a call to localtime() 
returns the DST setting in effect for that date, a second mktime() with the correct DST setting returns the 
correct time. (By "correct" I mean that localtime(mktime(t)) == t).

time_t mktime_with_dst(const struct tm* ptms)
{
   // this silly stuff is required to correctly handle daylight savings time (Summer time/Winter time)
   // when we fill "struct tm" from user input, we cannot know if daylight savings time is in effect
   // and we do not know how to initialize the value of tms->tm_isdst.
   // This can cause the output of mktime() to be off by one hour.
   // (Rules for daylight savings time are set by national and local govt and in some locations, changes 
yearly)
   // (There are no locations with 2 hour or half-hour daylight savings that I know of)
   // (Yes, "man mktime" talks about using "tms->tm_isdst = -1")
   //
   // We assume the user is using local time and we convert in two steps:
   //
   // first we convert "struct tm" to "time_t" using mktime() with unknown tm_isdst
   // second we convert "time_t" back to "struct tm" using localtime_r()
   // this fills "tm_isdst" with correct value from the system time zone database
   // then we reset all the time fields (except for sub-minute fields not affected by daylight savings)
   // and call mktime() again, now with the correct value of "tm_isdst".
   // K.O. 2013-09-14

   struct tm tms = *ptms;
   struct tm tms2;
   time_t t1 = mktime(&tms);
   localtime_r(&t1, &tms2);
   tms2.tm_year = ptms->tm_year;
   tms2.tm_mon  = ptms->tm_mon;
   tms2.tm_mday = ptms->tm_mday;
   tms2.tm_hour = ptms->tm_hour;
   tms2.tm_min  = ptms->tm_min;
   time_t t2 = mktime(&tms2);
   //printf("t1 %.0f, t2 %.0f, diff %d\n", (double)t1, (double)t2, (int)(t1-t2));
   return t2;
}

K.O.

I vaguely remember that I had a similar problem with ELOG. The solution was to call tzset() at the beginning of the program. The man page says that 
this function is called automatically by programs using time zones, but apparently it is not. Can you try that? There is also the TZ environment 
variable and /etc/localtime. I never understood the details, but playing with these things can influence mktime() and localtime().

/Stefan

> I vaguely remember that I had a similar problem with ELOG. The solution was to call tzset() at the beginning of the program. The man page says that 
> this function is called automatically by programs using time zones, but apparently it is not. Can you try that? There is also the TZ environment 
> variable and /etc/localtime. I never understood the details, but playing with these things can influence mktime() and localtime().

I confirm that the timezone is set correctly - I do get the correct time eventually - so there is no missing call to tzet().

K.O.

> > I vaguely remember that I had a similar problem with ELOG. The solution was to call tzset() at the beginning of the program. The man page says that 
> > this function is called automatically by programs using time zones, but apparently it is not. Can you try that? There is also the TZ environment 
> > variable and /etc/localtime. I never understood the details, but playing with these things can influence mktime() and localtime().
> 
> I confirm that the timezone is set correctly - I do get the correct time eventually - so there is no missing call to tzet().
> 
> K.O.

tzset() not only sets the time zone, but also DST.

> > > I vaguely remember that I had a similar problem with ELOG. The solution was to call tzset() at the beginning of the program. The man page says that 
> > > this function is called automatically by programs using time zones, but apparently it is not. Can you try that? There is also the TZ environment 
> > > variable and /etc/localtime. I never understood the details, but playing with these things can influence mktime() and localtime().
> > 
> > I confirm that the timezone is set correctly - I do get the correct time eventually - so there is no missing call to tzet().
> > 
> > K.O.
> 
> tzset() not only sets the time zone, but also DST.

I found following code in elogd.c, maybe it helps:

/* workaround for wong timezone under MAX OSX */
long my_timezone()
{
#if defined(OS_MACOSX) || defined(__FreeBSD__) || defined(__OpenBSD__)
   time_t tp;
   time(&tp);
   return -localtime(&tp)->tm_gmtoff;
#else
   return timezone;
#endif
}



void get_rfc2822_date(char *date, int size, time_t ltime)
{
   time_t now;
   char buf[256];
   int offset;
   struct tm *ts;

   /* switch locale temporarily back to english to comply with RFC2822 date format */
   setlocale(LC_ALL, "C");

   if (ltime == 0)
      time(&now);
   else
      now = ltime;
   ts = localtime(&now);
   assert(ts);
   strftime(buf, sizeof(buf), "%a, %d %b %Y %H:%M:%S", ts);
   offset = (-(int) my_timezone());
   if (ts->tm_isdst)
      offset += 3600;
   snprintf(date, size - 1, "%s %+03d%02d", buf, (int) (offset / 3600),
            (int) ((abs((int) offset) / 60) % 60));
}

Dear MIDAS programmers,

I have been using your software in my lab (APC, Paris)
to run our data acqusition system. It is very robust and flexible.s

I would like to give you the large amount of credit which you are due.
How should I cite both MIDAS and ROODY? I have not been able to find any
information in the usual places.

Cheers, and thanks for the great program!
-Carl

> 
> I have been using your software in my lab (APC, Paris)
> to run our data acqusition system. It is very robust and flexible.s
> 
> I would like to give you the large amount of credit which you are due.
> How should I cite both MIDAS and ROODY? I have not been able to find any
> information in the usual places.
> 

Good to hear from a happy user.

