Dear all,

I have problem in event buffer size.

When run MIDAS, I got error "total event size (1307072) larger than buffer size
(1048576)", so I guess that the EVENT_BUFFER_SIZE is small.

I change EVENT_BUFFER_SIZE in midas.h from 0x100000 to 0x200000. After compiling
and run MIDAS, I got other error "Shared memory segment with key 0x4d040761
already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" in
system.C

I check the shmget() function in system.C and it is said that error come from
Shared memory segments larger than 16,773,120 bytes and create teraspace shared
memory segments

Anyone has this problem before?
Thanks for your help

M.T

> I have problem in event buffer size.
> 
> When run MIDAS, I got error "total event size (1307072) larger than buffer size
> (1048576)", so I guess that the EVENT_BUFFER_SIZE is small.
>

Correct. You have a choice of sending smaller events or increasing the buffer size.

Increasing the buffer size consumes computer memory, how much memory do you have on your machine?

> 
> I change EVENT_BUFFER_SIZE in midas.h from 0x100000 to 0x200000. After compiling
> and run MIDAS, I got other error "Shared memory segment with key 0x4d040761
> already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" in
> system.C
> 

This is not normal. In recent versions of MIDAS (for the last few years)

a) buffer size is changed via ODB "/Experiment/buffer sizes", no need to edit midas.h
b) shared memory was switched from SYSV shared memory to POSIX shared memory, and you should not see any references to 
SYSV shared memory functions like "ipcrm", "shmget" and "segment key".

Are you using a very old version of MIDAS? Or maybe you have a MIDAS installation that still uses SYSV shared memory. Check 
the contents of .SHM_TYPE.TXT (in the same directory as .ODB.SHM), if would normally say "POSIXv2_SHM". If it says 
something else, it is best to convert to POSIX SHM. Simplest way is to stop everything, save odb to text file, delete 
.SHM_TYPE.TXT, restart odb with odbedit, reload from text file. Now check that .SHM_TYPE.TXT says "POSIXv2_SHM".

>
> I check the shmget() function in system.C and it is said that error come from
> Shared memory segments larger than 16,773,120 bytes and create teraspace shared
> memory segments
> 

What teraspace?!? You changed the size from 1 Mbyte to 2 Mbyte (0x200000), this is still below even the value you have above 
(16,773,120).

At the end, it is not clear what your problem is. After changing the shared memory size (via odb or via midas.h),
the midas *will* complain about the mismatch in size (existing vs expected) and will tell you how to fix it, (run "ipcrm").
After does this, is there still an error? Normally everything will just work. (you might also have to erase .SYSTEM.SHM,
midas will tell you to do so if it is needed).

So what is your final error? (After running ipcrm?)

K.O.

I am sorry for my late reply 

memory in my PC is 16 GB 

I check the contents of .SHM_TYPE.TXT and it is "POSIXv2_SHM". 
But there is no buffer sizes in "/Experiment" 

After run "ipcrm -M 0x4d040761 size0x204a3c", remove .SYSTEM.SHM and run MIDAS again, I still get error "Shared memory segment
with key 0x4d040761 already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" M.T

> memory in my PC is 16 GB 

You can safely go to buffer size 100 Mbytes or more.

> I check the contents of .SHM_TYPE.TXT and it is "POSIXv2_SHM".

Good.

> But there is no buffer sizes in "/Experiment" 

This is strange. How old is your midas? What does it say on the "help" page in "Revision"?

> After run "ipcrm -M 0x4d040761 size0x204a3c"

This command is wrong. It probably gave you an error instead of removing the shared memory, that's why
nothing worked afterwards.

My copy of system.c reads this:
cm_msg(MERROR, "ss_shm_open", "Shared memory segment with key 0x%x already exists, please remove it manually: ipcrm -M 0x%x", key, 
key);

Note how there is no text "size0x..." in my copy? What does your copy say? Did somebody change it?

> remove .SYSTEM.SHM and run MIDAS again, I still get error "Shared memory segment
> with key 0x4d040761 already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" M.T

Yes, that's because the ipcrm command is wrong and did not work,
it should read "ipcrm -M 0x4d040761" without the spurious "size..." text.

K.O.

> > memory in my PC is 16 GB 
> 
> You can safely go to buffer size 100 Mbytes or more.
> 
> > I check the contents of .SHM_TYPE.TXT and it is "POSIXv2_SHM".
> 
> Good.


No, wait, this is all wrong. If it says POSIX shared memory, how come it later
complains about SYSV shared memory and tells you to run SYSV shared memory
commands like ipcrm?!?


> > But there is no buffer sizes in "/Experiment" 


Now this kind of makes sense - you are probably running a strange mixture
of very old and recently new MIDAS. Probably you current version is so old
that it does not use .SHM_TYPE.TXT and can only do SYSV shared memory
and so old it does not have "/Experiment/buffer sizes".

But at some point you must have run a recent version of midas, or you would
not have the file .SHM_TYPE.TXT in your experiment directory.

I say:

a) run the correct ipcrm command (without the spurious "size..." text)
b) review your computer contents to identify all the versions of midas
   and to make sure you are using the midas you want to use (old or new,
   whatever), but not some wrong version by accident (incorrect PATH setting, etc)

As MIDAS developers, we usually recommend that you use the latest version of MIDAS,
certainly latest version is simpler to debug.

K.O.

Dear all,

I have problem in event buffer size.

When run MIDAS, I got error "total event size (1307072) larger than buffer size
(1048576)", so I guess that the EVENT_BUFFER_SIZE is small.

I change EVENT_BUFFER_SIZE in midas.h from 0x100000 to 0x200000. After compiling
and run MIDAS, I got other error "Shared memory segment with key 0x4d040761
already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" in
system.C

I check the shmget() function in system.C and it is said that error come from
Shared memory segments larger than 16,773,120 bytes and create teraspace shared
memory segments

Anyone has this problem before?
Thanks for your help

M.T

As discussed before, the midas omnibus javascript file mhttpd.js has been split into three pieces:

midas.js - midas "public api" for building web pages that interact with midas
mhttpd.js - javascript functions used by mhttpd web pages
obsolete.js - functions still in use, but not recommended for new designs, mostly because of the deprecated "Synchronous XMLHttpRequest" business.

Consider these use cases:

a) completely standalone web pages served from some other web server (not mhttpd): loading midas.js, set the mhttpd location (base URL) via mjsonrpc_set_url(url) and issue 
midas json-rpc requests as normal. (mhttpd fully supports the cross-site scripting (CORS) function).

b) custom pages loaded from mhttpd without midas styling: same as above, but no need to set the mhttpd base url.

c) custom pages loaded from mhttpd with midas styling: load midas.js, load mhttpd.js, load midas.css or mhttpd.css, see aaa_template.html or example.html to see how it all fits 
together.

d) custom replacement for mhttpd standard web pages: to replace (for example) the standard "alarms" page, copy (or create a new one) alarms.html into the experiment directory 
($MIDAS_DIR, same place as .ODB.SHM) and hack away. You can start from alarms.html, from aaa_template.html or from example.html.

K.O.

P.S. I am also reviewing mhttpd.css - the existing css file severely changes standard html formatting making it difficult to create custom web pages (all online tutorials and examples 
look nothing like that are supposed to look like). The new CSS file midas.css fixes this by only changing formatting of html elements that explicitly ask for "midas styling", without 
contaminating the standard html formatting. midas.css only works for example.html and aaa_template.html for now.

P.P.S. Here is the complete list of javascript functions in all 3 files:

