Remote Callback Works Only with 32-Bit Clients

• Microsoft Visual Basic Enterprise Edition, version 4.0, for Windows

SUMMARY

Remote Callback is a Remote Automation process in which a server uses an object reference to a client class to asynchronously trigger its methods or change its properties. Callback, or Asynchronous Notification, is especially useful for monitoring real time data. For a Callback process to be successful, the client need to be running on a 32-bit system.

MORE INFORMATION

When a Remote Automation server attempts to Callback a client object, it makes a certain request. For instance, the server could request to trigger a client's method. The automation proxy (AUTPRX32.DLL) on the server side carries this request across the network. A method request by the automation proxy expects to be met by the Automation Manager, and then served by the client. In other words, the client needs to act as a server for the Callback to be successful. Because 16-bit systems cannot run the Automation Manager, they cannot run a Remote Automation server. Therefore, a 16-bit client cannot be called back remotely.

REFERENCES

• Enterprise Edition Documentation, Building Client/Server Applications, Chapter 7, Implementing OLE Servers
• Professional Edition Documentation, Creating OLE Servers, Chapter 3, Standards and Guidelines, Performance Issues
• CALLBACK Sample Application in ..\Samples\RemAuto\Callback