The BBDO protocol

The BBDO protocol has been created to be the default protocol of Centreon Broker. It is lightweight on the wire and easy to decode. It is especially designed the for monitoring area of Centreon Broker.

Introduction

BBDO stands for Broker Binary Data Object. BBDO is designed to transfer "data packets" from a node to another. These "data packets" are most of the time monitoring information provided by the monitoring engine (eg. Centreon Engine or Nagios). It uses mostly raw binary values which allows it to consume very few memory.

Types

As a binary protocol, BBDO uses data types to serialize data. They are written in a Big Endian format and described in the following table.

Type	Representation	Size (bytes)
integer	binary	4
short integer	binary	2
long integer	binary	8
time	binary (timestamp)	8
boolean	binary (0 is false, everything else is true)	1
string	nul-terminated UTF-8 string	variable
real	nul-terminated UTF-8 string (either in fixed (2013) or scientific (2.013e+3) format)	variable

Packet format

The packets format of Centreon Broker introduce only 16 bytes of header to transmit each monitoring event (usually about 100-200 bytes each). Fields are provided in the big endian format.

Field	Type	Description
checksum	unsigned short integer	CRC-16-CCITT X.25 of size, id, source and destination. The checksum can be used to recover from an incomplete data packet sent in the stream by dropping bytes one by one.
size	unsigned short integer	Size of the packet, excluding header.
id	unsigned integer	ID of the event.
source_id	unsigned integer	The id of the source instance of this event.
destination_id	unsigned integer	The id of the destination instance for this event.
data		Payload data.

Packet ID

As seen in the previous paragraph, every packet holds an ID that express by itself how data is encoded. This ID can be splitted in two 16-bits components. The 16 most significant bits are the event category and the 16 least significant bits the event type.

The event categories serialize events properties one after the other, so order is very important to not loose track when unserializing events.

Event categories

The current available categories are described in the table below.

Category	API macro	Value	Description
NEB	BBDO_NEB_TYPE	1	Classical monitoring events (hosts, services, notifications, event handlers, plugin execution, ...).
BBDO	BBDO_BBDO_TYPE	2	Category internal to the BBDO protocol.
Storage	BBDO_STORAGE_TYPE	3	Category related to RRD graph building.
Correlation	BBDO_CORRELATION_TYPE	4	Status correlation.
Dumper	BBDO_DUMPER_TYPE	5	Dumper events.
Bam	BBDO_BAM_TYPE	6	Bam events.
Extcmd	BBDO_EXTCMD_TYPE	7	Centreon Broker external commands.
Internal	BBDO_INTERNAL_TYPE	65535	Reserved for internal protocol use.

NEB

The table below lists event types available in the NEB category. They have to be mixed with the BBDO_NEB_TYPE category to get a BBDO event ID.

Type	Value
Acknowledgement	1
Comment	2
Custom variable	3
Custom variable status	4
Downtime	5
Event handler	6
Flapping status	7
Host check	8
Host dependency	9
Host group	10
Host group member	11
Host	12
Host parent	13
Host status	14
Instance	15
Instance status	16
Log entry	17
Module	18
Service check	19
Service dependency	20
Service group	21
Service group member	22
Service	23
Service status	24
Instance Configuration	25

Storage

The table below lists event types available in the Storage category. They have to be mixed with the BBDO_STORAGE_TYPE category to get a BBDO event ID.

Type	Value
metric	1
rebuild	2
remove_graph	3
status	4
index mapping	5
metric mapping	6

BBDO

The table below lists event types available in the BBDO category. They have to be mixed with the BBDO_BBDO_TYPE category to get a BBDO event ID.

Type	Value
version_response	1
ack	2

BAM

The table below lists event types available in the BAM category. They have to be mixed with the BBDO_BAM_TYPE category to get a BBDO event ID.

Type	Value
ba_status	1
kpi_status	2
meta_service_status	3
ba_event	4
kpi_event	5
ba_duration_event	6
dimension_ba_event	7
dimension_kpi_event	8
dimension_ba_bv_relation_event	9
dimension_bv_event	10
dimension_truncate_table_signal	11
rebuild	12
dimension_timeperiod	13
dimension_ba_timeperiod_relation	14
dimension_timeperiod_exception	15
dimension_timeperiod_exclusion	16
inherited_downtime	17

Dumper

The table below lists event types available in the Dumper category. They have to be mixed with the BBDO_DUMPER_TYPE category to get a BBDO event ID.