8s-macbook-pro:resources 8ss$ grep ^function midas.js mhttpd.js obsolete.js
midas.js:function mjsonrpc_set_url(url)
midas.js:function mjsonrpc_send_request(req)
midas.js:function mjsonrpc_debug_alert(rpc) {
midas.js:function mjsonrpc_decode_error(error) {
midas.js:function mjsonrpc_error_alert(error) {
midas.js:function mjsonrpc_make_request(method, params, id)
midas.js:function mjsonrpc_call(method, params, id)
midas.js:function mjsonrpc_start_program(name, id) {
midas.js:function mjsonrpc_stop_program(name, unique, id) {
midas.js:function mjsonrpc_cm_exist(name, unique, id) {
midas.js:function mjsonrpc_al_reset_alarm(alarms, id) {
midas.js:function mjsonrpc_al_trigger_alarm(name, message, xclass, condition, type, id) {
midas.js:function mjsonrpc_db_copy(paths, id) {
midas.js:function mjsonrpc_db_get_values(paths, id) {
midas.js:function mjsonrpc_db_ls(paths, id) {
midas.js:function mjsonrpc_db_resize(paths, new_lengths, id) {
midas.js:function mjsonrpc_db_key(paths, id) {
midas.js:function mjsonrpc_db_delete(paths, id) {
midas.js:function mjsonrpc_db_paste(paths, values, id) {
midas.js:function mjsonrpc_db_create(paths, id) {
midas.js:function mjsonrpc_cm_msg(message, type, id) {
mhttpd.js:function ODBFinishInlineEdit(p, path, bracket)
mhttpd.js:function ODBInlineEditKeydown(event, p, path, bracket)
mhttpd.js:function ODBInlineEdit(p, odb_path, bracket)
mhttpd.js:function mhttpd_disable_button(button)
mhttpd.js:function mhttpd_enable_button(button)
mhttpd.js:function mhttpd_hide_button(button)
mhttpd.js:function mhttpd_unhide_button(button)
mhttpd.js:function mhttpd_init_overlay(overlay)
mhttpd.js:function mhttpd_hide_overlay(overlay)
mhttpd.js:function mhttpd_unhide_overlay(overlay)
mhttpd.js:function mhttpd_getParameterByName(name) {
mhttpd.js:function mhttpd_goto_page(page) {
mhttpd.js:function mhttpd_navigation_bar(current_page)
mhttpd.js:function mhttpd_page_footer()
mhttpd.js:function mhttpd_create_page_handle_create(mouseEvent)
mhttpd.js:function mhttpd_create_page_handle_cancel(mouseEvent)
mhttpd.js:function mhttpd_delete_page_handle_delete(mouseEvent)
mhttpd.js:function mhttpd_delete_page_handle_cancel(mouseEvent)
mhttpd.js:function mhttpd_start_run()
mhttpd.js:function mhttpd_stop_run()
mhttpd.js:function mhttpd_pause_run()
mhttpd.js:function mhttpd_resume_run()
mhttpd.js:function mhttpd_cancel_transition()
mhttpd.js:function mhttpd_reset_alarm(alarm_name)
mhttpd.js:function msg_load(f)
mhttpd.js:function msg_prepend(msg)
mhttpd.js:function msg_append(msg)
mhttpd.js:function findPos(obj) {
mhttpd.js:function msg_extend()
mhttpd.js:function alarm_load()
mhttpd.js:function aspeak_click(t)
mhttpd.js:function mhttpd_alarm_speak(t)
mhttpd.js:function chat_kp(e)
mhttpd.js:function rb()
mhttpd.js:function speak_click(t)
mhttpd.js:function chat_send()
mhttpd.js:function chat_load()
mhttpd.js:function chat_format(line)
mhttpd.js:function chat_prepend(msg)
mhttpd.js:function chat_append(msg)
mhttpd.js:function chat_reformat()
mhttpd.js:function chat_extend()
obsolete.js:function XMLHttpRequestGeneric()
obsolete.js:function ODBSetURL(url)
obsolete.js:function ODBSet(path, value, pwdname)
obsolete.js:function ODBGet(path, format, defval, len, type)
obsolete.js:function ODBMGet(paths, callback, formats)
obsolete.js:function ODBGetRecord(path)
obsolete.js:function ODBExtractRecord(record, key)
obsolete.js:function ODBKey(path)
obsolete.js:function ODBCopy(path, format)
obsolete.js:function ODBCall(url, callback)
obsolete.js:function ODBMCopy(paths, callback, encoding)
obsolete.js:function ODBMLs(paths, callback)
obsolete.js:function ODBMCreate(paths, types, arraylengths, stringlengths, callback)
obsolete.js:function ODBMResize(paths, arraylengths, stringlengths, callback)
obsolete.js:function ODBMRename(paths, names, callback)
obsolete.js:function ODBMLink(paths, links, callback)
obsolete.js:function ODBMReorder(paths, indices, callback)
obsolete.js:function ODBMKey(paths, callback)
obsolete.js:function ODBMDelete(paths, callback)
obsolete.js:function ODBRpc_rev0(name, rpc, args)
obsolete.js:function ODBRpc_rev1(name, rpc, max_reply_length, args)
obsolete.js:function ODBRpc(program_name, command_name, arguments_string, callback, max_reply_length)
obsolete.js:function ODBGetMsg(facility, start, n)
obsolete.js:function ODBGenerateMsg(type,facility,user,msg)
obsolete.js:function ODBGetAlarms()
obsolete.js:function ODBEdit(path)
obsolete.js:function getMouseXY(e)
8s-macbook-pro:resources 8ss$

K.O.

I've recently run into issues when using JSON.parse on ODB keys containing 
8-bit data.

For JSON.parse to successfully parse a string, (A) the string must be valid 
UTF-8, (B) several whitespace characters, control characters, and the 
characters " and \ must be escaped, and (C) you've got to follow the key-
value rules laid out in http://www.json.org/.

The web browser takes care of (A), and I verified that for this key Midas 
handled (C) correctly.  In principle, the function json_write in odb.c 
handles (B) - but json_write does not escape control characters.

To manage this problem, I modified json_write (in odb.c) to replace any 
control character with the more-inocuous character, 'C'.  My default case 
now looks like:

default:
         {
           // if a char is a control character,
           // print 'C' in its place
           // note that this loses data:
           // a more-correct method would be to print
           // \uXXXX, where XXXX is the character in hex
           if(iscntrl(*s)){
             (*buffer)[(*buffer_end)++] = 'C';
             s++;
           } else {
             (*buffer)[(*buffer_end)++] = *s++;
           }
         }
      
Where the call to iscntrl(*s) requires the addition of the ctype.h header 
file.

I'm guessing a blanket replacement of control characters with 'C' isn't 
something all Midas users would want to do.  Replacing the control character 
with its hex value seems like a good choice - but not without adding bounds 
checking!

An alternative to changing odb.c could be to add a regex to Midas response 
text which removes all control characters (U+0000 - U+001F): 

var resp_lint = req.response.replace(/[\u{0000}-\u{001F}]/gmu, '');
var json_obj = JSON.parse(resp_lint);

Unfortunately, the 'u' regex flax doesn't work on the Firefox version 
included in Scientific Linux 6.8.  

> I've recently run into issues when using JSON.parse on ODB keys containing 
> 8-bit data.

I am tempted to take a hard line and say that in general MIDAS TID_STRING data should be valid 
UTF-8 encoded Unicode. In the modern mixed javascript/json/whatever environment I think
it is impractical to handle or permit invalid UTF-8 strings.

Certainly in the general case, replacing all control characters with something else or escaping them or 
otherwise changing the value if TID_STRING data would wreck *valid* UTF-8 strings, which I would 
assume to be the normal use.

In other words, non-UTF-8 strings are following non-IEEE-754 floating point values into oblivion - as 
we do not check the TID_FLOAT and TID_DOUBLE is valid IEEE-754 values, we should not check 
that TID_STRING is valid UTF-8.

But in your specific case, why do you have random control characters in your TID_STRING data? 
Maybe you are using TID_STRING as general storage instead of arrays of TID_CHAR or 
TID_DWORD?

K.O.



> 
> For JSON.parse to successfully parse a string, (A) the string must be valid 
> UTF-8, (B) several whitespace characters, control characters, and the 
> characters " and \ must be escaped, and (C) you've got to follow the key-
> value rules laid out in http://www.json.org/.
> 
> The web browser takes care of (A), and I verified that for this key Midas 
> handled (C) correctly.  In principle, the function json_write in odb.c 
> handles (B) - but json_write does not escape control characters.
> 
> To manage this problem, I modified json_write (in odb.c) to replace any 
> control character with the more-inocuous character, 'C'.  My default case 
> now looks like:
> 
> default:
>          {
>            // if a char is a control character,
>            // print 'C' in its place
>            // note that this loses data:
>            // a more-correct method would be to print
>            // \uXXXX, where XXXX is the character in hex
>            if(iscntrl(*s)){
>              (*buffer)[(*buffer_end)++] = 'C';
>              s++;
>            } else {
>              (*buffer)[(*buffer_end)++] = *s++;
>            }
>          }
>       
> Where the call to iscntrl(*s) requires the addition of the ctype.h header 
> file.
> 
> I'm guessing a blanket replacement of control characters with 'C' isn't 
> something all Midas users would want to do.  Replacing the control character 
> with its hex value seems like a good choice - but not without adding bounds 
> checking!
> 
> An alternative to changing odb.c could be to add a regex to Midas response 
> text which removes all control characters (U+0000 - U+001F): 
> 
> var resp_lint = req.response.replace(/[\u{0000}-\u{001F}]/gmu, '');
> var json_obj = JSON.parse(resp_lint);
> 
> Unfortunately, the 'u' regex flax doesn't work on the Firefox version 
> included in Scientific Linux 6.8.  

> > I've recently run into issues when using JSON.parse on ODB keys containing 
> > 8-bit data.
> 
> I am tempted to take a hard line and say that in general MIDAS TID_STRING data should be valid 
> UTF-8 encoded Unicode. In the modern mixed javascript/json/whatever environment I think
> it is impractical to handle or permit invalid UTF-8 strings.
> ....
> But in your specific case, why do you have random control characters in your TID_STRING data? 
> Maybe you are using TID_STRING as general storage instead of arrays of TID_CHAR or 
> TID_DWORD?

I'm a little confused by this report and want to make sure I understand the situation.  Konstantin points
out that the TID_STRING should be valid UTF-8.  But I think that Amy agreed that the string was valid UTF-8.
 My understanding was that Amy's contention was that the valid UTF-8 string didn't get returned as valid JSON.

But I am having trouble reproducing your behaviour Amy.  I created a ODB string variable with a tab control
control character

  sprintf(mystring,"first line \t second line");
  status = db_set_value(hDB, 0,"/test2/mystring", &mystring, size, 1, TID_STRING);

and what I tried to pull the ODB using jcopy

http://neut18:8081/?cmd=jcopy&odb=/test2/mystring&format=json

I got 

{
"mystring/key" : { "type" : 12, "item_size" : 32, "access_mode" : 7, "last_written" : 1477416322 },
"mystring" : "first line \t second line"
}

which seems to be valid JSON.  

I only tried this with tab.  Are there other control characters that you are having trouble with?  Or maybe
I misunderstand the question?