I think the best way to give us credit is to recommend MIDAS to 10 of your friends.

For MIDAS citations, I think Pierre and Stefan have a standard one somewhere, we should have it linked from 
midas.triumf.ca.

For ROODY citations, I am not sure we have one. The idea behind it was to make a ROOT version of PAW++. 
Main authors are Greg King (UBC COOP student, where is he now?), Joe Chuma (also author of PHYSICA, 
R.I.P.), Pierre Amaudruz, myself and a few others.

K.O.

> Dear MIDAS programmers,
> 
> I have been using your software in my lab (APC, Paris)
> to run our data acqusition system. It is very robust and flexible.s
> 
> I would like to give you the large amount of credit which you are due.
> How should I cite both MIDAS and ROODY? I have not been able to find any
> information in the usual places.
> 
> Cheers, and thanks for the great program!
> -Carl

The standard citation for midas is a link to

http://midas.psi.ch

At the moment this points automatically to http://midas.triumf.ca, so both institutes are credited.

/Stefan

Javascript "AJAX" functions (and their MIDAS wrappers - ODBGet/ODBSet) are subject to something called 
"same origin policy" intended to prevent something called "cross-site scripting attacks", i.e. see
http://en.wikipedia.org/wiki/Same-origin_policy

In practice it means that if you load the MIDAS custom web page from test.foo.com and try to access 
mhttpd at midas.foo.com, ODBSet/ODBGet will not work.

I always thought that this meant that the requests are blocked by the browser and are a form of 
protection of the web server - only scripts loaded from mhttpd can do AJAX (ODBGet/ODBSet) to mhttpd.

It turns out that I was wrong. This is what actually happens: the "cross-site" requests are still sent to the 
server (mhttpd), the response it received, parsed and discarded if "same origin" conditions are not met.

This means that the "same origin" policy does not protect mhttpd at all - any script from any page 
anywhere can issue AJAX requests into any mhttpd, these requests will be successfully sent, received
and processed by mhttpd, including requests for writing into ODB ("jset" command using the HTTP GET 
method).

So for the case of MIDAS, "same origin" does not prevent malicious (or buggy) scripts from writing into the 
wrong mhttpd of the wrong experiment.

All it does is prevent desired and intentional access to mhttpd (ODBGet) from scripts that happen to have 
been loaded outside of mhttpd (i.e. from a developer own test page).

Then it turns out that there is an "official" way to disable this unwanted protection policy, called CORS, see
http://www.w3.org/TR/cors/

I have now implemented this in mhttpd and added an mhttpd.js function ODBSetURL() to explicitly set the 
URL of mhttpd that we want to talk to.

This work is on the feature/ajax branch, to be merged soon. For the impatient, here is what you need to 
do in mhttpd:

diff --git a/src/mhttpd.cxx b/src/mhttpd.cxx
index 1d9d1cc..0460cec 100755
--- a/src/mhttpd.cxx
+++ b/src/mhttpd.cxx
@@ -1070,6 +1070,7 @@ void show_text_header()
 {
    rsprintf("HTTP/1.0 200 Document follows\r\n");
    rsprintf("Server: MIDAS HTTP %d\r\n", mhttpd_revision());
+   rsprintf("Access-Control-Allow-Origin: *\r\n");
    rsprintf("Pragma: no-cache\r\n");
    rsprintf("Expires: Fri, 01 Jan 1983 00:00:00 GMT\r\n");
    rsprintf("Content-Type: text/plain; charset=iso-8859-1\r\n\r\n");

K.O.

As of commit
https://bitbucket.org/tmidas/midas/commits/dfa5fb1a93cae11a2960d441044c7fd277e1f0ec
(we are now liberated from the tyranny of SVN IDs),
multithreaded run transitions seem to work reliably and are now the default in mhttpd.

In odbedit and mtransition, the default is the old sequential transitions. "-m" and "-a" flags activate 
the new multithread run transitions. mhttpd now uses the equivalent of "mtransition -a" 
(mutithreaded asynchronous).

This is one of the new features implemented by Stefan while at TRIUMF.

K.O.

(We hope to write up all the recent changes soon).

odbedit uses a fixed size buffer for ODB data. If an array in ODB is bugger than this size, 
db_get_data() correctly returns DB_TRUNCATED and there is no memory overwrite, but the following 
code for printing the data does not know about this truncation and proceeds printing memory 
values contained after the end of the fixed size data buffer - in the current case, this memory 
somehow had the contents of the shell history - this very confused the MIDAS users as they though 
that the funny printout was actually in ODB. This is in the print_key() function. If db_get_data() 
returns DB_TRUNCATED, it should allocate a buffer of bigger size. This (and the previous) bug found 
by the TIGRESS experiment. K.O.

The odb.c function merge_records() has a fixed size array of 10000 bytes to handle the data and it 
aborts with an assert() if passed data bigger than that. It is called from db_create_record() which 
already allocates a data buffer of correct size for it's operations.
K.O.

We are happy to announce the creation of the MidasWiki at TRIUMF (https://midas.triumf.ca) as the 
new location of MIDAS documentation, user instructions, examples, etc.

https://midas.triumf.ca
K.O.

> We are happy to announce the creation of the MidasWiki at TRIUMF
> https://midas.triumf.ca

We are running MediaWiki in the world-readable, authenticated-user-writable mode.

