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Thread: Do this plan sound feasible?

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Do this plan sound feasible?
"Michael" <michael.howden[ at ]gmail.com> 16.09.2006 10:10:16
Hello all,
First of all, I would like to thank everyone who has posted information
of this (and other forums). It has been incredibly useful browsing the
huge amount of information that people have posted, and I am incredibly
appreciative of everyone who has contributed.

I have a database which needs to run in 2 different offices (Jakarta
and Banda Aceh - it's for an NGO working with the Tsunami relief).
There is a shared network drive ( the "I: drive" - hosted in
Jakarta) between the 2 offices (set up using MS Server). However the
connection is too slow to run the DB over.

I am facing a problem which I think is best solved by replication. I
have scanned the forum posts, read the documentation and FAQs, and this
is what I have come with:

Place the Back End of the database on the "I: drive". Create a
replica for the users in Jakarta (keep the Design Master safe somewhere
else on the "I: drive"). When I am in Banda Aceh, I will use the
Design Master (running from the "I: drive" in Jakarta) to create
another Replica, which I will put on a network drive in the Banda Aceh
office. Is this feasible so far?

The users in the 2 different locations can use their different
versions, which can then be synchronized weekly.

Which brings me to my next question: Direct or Indirect
Synchronization? Because the "I: drive" is accessible from Banda
Aceh, could I do direct synchronization? This seems easier, because I
can just train someone to use the inbuilt tool in Access (I don't
have the Replication Manager). Or is this unadvisable, because the
connection is slow, and maybe not the most reliable - which will
result in corrupting the files? I think that this is more likely.
I believe this leaves me the only other options of using Michael
Kaplan's TSI Synchronizer Object to do indirect synchronization.
I've downloaded the files (synch40.dll and synch40.h), although I'm
not too sure what to do with them. Presumably link the dll (VB:
Tools>References), but what do I do with the H file?
Can I use the TSI functions with a replica created from Access?

One question, unrelated my currently problem: why couldn't indirect
syncrohnisation work between 2 computers connected with a flash drive
which is carried between them? With the dropbox on the flash drive?
There's probably a really good reason, but it beats me!

Will I need to re-link the tables after each synchronization?

There is one problem. I am only here for a few weeks. I may need to
make changes to the database after I have left. I don't presume that
this will be a problem if I am changing the Front End. However after
replication, will I will no longer be able to get the users to email me
the Back End File, so I can make changes to it, and then email it back?

I presume the solution in this situation is to write code in the front
end, which will automatically make any changes which I need (but is
only run when the front end is connected to the back end).
Is there a way I could get the staff here to send me a Non-Replica copy
of the database to me?

I would appreciate any feedback, if you think that this is feasible,
any tips, or ideas where I may experience challenges.

Thanks again

Michael Howden

Re: Do this plan sound feasible?
"David W. Fenton" <XXXusenet[ at ]dfenton.com.invalid> 16.09.2006 21:36:47
"Michael" <michael.howden[ at ]gmail.com> wrote in
news:1158401415.962374.192480[ at ]i42g2000cwa.googlegroups.com:

[Quoted Text]
> I have a database which needs to run in 2 different offices
> (Jakarta and Banda Aceh - it's for an NGO working with the Tsunami
> relief). There is a shared network drive ( the "I: drive" - hosted
> in Jakarta) between the 2 offices (set up using MS Server).
> However the connection is too slow to run the DB over.

If it's an always-on connection, then your best solution is to *not*
use repliation at all, but to host the application on a Windows
Terminal Server on one end of the connection. This will be much,
much easier to set up and maintain than indirect replication (which
will be required for a WAN synch).

> I am facing a problem which I think is best solved by replication.
> I have scanned the forum posts, read the documentation and FAQs,
> and this is what I have come with:
>
> Place the Back End of the database on the "I: drive". Create a
> replica for the users in Jakarta (keep the Design Master safe
> somewhere else on the "I: drive"). When I am in Banda Aceh, I will
> use the Design Master (running from the "I: drive" in Jakarta) to
> create another Replica, which I will put on a network drive in the
> Banda Aceh office. Is this feasible so far?

