Message Header

IOTMP Message Header

The header is a part of a message that contains information about the type of message and the size of the data being transmitted.

Each IOTMP message contains a header that describes the Type and its Size over the wire. The minimum header length is 2 bytes.

Field	Type	Mandatory	Description
Message Type	varint	Yes	Specifies the Message Type.
Message Size	varint	Yes	Specifies the Message Size, without taking into account the header size.

Message Type

A message type can be any of the following:

Message Type	Value	Description
Reserved	0x00	Reserved field
Ok	0x01	Success
Error	0x02	Error
Connect	0x03	Initiates a connection and its parameters
Disconnect	0x04	Disconnect the current connection
Keep Alive	0x05	Keep connection alive
Run Resource	0x06	Execute a resource
Describe Resources	0x07	Describe available resources
Start Stream	0x08	Start a stream on the specified resource
Stop Stream	0x09	Stop the ongoing stream
Stream Data	0x0A	Stream data

Message Size

This field specifies the message size in bytes, that is, the remaining number of bytes on the stream (including zero if the message has no remaining bytes).