> 
> > 
> > For JSON.parse to successfully parse a string, (A) the string must be valid 
> > UTF-8, (B) several whitespace characters, control characters, and the 
> > characters " and \ must be escaped, and (C) you've got to follow the key-
> > value rules laid out in http://www.json.org/.
> > 
> > The web browser takes care of (A), and I verified that for this key Midas 
> > handled (C) correctly.  In principle, the function json_write in odb.c 
> > handles (B) - but json_write does not escape control characters.
> > 
> > To manage this problem, I modified json_write (in odb.c) to replace any 
> > control character with the more-inocuous character, 'C'.  My default case 
> > now looks like:
> > 
> > default:
> >          {
> >            // if a char is a control character,
> >            // print 'C' in its place
> >            // note that this loses data:
> >            // a more-correct method would be to print
> >            // \uXXXX, where XXXX is the character in hex
> >            if(iscntrl(*s)){
> >              (*buffer)[(*buffer_end)++] = 'C';
> >              s++;
> >            } else {
> >              (*buffer)[(*buffer_end)++] = *s++;
> >            }
> >          }
> >       
> > Where the call to iscntrl(*s) requires the addition of the ctype.h header 
> > file.
> > 
> > I'm guessing a blanket replacement of control characters with 'C' isn't 
> > something all Midas users would want to do.  Replacing the control character 
> > with its hex value seems like a good choice - but not without adding bounds 
> > checking!
> > 
> > An alternative to changing odb.c could be to add a regex to Midas response 
> > text which removes all control characters (U+0000 - U+001F): 
> > 
> > var resp_lint = req.response.replace(/[\u{0000}-\u{001F}]/gmu, '');
> > var json_obj = JSON.parse(resp_lint);
> > 
> > Unfortunately, the 'u' regex flax doesn't work on the Firefox version 
> > included in Scientific Linux 6.8.  

> > I've recently run into issues when using JSON.parse on ODB keys containing 
> > 8-bit data.
> 
> I am tempted to take a hard line and say that in general MIDAS TID_STRING data should be valid 
> UTF-8 encoded Unicode. In the modern mixed javascript/json/whatever environment I think
> it is impractical to handle or permit invalid UTF-8 strings.
> 
> Certainly in the general case, replacing all control characters with something else or escaping them or 
> otherwise changing the value if TID_STRING data would wreck *valid* UTF-8 strings, which I would 
> assume to be the normal use.
> 
> In other words, non-UTF-8 strings are following non-IEEE-754 floating point values into oblivion - as 
> we do not check the TID_FLOAT and TID_DOUBLE is valid IEEE-754 values, we should not check 
> that TID_STRING is valid UTF-8.

I agree that I think we should start requiring strings to be UTF-8 encoded unicode. 

I'd suggest that before worrying about the TID_STRING data, we should start by sanitizing the ODB key names.
 I've seen a couple cases where the ODB key name is a non-UTF-8 string.  It is very awkward to use odbedit
to delete these keys.

I attach a suggested modification to odb.c that rejects calls to db_create_key with non-UTF-8 key names.  It
uses some random function I found on the internet that is supposed to check if a string is valid UTF-8.  I
checked a couple of strings with invalid UTF-8 characters and it correctly identified them.  But I won't
claim to be certain that this is really identifying all UTF-8 vs non-UTF-8 cases.  Maybe others have a
better way of identifying this.

> > In other words, non-UTF-8 strings are following non-IEEE-754 floating point values into oblivion - as 
> > we do not check the TID_FLOAT and TID_DOUBLE is valid IEEE-754 values, we should not check 
> > that TID_STRING is valid UTF-8.
> ...
> I attach a suggested modification to odb.c that rejects calls to db_create_key with non-UTF-8 key names.  It
> uses some random function I found on the internet that is supposed to check if a string is valid UTF-8.  I
> checked a couple of strings with invalid UTF-8 characters and it correctly identified them.  But I won't
> claim to be certain that this is really identifying all UTF-8 vs non-UTF-8 cases.  Maybe others have a
> better way of identifying this.

At Konstantin's suggestion, I committed the function I found for checking if a string was UTF-8 compatible to
odb.c.  The function is currently not used; I commented out a proposed use in db_create_key.  Experts can decide
if the code was good enough to use.

> At Konstantin's suggestion, I committed the function I found for checking if a string was UTF-8 compatible to
> odb.c.  The function is currently not used; I commented out a proposed use in db_create_key.  Experts can decide
> if the code was good enough to use.

After more discussion, I have enabled the parts of the ODB code that check that key names are UTF-8 compliant. 

This check will show up in (at least) two ways:

1) Attempts to create a new ODB variable if the ODB key is not UTF-8 compliant.  You will see error messages like

[fesimdaq,ERROR] [odb.c:572:db_validate_name,ERROR] Invalid name "Eur€" passed to db_create_key: UTF-8 incompatible
string

2) When a program first connects to the ODB, it runs a check to ensure that the ODB is valid.  This will now include
a check that all key names are UTF-8 compliant. Any non-UTF8 compliant key names will be replaced by a string of the
pointer to the key.  You will see error messages like:

[fesimdaq,ERROR] [odb.c:572:db_validate_name,ERROR] Invalid name "Eur€" passed to db_validate_key: UTF-8
incompatible string
[fesimdaq,ERROR] [odb.c:647:db_validate_key,ERROR] Warning: corrected key "/Equipment/SIMDAQ/Eur€": invalid name
"Eur€" replaced with "0x7f74be63f970"

This behaviour (checking UTF-8 compatibility and automatically fixing ODB names) can be disabled by setting an
environment variable

MIDAS_INVALID_STRING_IS_OK

It doesn't matter what the environment variable is set to; it just needs to be set.  Note also that this variable is
only checked once, when a program starts.

> 
> > At Konstantin's suggestion, I committed the function I found for checking if a string was UTF-8 compatible to
> > odb.c.  The function is currently not used; I commented out a proposed use in db_create_key.  Experts can decide
> > if the code was good enough to use.
> 
> After more discussion, I have enabled the parts of the ODB code that check that key names are UTF-8 compliant. 
> 
> This check will show up in (at least) two ways:
> 
> 1) Attempts to create a new ODB variable if the ODB key is not UTF-8 compliant.  You will see error messages like
> 
> [fesimdaq,ERROR] [odb.c:572:db_validate_name,ERROR] Invalid name "Eur€" passed to db_create_key: UTF-8 incompatible
> string
> 
> 2) When a program first connects to the ODB, it runs a check to ensure that the ODB is valid.  This will now include
> a check that all key names are UTF-8 compliant. Any non-UTF8 compliant key names will be replaced by a string of the
> pointer to the key.  You will see error messages like:
> 
> [fesimdaq,ERROR] [odb.c:572:db_validate_name,ERROR] Invalid name "Eur€" passed to db_validate_key: UTF-8
> incompatible string
> [fesimdaq,ERROR] [odb.c:647:db_validate_key,ERROR] Warning: corrected key "/Equipment/SIMDAQ/Eur€": invalid name
> "Eur€" replaced with "0x7f74be63f970"
> 
> This behaviour (checking UTF-8 compatibility and automatically fixing ODB names) can be disabled by setting an
> environment variable
> 
> MIDAS_INVALID_STRING_IS_OK
> 
> It doesn't matter what the environment variable is set to; it just needs to be set.  Note also that this variable is
> only checked once, when a program starts.



I see you put some switches into the environment ("MIDAS_INVALID_STRING_IS_OK"). Do you think this is a good idea? Most variables are 
sitting in the ODB (/experiment/xxx), except those which cannot be in the ODB because we need it before we open the ODB, like MIDAS_DIR. 
Having them in the ODB has the advantage that everything is in one place, and we see a "list" of things we can change. From an empty 
environment it is not clear that such a thing like "MIDAS_INVALID_STRING_IS_OK" does exist, while if it would be an ODB key it would be 
obvious. Can I convince you to move this flag into the ODB?

> 
> I see you put some switches into the environment ("MIDAS_INVALID_STRING_IS_OK"). Do you think this is a good idea? Most variables are 
> sitting in the ODB (/experiment/xxx), except those which cannot be in the ODB because we need it before we open the ODB, like MIDAS_DIR. 
> Having them in the ODB has the advantage that everything is in one place, and we see a "list" of things we can change. From an empty 
> environment it is not clear that such a thing like "MIDAS_INVALID_STRING_IS_OK" does exist, while if it would be an ODB key it would be 
> obvious. Can I convince you to move this flag into the ODB?
>


Some additional explanation.

Time passed, the world turned, and the current web-compatible standard for text strings is UTF-8 encoded Unicode, see 
https://en.wikipedia.org/wiki/UTF-8
(ObCanadianContent, UTF-8 was invented the Canadian Rob Pike https://en.wikipedia.org/wiki/Rob_Pike)
(and by some other guy https://en.wikipedia.org/wiki/Ken_Thompson).

It turns out that not every combination of 8-bit characters (char*) is valid UTF-8 Unicode.

In the MIDAS world we run into this when MIDAS ODB strings are exported to Javascript running inside web
browsers ("custom pages", etc). ODB strings (TID_STRING) and ODB key names that are not valid UTF-8
make such web pages malfunction and do not work right.

One solution to this is to declare that ODB strings (TID_STRING) and ODB key names *must* be valid UTF-8 Unicode.

The present commits implemented this solution. Invalid UTF-8 is rejected by db_create() & co and by the ODB integrity validator.