Type	Value
Dump	1
Timestamp cache	2
Remove	3
Reload	4
Db dump	5
Db dump committed	6
Entries Ba	7
Entries Ba type	8
Entries boolean	9
Entries host	10
Entries kpi	11
Entries organization	12
Entries service	13
Directory dump	14
Directory dump committed	15

Extcmd

The table below lists event types available in the Extcmd category. They have to be mixed with the BBDO_EXTCMD_TYPE category to get a BBDO event ID.

Type	Value
Command request	1
Command result	2

Event serialization

Most events listed in each event category have a mapping used to serialize their content. Indeed their content is directly serialized in the packet payload data, one field after the other in the order described in the mapping tables. They are encoded following rules described in the types paragraph.

Example

Let's take an example and see how an host check event gets sent in a packet. Its mapping is as follow :

Property	Type	Value in example
active_checks_enabled	boolean	True.
check_type	short integer	0 (active host check).
host_id	unsigned integer	42
next_check	time	1365080225
command_line	string	./my_plugin -H 127.0.0.1

And gives the following packet with values in hexadecimal.

+-----------------+-----------------+-----------------------------------+
|      CRC16      |      SIZE       |                ID                 |
+========+========+========+========+========+========+========+========+
|   0A   |   23   |   00   |   28   |   00   |   01   |   00   |   09   |
+--------+--------+--------+--------+--------+--------+--------+--------+

+--------+-----------------+-----------------------------------+--------
| active_|                 |                                   |
| checks_|    check_type   |              host_id              |    =>
| enabled|                 |                                   |
+========+========+========+========+==========================+========+
|   01   |   00   |   00   |   00   |   00   |   00   |   2A   |   00   |
+--------+--------+--------+--------+--------+--------+--------+--------+

--------------------------+--------------------------------------------
                            =>  next_check                      |    =>
+========+========+========+========+========+========+========+========+
|   00   |   00   |   00   |   51   |   5D   |   78   |   A1   |   2E   |
+--------+--------+--------+--------+--------+--------+--------+--------+

-----------------------------------------------------------------------
                            => command_line =>
+========+========+========+========+========+========+========+========+
|   2F   |   6D   |   79   |   5F   |   70   |   6C   |   75   |   67   |
+--------+--------+--------+--------+--------+--------+--------+--------+

-----------------------------------------------------------------------
                            => command_line =>
+========+========+========+========+========+========+========+========+
|   69   |   6E   |   20   |   2D   |   48   |   20   |   31   |   32   |
+--------+--------+--------+--------+--------+--------+--------+--------+

-----------------------------------------------------------------------+
                            => command_line                              |
+========+========+========+========+========+========+========+========+
|   37   |   2E   |   30   |   2E   |   30   |   2E   |   31   |   00   |
+--------+--------+--------+--------+--------+--------+--------+--------+

Connection establishment

BBDO is a protocol which can negotiate features. When establishing a connection, a version_response packet is sent by the client. It provides its supported BBDO protocol version and extensions. The server replies to this message with another version_response packet containing its own supported protocol version and extensions. If protocol versions match, then starts the extensions negotiation.

Currently two extensions are supported : TLS and compression. Right after the version_response packet, each peer search in the other peer's extension list the extensions it supports. When one is found, it is enabled (ie. it immediately starts).

Example

Let's have C the client and S the server. The following steps are performed sequentially.

• C initiates a TCP connection with S and connection gets established
• C sends a version_response packet with the following attributes
  • protocol major : 1
  • protocol minor : 0
  • protocol patch : 0
  • extensions : "TLS compression"
• S sends its own version_response packet in reply to C's
  • protocol major : 1
  • protocol minor : 0
  • protocol patch : 0
  • extensions : "TLS compression"
• C and S determines which extensions they have in common (here TLS and compression)
• if order is important, extensions are applied in the order provided by the server
• TLS connection is initiated, handshake performed, ...
• compression connection is opened
• now data transmitted between C and S is both encrypted and compressed !

Acknowledgement

So called 'clever' clients/servers can acknowledge packets sent their ways. This is used by Centreon Broker to insure every packet is accounted for, and to start retention procedure in case the other side is unresponsive.

To do so, the other side must periodically send a BBDO 'ack' packet back the same TCP channel. This packet has the number of packet acknowledged by the client.

'Clever'/'Dumb' modes are configured on each TCP output, on a per Broker basis.