client disconnected...

Hello,

I would like to know how NexusDB handles the following situation.

Server on Window 2000 and 5 clients using Windows 98. All 5 clients are
connected to the server (one database using a real C/S solution - not
embedded in the exe) and 1 of the client's computer freezes (for whatever
reason) and all that he can do is: Ctrl-Alt-Delete. Well, the client was
connected to the server. And now... is the client automatically disconnected
(in other words, is the server enabled to "see" this)? Or does a Lock
remains on the server and the client needs to be unlocked (using a server
utility)? Or, in the worst case, need the server to be re-booted?

Not that NexusDB is bad or my program for that matter, but there are many
reasons why a Windows 98 client's computer may freeze, so it is not a
question if this happens but when. And when it does, a server re-boot is out
of the question because it means disconnecting all other users as well. But
as I mentioned, this is a worst-case situation. Oh, and if this may sound
stupid, up to now I only have been using file-server based databases. No C/S
experience, whatsoever.

If anyone can elaborate on this, it is much appreciated. I am still not sure
if NexusDB is suited for me or that I will stick to the database I currently
use. I have till the end of the month to decide. Much of NexusDB I do like,
but questions like these need to be answered in order for me to decide.

Thanks in advance.

Regards,
Fons Neelen
The Netherlands

> Well, the client was
> connected to the server. And now... is the client automatically
disconnected
> (in other words, is the server enabled to "see" this)? Or does a Lock
> remains on the server and the client needs to be unlocked (using a server
> utility)? Or, in the worst case, need the server to be re-booted?

The Winsock and the NamedPipe transport will instantly detect the
disconnection. (Both transports have a open read request on all incoming
sockets/pipes. If the remote end of the socket or pipe dies the operating
system will return the read request with an error code). The server engine
is informed about the disconnect and will clean up all sessions from that
client. This includes releasing all open locks and rolling back all
currently active transactions from that client.

For the COM Transport I've not yet done extensive stress testing in this
regard. But when the COM framework realizes that a connection is lost it
reduces the reference count for interfaces that have been used over that
connection. In a few simple tests I just did (killing EM while it was
running under the IDE and connected to an external server) this worked just
fine.

> Oh, and if this may sound
> stupid, up to now I only have been using file-server based databases. No
C/S
> experience, whatsoever.

One of the big advantages of a real C/S solution is the automatic handling
of client disconnects by the server.

> If anyone can elaborate on this, it is much appreciated. I am still not
sure
> if NexusDB is suited for me or that I will stick to the database I
currently
> use. I have till the end of the month to decide. Much of NexusDB I do
like,
> but questions like these need to be answered in order for me to decide.

Feel free to ask whatever you need to know to support your decision.


--
Thorsten Engler [NexusDB Architect]

Thorsten,

Thank you very much for that fast reply and completeness of the answer.

This is one big step forwards in favour of NexusDB. Now, what else do I need
to know....

Thanks again,
Fons

Fons,

I would suggest that you send your project to the NX team/freelance
gurus for evaluation if it continues to die.

I can assure you that once you work with NX and C/S, you won't look
back. Your experience is not the norm!

Good luck,

John

Fons Neelen wrote:

> Thorsten,
>
> Thank you very much for that fast reply and completeness of the answer.
>
> This is one big step forwards in favour of NexusDB. Now, what else do I need
> to know....
>
> Thanks again,
> Fons
>
>
>

Hello John,

> I would suggest that you send your project to the NX team/freelance
> gurus for evaluation if it continues to die.
>Your experience is not the norm!

Thanks for the suggestion, but you probably misunderstood my question. This
was not a real-life situation, but just an example and I needed to know how
NexusDB deals with such situations. Since I only have been using file-server
databases up to now.

> I can assure you that once you work with NX and C/S, you won't look
> back.

I think so too, but I have not yet decided to go with NexusDB though. There
are still a couple of things I need to know. I will post my remaining
questions soon. And then decide. To be fair, chances are pretty in favour of
NexusDB and so I will probably quit using my current database solution.