Don't create a replica across the WAN link. Instead, just copy an
existing replica. It will end up as a new replica as soon as it is
opened. This is the only scenario in which a file system copy is OK,
i.e., in initializing your replica in its new location.

> The users in the 2 different locations can use their different
> versions, which can then be synchronized weekly.
>
> Which brings me to my next question: Direct or Indirect
> Synchronization? Because the "I: drive" is accessible from Banda
> Aceh, could I do direct synchronization?

No, for the same reason that you can't just use a linked table -- if
the connection is too slow/unreliable to use Access across it, then
it's too slow/unreliable for direct replication. You *must* use
indirect replication in this type of scenario, or you'll risk
corruption/data loss.

> This seems easier, because I
> can just train someone to use the inbuilt tool in Access (I don't
> have the Replication Manager). Or is this unadvisable, because the
> connection is slow, and maybe not the most reliable - which will
> result in corrupting the files? I think that this is more likely.

That's correct.

> I believe this leaves me the only other options of using Michael
> Kaplan's TSI Synchronizer Object to do indirect synchronization.
> I've downloaded the files (synch40.dll and synch40.h), although
> I'm not too sure what to do with them. Presumably link the dll
> (VB: Tools>References), but what do I do with the H file?
> Can I use the TSI functions with a replica created from Access?

I don't understand the question. The TSI functions are intended to
be used with MDB files (whether created with Access or not).

> One question, unrelated my currently problem: why couldn't
> indirect syncrohnisation work between 2 computers connected with a
> flash drive which is carried between them? With the dropbox on the
> flash drive? There's probably a really good reason, but it beats
> me!

Because both dropboxes have to be visible to both synchronizers.
Synchronizer A puts messages in Dropbox B, and Synchronizer B reads
the messages from Dropbox B, and then puts messages in Dropbox A,
which Synchronizer A reads. What you've described would only work in
the case where a synch is one-way and requires only one stage. That
is not how most indirect synchs work -- they have multiple stages of
message files dropped into each dropbox and read from there.

It would likely take several trips back and forth with the flash
drive to get the two databases completely synched.

> Will I need to re-link the tables after each synchronization?

No. Why would you think you would?

> There is one problem. I am only here for a few weeks. I may need
> to make changes to the database after I have left. I don't presume
> that this will be a problem if I am changing the Front End.
> However after replication, will I will no longer be able to get
> the users to email me the Back End File, so I can make changes to
> it, and then email it back?

Absolutely not. If they email you a replica and you open it, it's no
longer the same replica (Jet assigns it a new Replica ID). For a DM,
that means it's no longer the design master.

Once a replica has been used, it has to be used and synched IN
PLACE. That means:

1. No email

2. No copying

3. No moving (except with the MOVE REPLICA command provided by Jet)

> I presume the solution in this situation is to write code in the
> front end, which will automatically make any changes which I need
> (but is only run when the front end is connected to the back end).
> Is there a way I could get the staff here to send me a Non-Replica
> copy of the database to me?

Again, the best way to do this is with Windows Terminal Server. You
will then be able to remotely alter the DM via a Remote Desktop
session.

> I would appreciate any feedback, if you think that this is
> feasible, any tips, or ideas where I may experience challenges.

Your circumstances don't work at all for replication. The Windows
Terminal Server situation is *always* best for two locations that
want to share data and have a WAN/Internet connection available at
all times.

--
David W. Fenton http://www.dfenton.com/
usenet at dfenton dot com http://www.dfenton.com/DFA/
Re: Do this plan sound feasible?
"Michael" <michael.howden[ at ]gmail.com> 18.09.2006 02:58:57
Hi,
Thanks a lot for the quick reply. Although I'm alittle disappointed and
confused that repliciation isn't an option.