This means some existing running experiment may suddenly break because somehow they have "old-style" ODB entries
or they mistakenly use TID_STRING to store arbitrary binary data (use array of TID_CHAR instead).

To permit such experiments to use current releases of MIDAS, we include a "defeat" device - to disable UTF-8 checks
until they figure out where non-UTF-8 strings come from and correct the problem.

Why is this defeat device non an ODB entry? Because it is not a normal mode of operation - there is no use-case where
an experiment will continue to use non-UTF-8 compatible ODB indefinitely, in the long term. For example, as the MIDAS user
interface moves to more and more to HTML+Javascript+"AJAX", such experiments will see that non-UTF-8 compatible ODB entries
cause all sorts of problems and will have to convert.


K.O.

> Some additional explanation.
> 
> Time passed, the world turned, and the current web-compatible standard for text strings is UTF-8 encoded Unicode, see 
> https://en.wikipedia.org/wiki/UTF-8
> (ObCanadianContent, UTF-8 was invented the Canadian Rob Pike https://en.wikipedia.org/wiki/Rob_Pike)
> (and by some other guy https://en.wikipedia.org/wiki/Ken_Thompson).
> 
> It turns out that not every combination of 8-bit characters (char*) is valid UTF-8 Unicode.
> 
> In the MIDAS world we run into this when MIDAS ODB strings are exported to Javascript running inside web
> browsers ("custom pages", etc). ODB strings (TID_STRING) and ODB key names that are not valid UTF-8
> make such web pages malfunction and do not work right.
> 
> One solution to this is to declare that ODB strings (TID_STRING) and ODB key names *must* be valid UTF-8 Unicode.
> 
> The present commits implemented this solution. Invalid UTF-8 is rejected by db_create() & co and by the ODB integrity validator.
> 
> This means some existing running experiment may suddenly break because somehow they have "old-style" ODB entries
> or they mistakenly use TID_STRING to store arbitrary binary data (use array of TID_CHAR instead).
> 
> To permit such experiments to use current releases of MIDAS, we include a "defeat" device - to disable UTF-8 checks
> until they figure out where non-UTF-8 strings come from and correct the problem.
> 
> Why is this defeat device non an ODB entry? Because it is not a normal mode of operation - there is no use-case where
> an experiment will continue to use non-UTF-8 compatible ODB indefinitely, in the long term. For example, as the MIDAS user
> interface moves to more and more to HTML+Javascript+"AJAX", such experiments will see that non-UTF-8 compatible ODB entries
> cause all sorts of problems and will have to convert.
> 
> 
> K.O.

Ok, I agree.

Stefan

creating a frontend on MAC Sierra OSX 10
include the midas.h file and when compiling with XCode I get an error based on
this entry in the midas.h include

#if !defined(OS_IRIX) && !defined(OS_VMS) && !defined(OS_MSDOS) &&
!defined(OS_UNIX) && !defined(OS_VXWORKS) && !defined(OS_WINNT)
#error MIDAS cannot be used on this operating system
#endif


Perhaps I should not use Xcode?
Perhaps I won't need Midas.h?

The MIDAS system is running on my MAC but I need to add a very simple front end
for testing and I encounted this error.

> creating a frontend on MAC Sierra OSX 10
> include the midas.h file and when compiling with XCode I get an error based on
> this entry in the midas.h include
> 
> #if !defined(OS_IRIX) && !defined(OS_VMS) && !defined(OS_MSDOS) &&
> !defined(OS_UNIX) && !defined(OS_VXWORKS) && !defined(OS_WINNT)
> #error MIDAS cannot be used on this operating system
> #endif
> 
> 
> Perhaps I should not use Xcode?
> Perhaps I won't need Midas.h?
> 
> The MIDAS system is running on my MAC but I need to add a very simple front end
> for testing and I encounted this error.

If you compile with the included Makefile, you will see a 

-DOS_LINUX -DOS_DARWIN

flag which tells the compiler that we are on a mac. If you do this with XCode, you have to do it via "Build Settings" (see 
attached picture).

Stefan

> 
> If you compile with the included Makefile, you will see a 
> 
> -DOS_LINUX -DOS_DARWIN
> 

Moving forward, it looks like I can define these variables in midas.h and remove the need to define them on the compiler command line.

This would be part of the Makefile and header files cleanup to get things working on Windows10.

K.O.

> > 
> > If you compile with the included Makefile, you will see a 
> > 
> > -DOS_LINUX -DOS_DARWIN
> > 
> 
> Moving forward, it looks like I can define these variables in midas.h and remove the need to define them on the compiler command line.
> 
> This would be part of the Makefile and header files cleanup to get things working on Windows10.
> 
> K.O.

Will you detect the underlying OS automatically in midas.h? Note that you have several compilers in MacOS (llvm and gcc), and they might use different 
predefined symbols. I appreciate however getting rid of these flags in the Makefile.

Stefan

I switched mhttpd to use the new javascript based run start and stop pages.

There are two new html pages:

resources/start.html - mimics the old run start page exactly - where you can enter the "edit on 
start" parameters and start the run.
resources/transition.html - monitors the transition progress, shows the status of every transition 
client, their sequence number, waiting list dependency, time spent making rpc calls, etc.

If the new pages do not work for you, please report it here and switch to the old pages
by editing src/mhttpd.cxx - comment-out the line "#define NEW_START_STOP 1"

K.O.

> I switched mhttpd to use the new javascript based run start and stop pages.

One initial complaint: the transition.html page doesn't seem to deal well with a frontend program using
a deferred transition.  Specifically, I find with my simulated frontend ([1]), which has a deferred
end-of-run transition, that two problems happen:

i) the page doesn't give any indication that a frontend has a deferred transition; in fact it says that
the frontend immediately has finished the transition.
ii) once the deferred transition has finished, the page doesn't switch to saying that the run has
stopped.  In fact, even if I reload the transition page it still continues to show that the run is
ongoing; the status page, by contrast, shows that the run has stopped.

I separately still think that the transition page should automatically go away after 5 seconds
(assuming that all the transitions were successful).  I think it is annoying that you need to click
back to the status page.

[1] https://github.com/thomaslindner/fesimdaq

> > I switched mhttpd to use the new javascript based run start and stop pages.
> 
> One initial complaint: the transition.html page doesn't seem to deal well with a frontend program using
> a deferred transition.
>

We now have a test frontend for deferred transitions, and this problem will likely be fixed.

> 
> I separately still think that the transition page should automatically go away after 5 seconds
>

This is a user-interface philosophy issue.

Instead of using personal preferences one should follow established design principles
(there is research done and books written about this).

I did not recently look at current recommendations for this type of interaction, but generally
one expects web pages to "do things" (such as switch to a different page) only when directed
by user input (press a button).

My personal opinion is that half the users will find 5 sec delay too slow, the other half will
find 5 sec too fast and the 3rd half will wonder "what happened, the web page flashed and disappeared,
did I miss something important, how do I get back to whatever is was?!?".

One idea is to implement the transition page as a implant on the state page - after the "start" page
you go back to the status page where you can see the progress of the transition. After the transition
completes, it's progress window "collapses" into a "success/failure" display with a link to the full
transition page to see any details of what happened. Any volunteers? (I would html-ize the status page first).

K.O.

> > > I switched mhttpd to use the new javascript based run start and stop pages.
> > 
> > One initial complaint: the transition.html page doesn't seem to deal well with a frontend program using
> > a deferred transition.
> >
> 
> We now have a test frontend for deferred transitions, and this problem will likely be fixed.
> 
> > 
> > I separately still think that the transition page should automatically go away after 5 seconds
> >
> 
> This is a user-interface philosophy issue.
> 
> Instead of using personal preferences one should follow established design principles
> (there is research done and books written about this).
> 
> I did not recently look at current recommendations for this type of interaction, but generally
> one expects web pages to "do things" (such as switch to a different page) only when directed
> by user input (press a button).
> 
> My personal opinion is that half the users will find 5 sec delay too slow, the other half will
> find 5 sec too fast and the 3rd half will wonder "what happened, the web page flashed and disappeared,
> did I miss something important, how do I get back to whatever is was?!?".
> 
> One idea is to implement the transition page as a implant on the state page - after the "start" page
> you go back to the status page where you can see the progress of the transition. After the transition
> completes, it's progress window "collapses" into a "success/failure" display with a link to the full
> transition page to see any details of what happened. Any volunteers? (I would html-ize the status page first).
> 
> K.O.

I agree with Konstantin's plans and volunteer for the "collapsable" display. We will address this during my next visit to TRIUMF.

midas wiki at https://midas.triumf.ca/MidasWiki/index.php/Main_Page
was updated to MediaWiki version 1.27.1, the current MediaWiki LTS release.
Everything should work as before, but if you see any problems or anomalies, please report
them on this forum here.
K.O.

Hi Midas forum,

I'm having a problem with odb hotlinks after increasing sub-directories in an 
odb. I now get the error code DB_NO_MEMORY after some db_open_record() calls. I 
tried 

1) increasing the parameter DEFAULT_ODB_SIZE in midas.h and make clean, make
but got the same error

2) increasing the parameter  MAX_OPEN_RECORDS in midas.h and make clean, make
but got fatal errors from odbedit and my midas FE and couldnt run anything

3) deleting my expts SHM files and starting odbedit with "odbedit -e SLAC -s 
0x1000000" to increse the odb size but got the same error?

4) I tried a different computer and got the same error code DB_NO_MEMORY

Maybe I running into some system limit that restricts the humber of open records? 
Or maybe I've not increased the correct midas parameter?

