SLI Interface Enhancement for Receiving Large Chains

The information in this article applies to:

• Microsoft SNA Server for Windows NT, version 2.11 SP1

SUMMARY

If an LUA SLI application issues an SLI_RECEIVE request and passes a data buffer that is smaller than the size of the chain being received, the SLI interface returns a primary_rc of LUA_UNSUCCESSFUL and secondary_rc = LUA_DATA_TRUNCATED. The SLI library returns as much data as possible to the application's data buffer, but the remaining data in the chain is lost and cannot be extracted on subsequent SLI_RECEIVE requests.

This forces the SLI application to allocate an SLI_RECEIVE data buffer large enough to handle the full chain size.

Microsoft has enhanced the SNA Server 2.11 32-bit Windows LUA SLI interface so an application does not have to preallocate the full buffer size when receiving data using the SLI_RECEIVE API.

MORE INFORMATION

This new feature is enabled with an update of the WINSLI32.DLL and the SNATRC.DLL, but has not been regression-tested. To enable this new feature, the Windows application must set the resv56[3] byte to 0x01 on the SLI_OPEN call. With this byte set, if the application issues SLI_RECEIVE and specifies a data buffer which is smaller than the chain of data to be received, SLI_RECEIVE returns with a primary_rc of LUA_OK and a secondary_rc of LUA_DATA_INCOMPLETE (0x00000060). The next SLI_RECEIVE returns the rest of the data for that chain, or as much as there is space in the receive buffer.

If the SLI_OPEN does not have the resv56[3] byte set to 0x01, then the SLI_RECEIVE is supported normally. In this case if an SLI_RECEIVE is issued with a buffer smaller than the chain of data received from the host then the SLI_RECEIVE returns with primary_rc = LUA_UNSUCCESFUL, and the secondary_rc = LUA_DATA_TRUNCATED (0x00000003). The remainder of data for that chain is discarded by the SLI library.