I worry if I confused the issue by mention the flash drives. This was
just something I was wondering about, and not applicable to the current
situation.

The offices are connected but:
a) The connection is slow
b) I don't want the users to have to rely on the connection being up is
order to use the DB. The infrastructure is not that robust, and there
is a fear of "online" systems.

Some clarification here would be appreciated. I don't believe
(considering these constraints) windows terminal server is an option.
Can I use replication?

Thanks Again

Michael

David W. Fenton wrote:
[Quoted Text]
> "Michael" <michael.howden[ at ]gmail.com> wrote in
> news:1158401415.962374.192480[ at ]i42g2000cwa.googlegroups.com:
>
> > I have a database which needs to run in 2 different offices
> > (Jakarta and Banda Aceh - it's for an NGO working with the Tsunami
> > relief). There is a shared network drive ( the "I: drive" - hosted
> > in Jakarta) between the 2 offices (set up using MS Server).
> > However the connection is too slow to run the DB over.
>
> If it's an always-on connection, then your best solution is to *not*
> use repliation at all, but to host the application on a Windows
> Terminal Server on one end of the connection. This will be much,
> much easier to set up and maintain than indirect replication (which
> will be required for a WAN synch).
>
> > I am facing a problem which I think is best solved by replication.
> > I have scanned the forum posts, read the documentation and FAQs,
> > and this is what I have come with:
> >
> > Place the Back End of the database on the "I: drive". Create a
> > replica for the users in Jakarta (keep the Design Master safe
> > somewhere else on the "I: drive"). When I am in Banda Aceh, I will
> > use the Design Master (running from the "I: drive" in Jakarta) to
> > create another Replica, which I will put on a network drive in the
> > Banda Aceh office. Is this feasible so far?
>
> Don't create a replica across the WAN link. Instead, just copy an
> existing replica. It will end up as a new replica as soon as it is
> opened. This is the only scenario in which a file system copy is OK,
> i.e., in initializing your replica in its new location.
>
> > The users in the 2 different locations can use their different
> > versions, which can then be synchronized weekly.
> >
> > Which brings me to my next question: Direct or Indirect
> > Synchronization? Because the "I: drive" is accessible from Banda
> > Aceh, could I do direct synchronization?
>
> No, for the same reason that you can't just use a linked table -- if
> the connection is too slow/unreliable to use Access across it, then
> it's too slow/unreliable for direct replication. You *must* use
> indirect replication in this type of scenario, or you'll risk
> corruption/data loss.
>
> > This seems easier, because I
> > can just train someone to use the inbuilt tool in Access (I don't
> > have the Replication Manager). Or is this unadvisable, because the
> > connection is slow, and maybe not the most reliable - which will
> > result in corrupting the files? I think that this is more likely.
>
> That's correct.
>
> > I believe this leaves me the only other options of using Michael
> > Kaplan's TSI Synchronizer Object to do indirect synchronization.
> > I've downloaded the files (synch40.dll and synch40.h), although
> > I'm not too sure what to do with them. Presumably link the dll
> > (VB: Tools>References), but what do I do with the H file?
> > Can I use the TSI functions with a replica created from Access?
>
> I don't understand the question. The TSI functions are intended to
> be used with MDB files (whether created with Access or not).
>
> > One question, unrelated my currently problem: why couldn't
> > indirect syncrohnisation work between 2 computers connected with a
> > flash drive which is carried between them? With the dropbox on the
> > flash drive? There's probably a really good reason, but it beats
> > me!
>
> Because both dropboxes have to be visible to both synchronizers.
> Synchronizer A puts messages in Dropbox B, and Synchronizer B reads
> the messages from Dropbox B, and then puts messages in Dropbox A,
> which Synchronizer A reads. What you've described would only work in
> the case where a synch is one-way and requires only one stage. That
> is not how most indirect synchs work -- they have multiple stages of
> message files dropped into each dropbox and read from there.
>
> It would likely take several trips back and forth with the flash
> drive to get the two databases completely synched.
>
> > Will I need to re-link the tables after each synchronization?
>
> No. Why would you think you would?
>
> > There is one problem. I am only here for a few weeks. I may need
> > to make changes to the database after I have left. I don't presume
> > that this will be a problem if I am changing the Front End.
> > However after replication, will I will no longer be able to get
> > the users to email me the Back End File, so I can make changes to
> > it, and then email it back?
>
> Absolutely not. If they email you a replica and you open it, it's no
> longer the same replica (Jet assigns it a new Replica ID). For a DM,
> that means it's no longer the design master.
>
> Once a replica has been used, it has to be used and synched IN
> PLACE. That means:
>
> 1. No email
>
> 2. No copying
>
> 3. No moving (except with the MOVE REPLICA command provided by Jet)
>
> > I presume the solution in this situation is to write code in the
> > front end, which will automatically make any changes which I need
> > (but is only run when the front end is connected to the back end).
> > Is there a way I could get the staff here to send me a Non-Replica
> > copy of the database to me?
>
> Again, the best way to do this is with Windows Terminal Server. You
> will then be able to remotely alter the DM via a Remote Desktop
> session.
>
> > I would appreciate any feedback, if you think that this is
> > feasible, any tips, or ideas where I may experience challenges.
>
> Your circumstances don't work at all for replication. The Windows
> Terminal Server situation is *always* best for two locations that
> want to share data and have a WAN/Internet connection available at
> all times.
>
> --
> David W. Fenton http://www.dfenton.com/
> usenet at dfenton dot com http://www.dfenton.com/DFA/