New user registration is done by the "confirm new user" extension (https://www.mediawiki.org/wiki/Extension:ConfirmAccount):
- go to https://midas.triumf.ca/MidasWiki/index.php/Special:RequestAccount
- fill the form, submit request - request goes to wiki administrator for confirmation
- wait for email about email address confirmation, follow instructions to confirm your email address
- wait for email about account confirmation
- try to login to the wiki.

K.O.

The MIDAS source code repository was converted from SVN to GIT, hosted as bitbucket: 
https://bitbucket.org/tmidas.

A clonable copy of the repository is located at TRIUMF: git clone 
http://daq.triumf.ca/~daqweb/git/midas.git (and mxml.git).

The documentation is being slowly updated with GIT instructions (git clone) instead of SVN (svn 
checkout).

The MIDAS code history goes all the way to CVS/SVN rev 1 dated Thu Oct 8 13:46:02 1998.

K.O.

Konstantin forgot to tell people outside of TRIUMF how to get the newest version of MIDAS. Here it is:

$ git clone https://bitbucket.org/tmidas/midas.git

Not that you can also browse the repository at

https://bitbucket.org/tmidas/midas

On some (older) systems, you might have to install git (http://git-scm.com/downloads).

/Stefan

The HTTPS SSL certificate on ladd00.triumf.ca has been updated. Same as the old
certificate, the new one is self-signed and your web browser may complain about
that and ask you to "save a security exception".

When you save the new certificate, you can verify that you are connected to the
real ladd00.triumf.ca by comparing the "SHA1 fingerprint" reported by your web
browser to the one given below (as reported by "svn update"):

Certificate information:
 - Hostname: ladd00.triumf.ca
 - Valid: from Mon, 10 Jun 2013 18:43:19 GMT until Tue, 10 Jun 2014 18:43:19 GMT
 - Issuer: DAQ, TRIUMF, Vancouver, BC, CA
 - Fingerprint: 3f:15:d0:1d:68:ae:f0:73:10:78:84:66:f3:af:c7:67:5c:70:00:62

At the same time, elogd was updated to latest version from Stefan (elog-2.9.2-1.i386).

Also as part of local computer updates, elogd is temporarily running on ladd03.triumf.ca. This should be 
transparent to all users but please let me know if there are strange artefacts, etc. (ladd03 will become the 
new ladd00 "soon").

K.O.

I updated the MIDAS javascript examples in examples/javascript1. All existing mhttpd.js functions are 
now exampled. (yes).

Here is the full list of functions, with notes:

ODBSet(path, value, pwdname);
ODBGet(path, format, defval, len, type);
ODBMGet(paths, callback, formats); --- doc incomplete - no example of callback() use
ODBGetRecord(path);
ODBExtractRecord(record, key);
new ODBKey(path); --- doc incomplete, wrong - one has to use "new ODBKey" - last_used was added.
ODBCopy(path, format); -- no doc
ODBRpc_rev0(name, rpc, args); --- doc refer to example
ODBRpc_rev1(name, rpc, max_reply_length, args); --- same
ODBGetMsg(n);
ODBGenerateMsg(m);
ODBGetAlarms(); --- no doc
ODBEdit(path); --- undoc - forces page reload

As annotated, the main documentation is partially incomplete and partially wrong (i.e. ODBKey() has to be 
invoked as "new ODBKey()"). I hope this will be corrected soon. In the mean time, I recommend that 
everybody uses this example as best documentation available.
http://ladd00.triumf.ca/~daqweb/doc/midas/html/RC_mhttpd_custom_js_lib.html

svn rev 5360
K.O.

> ODBCopy(path, format); -- no doc

Updated example of ODBCopy:

format="" returns data in traditional ODB save format
format="xml" returns data in XML encoding
format="json" returns data in JSON encoding.

K.O.

If the MIDAS Alarm property "write elog message" is enabled, an uninitialized variable "tag" is passed to 
el_submit() and depending on your luck, cause a crash. "tag" is supposed to be and is now a NUL-
terminated string. The only other use of el_submit() is in mhttpd.cxx and mserver.c, where it is called 
correctly.

alarm.c svn rev 5361
K.O.

The MIDAS web page at TRIUMF (http://midas.triumf.ca) moved from the daq-plone site to the DAQWiki 
(MediaWiki) site. Links were updated, checked and corrected:
https://www.triumf.info/wiki/DAQwiki/index.php/MIDAS

Included is the link to our MIDAS installation instructions. These are more complete compared to the 
instructions in the MIDAS documentation:
https://www.triumf.info/wiki/DAQwiki/index.php/Setup_MIDAS_experiment
K.O.

A little while ago, PSI made some changes to the SVN hosting. The main SVN URL seems to remain the 
same, but SVN viewer moved to a new URL (it seems a bit faster compared to the old viewer): 
https://savannah.psi.ch/viewvc/meg_midas/trunk/

Also the SSH host key has changed to:

savannah.psi.ch,192.33.120.96 ssh-rsa 
AAAAB3NzaC1yc2EAAAABIwAAAQEAwVWEoaOmF9uggkUEV2/HhZo2ncH0zUfd0ExzzgW1m0HZQ5df1OYIb
pyBH6WD7ySU7fWkihbt2+SpyClMkWEJMvb5W82SrXtmzd9PFb3G7ouL++64geVKHdIKAVoqm8yGaIKIS0684
dyNO79ZacbOYC9l9YehuMHPHDUPPdNCFW2Gr5mkf/uReMIoYz81XmgAIHXPSgErv2Nv/BAA1PCWt6THMMX
E2O2jGTzJCXuZsJ2RoyVVR4Q0Cow1ekloXn/rdGkbUPMt/m3kNuVFhSzYGdprv+g3l7l1PWwEcz7V1BW9LNPp
eIJhxy9/DNUsF1+funzBOc/UsPFyNyJEo0p0Xw==

Fingerprint: a3:18:18:c4:14:f9:3e:79:2c:9c:fa:90:9a:d6:d2:fc

The change of host key is annoying because it makes "svn update" fail with an unhelpful message (some 
mumble about ssh -q). To fix this fault, run "ssh svn@savannah.psi.ch", then fixup the ssh host key as 
usual.