Best ,Tim.

oOne additional comment. I was able to trace the setting of the error code DB_NO_MEMORY 
to a call to the db_add_open_record() by mserver that is initiated during the start-up 
of my frontend via an RPC call. I checked with a debug printout that I have indeed 
reached the number of MAX_OPEN_RECORDS

> Hi Midas forum,
> 
> I'm having a problem with odb hotlinks after increasing sub-directories in an 
> odb. I now get the error code DB_NO_MEMORY after some db_open_record() calls. I 
> tried 
> 
> 1) increasing the parameter DEFAULT_ODB_SIZE in midas.h and make clean, make
> but got the same error
> 
> 2) increasing the parameter  MAX_OPEN_RECORDS in midas.h and make clean, make
> but got fatal errors from odbedit and my midas FE and couldnt run anything
> 
> 3) deleting my expts SHM files and starting odbedit with "odbedit -e SLAC -s 
> 0x1000000" to increse the odb size but got the same error?
> 
> 4) I tried a different computer and got the same error code DB_NO_MEMORY
> 
> Maybe I running into some system limit that restricts the humber of open records? 
> Or maybe I've not increased the correct midas parameter?
> 
> Best ,Tim.

Hi Tim,

I reproduced your problem and then managed to go through a procedure to increase the number
of allowable open records.  The following is the procedure that I used 

1) Use odbedit to save current ODB

odbedit
save current_odb.odb

2) Stop all the running MIDAS processes, including mlogger and mserver using the web
interface. Then stop mhttpd as well.


3) Remove your old ODB (we will recreate it after modifying MIDAS, using the backup you just
made).

mv .ODB.SHM .ODB.SHM.20161104
rm /dev/shm/thomas_ODB_SHM

4) Make the following modifications to midas.  In this particular case I have increased the
max number of open records from 256 to 1024.  You would need to change the constants if you
want to change to other values

diff --git a/include/midas.h b/include/midas.h
index 02b30dd..33be7be 100644
--- a/include/midas.h
+++ b/include/midas.h
@@ -254,7 +254,7 @@ typedef std::vector<std::string> STRING_LIST;
-#define MAX_OPEN_RECORDS       256           /**< number of open DB records   */
+#define MAX_OPEN_RECORDS       1024           /**< number of open DB records   */
diff --git a/src/odb.c b/src/odb.c
index 47ace8f..ac1bef3 100755
--- a/src/odb.c
+++ b/src/odb.c
@@ -699,8 +699,8 @@ static void db_validate_sizes()
-   assert(sizeof(DATABASE_CLIENT) == 2112);
-   assert(sizeof(DATABASE_HEADER) == 135232);
+   assert(sizeof(DATABASE_CLIENT) == 8256);
+   assert(sizeof(DATABASE_HEADER) == 528448);

The calculation is as follows (in case you want a different number of open records): 
DATABASE_CLIENT = 64 + 8*MAX_OPEN_ERCORDS = 64 + 8*1024 = 8256
DATABASE_HEADER = 64 + 64*DATABASE_CLIENT = 64 + 64*8256 = 528448

5) Rebuild MIDAS

make clean; make

6) Create new ODB

odbedit -s 1000000

Change the size of the ODB to whatever you want.

7) reload your original ODB 

load  current_odb.odb

8) Rebuild your frontend against new MIDAS; then it should work and you should be able to
produce more open records.

8.5*) Actually, I had a weird error where I needed to remove my .SYSTEM.SHM file as well
when I first restarted my front-end.  Not sure if that was some unrelated error, but I
mention it here for completeness.

This was a procedure based on something that originally was used for T2K (procedure by Renee
Poutissou).  It is possible that not all steps are necessary and that there is a better way.
 But this worked for me.

Also, any objections from other developers to tweaking the assert checks in odb.c so that
the values are calculated automatically and MIDAS only needs to be touched in one place to
modify the number of open records?

Let me know if it worked for you and I'll add these instructions to the Wiki.

Thomas



> oOne additional comment. I was able to trace the setting of the error code DB_NO_MEMORY 
> to a call to the db_add_open_record() by mserver that is initiated during the start-up 
> of my frontend via an RPC call. I checked with a debug printout that I have indeed 
> reached the number of MAX_OPEN_RECORDS
> 
> > Hi Midas forum,
> > 
> > I'm having a problem with odb hotlinks after increasing sub-directories in an 
> > odb. I now get the error code DB_NO_MEMORY after some db_open_record() calls. I 
> > tried 
> > 
> > 1) increasing the parameter DEFAULT_ODB_SIZE in midas.h and make clean, make
> > but got the same error
> > 
> > 2) increasing the parameter  MAX_OPEN_RECORDS in midas.h and make clean, make
> > but got fatal errors from odbedit and my midas FE and couldnt run anything
> > 
> > 3) deleting my expts SHM files and starting odbedit with "odbedit -e SLAC -s 
> > 0x1000000" to increse the odb size but got the same error?
> > 
> > 4) I tried a different computer and got the same error code DB_NO_MEMORY
> > 
> > Maybe I running into some system limit that restricts the humber of open records? 
> > Or maybe I've not increased the correct midas parameter?
> > 
> > Best ,Tim.

The procedure I wrote seemed to work for Tim too, so I added a page to the wiki about it here:

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


> Hi Tim,
> 
> I reproduced your problem and then managed to go through a procedure to increase the number
> of allowable open records.  The following is the procedure that I used 
> 
> 1) Use odbedit to save current ODB
> 
> odbedit
> save current_odb.odb
> 
> 2) Stop all the running MIDAS processes, including mlogger and mserver using the web
> interface. Then stop mhttpd as well.
> 
> 
> 3) Remove your old ODB (we will recreate it after modifying MIDAS, using the backup you just
> made).
> 
> mv .ODB.SHM .ODB.SHM.20161104
> rm /dev/shm/thomas_ODB_SHM
> 
> 4) Make the following modifications to midas.  In this particular case I have increased the
> max number of open records from 256 to 1024.  You would need to change the constants if you
> want to change to other values
> 
> diff --git a/include/midas.h b/include/midas.h
> index 02b30dd..33be7be 100644
> --- a/include/midas.h
> +++ b/include/midas.h
> @@ -254,7 +254,7 @@ typedef std::vector<std::string> STRING_LIST;
> -#define MAX_OPEN_RECORDS       256           /**< number of open DB records   */
> +#define MAX_OPEN_RECORDS       1024           /**< number of open DB records   */
> diff --git a/src/odb.c b/src/odb.c
> index 47ace8f..ac1bef3 100755
> --- a/src/odb.c
> +++ b/src/odb.c
> @@ -699,8 +699,8 @@ static void db_validate_sizes()
> -   assert(sizeof(DATABASE_CLIENT) == 2112);
> -   assert(sizeof(DATABASE_HEADER) == 135232);
> +   assert(sizeof(DATABASE_CLIENT) == 8256);
> +   assert(sizeof(DATABASE_HEADER) == 528448);
> 
> The calculation is as follows (in case you want a different number of open records): 
> DATABASE_CLIENT = 64 + 8*MAX_OPEN_ERCORDS = 64 + 8*1024 = 8256
> DATABASE_HEADER = 64 + 64*DATABASE_CLIENT = 64 + 64*8256 = 528448
> 
> 5) Rebuild MIDAS
> 
> make clean; make
> 
> 6) Create new ODB
> 
> odbedit -s 1000000
> 
> Change the size of the ODB to whatever you want.
> 
> 7) reload your original ODB 
> 
> load  current_odb.odb
> 
> 8) Rebuild your frontend against new MIDAS; then it should work and you should be able to
> produce more open records.
> 
> 8.5*) Actually, I had a weird error where I needed to remove my .SYSTEM.SHM file as well
> when I first restarted my front-end.  Not sure if that was some unrelated error, but I
> mention it here for completeness.
> 
> This was a procedure based on something that originally was used for T2K (procedure by Renee
> Poutissou).  It is possible that not all steps are necessary and that there is a better way.
>  But this worked for me.
> 
> Also, any objections from other developers to tweaking the assert checks in odb.c so that
> the values are calculated automatically and MIDAS only needs to be touched in one place to
> modify the number of open records?
> 
> Let me know if it worked for you and I'll add these instructions to the Wiki.
> 
> Thomas
> 
> 
> 
> > oOne additional comment. I was able to trace the setting of the error code DB_NO_MEMORY 
> > to a call to the db_add_open_record() by mserver that is initiated during the start-up 
> > of my frontend via an RPC call. I checked with a debug printout that I have indeed 
> > reached the number of MAX_OPEN_RECORDS
> > 
> > > Hi Midas forum,
> > > 
> > > I'm having a problem with odb hotlinks after increasing sub-directories in an 
> > > odb. I now get the error code DB_NO_MEMORY after some db_open_record() calls. I 
> > > tried 
> > > 
> > > 1) increasing the parameter DEFAULT_ODB_SIZE in midas.h and make clean, make
> > > but got the same error
> > > 
> > > 2) increasing the parameter  MAX_OPEN_RECORDS in midas.h and make clean, make
> > > but got fatal errors from odbedit and my midas FE and couldnt run anything
> > > 
> > > 3) deleting my expts SHM files and starting odbedit with "odbedit -e SLAC -s 
> > > 0x1000000" to increse the odb size but got the same error?
> > > 
> > > 4) I tried a different computer and got the same error code DB_NO_MEMORY
> > > 
> > > Maybe I running into some system limit that restricts the humber of open records? 
> > > Or maybe I've not increased the correct midas parameter?
> > > 
> > > Best ,Tim.

