Thursday, April 23, 2020

Legacy Applications

OK - here is the problem:

Old Application started with TP 3, grown to many Mio. LOC.
Full of Moves, Records, and other stuff that is not ready to move from pre Unicode to Unicode.

That means no real RTTI, Generics, FireDac, native HTTP, ITask, and other stuff you love if you are using 10.x. 

With a look at the roadmap ;-) the new records would help, but anyway it's a huge task to get it running with XE.

The first idea was to use a DLL - of course -  this works, but not really, because of no real working share mem and an FMX-DLL has also problems. 

So you have to serialize everything over to and back from the DLL. If you have to serialize everything you could do this also over TCP. 

The multi-user network sharing is working but should have some improvements.

A local Database would also be a good idea and take out the old Enz-ISAM that I've ported to windows a long time ago.

Installing a real DB-Server is not possible. Any options?

I could install a Service on each workstation in the network.

What can a Service do for you?
First of all - no problems with admin rights anymore. Installation of anything else is a piece of cake.
The Service Apps of each workstation could talk over a TCP connection to each other. So without a dedicated Server, the Service-Apps could name one as "The Server" if the workstation is going to do a shutdown, another workstation could be named as "The Server" from now on.
Every running App could ask the local server on - "Hey give me the IP of the Server". No need for configs. instead of 4GB the Server could use all the memory and load DLL for different tasks. 

And the client-side?
The client can use a simple interface for the Service, like OpenDB, LockTable, WriteData, UnlockTable, and CloseDB (CRUD with locking) - Every command must (again) be serialized over TCP. The Server could maintain the locking for each table. Vola - a dedicated SQLite Server, or any other DB. (And of course many more).
Internet-Updates, DBCache, and any other service that is much easier to write in XE than in D2007.

This is the Idea...

Do you want to see me struggling to implement this? Perhaps on a live Youtube-Session?
Or are your more into FMX and MVVM?

Anyway - please subscribe to my YouTube Channel and leave a comment on what you want to see next?

Have a nice separation...

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