User`s guide

2: DDCMP DLI Functions

DC 900-1343D 27

• transport subsystem interface (TSI) connection conﬁguration

• protocol-speciﬁc ICP link conﬁguration

The Freeway server is normally conﬁgured only once, during the installation proce-

dures described in the Freeway User’s Guide. DLI session and TSI connection conﬁgu-

rations are deﬁned by specifying parameters in DLI and TSI ASCII conﬁguration ﬁles

and then running two preprocessor programs,

dlicfg and tsicfg, to create binary con-

ﬁguration ﬁles. Refer to Appendix B of this document, as well as the Freeway Data Link

Interface Reference Guide and the Freeway Transport Subsystem Interface Reference

Guide. You must perform ICP link configuration within the client application

(described in Section 2.5.1.1).

2.1.2 Normal versus Raw Operation

The Freeway Data Link Interface Reference Guide describes two types of DLI operation,

Normal and Raw. However, the DDCMP protocol requires Raw operation so that the

write (Section 2.5) and read (Section 2.6) requests can specify protocol-speciﬁc infor-

mation. The embedded DLITE interface also requires Raw operation.

2.1.3 Blocking versus Non-blocking I/O

Note

Earlier Freeway releases used the term “synchronous” for blocking

I/O and “asynchronous” for non-blocking I/O. Some parameter

names reﬂect the previous terminology.

Non-blocking I/O applications are useful when doing I/O to multiple channels with a

single process where it is not possible to “block” on any one channel waiting for I/O

completion. Blocking I/O applications are useful when it is reasonable to have the call-

ing process wait for I/O completion.