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

Correlation

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

Type Value
engine_state 1
issue 2
issue_parent 3
state 4
log issue 5

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 negociate 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 negociation.

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).

You can find more details in the TLS module documentation and the compression module documentation.

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.