K.O.

Latest news - the ROOT project switched from SVN to GIT.

Announcement:
http://root.cern.ch/drupal/content/root-has-moved-git

Fons's presentation with details on the conversion process, repository size and performance 
improvements:
https://indico.cern.ch/getFile.py/access?contribId=0&resId=0&materialId=slides&confId=246803

"no switch yard" work flow:
http://root.cern.ch/drupal/content/suggested-work-flow-distributed-projects-nosy

GIT cheat sheet:
http://root.cern.ch/drupal/content/git-tips-and-tricks

K.O.

> [system.c:308:ss_shm_open,ERROR] Shared memory segment with key 0x4d008002 already exists, 
please remove it manually: ipcrm -M 0x4d008002
> [midas.c:1950:cm_connect_experiment1,ERROR] cannot open database
> Unexpected error #304

For the record, the SYSV shared memory with it's keys and segments has always been brittle and hard to 
debug with problems such as you describe.

Also SYSV shared memory suffers from key aliasing - shared memory segments created with different 
names all map into the same key, collide and nothing works. You may not see this if all the files are 
located on a local disk, but if the .SHM files are located on an NFS disk, it can happen (and did happen in 
T2K).

For this reason, since around August 2010, MIDAS also implements the POSIX shared memory and for new 
MIDAS installations, POSIX shared memory is the default. (On MacOS, POSIX shared memory was always 
the default because MacOS has very small maximum SYSV shared memory size).

The type of shared memory is set by the contents of .SHM_TYPE.TXT and it is possible to switch between 
SYSV and POSIX shared memory at will. (Ask me).

MIDAS still uses SYSV semaphores because they have a built-in feature to automatically unlock the 
semaphore if the program that locked it dies for any reason. POSIX semaphores do not have this built-in 
feature and we would have to implement some kind of detection and recovery for the case when a 
semaphore is locked by a program that died (and will never unlock it back).

K.O.

P.S. I will address the rest of Prof. Thorsten's question in a private email.

P.P.S. Please post elog messages in the "plain" format. NOT HTML or ELCODE.

[quote="Stefan Ritt"][quote="Thorsten Lux"]In addition now I cannot start
anymore the mlogger from the web interface but only manually. However, I can
stop it from the web interface.[/quote]

At least that one can be fixed easily. Each program has a certain command with
which one can start it. This has to be put into the ODB under
/Programs/<program>. In your case you probably need

/Programs/Logger/Start command = mlogger -D

to start the logger from the Web page. To debug your run stop problems, I would
recommend to start all programs in a terminal window and look which one crashes
on the run end.

/Stefan[/quote]


Hi Stefan,

under /Programs/Logger/Start command I have
/home/next/MIDAS/midas/linux/bin/mlogger -D . This command does not work if I
press the "Start Logger" button on the mhttpd webpage but when I copy and paste
this command to a terminal window, it does the job. 

Well, thanks to you both for the fast response. I wrote Konstantin an email with
the results of the tests he suggested me to do.

Ciao

> Hi Stefan,
> 
> under /Programs/Logger/Start command I have
> /home/next/MIDAS/midas/linux/bin/mlogger -D . This command does not work if I
> press the "Start Logger" button on the mhttpd webpage but when I copy and paste
> this command to a terminal window, it does the job. 
> 
> Well, thanks to you both for the fast response. I wrote Konstantin an email with
> the results of the tests he suggested me to do.
> 
> Ciao

Let me guess: mhttpd is started under root (to be able to connect to port 80), and for root the mlogger program 
is not in the path. Try to put into the odb the full path:

/Programs/Logger Start command = /usr/local/bin/mlogger -D

> 
> > Hi Stefan,
> > 
> > under /Programs/Logger/Start command I have
> > /home/next/MIDAS/midas/linux/bin/mlogger -D . This command does not work if I
> > press the "Start Logger" button on the mhttpd webpage but when I copy and paste
> > this command to a terminal window, it does the job. 
> > 
> > Well, thanks to you both for the fast response. I wrote Konstantin an email with
> > the results of the tests he suggested me to do.
> > 
> > Ciao
> 
> Let me guess: mhttpd is started under root (to be able to connect to port 80), and for root the mlogger program 
> is not in the path. Try to put into the odb the full path:
> 
> /Programs/Logger Start command = /usr/local/bin/mlogger -D

Yes, mhttpd is started as sudo, but I have the full path in the start command. And every user has the right to
execute mlogger. But okay, I will concentrate first to get the rest working again and then I will fight this problem.

Thanks!

