To handle the communication between 4D Client and 4D Server, 4D proposes 3 different network layers:

• Legacy,
• ServerNet,
• and QUIC.

The Legacy network layer was introduced 30 years ago in 4D v3. It was originally developed for AppleTalk, enhanced for ISDN, and then added IPX and finally TCP/IP.

It was created for a very different Client/Server usage than 4D works today: it is single-threaded, optimized for slow networks with no encryption, and available for many different network protocols. As such, it is not optimized at all for modern network communications and supports a very limited number of features.

That’s why, with 4D 20 R5, we have decided to make the Legacy network layer obsolete and plan to remove it soon. We encourage you to move to ServerNet now if you are still using it. Let me explain what benefits you will get from the switch.