Hello, 
I'm trying to make Wiener PCIVME link work with MIDAS. 
In documentation/VME dirvers/ it's saying: "wevmemm.c PCI/VME Wiener board
supported. (see Wiener PCI)".
Provided link is dead. Does anyone have that file? I would appreciate very very
much if someone could send it to me.

Thank you and best regards, 
L.P.

> Hello, 
> I'm trying to make Wiener PCIVME link work with MIDAS. 
> In documentation/VME dirvers/ it's saying: "wevmemm.c PCI/VME Wiener board
> supported. (see Wiener PCI)".
> Provided link is dead. Does anyone have that file? I would appreciate very very
> much if someone could send it to me.
> 
> Thank you and best regards, 
> L.P.

Hi, I am not familiar with this module, I am pretty sure I have never seen one.
I do not see any code for it in the midas distribution.
I do not see any reference to it on the wiener web site (http://www.wiener-d.com/)

For obsolete modules, they direct us to http://file.wiener-d.com/ which is dead.

The next best step is to contact Wiener customer support. They usually reply very quickly.

If you have no luck getting answer directly from Wiener, you can ask me to contact them through
our sales representative. He is always super very helpful.

K.O.

> > Hello, 
> > I'm trying to make Wiener PCIVME link work with MIDAS. 
> > In documentation/VME dirvers/ it's saying: "wevmemm.c PCI/VME Wiener 
board
> > supported. (see Wiener PCI)".
> > Provided link is dead. Does anyone have that file? I would appreciate 
very very
> > much if someone could send it to me.
> > 
> > Thank you and best regards, 
> > L.P.
> 
> Hi, I am not familiar with this module, I am pretty sure I have never 
seen one.
> I do not see any code for it in the midas distribution.
> I do not see any reference to it on the wiener web site 
(http://www.wiener-d.com/)
> 
> For obsolete modules, they direct us to http://file.wiener-d.com/ which 
is dead.
> 
> The next best step is to contact Wiener customer support. They usually 
reply very quickly.
> 
> If you have no luck getting answer directly from Wiener, you can ask me 
to contact them through
> our sales representative. He is always super very helpful.
> 
> K.O.

Hi, I do recall that we had this interface a while ago. 
I'll be meeting with Wiener during the weekend and will post my findings 
later. 
PAA 

odbinit is a new utility program to initialize new ODB and to recover from corrupted ODB.

Right now, midas odb has some strange properties different from typical behavior of other 
database packages:

a) a new odb of default size is automatically create run running *any* midas program (surprise: now 
way to specify the size of odb).
b) the size of ODB is not saved anywhere. If your experiment requires an ODB of big size, one 
always forgets to use "odbedit -s" when recovering from odb corruption, leading to massive 
confusion: nothing works, odb is corrupted? (maybe not), recreate odb (of default size instead of 
large size), reload odb, (reload fails, odb is too small), now really for sure nothing works. Been 
there, done that myself 100 times. Tired.
c) there is no midas tool to automatically recover from odb corruption (or any generic ODB 
malfunction, such as stuck ODB semaphore): shared memory has to be deleted, old .ODB.SHM 
has to be deleted, old semaphore has to be deleted. Some of these steps are different on Linux 
and MacOS (hello Apple, where is MacOS "ls -l /dev/shm"?!?).

The new odbinit tool corrects these problems:

1) ODB size is saved to .ODB_SIZE.TXT, then is used to recreate ODB after corruption recovery
2) "odbinit -s different_size_from_saved_size" will ask "are you sure?". No way to unintentionally 
change size of ODB.
3) if you already have an ODB, it will insist that you say "odbinit --cleanup"
4) there is a "-n" mode, to report what will be done, but "do nothing"
5) "odbinit --cleanup" tries very hard to recover from any and all possible ODB problems.
6) old .ODB.SHM is never deleted, always renamed to .ODB.SHM.timestamp
7) if "odbinit" gets to "Done!", you have a working ODB, 100% guaranteed, for sure.
8) output of "odbinit" is very verbose for pasting into this forum here to make it possible to debug 
your problem. (in the unlikely case odbinit fails).

Next step will be to remove the automatic creation of ODB (and event buffers) and require running 
"odbinit" to create a new experiment. ("odbedit -s nnn" will be removed).

But not today, as all that requires changes to the midas internal APIs: ss_shm_open() needs to 
return the size of connected shared memory, there needs to be ss_shm_create() and 
db_create_database(), etc.

This will make ODB to work more like a normal database: with a tool to create a new database and 
a tool to recover from corruption/malfunction.

K.O.

Dear friends,

We have some questions on using midas.
We use a Caen digitizer V1751 to take waveforms.
When testing with caen provided programs, we roughly know it can work fine at 1000 Hz event rate, and 30 M/s data can be written to disk.
The test with Midas, however, is a little confusing. We use CAENDigitizer library with Midas. First, it works, data were taken, and there seems no error.
The only problem is we cannot go to a higher event rate, for example we can only work on a rate of 40 Hz, and only 3 M/s data recording. Otherwise it will crush.

We may miss something really simple. Would you please give some suggestions? for example, other people's discussions or documents?

Thank you very much.

Dear friends,

I may add a little more information.
For polling event, we check the data-ready register for the status of the digitizer.
In the readout routine, we create a bank, readout the data and write it out.

We commented out or made some replacement for each part of the subroutines to figure our where exactly goes wrong.
for example, replace the readout from the digitizer with a random generation of some fake events.
By replacing the readout by a random generation, the program runs fine and reach a very high event rates.

Any suggestions or ideas from experts?

Thank you very much.

--
Best regards,
Zhe Wang


> Dear friends,
> 
> We have some questions on using midas.
> We use a Caen digitizer V1751 to take waveforms.
> When testing with caen provided programs, we roughly know it can work fine at 1000 Hz event rate, and 30 M/s data can be written to disk.
> The test with Midas, however, is a little confusing. We use CAENDigitizer library with Midas. First, it works, data were taken, and there seems no error.
> The only problem is we cannot go to a higher event rate, for example we can only work on a rate of 40 Hz, and only 3 M/s data recording. Otherwise it will crush.
> 
> We may miss something really simple. Would you please give some suggestions? for example, other people's discussions or documents?
> 
> Thank you very much.

Dear friends,

In case anyone need the source code, it is attached. 
We use optic fiber to connect to a VME controler, which talks to V1751 via VME bus.

--
Zhe Wang

> Dear friends,
> 
> I may add a little more information.
> For polling event, we check the data-ready register for the status of the digitizer.
> In the readout routine, we create a bank, readout the data and write it out.
> 
> We commented out or made some replacement for each part of the subroutines to figure our where exactly goes wrong.
> for example, replace the readout from the digitizer with a random generation of some fake events.
> By replacing the readout by a random generation, the program runs fine and reach a very high event rates.
> 
> Any suggestions or ideas from experts?
> 
> Thank you very much.
> 
> --
> Best regards,
> Zhe Wang
> 
> 
> > Dear friends,
> > 
> > We have some questions on using midas.
> > We use a Caen digitizer V1751 to take waveforms.
> > When testing with caen provided programs, we roughly know it can work fine at 1000 Hz event rate, and 30 M/s data can be written to disk.
> > The test with Midas, however, is a little confusing. We use CAENDigitizer library with Midas. First, it works, data were taken, and there seems no error.
> > The only problem is we cannot go to a higher event rate, for example we can only work on a rate of 40 Hz, and only 3 M/s data recording. Otherwise it will crush.
> > 
> > We may miss something really simple. Would you please give some suggestions? for example, other people's discussions or documents?
> > 
> > Thank you very much.

Somehow I don't understand why people's reply is only in my mail box.
So I pasted them here. I hope they don't mind and these information may be useful for others.

The following is some discussion.
==========================================================================================
> In read_trigger_event(), you creating a secondary bank with time in
> second. For your information, this time in second is already written in
> the event header. You can retrieve the time using macros from the
> midas.h   time = TIME_STAMP(pevent)

Removed.

>
> In frontend_init() you loop over NFADC (1) and call for each loop
> frontend_config() after opening the device on that card. In
> frontend_config() you redo a loop over NFADC, meaning that in case of
> more than one card you will find the second one not open on the first
> frontend_config (ok for one card though).
>

Corrected.

> In frontend_config() what is the return sCAEN from MallocReadoutBuffer()?
> What is the size of the requested allocated buffer?

The return size of allocated buffer is 134936.

>
> What is the value of the sCAEN from the ReadData() function in
> read_trigger_event()?

It is always 0 for success until it crashes.
However, even for the event it crashes, it also appears as 0.

>
> I didn't check all the config parameters!
>
> What is the value of count in the poll_event(). It is true if the test
> in poll_event() is too short, it cause timing corruption during
> calibration. 

Do you mean Midas timing calibration for poll_event() before all finally start up?
We havn't observed corruption at this stage.

> This never happen during CAMAC time... to be fixed!
> The alternative is to include a ss_sleep(1) instead of the prescale.
> a 1ms delay between every poll is short enough to ensure your 1KHz trigger.

We tried ss_sleep(1) in poll_event(), and it doesn't help.
We also tried add a ss_sleep(10) in the read_trigger_event().
This may work. But we can only reach 100 Hz and 1 MB/s rate. Still low.

>
> How long do you spend in the read_trigger_event()? To be measured.

