PeSIT E protocol
PeSIT Wizard implements PeSIT E — the TLS-capable version of the protocol used on the SIT network and by IBM Sterling Connect:Express — and is validated for interoperability against Connect:Express 1.5.
What the node implements
| Feature | Notes |
|---|---|
| CRC (PI 1) | Fletcher checksum negotiated in CONNECT / ACONNECT, verified on every entity. |
| Compression (PI 21) | Horizontal / vertical / mixed, negotiated in ORF / ACK(ORF). |
| Multi-article DTF | Up to 255 articles per DTF, entities filled up to the negotiated size (PI 25). |
| Segmentation | DTFDA / DTFMA / DTFFA carry one article that spans several entities. |
| Synchronisation points | With a window (PI 7 byte 3); asynchronous acknowledgement. |
| Restart / resynchronisation | Persistent per-transfer checkpoints (sync number ↔ byte offset ↔ article count), correct PI 13 / 15 / 18 on both sides. |
| Record formats | Binary undefined / fixed / variable, text variable / fixed. |
| EBCDIC (PI 16) | CP037 translation of article bytes on the wire. |
| Extra PIs | Label (PI 37), SIT client / bank ids (PI 61 / 62) and free message (PI 99) on requests. |
| Diagnostics | The full Annex D catalogue with Connect:Express-compatible texts, plus PI 29 complements. |
| TLS | With or without a transport-length header (TCPIP_HEADER), mTLS, PEM material. |
| Pre-connection | The 24-byte EBCDIC hors-SIT message, for Connect:Express partners of type T / O. |
| Clean cancellation | F.CANCEL (IDT) then CRF / DESELECT / RELEASE. |
Record formats
An article is one logical record. On the wire:
- Binary undefined (
BU) — cut into articles of the record length; the last may be shorter. The default for arbitrary files. - Binary fixed (
BF) — every article is exactly the record length. - Text variable (
TV) — one article per line; the line feed is stripped on send and appended on receive. - Text fixed (
TF) — likeTV, padded with spaces to the record length.
Set text: true on a virtual file for text records, and ebcdic: true to translate them to EBCDIC CP037 on the wire.
State machine
The session engines are driven by the protocol state tables as data (the same shape as the Connect:Express tables), shared by the listening and initiating roles. This is what lets the node handle RESYN / IDT collisions, windowed synchronisation and restart correctly.
For the full parameter catalogue and state tables, see the source documentation.