Hi,

it seems that I solved the problem in a quite brutal way.
I opened the database with odbedit and saved first the whole database as a ASCII
file and then I did the same for each section separately. Then I closed odbedit.
Afterwards I deleted all .*.SHM files including .ODB.SHM and rebooted the system.
After the restart I opened odbedit and started mhttpd. With this blank system
the problem had disappeared. Afterwards I loaded section by section from the
previous created ASCII files. After each section I tested if I can start and
stop runs and it worked without problems. At the end I also loaded the ASCII
file which contained the whole database. In this case I got the following error
message:
[odb.c:6038:db_paste,ERROR] found string exceeding MAX_STRING_LENGTH

However, after a reboot everything worked fine. I can start and stop runs, with
and without frontend, without any error message. Only the mlogger resisted to
work again. 

But also this problem we solved. It seems it was related to a missing library
path. It is strange since while in the mhttpd web page the command does not work
and is not giving any error message, copying the same command to a terminal and
to start it manually does the job. We solved it by putting the start of mlogger
in a simple shell script and to execute it then from the mhttpd web page.
Probably not an elegant solution but it does the job.

Well, with this I can enjoy my weekend to start over with data taking next week!

Thanks a lot!

Thorsten

> [odb.c:6038:db_paste,ERROR] found string exceeding MAX_STRING_LENGTH

Ok, so here is what probably happened. Some user program wrote a long string into the ODB and somehow corrupted it. This corruption persists as long as you work with 
binary data. Indeed "rebuilding" the ODB helps in that case. What we do actually is at the beginning of every run, the ODB contents is dumped into the data file via

/Logger/Channels/0/Setting/ODB dump

in case we get ODB corruption, we clear all *.shm files as well as the shared memory segments, create a fresh ODB, extract the ODB from the last successful run via

odbhist -e runxxx.mid

and load it via odbedit. I put some additional code in most midas functions to prevent this corruption (and thus your saw the above error "found string exceeding 
MAX_STRING_LENGTH"), but since the ODB is physically in the address space of each midas program, they can theoretically bypass the midas functions and write accidentally 
into the ODB with an uninitialized pointer or so.

Best regards,
Stefan

I have done a review of github and bitbucket as candidates for hosting GIT repositories for collaborative 
DAQ-type projects. Here is my impressions.

1. GIT as a software management tool seems to be a reasonable choice for DAQ-type projects. "master" 
repositories can be hosted at places like github or self-hosted (in the simplest case, only 
http://host/~user web access is required to host a git repository), for each "daq project" aka "experiment" 
one would "clone" the master repository, perform any local modifications as required, with full local 
version control, and when desired feed the changes back to the master repository as direct commits (git 
push), as patches posted to github ("pull requests") or patches emailed to the maintainers (git format-
patch).

2. Modern requirements for hosting a DAQ-type project include:
a) code repository (GIT, etc) with reasonably easy user access control (i.e. commit privileges should be 
assigned by the project administrators directly, regardless of who is on the payroll at which lab or who is 
a registered user of CERN or who is in some LDAP database managed by some IT departement 
somewhere).
b) a wiki for documentation, with similar user access control requirements.
c) a mailing list, forum or bug tracking system for communication and "community building"
d) an ability to web host large static files (schematics, datasheets, firmware files, etc)
e) reasonable web-based tools for browsing the files, looking at diffs, "cvs annotate/git blame", etc.

3. Both github and bitbucket satisfy most of these requirements in similar ways:

a) GIT repositories:
aa) access using git, ssh and https with password protection. ssh keys can be uploaded to the server, 
permitting automatic commits from scripts and cron jobs.
bb) anonymous checkout possible (cannot be disabled)
cc) user management is simple: participants have to self-register, confirm their email address, the project 
administrator to gives them commit access to specific git repositories (and wikis).
dd) for the case of multiple project administrators, one creates "teams" of participants. In this 
configuration the repositories are owned by the "team" and all designated "team administrators" have 
equal administrative access to the project.

b) Wiki:
aa) both github and bitbucket provide rudimentary wikis, with wiki pages stored in secondary git 
repositories (*NOT* as a branch or subdirectory of the main repo).
bb) github supports "markdown" and "mediawiki" syntax
cc) bitbucket supports "markdown" and "creole" syntax (all documentation and examples use the "creole" 
syntax).
dd) there does not seem to be any way to set the "project standard" syntax - both wikis have the "new 
page" editor default to the "markdown" syntax.
ee) compared to mediawiki (wikipedia, triumf daq wiki) and even plone, both github and bitbucket wikis 
lack important features:
1) cannot edit individual sections of a page, only the whole page at once, bad if you have long pages.
2) cannot upload images (and other documents) directly through the web editor/interface. Both wikis 
require that you clone the wiki git repository, commit image and other files locally and push the wiki git 
repo into the server (hopefully without any collisions), only then you can use the images and documents 
in the wiki.
3) there is no "preview" function for images - in mediawiki I can have small size automatically generated 
"preview" images on the wiki page, when I click on them I get the full size image. (Even "elog" can do this!)
ff) to be extra helpful, the wiki git repository is invisible to the normal git repository graphical tools for 
looking at revisions, branches, diffs, etc. While github has a special web page listing all existing wiki 
pages, bitbucket does not have such a page, so you better write down the filenames on a piece of paper.

c) mailing list/forum/bug tracking:
aa) both github and bitbucket implement reasonable bug tracking systems (but in both systems I do not 
see any button to export the bug database - all data is stuck inside the hosting provider. Perhaps there is 
a "hidden button" somewhere).
bb) bitbucket sends quite reasonable email notifications
cc) github is silent, I do not see any email notifications at all about anything. Maybe github thinks I do not 
want to see notices about my own activities, good of it to make such decisions for me.

d) hosting of large files: both git and wiki functions can host arbitrary files (compared to mediawiki only 
accepting some file types, i.e. Quartus pof files are rejected).

e) web based tools: thumbs up to both! web interfaces are slick and responsive, easy to use.

