WebSocket Connection Failure

1. You (the admin) log in to the FineDataLink system, choose System Management > Data Connection to enter the data connection editing page. There may be cases where multiple people simultaneously edit the same data connection.

In this case, a message will be displayed in the upper part: " WebSocket is not connected.  Conflicts may occur due to concurrent edits.  The related ports may not be open."

2. The Load, Memory Utilization, and CPU Utilization parameters appear empty on the Real-time Load tab page after you log in to the FineDataLink system as admin and choose System Management > Intelligent O&M > Load Management.

A message is displayed in the upper part: " WebSocket is not connected.  Conflicts may occur due to concurrent edits.  The related ports may not be open."

3. Real-time forcible logout fails. The login page is displayed within the data platform instead of a redirection, as shown in the following figure.

Note:

This problem occurs in scenarios such as single forcible logout, user disabling, user password modification, authentication method modification, switchover to synchronous import, forbidding platform users from disabling users or enabling User Restriction, and license change.

4. No prompt message window pops up in the lower right corner. No message is prompted by the bell icon, but messages can be viewed when you click the bell icon and enter the message panel.

5. The system cannot retrieve the correct token validity period, resulting in the inability to log out users automatically due to the login timeout setting.

For example, a user logs in to FineDataLink at 3 o'clock with Keep Logged In unticked and stops performing operations on the platform at 3:20. You (the admin) have set Login Timeout to 60 Minutes.

• If WebSocket is connected successfully, the user will be forcibly logged out at 4:20.

• If WebSocket is not connected, the system will fail to reacquire the token, and the user will be forcibly logged out at 4 o'clock.

By default, a user who logs in with Keep Logged In ticked will be forcibly logged out after 14 days of inactivity. However, if the WebSocket is disconnected, the system cannot refresh the token, causing a forced logout after 14 days, despite any user activity within the period.

After you log in to the platform as the admin, a message is displayed in the upper part: "WebSocket is not connected.  Conflicts may occur due to concurrent edits.  The related ports may not be open." 

6. No success or failure prompt pops up when you install or uninstall plugins in the plugin store.

7. The task operation log is blank.

You can verify WebSocket connection failure through the following three methods:

1. Log in to the FineDataLink system as the admin, choose System Management > Intelligent O&M > Load Management, enable Real-time Load, and check whether the Load, Memory Utilization, and CPU Utilization parameters appear empty. If so, WebSocket is not connected.

 2. Open the console by pressing F12 and enter Dec.socket.connected. If false is returned, the WebSocket is not connected.

3. Open the console by pressing F12. If an error message about Socket ports like 58889 (default for servers) is displayed, WebSocket is not connected.

You need to troubleshoot and optimize settings in sequence as follows.

Checking Port Occupancy

Check the following parameters to view the WebSocket port and forwarding port. For details, see Modifying fine_conf_entity Manually.

Check whether the port or forwarding port is occupied by other processes. If so (especially occupied by important processes), switch to another available port.

Super admin can modify the WebSocket port and forwarding port via the data entry report. The settings take effect after the server is restarted.

Note:

1. If you upgrade FineDataLink from versions before V4.0.6 to V4.0.6 or later versions, the WebSocket port/forwarding port will remain the same as that in the previous versions.

2. For details about how to modify values of parameters in the fine_conf_entity table, see Modifying fine_conf_entity Manually.

3. Super admin can view and modify the WebSocket port by using the FINE_CONF_ENTITY Visualization Configuration plugin, but cannot view or modify the WebSocket forwarding port through this plugin.

Checking Port Configuration Validity

The following lists some precautions for setting the WebSocket port and forwarding port. Check whether the port number has been set correctly.

1. The port number ranges from 1024 to 65535. If there are multiple values, separate them with commas (,), for example, [Port number 1, Port number 2, Port number 3].

2. You are advised to configure multiple values for the WebSocket port as backups to prevent port conflicts when multiple projects are deployed on a single server.

3. Do not set the port number to 3389 (which is for remote server connection).

4. If there are trailing spaces in WebSocketConfig.port and WebSocketConfig.requestPort, the configuration will not take effect.

5. The WebSocketConfig.port and WebSocketConfig.requestPort parameters are case-sensitive. Wrong capitalization will prevent the configuration from taking effect.

Verifying Port Accessibility

Troubleshooting:

After confirming that the WebSocket port or forwarding port is not occupied by other processes, check whether the configured port is accessible from external networks.

• Linux: nc -vz -w 2 IP address Port number

• Windows: telnet Server IP address WebSocket port number

Solution:

1. Open the corresponding port in the server's firewall.

2. Enable the port in the security group settings of Alibaba Cloud, Huawei Cloud, or Microsoft Azure.

3. Disable the health check function on Alibaba Cloud.

Checking Whether an HTTPS Environment Is Deployed

WebSocket needs to be configured in the HTTPS environment for certificate configuration. For details, see Configuring WebSocket with HTTPS.

1. Key path limitations are as follows:

• Both absolute and relative paths can be used in the Tomcat configuration file server.xml.

• The value of SSL Key Path under System Management > System Setting > General > HTTPS Setting in the FineDataLink system can only be set to an absolute path.

2. You can access HTTPS-enabled projects through both HTTP and HTTPS. However, WebSocket allows you to access only through HTTPS or HTTP.

JAR Package Conflict

Issue:

If a JAR package conflict occurs in the project, a server deployment wizard will pop up, indicating a WebSocket port exception, as shown in the following figure.

Solution:

Remove the conflict-incurring JAR package, kill the process of the project, wait 2 minutes for the port to be released, and restart the project.

If Apache Impala is downloaded from the official website, do not put slf4j-log4j12-1.5.11.jar and slf4j-api-1.5.11.jar in the FineDataLink installation directory\webapps\webroot\WEB-INF\lib. Otherwise, a WebSocket port exception may occur.

Checking Whether the Server Request Responds Slowly

The WebSocket connection timeout is set to 20 seconds in the code. If a request exceeds this duration, the WebSocket connection will be considered as failed.

Checking Errors in Console

Press F12 to open the browser's developer console. Common WebSocket errors and potential causes are listed below:

• net::ERR_SSL_PROTOCOL_ERROR: The project is configured for HTTPS, but WebSocket is not.

• net::ERR_EMPTY_RESPONSE: The server configured with HTTPS is accessed through HTTP.

• net::ERR_CONNECTION_REFUSED: The port is not open or being listened to.

• net::ERR_CONNECTION_TIMEOUT: The domain name is parsed slowly due to network issues.

Browser Cache

Issue: You access the project from different browsers on the same computer, and WebSocket connections succeed in some browsers but fail in others.

Solution: Clear the browser cache.

1. When restarting the project, kill the running project processes, wait 2 minutes for ports to be released, and then restart the project. Otherwise, the restart may fail.

2. If the WebSocket is connected properly after you troubleshoot issues and make modifications following the previous steps, only post-connection data can be obtained, such as memory utilization and CPU utilization, and historical data cannot be recovered.