Scalable Delphi TCP server implementation

Question

Any suggestions for components to use as a base for a scalable TCP server? I currently have an implementation that uses Indy which works well for say 100 relatively active c

Answer 1

You should look at RealThinClient SDK http://www.realthinclient.com/about.htm

Well proven solution. Good support. Test results for different server solutions on the home page.

Answer 2

The real deciding fact is what you plan on doing on each of those transactions.

I use Indy with Network Load Balanced windows servers. One of these Delphi applications is serviced by 3 physical servers listening one public IP address where we have received millions of requests since yesterday with zero errors. Load overnight is pretty idle so the actual requests are around 350/second/server during the day and there's plenty of room for growth.

If there's not a lot of CPU/Memory needed per transaction you might get away with it on one box using Indy. It all depends on the load...as you likely can't write to 1000 different files every second.

There's other items to worry about too - like the OS supporting this amount of activity. You may need to tweak some registry settings. (see this stackoverflow question)

IOCP is the way to go for ultra-capacity servers. I have used Indy for ease of use in implementation/debugging for a very long time. I have my own IOCP implementation that I wrote years ago but never rolled it out on production as we simply haven't needed to.

My simple advice - I'd highly suggest rolling it out in Indy, using NLB as your crutch for load, and after that if you are still desiring the utmost speed, write your own IOCP implementation so you can craft it towards your specific requirements. Note that this is based on knowing nothing of the actual implementation requirements.

Answer 3

I've tried multiple Delphi solutions to do networking, and found that many if not all solutions add complexity and code which impacts on either performance or footprint or both. So I started searching for the lightest wrapper around the winsock API. The I (re)discovered Delphi's own TTcpClient and TTcpServer components. Used in blocking mode, and overriding TCustomTcpServer overriding the DoAccept method, I've had the best results till now.

If you expect to have a really high number of incoming connections and (small) responses to serve to (small) requests, it's highly advisable to implement I/O completion ports, as this handles incoming requests better.

Answer 4

My favorite Delphi network layer is ICS by Francois Piette. It's fantastically easy to understand, very scalable, and ultra-high performance. Free, and open source. Will probably scale to 1000 clients for most people, without significant effort, and without the complexity that gives me trouble when I use Indy.

I got about a 20% scalability/performance boost from switching all my stuff from Indy to ICS.

Answer 5

There is a project at http://voipobjects.com/ which is based on the former iopcclasses project.

It claims to handle thousands simultaneous connections:

IOCP engine is set of classes, components and routines for rapid creation high scalable and performance TCP/UDP applications. Application created using IOCP classes can handle thousands simultaneous connections.

Library is written in Delphi - Delphi 7 - 2010 are supported.

Library uses IO completion ports technology. There is most powerful technology in Win32 world for creation highly scalable and performance TCP/UDP applications. This technology is supported in all desktop Windows OSes except old Win9x/WinME versions.

This library is licensed under MPL1.1. Also It includes some files from Jedi project (Winsock2 header translation).

https://bitbucket.org/voipobjects/iocpengine

Answer 6

I have been using ICS for the last 12 years. It is non-blocking. I support upto 2000 concurrent connections, each getting atleast 5000 bytes per second, sent as 1000 bytes every 200 msec. Never faced any problem and cpu usage of the app is very small. Good support in forum, but not required at all.

Shekar