Conclusions:

Both github and bitbucket provide similar full-featured git repository hosting, user management and bug 
tracking.

Both provide very rudimentary wiki systems. Compared to full featured wikis (i.e. mediawiki), this is like 
going back to SCCS for code management (from before RCS, before CVS, before SVN). Disappointing. A 
deal breaker if my vote counts.

K.O.

Let me add my five cents:

We use bitbucket now since two months at PSI, and are very happy with it.

Pros:

- We like the GIT flow model (http://nvie.com/posts/a-successful-git-branching-model/). You can at the same time do hot fixes, have a "distribution 
version", and keep a development branch, where you can try new things without compromising the distribution.
- Nice and fast Web interface, especially the "blame" is lightning fast compared to SVN/CVS
- GIT is non-centralized, so your local clone of a repository contains everything. If bitbucket is down/asks for money, you can continue with your local 
repository and clone it to some other hosting service, or host it yourself
- SourceTree (http://www.sourcetreeapp.com/) is a nice GUI for Mac lovers. 
- Easy user management
- Free for academic use

Con:

- Wiki is limited as KO wrote, so it should not be used as a "full" wiki to replace Plone for example, just to annotate your project
- SVN revision number is gone. This is on purpose since it does not make sense any more if you keep several parallel branches (merging becomes a 
nightmare), so one has to use either the (random) commit-ID or start tagging again.

So I conclusion, I would say that it's time to switch MIDAS to GIT. We'll probably do that in July when I will be at TRIUMF.

/Stefan

And my 2ct:

Go for git!

I've been using git since 2007 or so, after cvs and svn. Git has some killer features which I can't miss any more:

* No central repo. Have all the history with you on the train.
* Branching and merging, with stable branches and feature branches.
  Happy hacking while my students do analysis on a stable version.
  Or multiple development branches for several features.
  And merging really works, including fixing up merge conflicts.
* "git bisect" for finding which commit introduced a (reproducible) bug.
* "gitk --all"

I use git for everything: Software, tex, even (Ooffice) Word documents.

Go for git. :-)

Randolf

Hi, thanks for your positive feedback. I have been using git for small private projects for a few years now
and I like it. It is similar to the old SCCS days - good version control without having to setup servers,
accounts, doodads, etc.

> * No central repo. Have all the history with you on the train.
> * Branching and merging, with stable branches and feature branches.
>   Happy hacking while my students do analysis on a stable version.
>   Or multiple development branches for several features.

This is the part that worries me the most. Without a "central" "authoritative" repository,
in just a few quick days, everybody will have their own incompatible version of midas.

I guess I am okey with your private midas diverging from mainstream, but when *I* end up
with 10 different incompatible versions just in *my* repository, can that be good?

>   And merging really works, including fixing up merge conflicts.

But somebody still has to do it. With a central repository, the problem takes care of
itself - each developer has to do their own merging - with svn, you cannot commit
to the head without merging the head into your code first. But with git, I can just throw
my changes int some branch out there hoping that somebody else would do the merging.
But guess what, there aint anybody home but us chickens. We do not have a mad finn here
to enforce discipline and keep us in shape...

As an example, look at the HADOOP/HDFS code development, they have at least 3 "mainstream"
branches going, neither has all the features combined together and each branch has bugs with
the fixes in a different branch. What a way to run a railroad.

> * "git bisect" for finding which commit introduced a (reproducible) bug.
> * "gitk --all"
>
> Go for git. :-)

Absolutely. For me, as soon as I can wrap my head around this business of "who does all the merging".

K.O.

Hi Konstantin,

> > * No central repo. Have all the history with you on the train.
> > * Branching and merging, with stable branches and feature branches.
> >   Happy hacking while my students do analysis on a stable version.
> >   Or multiple development branches for several features.
> 
> This is the part that worries me the most. Without a "central" "authoritative" repository,
> in just a few quick days, everybody will have their own incompatible version of midas.

No! This is probably one of the biggest misunderstandings of the git workflow.

You can of course _define_ one central repo: This is the one that you and Stefan decide to be "the source" (as
Linus does for the kernel). It's like the central svn repo: Only Stefan and you can push to it, and everybody
else will pull from it. Why should I pull MIDAS from some obscure source, when your "public" repo is available.

Look at the Linux Kernel: Linus' version is authoritative, even though everybody and his best friend has his
own kernel repo.

So, the main workflow does not change a lot: You collect patches, commit them, and "push" them to the central
repo. All users "pull" from this central repo. This is very much what svn offers.

> 
> I guess I am okey with your private midas diverging from mainstream, but when *I* end up
> with 10 different incompatible versions just in *my* repository, can that be good?

See above: _You_ define what the central repo is.

