[Freeswitch-users] Spidermonkey ODBC

Mon Feb 25 17:31:13 PST 2008

This is quite the thread. Maybe we can generate this enthusiasm for other aspects of the project as well.

Does anyone want to volunteer to test the code by using 
the odbc in both the sofia module as the reg db and from javascript
in some random application and simulate the db going down using odbc against several popular db variants and finding the best code to make sure that nothing goes wrong? I am more than happy to accept the result of such a vigorous endeavor over just speculation about what's best.

I have to do most of the code you see here by myself so I have limited
time to devote to certain aspects so please let me know if anyone wants to adopt some tasks and help make the project better.

Anthony Minessale II

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----- Original Message ----
From: Łukasz Zwierko <lzwierko at gmail.com>
To: freeswitch-users at lists.freeswitch.org
Sent: Wednesday, February 20, 2008 8:51:51 AM
Subject: Re: [Freeswitch-users] Spidermonkey ODBC

Hi,

I think you guys have a wrong approach to this issue, as far as I'm concerned, a well written application should have clear distinction between connection layer and sql layer. What I mean is that if application wants to do a query to DB, than handling issues like dropped connection should not be mixed with inserts/selects. 

So, for example, there should exist a separate layer  which is responsible for generating queries, and separate layer which actually makes the query, handles errors and optionally, repeats the query or insert (refer to java spring/hibernate - quite heavy java engines).

This way you could avoid any "select 1" or such like stuff every time you want to do a transaction to DB.
Still you feel that "select 1" is a better choice, but not all DB support it, you could just make an assumption, that in each DB there shall exist a table with just one column and row, and make a query to it (can call it KeepAliveTable).

Still, in my opinion the application should not test the connection each time it wants to make a transaction as the overhead will be huge.

Łukasz

2008/2/20, Anthony Minessale <anthmct at yahoo.com>:
Many databases break silently or the connection drops
without any way to know for sure w/o trying to use it.

I choose to ensure in the core that the data is connected.

executing "select 1" is a small price to pay to make sure
that the database is connected considering the importance
of persistent connectivity in the sip, jingle and call
limit databases as well as the javascript that rely on it.

All of those applications to make the safe
assumption that the core will keep the db connected and
to change that would be drastic behavior change and 
destabilize the code on the eve of our release.

Therefore i guess we should focus on better heuristics
to detect firebird, preferably based on the driver name
and not by doing a 2nd sql stmt every
 time.

Anthony Minessale II

FreeSWITCH http://www.freeswitch.org/

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MSN:anthony_minessale at hotmail.com

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----- Original Message ----
From: David Revill <davidrevill at datarun.co.uk>

To: freeswitch-users at lists.freeswitch.org
Sent: Tuesday, February 19, 2008 4:37:28
 PM
Subject: Re: [Freeswitch-users] Spidermonkey ODBC

Unfortunately, there isn't a universal ansi sql 
stmt that will do it as the only statements which can be guaranteed to follow 
the ansi standard are the simple select, update and delete statements which rely 
on knowing some table name .  

I think we are trying to solve a problem which need 
not exist. The Javascript application should handle the idle timeout. It 
should close the connection if it will not be using it for a while, 
and,if it needs to, can do what db_is_up is attempting to do in the 
application code. Testing for connection before every query seems an 
unneccessary overhead. 

  ----- Original Message ----- 

From: 
  Anthony 
  Minessale 

  To: freeswitch-users at lists.freeswitch.org 

  Sent: Tuesday, February 19, 2008 6:38 
  PM

  Subject: Re: [Freeswitch-users] 
  Spidermonkey ODBC

  is 
  there some universal ansi sql stmt that is small and harmless
but is 
  supported by everything? to replace "select 1"

  Anthony Minessale II

FreeSWITCH http://www.freeswitch.org/
ClueCon http://www.cluecon.com/

AIM: 
  anthm
MSN:anthony_minessale at hotmail.com
GTALK/JABBER/PAYPAL:anthony.minessale at gmail.com

IRC: 
  irc.freenode.net #freeswitch

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  Conference
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  ----- 
  Original Message ----
From: David Revill 
  <davidrevill at datarun.co.uk>
To: 
  freeswitch-users at lists.freeswitch.org
Sent: Tuesday, February 19, 2008 
  6:56:31 AM
Subject: Re: [Freeswitch-users] Spidermonkey ODBC

  One way to detect firebird would be to put the 
  'Select first 1  * from RDB$relations' into switch_odbc_handle_connect. 
  If it succeeds then it is Firebird. A better query might be 'select * from 
  rdb$database' as the system table rdb$database only ever has 1 
  record.

    ----- 
    Original Message ----- 

From: 
    Jonas 
    Gauffin 

    To: 
    freeswitch-users at lists.freeswitch.org 

    Sent: 
    Tuesday, February 19, 2008 12:18 PM

    Subject: 
    Re: [Freeswitch-users] Spidermonkey ODBC

I''ve only tested it with firebird on windows. As you said, 
    your driver name doesnt match any of the names I used to detect if it's 
    firebird.

The problem is that most databases supports "SELECT 1" as a 
    query. It will always be successful if the the connection is up. However, 
    firebird did not support "SELECT 1" and therefore i did query the system 
    database instead.

If the firebird check fails, it will try to invoke 
    "SELECT 1", and on firebird that query will fail. And the failure is 
    interpreted as the connection is down, and therefore it tries to 
    reconnect.

That's probably why you get that error. If you have any 
    other idea on how I can detect if it's a firebird db, please let me know and 
    i'll fix the odbc code.

