public synchronized void start() {
        try {
            final SLF4JLogFactory logger = new SLF4JLogFactory(this.sessionSettings);

            this.acceptor = new SocketAcceptor(this.application,
                                               this.messageStoreFactory,
                                               this.sessionSettings,
                                               logger,
                                               this.msgFactory);

            this.acceptor.setSessionProvider(new InetSocketAddress("0.0.0.0", 50000),
                                             new DynamicAcceptorSessionProvider(
                                                     this.sessionSettings,
                                                     new SessionID("FIX.4.4", "SENDCOMPID", "TARGETCOMPID"),
                                                     this.application,
                                                     this.messageStoreFactory,
                                                     logger,
                                                     this.msgFactory));
            this.acceptor.start();
        } catch (ConfigError ex) {
            log.error("Failed to start QuickFIX-J socket acceptor.", ex);
            this.acceptor = null;
        }
    }

quickfix.mina.acceptor.AbstractSocketAcceptor
private void createSessions(SessionSettings settings) throws ConfigError, FieldConvertError {
        HashMap<SessionID, Session> allSessions = new HashMap<>();
        for (Iterator<SessionID> i = settings.sectionIterator(); i.hasNext();) {
            SessionID sessionID = i.next();
            String connectionType = settings.getString(sessionID,
                    SessionFactory.SETTING_CONNECTION_TYPE);

            boolean isTemplate = false;
            if (settings.isSetting(sessionID, Acceptor.SETTING_ACCEPTOR_TEMPLATE)) {
                isTemplate = settings.getBool(sessionID, Acceptor.SETTING_ACCEPTOR_TEMPLATE);
            }

            if (connectionType.equals(SessionFactory.ACCEPTOR_CONNECTION_TYPE)) {
                AcceptorSocketDescriptor descriptor = getAcceptorSocketDescriptor(settings, sessionID);
                if (!isTemplate) {
                    Session session = sessionFactory.create(sessionID, settings);
                    descriptor.acceptSession(session);
                    allSessions.put(sessionID, session);
                }
            }
        }
        setSessions(allSessions);

        if (socketDescriptorForAddress.isEmpty()) {
            throw new ConfigError("No acceptor sessions found in settings.");
        }
    }