Remote data access on LAN

  • Thread starter Thread starter Loopy Lou
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Loopy Lou

An application (written in Visual C++) resides on machine A. Data used
by this application also resides on machine A.

We want to execute this application from machine B. The executable and
data will reside only on machine A. Both machines are running Windows
XP.

A shortcut has been created on machine B to the shared folder on
machine A which contains the executable. When this shortcut is clicked,
the application starts properly on machine B. However, attempting to
read the data gives errors.

The application specifies a full path to the data (e g,
C:\MyDirectory\MyData.txt). From the viewpoint of machine B, that
probably means B's drive C:. That is wrong, because the data is on A's
drive C:.

How can the application specify that the path resides on the same
machine as the executable? I have tried prefixing the path with the
hostname of machine A (e g, \\MyHost\C:\MyDirectory\MyData.txt), but
this gives an error when application is started on machine A.

Can anyone explain how to accomplish this remote access to the data?
 
If I understand it correctly, you want local execution but remote data
access for a remotely stored executable.

It might have been useful if you provided a specific error message or #, but
I suspect the problem is not finding the data, but an issue of
security/authorization. Btw, what is the transport protocol (tcp/ip,
netbeui, smb)?

I'm surprised you're not using RPC (Remote Procedure Call) for this app. Of
course, this would result in remote execution, which perhaps isn't what you
want. But it would avoid the current problem, it keeps data access local to
execution. You could use an RPC just for data retreival, though. The
reason an RPC will work is because it provides an authorization model. It's
either that, or use a formal protocol like FTP, HTTP, whatever makes sense.
Windows is probably not going to authorize remote data access via Windows
workgroup authorization, which seems to be what you are assuming.

HTH

Jim
 
Yes, local execution and remote data, with a remotely stored
executable.

The error occurs with C RTL fopen. I did not note errno.

The transport protocol is whatever the default is for Microsoft Windows
networks.

The reason for not using RPC is that the app was written to run on a
local machine, and all we want to do is run another copy on a remote
machine, with minimal program modifications.

We can access the data from the remote machine using Windows Explorer,
so it probably isn't an authorization problem.
 
Loopy Lou said:
Yes, local execution and remote data, with a remotely stored
executable.

The error occurs with C RTL fopen. I did not note errno.

The transport protocol is whatever the default is for Microsoft Windows
networks.

The reason for not using RPC is that the app was written to run on a
local machine, and all we want to do is run another copy on a remote
machine, with minimal program modifications.

We can access the data from the remote machine using Windows Explorer,
so it probably isn't an authorization problem.
Click to expand...

Wrong! The fact the data is accessible to Windows Explorer does NOT mean it
is authorized to any application. That's why this is tricky. Even Windows
Explorer needs permission, which you give by providing a logon to the remote
Windows PC. That doesn't mean all application therefore inherit this
authorization, each needs it own. If all you are doing is simply
referencing the remote data in your local execution, it's sure to fail.
Heck, if this wasn't the case, what would be the point of authorizations
anyway, anyone could simply run an application remotely and access YOUR
data. Again, I suspect your assuming that somehow, someway, authorization
is either not needed, or happening impliciting, it's not.

Jim
 
Suggestion, give BOTH machines the same username/password, and then try
again. If it now works, then its definitely an authorization problem.

Jim
 
If rights are set correctly, here are a few thoughts.

Firstly, your UNC path syntax is incorrect )(
\\MyHost\C:\MyDirectory\MyData.txt ). Where you show C: you should be
showing the sharename or the other drive. This may be C with no colon or
whatever else was chosen. It cannot be C:(colon). You could test your
syntax in a command prompt with a net use command before using it with the
program.

Second, some older applications (I don't know if this is true in your case)
may have a problem with UNC paths but can be used with a mapped drive. In
that case, a batch file like the following can be used to launch the
program.

NET USE Q: \\server\share [/USER: username password IF NEEDED]
Q:
CD QAC
QA1.exe
NET USE Q: /delete /Yes
cls
exit
 
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