But: I _bet_ you will very soon have 10 versions in your personal repo, because _you choose_ to do so. It's
just SO much easier. The non-linear history with many branches is a _feature_. I can't live without it any more:


Looking at my MIDAS analyzer:

I have a "public" repo in /pub/git/lamb.git. This is where I publish my analyzer versions. All my collaborators
pull from this.

Then I have my personal repo in ~/src/lamb. 
This is where I develop. When I think something is ready for the public, I merge this branch into the public repo. 

Whenever I start to work on a new feature, I create a branch in my _local_ repo (~/src/lamb).  I can fiddle and
play, not affecting anybody else, because it never sees the public repo.
OK, collaborator A finds a bug. I switch to my local copy of the public version, fix the bug, and push the fix
to the publix repo. Then I go back to my (local) feature branch, merge the bug fix, and continue hacking.
Only when the feature is ready, I push it to the public repo.

Things get moe interesting as you work on several features simultaneously. You have e.g. 3 topic branches:
(a) is nearly ready, and you want a bunch of people to test it.
    push branch "feature (a)" to the public repo and tell the people which branch to pull.
(b) is WIP, you hack on it without affecting (a).
(c) is bug fixes which may or may not affect (a) or (b).
And so on.

You will soon discover the beauty of several parallel branches.

Plus, git merges are SO simple that you never think about "how to merge"

> 
> >   And merging really works, including fixing up merge conflicts.
> 
> But somebody still has to do it. With a central repository, the problem takes care of
> itself - each developer has to do their own merging - with svn, you cannot commit
> to the head without merging the head into your code first. But with git, I can just throw
> my changes int some branch out there hoping that somebody else would do the merging.
> But guess what, there aint anybody home but us chickens. We do not have a mad finn here
> to enforce discipline and keep us in shape...

See above: You will have the exact same workflow in git, if you like.




> As an example, look at the HADOOP/HDFS code development, they have at least 3 "mainstream"
> branches going, neither has all the features combined together and each branch has bugs with
> the fixes in a different branch. What a way to run a railroad.

I haven't look at this. All I can say: Branches are one of the best features.

> 
> > * "git bisect" for finding which commit introduced a (reproducible) bug.
> > * "gitk --all"
> >
> > Go for git. :-)
> 
> Absolutely. For me, as soon as I can wrap my head around this business of "who does all the merging".

Easy: YOU do it.

Keep going as in svn: Collect patches, and send them out.

And then, try "git checkout -b my_first_branch", hack, hack, hack,
"git merge master".

Best,

Randolf


> 
> K.O.

> * "git bisect" for finding which commit introduced a (reproducible) bug.

I did not know this command, so I read about it. This IS WONDERFUL! I had once (actually with MSCB) the case that a bug was introduced i the last 100 
revisions, but I did not know in which. So I checked out -1, -2, -3 revisions, then thought a bit, then tried -99, -98, then had the bright idea to try -50, then 
slowly converged. Later I realised that I should have done a binary search, like -50, if ok try -25, if bad try -37, and so on to iteratively find the offending 
commit. Finding that there is a command it git which does this automatically is great news.

Stefan

> > * "git bisect" for finding which commit introduced a (reproducible) bug.
> 
> I did not know this command, so I read about it. This IS WONDERFUL! I had once (actually with MSCB) the case that a bug was introduced i the last 100 
> revisions, but I did not know in which. So I checked out -1, -2, -3 revisions, then thought a bit, then tried -99, -98, then had the bright idea to try -50, then 
> slowly converged. Later I realised that I should have done a binary search, like -50, if ok try -25, if bad try -37, and so on to iteratively find the offending 
> commit. Finding that there is a command it git which does this automatically is great news.

even more so considering the nonlinear history (due to branching) in a regular git repo.

Somebody pointed out an error in the MIDAS documentation regarding maximum event size 
supported by MIDAS and the MAX_EVENT_SIZE #define in midas.h.

Since MIDAS svn rev 4801 (August 2010), one can create events with size bigger than 
MAX_EVENT_SIZE in midas.h (without having to recompile MIDAS):

To do so, one must increase:
- the value of ODB /Experiment/MAX_EVENT_SIZE
- the size of the SYSTEM shared memory event buffer (and any buffers used by the event builder, 
etc)
- max_event_size & co in your frontend.

Actual limits on the bank size and event size are written up here:
https://ladd00.triumf.ca/elog/Midas/757

The bottom line is that the maximum event size is limited by the size of the SYSTEM buffer which is 
limited by the physical memory of your computer. No recompilation of MIDAS necessary.

K.O.

I am getting a series of errors from MIDAS that I do not understand, so I hope
someone can help me figure this out.

I am attempting to run many frontends on one machine. I can run 8 with no
problem, but if I try to add a 9th I get errors relating to send_tcp. 

I have tried adjusting the max event sizes and buffer sizes, but it has not
resolved the problem. I also tried adjusting the data rates and the total data
volume going through each frontend, but there was no change. And as far as I can
tell I am not up against any hardware limits.

The errors are repeated continuously while a run is going. The three errors I
get are:

16:45:22 [FakeData09,ERROR] [midas.c:9958:rpc_client_call,ERROR] send_tcp() failed
16:45:22 [FakeData09,ERROR] [frontend_rpc.c:191:rpc_call,ERROR] No RPC to master
16:45:22 [FakeData09,ERROR] [system.c:4166:send_tcp,ERROR]
send(socket=9,size=16) returned -1, errno: 32 (Broken pipe)

If you have any suggestions of how I can debug this, please let me know. Thanks!