We add some timers in this part of the program.
The time spent on CAEN_DGTZ_ReadData is about 100 us.
To sleep 1 ms in read_trigger_event may delay the crush, but just one minute.
To sleep 10 ms works.

>
> I still don't understand your setup as you mention using optic fiber to
> access the VME controller? do you have a A3818 or similar to the
> controller? If so why don't you connect directly the optic to the VX1751
> and prevent the use of the VME backplane?

Our connect is:
A2818 (PCI) - fiber - V2718 (Bridge) - VME - V1751
We probably need to configure other vme boards through VME at the same time,
however, these boards don't have a fiber connection.

We also tested direct fiber connect for V1751 today.
But it crashes with the same symptom.
==========================================================================================

Suggestion from John and my reply.

> We have achieved very high rates, but only with some care.

> The biggest issue was to make sure when you compile the CAEN driver for the A3818 board that you turn on the MIDAS switch.  Without that problems occur with some 
> probability given by the number of bytes processed - which translates into very soon if you have a high rate.  (The underlying cause is that both MIDAS and the A3818
> use unix Alarm signals, but the CAEN folks have a compile option to turn this off.)

> We use as little as possible of the CAENDigitizerLibrary - instead we program the registers directly on the board.

> There is still some kind of memory leak which we have not yet tracked down, so every few hours we shut down the frontend then restart it. 

We use A2818 (PCI) - fiber - V2718 (Bridge) - VME - V1751.
I actually didn't find a MIDAS switch in the Makefile.

More suggestions from John and my reply.

> we also don't use the VME back plane - it's just too slow - mixing VME commands to plain modules and digitizer modules is unreliable....

> We use CAEN fiberoptic version 2 to talk to the digitizers directly, we have upto 12 digitizers, and can use all channels for several hours, and can fill to about 75% 
of the A3818 bandwidth... 

So far we are limitted to 30 MB/s, if tested with CAEN examples, for example, the wavedump program by CAEN.
I think is kind of the limit by IDE hard drive.
Unfortunately we are still far from that limit, only ~ 1 MB/s now.  :(

> 
> More suggestions from John and my reply.
> 
> > we also don't use the VME back plane - it's just too slow - mixing VME commands to plain modules and digitizer modules is unreliable....
> 
> > We use CAEN fiberoptic version 2 to talk to the digitizers directly, we have upto 12 digitizers, and can use all channels for several hours, and can fill to about 75% 
> of the A3818 bandwidth... 
> 
> So far we are limitted to 30 MB/s, if tested with CAEN examples, for example, the wavedump program by CAEN.
> I think is kind of the limit by IDE hard drive.
> Unfortunately we are still far from that limit, only ~ 1 MB/s now.  :(
>

From writing MIDAS frontends for many years, I am starting to form an opinion that this type of problem is undebuggable
in the current midas frontend framework - it is impossible to separate problems in vendor-supplied libraries and linux kernel modules
from problems with midas (i.e. incorrectly created data banks, too-small event buffers getting full) from problems with
bad interaction (collision over the SIGALARM handlers).

I am pondering on a new scheme for midas frontend writing. Perhaps such a new scheme should have a "no midas" mode where you can
compile and link a midas frontend "without midas", leaving you to debug just your code and the vendor code and their interactions.

K.O.

Midas has a nice alarm system. I am wondering whether it is easily possible to
get the Alarm/Warning banner also on top of custom pages?!

> Midas has a nice alarm system. I am wondering whether it is easily possible to
> get the Alarm/Warning banner also on top of custom pages?!

K.O. made nice JavaScript routines to access the alarm status. The new alarm page is completely 
made dynamically from JavaScript code (mhttpd does not supply any HTML code any more, only 
functions to obtain ODB values etc). Part of this new dynamic page must be some code to display 
the alarm status. You just need to copy this to your custom page. K.O. can tell you details.

Stefan

> > Midas has a nice alarm system. I am wondering whether it is easily possible to
> > get the Alarm/Warning banner also on top of custom pages?!
> 
> K.O. made nice JavaScript routines to access the alarm status. The new alarm page is completely 
> made dynamically from JavaScript code (mhttpd does not supply any HTML code any more, only 
> functions to obtain ODB values etc). Part of this new dynamic page must be some code to display 
> the alarm status. You just need to copy this to your custom page. K.O. can tell you details.
> 

Yes, please look at resources/alarm.html and the "get_alarms" JSON-RPC method. The "get_alarms" example in 
resources/example.html probably already does exactly what you need. Also note the presence of "al_reset_alarm" and 
"al_trigger_alarm" JSON_RPC methods.

K.O.

I recently needed to watch the Midas messages for a particular error - and 
thus needed a command to "get all the messages since a time t".

The documentation (https://midas.triumf.ca/MidasWiki/index.php/AJAX#jmsg) 
documents a way to "get the most recent n messages" - but when I dug into the 
code, I was delighted to find that the existing Midas code also supports the 
"get all messages since t" query.

For the "get all messages since t" query, the parameter t should be the unix 
timestamp in seconds, and the parameter n should be zero: curl -X GET 
"http://localhost:8081/?cmd=jmsg&n=0&t=1473437918".

Pretty useful!  Perhaps this should be added to the AJAX documentation?

> I recently needed to watch the Midas messages for a particular error - and 
> thus needed a command to "get all the messages since a time t".
> 
> The documentation (https://midas.triumf.ca/MidasWiki/index.php/AJAX#jmsg) 
> documents a way to "get the most recent n messages" - but when I dug into the 
> code, I was delighted to find that the existing Midas code also supports the 
> "get all messages since t" query.
> 
> For the "get all messages since t" query, the parameter t should be the unix 
> timestamp in seconds, and the parameter n should be zero: curl -X GET 
> "http://localhost:8081/?cmd=jmsg&n=0&t=1473437918".
> 
> Pretty useful!  Perhaps this should be added to the AJAX documentation?

The "jmsg" methods are obsolete - please use the JSON-RPC method "cm_msg_retrieve" as shown in resources/example.html. It takes all the same parameters as the midas.h 
cm_msg_retrieve() function, see the snipped from example.html below.

To see the full list of JSON-RPC methods, go to the "help" page and press the button for "json-rpc schema in text table format".

The entry for "cm_msg_retrieve" has this:

------------------------------------------------------------------------------------
cm_msg_retrieve?      | Retrieve midas messages using cm_msg_retrieve2()
                      | ------------------------------------------------------------
                      | params   | facility?           | string         | message facility, default is "midas"
                      |          | min_messages?       | integer        | get at least this many messages, default is 1
                      |          | time?               | number         | start from given timestamp, value 0 means give me newest messages, default is 0
                      | ------------------------------------------------------------
                      | result   | num_messages        | integer        | number of messages returned
                      |          | messages            | string         | messages separated by \n
                      |          | status              | integer        | return status of cm_msg_retrieve2()
------------------------------------------------------------------------------------

Snippet from resources/example.html: (to add "time" parameter, put "time":12345 next to "min_messages").

<input type=button value='Get last 10 midas messages'
          onClick='mjsonrpc_call("cm_msg_retrieve", { "min_messages": 10 })
                   .then(function(rpc) {
                   document.getElementById("cm_msg_retrieve_num_messages").innerHTML = JSON.stringify(rpc.result.num_messages);
                   document.getElementById("cm_msg_retrieve_messages").innerHTML = JSON.stringify(rpc.result.messages);
                   //mjsonrpc_debug_alert(rpc);
                   })
                   .catch(function(error) {
                   mjsonrpc_error_alert(error);
                   });'></input>

latest version of mongoose web server library (v6.4) is now implemented in midas. To try it out, edit 
the Makefile, comment-out USE_MONGOOSE4, uncomment USE_MONGOOSE6, make clean, 
make.

After some more testing mongoose v6 will be made the default. (if you see problems, please report 
them here).

Main user-visible change is implementation of pipelined http requests, where the same socket 
connection is reused for many requests (instead of opening a new connection for each request). 
This is supposed to significantly speed up things like ajax requests over https (ssl handshake is 
done only once). (As a buglet, some midas web pages do not generated the "ContentLength" 
header, and force connection reset).

Special features: (implemented in mhttpd.cxx)

- https support (same as mongoose v4)
- https score A- at SSLlabs (if ignore whining about self-signed certificate)
- CORS support (same as v4) (cross-origin AJAX requests - web pages loaded from some other 
web server can make requests into midas)
- password protection (same as v4, uses http digest authentication)
- http-to-https redirect (same as v4)
- setuid-root mode for binding to port 80 (special request from PSI).

K.O.

> latest version of mongoose web server library (v6.4) is now implemented in midas.

A number of bugs were found in the mongoose v6 implementation of HTTP digest authentication:

- unusual URL in the form "https://blah:8443/?" (notice trailing "?") were rejected. These URLs are sometimes generated by 
MIDAS.
- URLs longer than 200 bytes were rejected
- a check for matching URIs between the HTTP request and in digest authentication was missing (required by specs)

If you are using mhttpd with mongoose v6 https, please update mhttpd.cxx to the latest version.

We continue to recommend that mhttpd be used behind a proper HTTPS proxy with password protection (i.e. apache httpd).

mongoose v4 does not seem to have the same bugs, old server does not support https so does not have these bugs.

K.O.

