Built-in C-ECHO SCP (Verification SOP Class).

Handles C-ECHO-RQ commands by returning a C-ECHO-RSP with status Success (0x0000). This is the DICOM equivalent of "ping" — it verifies that a DICOM association can be established and that the SCP is responsive.

This module is used as the default echo handler and can also serve as a reference implementation for other SCP service class handlers.

DICOM Reference

• Verification SOP Class UID: 1.2.840.10008.1.1
• PS3.7 Section 9.1.5 (C-ECHO Service)
• PS3.4 Section A.4 (Verification Service Class)

Wire Sequence

SCU                          SCP
 │                            │
 │── C-ECHO-RQ ──────────────>│
 │                            │
 │<───────────── C-ECHO-RSP ──│
 │            (status 0x0000) │