Apama 10.15.4 | Connecting Apama Applications to External Components | Standard IAF Plug-ins | The Database Connector IAF Adapter (ADBC) | The ADBC Event application programming interface | Discovering databases
 
Discovering databases
If your application needs to find available databases, implement the following steps.
*To discover databases
1. Given a Datasource event, call the event's getDatabases action.
2. Create a handler action to perform callback actions on the results of the getDatabases action.
3. In the handler action, declare a variable for a Database event.
The definitions for the two forms of the getDatabases action are:
action getDatabases(
  string serviceId,
  string user,
  string password,
  action<string, sequence<Database>> callback)
and
action getDatabasesFull(
  string serviceId,
  string locationURL,
  string user,
  string password,
  dictionary<string,string> extraParams,
  action <string, sequence<Database>> callback)
Note:
JDBC data sources will usually require user and password values.
The definition of the Database event is:
event Database
{
  string shortName;
  string dbUrl;
  string description;
  dictionary<string,string> extraParams;
}
*shortName — A short display name
*dbUrl — The complete URL of the database, for example, jdbc:sqlserver://localhost/ApamaTest.
*extraParams — Optional parameters.
The relevant code is similar to this:
action handleAvailableServers(string error,
    sequence<com.apama.database.DataSource> results)
  {
    if error.length() != 0 {
      log "Error occurred getting available data sources: " +
           error at ERROR;
    }
    else {
      if results.size() > 0 {
        
        // Save off first service ID found.
        // Assumes first data source has at least one db
        if getDbServiceId() = "" {
          dbServiceId := results[0].serviceId;
        }
        com.apama.database.DataSource ds;
        log " DataSources: " at INFO;
        for ds in results {
          log " " + ds.name + " - " + ds.serviceId at INFO;
        }
        log "Finding Databases ..." at INFO;

        for ds in results {
          adbc.getDatabases(ds.serviceId, USER, PASSWORD,
             handleAvailableDatabases);  
        }
      }
      else {
        log " No DataSources found" at INFO;
      }
    }    
  }

string dbName;

action handleAvailableDatabases(string error,
sequence<com.apama.database.Database> results)  
{
    if error.length() != 0 {
      log "Error occurred getting available databases: " +
           error at ERROR;
    }
    else {
      if results.size() > 0 {
        // Save name of first db found
        if getDbName() = "" {
          dbName := results[0].shortName;
        }
        com.apama.database.Database db;
        log " Databases: ";
        for db in results {
          log " " + db.shortName + " - " +
              db.description + " - " + db.dbUrl at INFO;
        }

        // ... other logic...

      }
      else {
        log " No Databases found" at INFO;
      }
    }
  }