> I am getting a series of errors from MIDAS that I do not understand, so I hope
> someone can help me figure this out.
> 
> I am attempting to run many frontends on one machine. I can run 8 with no
> problem, but if I try to add a 9th I get errors relating to send_tcp. 
> 
> I have tried adjusting the max event sizes and buffer sizes, but it has not
> resolved the problem. I also tried adjusting the data rates and the total data
> volume going through each frontend, but there was no change. And as far as I can
> tell I am not up against any hardware limits.
> 
> The errors are repeated continuously while a run is going. The three errors I
> get are:
> 
> 16:45:22 [FakeData09,ERROR] [midas.c:9958:rpc_client_call,ERROR] send_tcp() failed
> 16:45:22 [FakeData09,ERROR] [frontend_rpc.c:191:rpc_call,ERROR] No RPC to master
> 16:45:22 [FakeData09,ERROR] [system.c:4166:send_tcp,ERROR]
> send(socket=9,size=16) returned -1, errno: 32 (Broken pipe)
> 
> If you have any suggestions of how I can debug this, please let me know. Thanks!

Can you tell me

- why you need 9 frontends
- what kind of data your frontends produce
- how your event builder looks like and how you assemble the fragments
- what messages/errors you see when you run odbedit BEFORE the crash

/Stefan

> > I am getting a series of errors from MIDAS that I do not understand, so I hope
> > someone can help me figure this out.
> > 
> > I am attempting to run many frontends on one machine. I can run 8 with no
> > problem, but if I try to add a 9th I get errors relating to send_tcp. 
> > 
> > I have tried adjusting the max event sizes and buffer sizes, but it has not
> > resolved the problem. I also tried adjusting the data rates and the total data
> > volume going through each frontend, but there was no change. And as far as I can
> > tell I am not up against any hardware limits.
> > 
> > The errors are repeated continuously while a run is going. The three errors I
> > get are:
> > 
> > 16:45:22 [FakeData09,ERROR] [midas.c:9958:rpc_client_call,ERROR] send_tcp() failed
> > 16:45:22 [FakeData09,ERROR] [frontend_rpc.c:191:rpc_call,ERROR] No RPC to master
> > 16:45:22 [FakeData09,ERROR] [system.c:4166:send_tcp,ERROR]
> > send(socket=9,size=16) returned -1, errno: 32 (Broken pipe)
> > 
> > If you have any suggestions of how I can debug this, please let me know. Thanks!
> 
> Can you tell me
> 
> - why you need 9 frontends
> - what kind of data your frontends produce
> - how your event builder looks like and how you assemble the fragments
> - what messages/errors you see when you run odbedit BEFORE the crash
> 
> /Stefan

Our experiment will need 24 frontends that will each run on its own machine. For now we
want to run 24 "fake" frontends on one machine for testing purposes. 9 is the limit
where it stops working properly. 

We have a pulser that is giving us periodic data at a constant rate. We have a master
frontend running on a different PC in interrupt mode that assembles the events, and then
N "FakeData" frontends running in polled mode on a single PC. 

We do have an event builder, but we get these errors whether the event builder is
running or not.

At the start of a run, I see the following messages:

[mtransition,INFO] Run #21 started
Sat Feb 9 16:14:57 2013 [FakeData09,ERROR] [system.c:4166:send_tcp,ERROR]
send(socket=9,size=16) returned -1, errno: 104 (Connection reset by peer)
Sat Feb 9 16:14:57 2013 [FakeData09,ERROR] [midas.c:9958:rpc_client_call,ERROR]
send_tcp() failed
Sat Feb 9 16:14:57 2013 [FakeData09,ERROR] [frontend_rpc.c:191:rpc_call,ERROR] No RPC to
master
Sat Feb 9 16:14:57 2013 [master,ERROR] [midas.c:10844:recv_tcp_server,ERROR] Cannot
allocate 268435512 bytes for network buffer
Sat Feb 9 16:14:57 2013 [master,ERROR] [midas.c:12893:rpc_server_receive,ERROR]
recv_tcp_server() returned -1, abort
Sat Feb 9 16:14:57 2013 [master,TALK] Program 'FakeData09' on host 'fe01' aborted

After this it recycles just the first three errors that I mentioned above.

Ok, now the picture is clearer. I have however no idea what the real problem is. The number of concurrent programs in midas is 64 as defined in midas.h (MAX_CLIENTS) so that should not be the problem. In our experiment we run 10 front-ends (but 
on 10 different machines) without problems. Other experiments used 27 front-ends.

The TCP error you see comes probably from the fact that the mserver side crashes or quits, then the socket gets broken. What you can try to debug this is to run mserver manually. Just remove mserver from inetd, and start it with "mserver -d" and 
watch what happens. Do you see any additional error messages. If the mserver segfaults, you should turn on core dumps and have a look there. Note that the mserver starts a child process on each incoming connection, so running mserver in gdb 
does not really help, since the child processes (which connect back to the front-ends) are not seen by gdb.

Have you tried to run the 9 front-ends on maybe two different PCs (5 and 4) to see if the problem is on the client side?


Best regards,
Stefan

Thank you for the help. As it turns out, the problem was due to the fact that we were compiling MIDAS on our 64 bit backend machine, but one of the frontend machines is 32 bit. The problem was resolved by compiling a 32 bit version of MIDAS in
addition to the 64 bit version.