====== HEARTBEAT [35=0] ======

The Heartbeat message maintains session connectivity.

===== Message Specification =====

**Message Direction:** Bidirectional

^ Tag ^ Field Name ^ Type ^ Req'd ^ Description ^
| | **Message Header** | | Y | MsgType = 0 |
| 112 | TestReqID | String | C | Required when responding to Test Request |
| | **Message Trailer** | | Y | |

===== Sample Messages =====

**Normal Heartbeat:**
<code>
8=FIX.4.2|9=50|35=0|49=T4Example|56=T4|50=T4FIX|52=20120905-17:54:49.359|10=123|
</code>

**Test Request Response:**
<code>
8=FIX.4.2|9=100|35=0|49=T4|56=T4Example|50=TraderName|52=20120905-18:09:12.103|
112=treqid.09.05.2012-13.09.12|10=234|
</code>

===== Notes =====
  * Default interval: 30 seconds
  * Timeout triggers Test Request
  * Failure to respond to Test Request causes Logout