| Subject | RE: [IBO] ConnectionWasLost Property |
|---|---|
| Author | Eric Tishler |
| Post date | 2004-03-23T15:46:34Z |
I has a solution that seems to work most of the time (95%). There is, however a small window in which a connection lost immediately following a successful reconnection, seems to cause as problem. This question is still pending to the forum since last week. (#30111 submitted Monday March 15)
My solution involves created a thread which repeated attempts reconnection in the background approximate once every 15 seconds.
You should probably have a data module with IB_Connection, IB_Transaction and IB_Session set up to start with.
I first create a hook to the IB_ConnectionError event for my IB_Connection object. In this handler I test the error code that cause this handler to be invoked in the first place with:
if IB_Session.ConnectionLostErrCode(ErrCode) then
begin
// code to start thread here ...
Thread.resume;
end;
I start my thread suspended and then resume it, once the connection error is detected. There is some code I am not showing here to keep the discussion simple. However, once the thread is started I loop once every 15 seconds attempting a reconnect something like this:
While not Application.Terminated and IB_Connection.ConnectionWasLost do
begin
sleep(15000);
try
IB_Connection.Connect; // Will get a connection
If not IB_Connection.ConnectionWasLost then
begin
suspend;
end;
except
// on e: exception do
// DebugLog(E.Message);
end;
end;
Once the thread has reconnected I was told I have to release this connection and reestablish the connection in my main code (out of the thread). This is because the thread has its own instance of IB_Connection.
So, once back in the main code, and in a state where I know I can reconnect, I execute the following code:
try
IB_Connection.Connect;
IB_Connection.VerifyConnection;
DbConnectionLost := IB_Connection.ConnectionWasLost;
except
end;
(Where DbConnectionLost is one of the global Booleans I use to control the flow in my application)
The above code re-establishes the connection for the original IB_Connection object.
I know this is complicated, and it took some Windows messaging as well as some global Boolean flags, but I hope this helps ...
BTW - Helen, Jason, I invite your participation in this discussion (or anyone else in the forum who has accomplished this 100% successfully)
Eric Tishler
Software Architect
Resolute Partners, LLC
Phone: 203.271.1122
Fax: 203.271.1460
etishler@...
-----Original Message-----
From: Matt Nielsen [mailto:mnielsen@...]
Sent: Tuesday, March 23, 2004 10:05 AM
To: IBObjects@yahoogroups.com
Subject: Re: [IBO] ConnectionWasLost Property
Thanks for the info. I guess my help file is out of date.
Can someone give some help on the other part of my question. How do
I recover from an error "connection forcibly closed by the remote
host" error# 335544721 after the database has come back.
Thanks,
Matt
--- In IBObjects@yahoogroups.com, "Eric Tishler" <etishler@r...>
wrote:
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click here
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without the need for BDE, ODBC or any other layer.
___________________________________________________________________________
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[Non-text portions of this message have been removed]
My solution involves created a thread which repeated attempts reconnection in the background approximate once every 15 seconds.
You should probably have a data module with IB_Connection, IB_Transaction and IB_Session set up to start with.
I first create a hook to the IB_ConnectionError event for my IB_Connection object. In this handler I test the error code that cause this handler to be invoked in the first place with:
if IB_Session.ConnectionLostErrCode(ErrCode) then
begin
// code to start thread here ...
Thread.resume;
end;
I start my thread suspended and then resume it, once the connection error is detected. There is some code I am not showing here to keep the discussion simple. However, once the thread is started I loop once every 15 seconds attempting a reconnect something like this:
While not Application.Terminated and IB_Connection.ConnectionWasLost do
begin
sleep(15000);
try
IB_Connection.Connect; // Will get a connection
If not IB_Connection.ConnectionWasLost then
begin
suspend;
end;
except
// on e: exception do
// DebugLog(E.Message);
end;
end;
Once the thread has reconnected I was told I have to release this connection and reestablish the connection in my main code (out of the thread). This is because the thread has its own instance of IB_Connection.
So, once back in the main code, and in a state where I know I can reconnect, I execute the following code:
try
IB_Connection.Connect;
IB_Connection.VerifyConnection;
DbConnectionLost := IB_Connection.ConnectionWasLost;
except
end;
(Where DbConnectionLost is one of the global Booleans I use to control the flow in my application)
The above code re-establishes the connection for the original IB_Connection object.
I know this is complicated, and it took some Windows messaging as well as some global Boolean flags, but I hope this helps ...
BTW - Helen, Jason, I invite your participation in this discussion (or anyone else in the forum who has accomplished this 100% successfully)
Eric Tishler
Software Architect
Resolute Partners, LLC
Phone: 203.271.1122
Fax: 203.271.1460
etishler@...
-----Original Message-----
From: Matt Nielsen [mailto:mnielsen@...]
Sent: Tuesday, March 23, 2004 10:05 AM
To: IBObjects@yahoogroups.com
Subject: Re: [IBO] ConnectionWasLost Property
Thanks for the info. I guess my help file is out of date.
Can someone give some help on the other part of my question. How do
I recover from an error "connection forcibly closed by the remote
host" error# 335544721 after the database has come back.
Thanks,
Matt
--- In IBObjects@yahoogroups.com, "Eric Tishler" <etishler@r...>
wrote:
> Direct from the IBO help file:connection to the database
>
> Flag to indicate if a connection was lost.
> Applies to
> TIB_Connection
> Declaration
> property ConnectionWasLost: boolean;
>
> It is true only when the TIB_Connection object has lost it's
>restart
> Eric Tishler
> Software Architect
> Resolute Partners, LLC
> Phone: 203.271.1122
> Fax: 203.271.1460
> etishler@r...
>
> -----Original Message-----
> From: Matt Nielsen [mailto:mnielsen@c...]
> Sent: Monday, March 22, 2004 4:17 PM
> To: IBObjects@yahoogroups.com
> Subject: [IBO] ConnectionWasLost Property
>
> What is the ConnectionWasLost property on the Database component
> for?
>
> I have a situation where a Service Application connects to the
> database when it starts but the database server may have been re-
> booted or the database service may have re-started and I need to be
> able to recover from a "connection forcibly closed by the remote
> host" error# 335544721 in my service so that I don't have to
> the service.______________________________________________________________________
>
> Thanks for the help,
>
> Matt
>
>
>
>
>
_____
> IB Objects - direct, complete, custom connectivity to Firebird orInterBase
> without the need for BDE, ODBC or any other layer.______________________________________________________________________
>
_____
> http://www.ibobjects.com - your IBO community resource for TechInfo papers,
> keyword-searchable FAQ, community code contributions andmore !
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IB Objects - direct, complete, custom connectivity to Firebird or InterBase
without the need for BDE, ODBC or any other layer.
___________________________________________________________________________
http://www.ibobjects.com - your IBO community resource for Tech Info papers,
keyword-searchable FAQ, community code contributions and more !
_____
Yahoo! Groups Links
* To visit your group on the web, go to:
http://groups.yahoo.com/group/IBObjects/
* To unsubscribe from this group, send an email to:
IBObjects-unsubscribe@yahoogroups.com <mailto:IBObjects-unsubscribe@yahoogroups.com?subject=Unsubscribe>
* Your use of Yahoo! Groups is subject to the Yahoo! Terms of <http://docs.yahoo.com/info/terms/> Service.
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