RE: xPL-Issue

["Ian Lowe" <ian.lowe@xxxxxxxxxxxxxxxxxx>]

This particular problem simply didn't happen when a separate hub was
mandated - the appearance of the v3 library which allows apps to be a
hub in and of themselves introduced  the scenario (which, as you say,
seems to be coming up more and more now) where the order of services
starting matters. Not ever time, but often enough to cause the issues
that Frank and I have seen.

As I see it, there are one of two things at play - either there is a
simple bug within the v3 code which causes it's hub to not work
correctly, in which case it probably needs an effort from all users to
help Tom find the issue by gathering as much info as possible - the
circumstances of failure, what happens *exactly* - that sort of thing.

The other option, is that this is a basic flaw within interoperation
between code that's going to use the v3 style mutex, and code that isn't
- basically, any of the OCX based apps, or pre-v3 code.

Mal's W800 app seems to have also caused this problem to be exhibited,
so which codebase is it using? V3, or something else? If something else,
is it using mutexes or not?

One thing is clear - we have an interoperability bug that's appearing
often enough to be a confirmable bug, rather than just the odd
misbehaving episode...

I wrote a simple app (part of our helpdesk environment here at work)
using the v3 code, and it's a nice to use tool - I don't, however, see
the inbuilt hub functionality as required, and I wonder if it's time to
remove this from the library - I don't see it as being an option to
simply say that everyone else (ie xplhal, or any ocx based software, or
the xpl4java environment) has to change their implementations to use v3
style mutexes - this problem only appeared with the v3 .net library, so
I think that *it* needs to be fixed here!

I can't recall who it was that said at the time (might have been Mal)
this was originally debated, that it would be preferable to have an
absolutely rock solid Hub service, and just insist that it's installed
before other services etc can be used, rather than have a variety of
applications that might or might not become hubs.

Can we have some opinions on this please?

Ian.


-----Original Message-----
From: ukha_xpl@xxxxxxx [mailto:ukha_xpl@xxxxxxx] On
Behalf Of Neil Wrightson
Sent: 09 September 2005 23:53
To: ukha_xpl@xxxxxxx
Subject: RE: [ukha_xpl] xPL-Issue

Hi Guys,

I seem to read issues with this HUB thing and xPLHAL every couple of
weeks.
It appears that the best practice is to ensure that the xPLHAL service
is up and running before everything else ??

I don't know a lot about the inner workings of services etc. When
looking at a service in the windows service manager, there is a
Dependencies TAB that lists the required services etc that must be
running for the currently selected service. Could the xPLHAL service be
added to this list for say the W800 service (Am I correct in assuming
the W800 is a service?) so that unless the xPLHAL is up and running the
W800 app won't not start, or if it tries to start it must start the
xPLHAL service first.

Alternatively, a separate app that is run at the PC start-up that starts
each of the services/apps one at a time and in the correct order. If a
service/app does not start a window could then be displayed stating that
there is a problem. As each service/app is selected from the start-up
list, it could be tested to ensure that it is running prior to moving
onto the next item.


Regards,

Neil Wrightson.

> -----Original Message-----
> From: Mal Lansell [mailto:mal@xxxxxxx]
> Sent: Thursday, 8 September 2005 7:43 AM
> To: ukha_xpl@xxxxxxx
> Subject: Re: [ukha_xpl] xPL-Issue
>
>
> Arrghh!! I don't read the list for two days and there's hassle with my

> W800 service!  The W800 service does provide a hub, but it should be
> compatible with the other V3 hubs out there (it doesn't write anything

> to the eventlog though).
>
> It does sound like the W800 service might be setting up a hub before
> xPLHal starts, and therefore causing the problem with the old style
> xPLHal hub.  For long term stability, I'd recommend turning off the
> xPLHal hub if you have newer hubbing apps in your system.
>
> Mal
>
>
> Tom Van den Panhuyzen wrote:
>
> > Hm... I remember having problems to where xPLHal stopped working
> > because it couldn't run its hub. But maybe that was an earlier
> > version.
> > (sorry for my maybe crude remark previously... didn't sleep well
+
> > stress at
> > work)
> > Tom