Re: Do this plan sound feasible?
"David W. Fenton" <XXXusenet[ at ]dfenton.com.invalid> 18.09.2006 21:24:11
"Michael" <michael.howden[ at ]gmail.com> wrote in
news:1158548337.320700.137840[ at ]m73g2000cwd.googlegroups.com:

[Quoted Text]
> Thanks a lot for the quick reply. Although I'm alittle
> disappointed and confused that repliciation isn't an option.

I didn't say replication is not an option -- I said it wasn't the
best option, given the information I had.

> I worry if I confused the issue by mention the flash drives. This
> was just something I was wondering about, and not applicable to
> the current situation.

I was doing some further reading this weekend, and it wouldn't work
at all, because even if you place the dropboxes on the same machine,
one of them is going to expect to have access to the other dropbox
via a share. That is, Synchronizer A puts files in Dropbox B, and
Synchronizer B puts files in Dropbox A, so from one side of the
exchange, one has to be getting access to the other dropbox through
the share. With the flash drive, that can't happen, as the dropbox
is associated with the synchronizer.

> The offices are connected but:
> a) The connection is slow

That's not much of an issue for Windows Terminal Server, which is
completely usable over dialup. Anything faster than that is going to
work pretty well. And there are Citrix extensions that can speed
that up even more, I believe.

> b) I don't want the users to have to rely on the connection being
> up is order to use the DB. The infrastructure is not that robust,
> and there is a fear of "online" systems.

What kind of connection is it? I have a client whose satellite
"offices" have 384K DSL Internet access, and they are running a
centrally located Terminal Server applicationl. Everyone is *very*
happy about it, and it's completely usable over what I consider a
*very* slow DSL line.

I can't think of any always-on Internet access is not going to be
reliable enough to run Terminal Server applications. If they are not
using the Internet for their WAN connection, maybe they should spend
$100 a month or so to get a broadband connection. It's going to be
cheaper to administer in the long-run than an indirect replication
scenario.

> Some clarification here would be appreciated. I don't believe
> (considering these constraints) windows terminal server is an
> option. Can I use replication?

Yes, but *I* wouldn't go that route until I'd determined that
there's no reasonable possibility of the Terminal Server option.
It's much easier to administer an application from a centralized
server than it is to have it distributed to two locations and the
data synched with indirect replication.

--
David W. Fenton http://www.dfenton.com/
usenet at dfenton dot com http://www.dfenton.com/DFA/

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