Deprecation of the Legacy Network Layer

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.

About 10 years ago, 4D started developing ServerNet, a new protocol based on modern hardware and networks that aims to replace the Legacy network layer. ServerNet is faster, more reliable, and more feature-rich. Today, our biggest customers use ServerNet daily to host more than a thousand simultaneous connections.

Benefits of ServerNet

ServerNet is preemptive: For each client preemptive process, we run a preemptive thread on the server. You can’t use the Legacy network to run preemptive threads on the client. If you have hundreds or even thousands of processes, ServerNet is mandatory.

Sleep Mode: When a client machine enters sleep mode, the Legacy network closes the network connection, forcing the client to quit the application. ServerNet, on the other hand, keeps the connection alive until the user wakes up their machine.

SSO (Single Sign On through Active Directory): Single Sign On on Windows allows you to automatically authenticate your users without any login dialog by using their Active Directory user. It’s only available on Windows and not on the Legacy layer.

A quick word about QUIC

With 4D 20, we announced we were working on a new network layer. The QUIC network layer uses the QUIC protocol (that supports HTTP/3, for example) and is aimed at improving the stability of the Client/Server connection on unreliable networks like Wi-Fi and 5G.

QUIC holds immense potential for future applications requiring better performance on these network types. We’re actively working on improving its stability, and we encourage you to stay tuned for exciting developments.

In the meantime, ServerNet remains our recommended choice for most applications due to its proven stability and feature set.

As usual, we welcome your questions and feedback about this change on the 4D forum. Share your experiences, and let’s discuss how these advancements can benefit your applications!