Since updating to the most recent midas commit, we get the following error if we try running mhttpd without su privileges: 

>mhttpd -e CR --http 8081
mhttpd is running in setuid-root mode.
mhttpd is listening on port 80
Mongoose version 4 cannot listen to port 80 in setuid mode. Please use mongoose version 6. Sorry, bye!
[mhttpd,ERROR] [midas.c:1960:,ERROR] cm_disconnect_experiment not called at end of program

It works if we run it as root, but that creates other problems. Is there a flag to turn off setuid-root mode? Or some other fix?

Thanks,
Wes

> Since updating to the most recent midas commit, we get the following error if we try running mhttpd without su privileges: 
> 
> >mhttpd -e CR --http 8081
> mhttpd is running in setuid-root mode.
> mhttpd is listening on port 80
> Mongoose version 4 cannot listen to port 80 in setuid mode. Please use mongoose version 6. Sorry, bye!
> [mhttpd,ERROR] [midas.c:1960:,ERROR] cm_disconnect_experiment not called at end of program
> 
> It works if we run it as root, but that creates other problems. Is there a flag to turn off setuid-root mode? Or some other fix?
> 


From these messages, it looks like you really are using the setuid-root mode. And indeed it is not usable with the mongoose version 4 implementation in MIDAS.

I can suggest several fixes:

1) the setuid-root mode was only ever intended for use at PSI because of peculiar network configuration of the PSI corporate firewall. It is not intended for general 
use.
1a) I as an author of MIDAS recommend against using the setuid-root mode and against installing mhttpd as setuid-root because it is not secure. (normally you 
would run mhttpd behind an apache https proxy providing https encryption and password protection).
1b) if you follow the midas installation instructions at https://midas.triumf.a you will see that we do not login as root and run "make install" to install mhttpd as 
setuid-root.
1c) if you follow these instructions, or if you run mhttpd from the midas build directory ($MIDASSYS/linux/bin/mhttpd), the setuid-root mode will not activate and 
everything will work ok.

2) you can run in the "old server" mode, but this more does not implement the JSON-RPC methods, so the "programs" and "alarms" pages will not work.
3) you can build mhttpd with the mongoose version 6 implementation, it will work even with the setuid-root mode. To do this, edit the Makefile, comment-out 
"USE_MONGOOSE4=1" and uncomment "USE_MONGOOSE6=1", then make clean, make.

K.O.

We have started a new elog for discussions of the ROOTANA MIDAS analyzer package
[1], which is used at TRIUMF and elsewhere for quick displays of MIDAS data. 
The forum is available here

https://midas.triumf.ca/elog/Rootana

I would note that we have recently finished implementing a system in rootana for
easy web displays of MIDAS data, using ROOT's THttpServer to post histograms. 
Details on this new scheme are here

https://midas.triumf.ca/elog/Rootana/1

and

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

Please sign up for the forum if you are interested in getting ROOTANA-related
discussions.

Thomas

[1] https://midas.triumf.ca/MidasWiki/index.php/ROOTANA

> We have started a new elog for discussions of the ROOTANA MIDAS analyzer package

Posting there is almost like talking to oneself - barely anybody is subscribed, not even me.

Hence this reminder.

If you use ROOTANA, click the "config" link, then click the "rootana" checkbutton, then "save".

K.O.

The code for the new pure html and javascript web pages was merged into main midas.

In this release, the "programs" and "alarms" pages are implemented as html files, see 
resources/programs.html and alarms.html.

Eventually we hope to implement all midas web pages in html, so this is just a start.

If you see problems with the new html code, you can revert to the old mhttpd-generated web 
pages by removing the files programs.html and alarms.html.

The new code for starting and stopping runs (start.html and transition.html) is also merged, but not 
yet enabled, pending a few more tests.

K.O.

I removed the example ssl certificate from the midas git repository (ssl_cert.pem). Now every midas 
installation must generate their own certificate - because to have any security at all each encryption 
private key has to be unique (and it has to be secret).

The command for generating a self-signed certificate is printed by mhttpd on startup:

openssl req -new -nodes -newkey rsa:2048 -sha256 -out ssl_cert.csr -keyout ssl_cert.key; openssl 
x509 -req -days 365 -sha256 -in ssl_cert.csr -signkey ssl_cert.key -out ssl_cert.pem; cat 
ssl_cert.key >> ssl_cert.pem

K.O.

mhttpd running as non-root cannot bind to standard https port 443. By default, mhttpd uses port 
8443 and it works just fine, but some applications such as the SSLlabs https tester insist on using 
port 443.

To connect mhttpd with port 443, I use the tcpproxy package from
git://git.spreadspace.org/tcpproxy.git

./tcpproxy -D -U -p 443 -r localhost4 -o 8443

(you can run this from rc.local)

(to remember, for best security one should run mhttpd behind an industry-standard https proxy)

K.O.

I recently upgraded my macbook to MacOS 10.11.  The compilation of MIDAS failed after the upgrade, 
complaining about  

gcc  -c -g -O2 -Wall <snip> src/mongoose.c
src/mongoose.c:322:10: fatal error: 'openssl/ssl.h' file not found

It seems that MacOS has now fully removed openssl header files (they were deprecated for a while).  There 
seems to be some notes on that here

http://lists.apple.com/archives/macnetworkprog/2015/Jun/msg00025.html

Konstantin suggested installing open-source builds of openssl using MacPorts.  I did that and MIDAS 
compiled fine.  I documented the procedure here:

https://midas.triumf.ca/MidasWiki/index.php/Installation/Compilation_problems#MacOS_10.11_.28El_Capitan.2
9_openssl_errors

> I recently upgraded my macbook to MacOS 10.11.  The compilation of MIDAS failed after the upgrade, 
> complaining about  
> 
> gcc  -c -g -O2 -Wall <snip> src/mongoose.c
> src/mongoose.c:322:10: fatal error: 'openssl/ssl.h' file not found
> 
> It seems that MacOS has now fully removed openssl header files (they were deprecated for a while).  There 
> seems to be some notes on that here
> 
> http://lists.apple.com/archives/macnetworkprog/2015/Jun/msg00025.html
> 
> Konstantin suggested installing open-source builds of openssl using MacPorts.  I did that and MIDAS 
> compiled fine.  I documented the procedure here:
> 
> https://midas.triumf.ca/MidasWiki/index.php/Installation/Compilation_problems#MacOS_10.11_.28El_Capitan.2
> 9_openssl_errors

The MIDAS Wiki page points to https://guide.macports.org/  which covers OSX up to 10.9. Installers for 10.10 and the current 10.11 
(El Captain) can be found here: https://www.macports.org/install.php

Stefan

> I recently upgraded my macbook to MacOS 10.11. 
> [ and midas would not compile ]
> It seems that MacOS has now fully removed openssl ...

My read of tea leaves - the macos version of openssl was so old it was almost useless, did not support any of the modern HTTPS 
features. So to use mhttpd with https you pretty much had to install openssl from macports anyway. For macos 10.11 maybe they 
looked at upgrading to newer version, but since the openssl kerfuffle last year, there is several forks of openssl (the OpenBSD fork 
named libressl is the best, IMO), so rather than picking and choosing, they deleted the whole thing.

Now back to MIDAS.

We use the mongoose web server module and I have expected by now for them to make a move on improving HTTPS support, but no 
move happened.

Right now mongoose support OpenSSL only (I would expect the OpenBSD LibreSSL fork to work to of the box, too). Other then that, 
they have:
a) their own mickey-mouse https library (krypton) which does not support any modern cryptography (RC4 only - when RC4 is known to 
be useless).
b) an adapter library (polar) for interfacing with PolarSSL (mbedtls)

At this point I would rather abandon the implicit dependency on the system-provided openssl and have an explicit dependancy on a 
modern https crypto library.

Option (b) would work for us - 
1) add "git clone mbedtls; cd mbedtls; make" to midas build instructions
2) add polarssl_compat.c to midas git (from cessanta/polar repo)
3) retest mhttpd against ssllabs https scanner, retest against all web browsers.

The downside of this route is loss of automatic nightly updates to the https crypto library (for better or for worse).

K.O.

P.S. Because on MacOS use of openssl from macports is pretty much required, it should be moved from the "tricks" page to the 
standard midas installation instructions ("install required packages").

Can the MIDAS Sequencer call an external script? It seems that it should be able to. I have a simple 
test script to do so. It claims to execute, but the bash script never appears to be executed. Any 
suggestions?

1 COMMENT "This is a MSL test file"
  2 RUNDESCRIPTION "Test run"
  3 
  4 LOOP setting, 1,2, 3
  5      SCRIPT test_wheel.sh ,$setting 
  6      TRANSITION START
  7      WAIT Seconds 10
  8      TRANSITION STOP
  9 ENDLOOP

I've also tried using an xml script with <Script params="1">test_wheel.sh</Script>, but with the same 
result.

Thanks!

Nevermind. I just had to give it a path to my script. Now it's fine. 

> Can the MIDAS Sequencer call an external script? It seems that it should be able to. I have a simple 
> test script to do so. It claims to execute, but the bash script never appears to be executed. Any 
> suggestions?
> 
> 1 COMMENT "This is a MSL test file"
>   2 RUNDESCRIPTION "Test run"
>   3 
>   4 LOOP setting, 1,2, 3
>   5      SCRIPT test_wheel.sh ,$setting 
>   6      TRANSITION START
>   7      WAIT Seconds 10
>   8      TRANSITION STOP
>   9 ENDLOOP
> 
> I've also tried using an xml script with <Script params="1">test_wheel.sh</Script>, but with the same 
> result.
> 
> Thanks!