Data transfer via air

[danasegarane]

Hi all,
We have application running in a ship and the data from ship db to be transferred to a our data center. But there is no internet connectivity between these two . What possible ways of doing this(any satellite communication ?)

Any links or ideas are welcome..

[gep13]

Hey,

Satellite communication is definitely an optional.

Your code would need to be more resilient to communication drop outs though, as it would be prone to this. It terms of hardware to do this, I am really not sure.

You also have the option of doing "offline" synchronization. i.e. export the changes to something like an XML file, ship that to shore, and then upload into database, and vice versa. Not pretty, but it would work.

Gary

[Shaggy Hiker]

Heck, I'd do the offline anyways. Whether you can establish a sat link or not, you would still have the XML package, or binary package, available for passing along by other means as they become available. Of course, you'd want to set up sufficient keys in that transfer package that it could be identified uniquely. Therefore, if the sat link works, but you get no confirmation, so you later try a land link, or re-try the sat link, the receiver can identify that it has already received the same package.

[danasegarane]

Hey,

Satellite communication is definitely an optional.

You also have the option of doing "offline" synchronization. i.e. export the changes to something like an XML file, ship that to shore, and then upload into database, and vice versa. Not pretty, but it would work.

Gary

But for this how can we connect to the server ?

[gep13]

But for this how can we connect to the server ?

Are you referring to the satellite comms, or the off-line package?

Gary

[danasegarane]

Are you referring to the satellite comms, or the off-line package?

Gary

Satellite communication

[gep13]

Hey,

Once you have the satellite connection up and running (the implementation of which I have no idea) you would connect to the server in the exact same way as you would normally, over the network. It would just be that the network went over a satellite connection, rather than your standard methods.

Gary

[namrekka]

It depends also how far the ship is of the coast. Ok...this is holland and we have ships on the rivers/canals. Then GSM is an option too.

[danasegarane]

It depends also how far the ship is of the coast. Ok...this is holland and we have ships on the rivers/canals. Then GSM is an option too.

It will be in river.

[gep13]

It will be in river.

Bottom line, you as the developer of the software shouldn't need to worry about "how" the connection is made, unless you are responsible for that part as well. You only need to know that you are dealing with a potentially "flaky" connection, and as such, you will need to build additional resilience into your code.

Gary

[stateofidleness]

I would think cellular would be the cheapest/easiest option to setup. Kind of like alarm systems that have alarm panels that report back the alarm signal and sometimes video over a cellular line.

[Shaggy Hiker]

Another option is to package the information into a file and send it via FTP. Keeping a continuous link for TCP communications might be a bit difficult, but dropping the data to an FTP site where it could be polled for by the program would be a potential way around that.

[jmcilhinney]

As Gary suggests, as a VB.NET developer, how a network connection is made is pretty much irrelevant, except to the extent that you should know whether your network connection is expected to be constant or not. Your question, as asked, has nothing whatsoever to do with VB.NET and doesn't belong in the VB.NET forum.

As far as designing an application for use in an environment where network connectivity is not consistent, there's a name for that:

http://social.msdn.microsoft.com/Sea...lications&ac=3

[danasegarane]

As Gary suggests, as a VB.NET developer, how a network connection is made is pretty much irrelevant, except to the extent that you should know whether your network connection is expected to be constant or not. Your question, as asked, has nothing whatsoever to do with VB.NET and doesn't belong in the VB.NET forum.

As far as designing an application for use in an environment where network connectivity is not consistent, there's a name for that:

http://social.msdn.microsoft.com/Sea...lications&ac=3

We don't have constant connection. Currently we have a application which uses message queuing technology to fetch data from other device.

[gep13]

Dana, what exactly are you responsible for? The hardware and the software?

Gary

[danasegarane]

Software only. But I wonder we have to come with a idea how to connect a offshore data center to onsite ship

[gep13]

Hey,

Ok, to summarize, the possible options would be as follows:

1) Satellite Communication Network
2) Offline transfer of files, perhaps in XML format, and perhaps via an FTP connection
3) GSM Mobile Network

You can put all of these back to your client, and they can investigate which one they want to go with. This will likely come down to cost and feasibility.

Gary

[jmcilhinney]

Software only. But I wonder we have to come with a idea how to connect a offshore data center to onsite ship

Like I said, nothing to do with VB.NET so doesn't belong in the VB.NET forum. It's a legitimate question alright, but please don't post any IT-related questions in the VB.NET forum just because you post your VB.NET questions here. There are other forums, even on this site, dedicated to those other topics.

[si_the_geek]

Thread moved to 'General Developer' forum.

[danasegarane]

Like I said, nothing to do with VB.NET so doesn't belong in the VB.NET forum. It's a legitimate question alright, but please don't post any IT-related questions in the VB.NET forum just because you post your VB.NET questions here. There are other forums, even on this site, dedicated to those other topics.

Noted

[dilettante]

Sometimes these kinds of infrastructure questions do have a major impact on the application design though.

I would think that river based communication could use cellular technology within metro areas but perhaps not so well if you go out into the hinterlands. In some regions rivers are used heavily enough that cellular towers can be as thick as those along highways in other regions though.

I'm not sure what the alternatives are, though satellite service might be viable. You need a commercial communication consultant I'd guess.


As far as software design goes you already said you're using message queuing for something else. This would seem like a logical approach instead of simulating the same thing by shoveling data around in BLOBs or XML via FTP or something. This works great for semi-connected scenarios.

For Windows some of the obvious choices are MSMQ, SQL Server RDA, and possibly even Jet Replication.

[Shaggy Hiker]

I would say that, if the design requires message queueing, as it appears to do, then that is certainly going to impact the application design. At this point, I would also say that you simply can't count on full connectivity, ever, so you really have only to decide the message transfer format. As long as you make consistent messages in some kind of consistent format, such as XML, then the transfer format isn't all that important. Therefore, the application should be designed to create those consistent messages, and deal with sending and receiving at unpredictable times and rates.

[ntg]

This is one of those special cases in which the physical world, choice of hardware and delivery method can heavily impact the software implementation.

If you'll go into satellite communications, bear in mind that the packet turnaround time is big compared to other methods (times can be in the thousands of milliseconds), that there are a lot of transmission errors (the hardware takes care of those but re-transmissions occur behind the scenes) and that session establishment take longer. You should choose a method of delivery that is appropriate and not too "chatty". For example, uploading via HTTP post has a lot more overhead than an FTP file transfer. You should also investigate (or at least inquire into) the hardware and underlying protocol that will be used to establish satellite coms. Latest-and-greatest equipment do a much better job in this scenario but if older equipment comes into play you might want to consider using a good compression algorithm and (if the data to be transmitted is relatively large) also have a way to resume data transfers from where they left off.