Cisco Cisco Firepower Management Center 4000 Guía Del Desarrollador
Version 5.3
Sourcefire 3D System eStreamer Integration Guide
25
Understanding the eStreamer Application Protocol
Null Message Format
Chapter 2
Null Message Format
Both the client application and the eStreamer service send null messages. The
null message has a type of 0 and contains no data after the message header.
The client sends a null message to the eStreamer server to indicate readiness to
The client sends a null message to the eStreamer server to indicate readiness to
accept more data. The eStreamer service sends null messages to the client to
keep the connection alive when no data is being transmitted. The message length
value for null messages is always set to 0.
TIP!
In data structure diagrams in this book, integers in parentheses such as (1)
or (115) represent constant field values. For example, Header Version (1) means
that the field in the data structure under discussion always has a value of 1.
The Null message format is shown below. The only non-zero value in the
message is the header version.
Message Type
uint16
Indicates the type of message transmitted.
For the list of current values, see the
Message
Length
uint32
Indicates the length of the content that
follows, and excludes the bytes in the
message header itself. A message with a
header and no data has a message length of
zero.
Standard eStreamer Message Header Fields (Continued)
F
IELD
D
ATA
T
YPE
D
ESCRIPTION
Byte
0
1
2
3
Bit
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Header Version (1)
Message Type (0)
Message Length (0)