What is the best Delphi n-tier low bandwidth technology?

Question

I need to deploy a Delphi app in an environment that needs centralized data and file storage system (for document imaging) but has multiple branch offices with relatively poor inter connectivity. I believe a 3 tier database application is the best way to go so I can provide a rich desktop experience with relatively light-weight data transfer needs. So far I have looked briefly at Delphi Datasnap, kbmMW and Remobjects SDK. It seems that kbmMW and Remobjects SDK use the least bandwidth. Does anyone have any experience in deploying any of these technologies in a challenging environments with a significant number of users (I need to support 700+)? Thanks!

Answer 1

Depends if you are tied to remote datasets. If you aren't dataset bound then SOAP would likely be a good choice. Or, what I've done is write my own protocol that is similar to SOAP in nature. This was done before SOAP was standard and I'm glad I did - this gives you the ability to control more of the flow of data. It's given that if you have poor connectivity then you will be spending time supporting it. It's very nice if it's your own code you are supporting versus having to wait on a vendor. (Although KBM and REM are known to be pretty good vendors.)

Personal note: 700 users in a document imaging application over poor connectivity sounds like a mess. Spend the money on upgrading connectivity as it'll be cheaper in the long run.

Answer 2

Both kbmMW and RO SDK offer binary format, which is more compact than SOAP format,specially you are working with documents.

RO sdk seems to offer more GUI tools to help you doing your services.

Also give a RealThinClient SDK a look, it's a lightweight remoting framework.

But what ever framework you go with, your design of work will make it fast or slow, I have some applications working on slow 128kb lines, and it's working perfect without any user complain, but I don't do a large transfer for files.

Answer 3

I don't know if it's the very best / most efficient (glad you asked this question!), but I've had good results w/RemObjects SDK + DataAbstract. The latter made much of the plumbing details less involved, which was helpful. Still implementing, but so far so good.

Answer 4

One thing to remember...its not the number of users, but the number of them using the resources at the same time that will be the issue. Attempt to develop your application "server stateless" if at all possible, this will allow greater flexibility in the long term if you find you have to add more servers to the pool to support your customer base. The hardest thing about n-tier is scaling beyond the first server...plan on that from the start. Each request should not know anything about a prior request...or at the very least the request should have a way of passing the context so the server can look it up in a session table or something.

Personally, I would recommend RemObjects. I have used it with good results.

Answer 5

If you really wanna go "low-bandwidth" use BSD Sockets API - that'll give you full control over what's being sent and there you can send as little information as you want. Of course then you'll have to implement all the tiers yourself, but hey - that's still an option :D