Create a connection

API used: hb_connection_create()

Use this function to connect to the MapR cluster.

This API takes three parameters:

const char *zk_ensemble,     /* [in] NULL terminated, comma separated
                                       *   string of CLDB servers. e.g.
                                       *   "<server1[:port]>,...". 
const char *zk_root,              /* [in] Ignored for MapR-DB. */
hb_connection_t *connection_ptr); /* [out] pointer to hb_connection_t */
There are two methods by which you can use the zk_ensemble parameter to determine how the MapR client connection locates the MapR cluster to connect to:
Set zk_ensemble to NULL to connect to the default cluster that is defined in the mapr-clusters.conf file.
MapR recommends this method, which uses the configuration information that is listed for the cluster in the mapr-clusters.conf file.
Set zk_ensemble to a string that includes hostnames or IP addresses.
With this method, the client application can connect to a non-default cluster explicitly. The client application searches through the mapr-clusters.conf file to find a cluster entry with a matching hostname/IP address. The first entry that is found to contain a matching hostname[:port]/IP address[:port} is used for the connection, as is the configuration information for that entry.

If none of the hostnames or IP addresses specified for zk_ensemble are located in entries in mapr-clusters.conf, or if mapr-clusters.conf does not exist, the client application tries to connect to the first specified hostname[:port]/IP address[:port]. If the client application cannot make a connection, it moves to the next specified hostname[:port]/IP address[:port].

Warning: Because no mapr-clusters.conf file is involved, no additional configuration information is used for connections. For example, connections made in this way cannot be secure because no security parameters are provided.

Examples

//connect to default cluster specified in mapr-clusters.conf (preferred)
if ((err = hb_connection_create(NULL,
                                NULL,
                                &connection)) != 0) {
  HBASE_LOG_ERROR("Could not create MapR-DB connection : errorCode = %d.",
err);
  goto cleanup;
}

//Connect directly to cluster with these specified IP addresses. 
//Typically this means there is no mapr-clusters.conf and security not used.
if ((err = hb_connection_create("192.168.1.1:7222,192.168.1.2:7222",
                                NULL /* ignored */,
                                &connection)) != 0) {
  HBASE_LOG_ERROR("Could not create MapR-DB connection : errorCode = %d.",
err);
  goto cleanup;
}

Code in the sample application

if ((retCode = hb_connection_create(zk_ensemble,
                                    zk_root_znode,
                                    &connection)) != 0) {
  HBASE_LOG_ERROR("Could not create HBase connection : errorCode = %d.", retCode);
  goto cleanup;
}

This API is defined in the header file connection.h: