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\page refCCDB Module 'CCDB'

CCDB API

The CCDB API class (CcdbApi) is implemented using libcurl and gives access to the CCDB via its REST api.

Usage :

// init
CcdbApi api;
map<string, string> metadata; // can be empty
api.init("http://ccdb-test.cern.ch:8080");
// store
auto h1 = new TH1F("object1", "object1", 100, 0, 99);
api.store(h1, "Test/Detector", metadata);
// retrieve
auto h1back = api.retrieve("Test/Detector", metadata);

Conditions MQ

Conditions MQ is a client/server CCDB implementation for O2. Currently the implementation supports two backends, an OCDB and a Riak one.

OCDB backend

To run the MQ server-client example with the MQ server replying with CDB objects to the client requests, the steps below should be followed:

  • Create a local O2CDB instance using the following macro in /bin/config/:
root -l fill_local_ocdb.C

This will create "DET/Calib/Histo" calibration objects for a hundred runs in the subdirectory O2CDB/ under the current directory.

  • In one shell run the server example:
o2-ccdb-conditions-server --id parmq-server --mq-config <installation directory>/bin/config/conditions-server.json --first-input-name local://<installation directory>/bin/config/O2CDB --first-input-type OCDB
  • In a separate shell run the client example:
o2-ccdb-conditions-client --id parmq-client --mq-config <installation directory>/bin/config/conditions-client.json --data-source OCDB --object-path <installation directory>/bin/config/O2CDB
  • We can also query the running conditions-server using any user code as demonstrated in standalone-client which works for an O2CDB generated from the unit test testWriteReadAny

Riak backend

To run the MQ server-client example with the MQ server executing PUT or GET commands to a Riak cluster through an MQ broker, the steps below should be followed:

  • In one shell run the server example:
conditions-server --id parmq-server --mq-config <installation directory>/bin/config/conditions-server.json
  • In a separate shell run the client example:
o2-ccdb-conditions-client --id parmq-client --mq-config <installation directory>/bin/config/conditions-client.json --data-source Riak

List of optional client arguments:

  • operation-type (default = "GET"): "PUT", "GET". Sets the operation type.
  • object-path (default = "./OCDB/"). Sets the directory that holds the condition objects.