Appendix C. JMS Extensions

Connection extensions allows overriding connection configurations like username or password in response to some environment changes like account rotation or authentication token expiration.

The extensions take the form of a BiFunction<Connection, URI, Object> passed into the ConnectionFactory using the AMQConnectionFactory#setExtension(String, BiFunction) or PooledConnectionFactory#setExtension(String, BiFunction).

A table below lists supported extensions.

The following example illustrates how expired OAUTH2 authentication token can be recreated.

final String connectionURL = "...";                                                                    
final TokenGenerator tokenGenerator = new TokenGenerator(...);                                         

final BiFunction<Connection, URI, Object> tokenExtension = new BiFunction<Connection, URI, Object>()   
{
    private volatile String token;
    private long currentTokenExpirationTime;

    @Override
    public Object apply(final Connection connection, final URI uri)
    {
        long currentTime = System.currentTimeMillis();
        if (currentTime > currentTokenExpirationTime)                                                  
        {
            this.token = tokenGenerator.generateAccessToken();                                         
            this.currentTokenExpirationTime = tokenGenerator.getTokenExpirationTime(token);            
        }
        return this.token;
    }
};
final AMQConnectionFactory factory = new AMQConnectionFactory(connectionURL);                          
factory.setExtension(ConnectionExtension.PASSWORD_OVERRIDE.name(), tokenExtension);                    

final Connection connection = factory.createConnection();                                              
          

In the snippet above an implementation of BiFunction<Connection, URI, Object> is created at (3) for access token provisioning. The function implementation checks the token expiration at (4) and regenerate the token at (5) using a helper object (2) implementing calls to OAUTH2 specific API. The token expiration time is preserved at (6) for the following reconnects attempts. An instance of AMQConnectionFactory is created at (7) for a given connection URL (1). A password extension is registered at (8). JMS connection is open at (9). The example uses a hypothetical class TokenGenerator invoking underlying OAUTH2 API to generate/renew access token and get token expiration time.

Connection Extensions can be used together with ConnectAttemptListener to change credentials on connectivity failures. Please check Section C.2, “ConnectAttemptListener” for more details.