Good documentation is very important to me and luckily the manual draft of
August 6th 2003 does meet my standards. Looking very good - even if it is
only a draft - with the exeption of some pages with massive pictures which
took almost 20 seconds to draw.

Regards,
Fons

I was about to mention this as well! I don't know why on earth you
chose PDF documentation when it's so unbelievably slow, making any real use
of the docs incredibly difficult. I've got a 3.0+gig machine with 1 gig of
ram and a 256 ultra Nividia card and it can tale as long as 60 seconds for a
page to draw when there are graphics on it. Html or even winHelp is much
faster and smoother!

"Fons Neelen" <fons.e-mail@xs4all.nl> wrote in message
news:3f3f469b@wic040d....
> Hello John,
>
> > I would suggest that you send your project to the NX team/freelance
> > gurus for evaluation if it continues to die.
> >Your experience is not the norm!
>
> Thanks for the suggestion, but you probably misunderstood my question.
This
> was not a real-life situation, but just an example and I needed to know
how
> NexusDB deals with such situations. Since I only have been using
file-server
> databases up to now.
>
> > I can assure you that once you work with NX and C/S, you won't look
> > back.
>
> I think so too, but I have not yet decided to go with NexusDB though.
There
> are still a couple of things I need to know. I will post my remaining
> questions soon. And then decide. To be fair, chances are pretty in favour
of
> NexusDB and so I will probably quit using my current database solution.
>
> Good documentation is very important to me and luckily the manual draft of
> August 6th 2003 does meet my standards. Looking very good - even if it is
> only a draft - with the exeption of some pages with massive pictures which
> took almost 20 seconds to draw.
>
> Regards,
> Fons
>
>

Well, PDF is normally ok for something which is supposed to be read in
larger chunks. Unfortunately Adobe Acrobat seems to have bugged on a couple
of our images (they are not gigantic to start with or anything). It will be
dealt with.

--


Eivind Bakkestuen [NDD]
Please, no email unless requested.
Search Borland and third-party newsgroups here: www.tamaracka.com


"Robert Meek" <rmeek1@comcast.net> wrote in message
news:3f3f9ade@wic040d....
> I was about to mention this as well! I don't know why on earth you
> chose PDF documentation when it's so unbelievably slow, making any real
use
> of the docs incredibly difficult. I've got a 3.0+gig machine with 1 gig
of
> ram and a 256 ultra Nividia card and it can tale as long as 60 seconds for
a
> page to draw when there are graphics on it. Html or even winHelp is much
> faster and smoother!
>
> "Fons Neelen" <fons.e-mail@xs4all.nl> wrote in message

Robert Meek wrote:
> I was about to mention this as well! I don't know why on earth you
> chose PDF documentation when it's so unbelievably slow, making any real use
> of the docs incredibly difficult. I've got a 3.0+gig machine with 1 gig of
> ram and a 256 ultra Nividia card and it can tale as long as 60 seconds for a
> page to draw when there are graphics on it. Html or even winHelp is much
> faster and smoother!

I believe Eivind said there is a bug in some of the figures that is
giving Adobe Reader problems.

There is also a winhelp file. The PDF is the _user's manual_, not the
online help.

--
David Marcus

The first block diagram on page 17 I believe is where printing died for me.

I just emailed the PDF to a printing/copying center, and for $13 USD I
had a manual.
John

David Marcus wrote:

> Robert Meek wrote:
>
>> I was about to mention this as well! I don't know why on earth you
>>chose PDF documentation when it's so unbelievably slow, making any real use
>>of the docs incredibly difficult. I've got a 3.0+gig machine with 1 gig of
>>ram and a 256 ultra Nividia card and it can tale as long as 60 seconds for a
>>page to draw when there are graphics on it. Html or even winHelp is much
>>faster and smoother!
>>
>
> I believe Eivind said there is a bug in some of the figures that is
> giving Adobe Reader problems.
>
> There is also a winhelp file. The PDF is the _user's manual_, not the
> online help.
>
>

John Turner wrote:
> I just emailed the PDF to a printing/copying center, and for $13 USD I
> had a manual.

What sort of binding?

--
David Marcus