    On Feb 19, 2008 1:05 PM, David Revill <davidrevill at datarun.co.uk> 
    wrote:

      That's a fair point, but db_is_up is only 
      called in 2 places and the attempted re-connect could be done if the 
      exec'd query fails. That way it would not be dependant on the name of the 
      driver.

      In my application, the database was queried 
      at the beginning of the script and the connection closed. It was 
      explicitly re-connected at the end to post data, so the connection timeout 
      was not an issue.

        ----- 
        Original Message ----- 

From: 
        Jonas Gauffin 

        To: 
        freeswitch-users at lists.freeswitch.org 

        Sent: 
        Tuesday, February 19, 2008 10:35 AM

        Subject: 
        Re: [Freeswitch-users] Spidermonkey ODBC

I did that code a couple of months ago.
The function 
        was added since connections are closed if they are idle too long, and 
        they were not reconnected again if that happened.

        On Feb 19, 2008 11:22 AM, David Revill <davidrevill at datarun.co.uk> 
        wrote:

          The problem is in switch_odbc.c function 
          db_is_up. It assumes that the variable is_firebird is true, but the 
          setting of this variable assumes that the Firebird driver name has 
          'FIREBIRD', 'FB64' or 'FB32' in it.

          I commented out  the code in 
          db_is_up and just returned a true value, as on closer inspection 
          could not see the point of this function.

          David Revill

            ----- 
            Original Message ----- 

From: 
            David Revill 

            To: 
            freeswitch-users at lists.freeswitch.org 

            Sent: 
            Tuesday, February 19, 2008 8:58 AM

            Subject: 
            Re: [Freeswitch-users] Spidermonkey ODBC

            I spotted this error a few months ago, 
            and to my shame did not let everyone know.  I have since 
            archived the project so cannot point you to the actual code. 
            However, the problem is  that it assumes the name of the 
            Firebird Driver (FB64?)  to set a boolean, so that it handle 
            the connection test differently.

            When looking at the actual code, I 
            actually felt that the connection test was redundant, as all it did 
            was a select from a system table. This meant it was doing two 
            queries for everyone required. (One to see if it could do a query, 
            and then one to do it). I therefore commented the connection test 
            function out.

            regards

            David Revill

              ----- 
              Original Message ----- 

From: 
              Steven Brown 

              To: 
              freeswitch-users at lists.freeswitch.org 

              Sent: 
              Monday, February 18, 2008 11:34 PM

              Subject: 
              [Freeswitch-users] Spidermonkey ODBC

              Hi,

              I'm experimenting with 
              spidermonkey for JavaScript call control, the basics seem 
              fine and I'm now trying to connect to an existing Firebird 
              database, the Firebird odbc lib is installed ok as is unixODBC and 
              I can confirm this and access the db no problem with isql, 
              something strange happens though when I connect in spidermonkey, 
              basically the odbc connection is made successfully, but then as 
              soon as I call either exec or query the odbc connection starts to 
              drop and re-connect continuously, 

              the isql output is below 

              isql -v 
              test
+---------------------------------------+
| 
              Connected!                            
              |
|                                       
              |
| 
              sql-statement                         
              |
| help 
              [tablename]                      
              |
| 
              quit                                  
              |
|                                       
              |
+---------------------------------------+
SQL> select 
              first 1 * from 
              pool_phones
+---------------------+------------+
| 
              GSMNO               
              | ORGNO      
              |
+---------------------+------------+
| 
              0712345678         | 
              1          
              |
+---------------------+------------+
SQLRowCount returns 
              1
1 rows fetched
SQL>

              however the following test code 
              calling the same query

              use("ODBC");

              var db = new 
              ODBC("test","SYSDBA","masterkey");
db.connect();
db.query("select 
              first 1 *  from pool_phones");

              db.nextRow();

              row = 
              db.getData();
console_log("INFO","HELLO " +  row["GSMNO"] 
               + "\n");

              exit();

              gives the following output and then 
              just loops disconnecting and reconnecting until I shutdown 
              freeswitch

              2008-02-18 23:26:03 [DEBUG] 
              switch_core_state_machine.c:144 switch_core_standard_on_execute() 
              sofia/default/1000 at 192.168.0.7:5060 Execute 
              javascript(/usr/scripts/test1.js)
2008-02-18 23:26:03 [DEBUG] 
              mod_spidermonkey.c:3150 js_api_use() Loading ODBC
2008-02-18 
              23:26:03 [DEBUG] switch_odbc.c:145 switch_odbc_handle_connect() 
              Connecting test
2008-02-18 23:26:03 [DEBUG] switch_odbc.c:174 
              switch_odbc_handle_connect() Connected to [test]
2008-02-18 
              23:26:03 [DEBUG] switch_odbc.c:95 switch_odbc_handle_disconnect() 
              Disconnected 0 from [test]
2008-02-18 23:26:03 [DEBUG] 
              switch_odbc.c:142 switch_odbc_handle_connect() Re-connecting 
              test
2008-02-18 23:26:03 [DEBUG] switch_odbc.c:145 
              switch_odbc_handle_connect() Connecting test
2008-02-18 
              23:26:03 [DEBUG] switch_odbc.c:174 switch_odbc_handle_connect() 
              Connected to [test]
2008-02-18 23:26:03 [CRIT] 
              switch_odbc.c:234 db_is_up() The sql server is not responding for 
              DSN test []
2008-02-18 23:26:03 [INFO] switch_odbc.c:239 
              db_is_up() The connection has been re-established

              ...

              Any ideas much appreciated

              Thanks

              Steve

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