Configure SCADA Web Configuration Services

nginx.conf

The SCADA Web Configuration application is hosted in the nginx web server. To update any parameter for nginx web server, you must edit the nginx.conf file.

You can update the following parameters in the nginx.conf file:

• listen: Enter the port number where you want to run your server.

  Note: The default port number is 9443.

• client_max_body_size: Enter the maximum size (in megabytes) of a client request that goes through the nginx server.

  Note: If this value is too low and the request is too big, a 413 Payload Too Large error will occur. If this value is too high, it could cause out-of-memory errors in the services and application, and could allow attackers to occupy the services for too long.

• proxy_read_timeout: Enter the maximum time that the nginx server will wait for a proxied response to be returned.

  The nginx server proxies requests from a client to the CIMPLICITY Configuration service and the OPC UA Browse service. If a response isn't returned by the service within this amount of time, a 404 Not Found error will occur.

  Note: If this value is too low, when you browse or create points, 404 errors may occur. If this value is too high, it may take longer for issues with services to be discovered, and could allow attackers to occupy the services for too long.

cim_config_service.json

cim-config service is a microservice which is an intermediary between the web server and CIMPLICITY. To update any parameter in cim_config_service, you must edit the cim_config_service.json file.

You can update the following parameters in the cim_config_service.json file:

• port: Enter the port number on which the cim-config service is listening.
  Note: You must also update the port number for cim-config service under the reverse proxy section of the nginx.conf file.
• maxWriteRequestObjects: Enter the number of points that can be sent in a single request for point creation. If there are several points to create, multiple requests are sent.
  Note: If this value is too high, a 413 Payload Too Large or 404 Not Found error may occur. If this value is too low, the point creation performance will be affected.

opcua-browse-config.json

OPC UA browse service is a microservice which is an intermediary between the web server and CIMPLICITY. To update any parameter in OPC UA browse service, you must edit the opcua-browse-config.json file.

You can update the following parameters in the opcua-browse-config.json file:

• port: Enter the port number on which the OPC UA browse service is listening.
  Note: You must also update the port number for OPC UA browse service under the reverse proxy section of the nginx.conf file.
• maxBrowseRequestObjects: Enter the number of nodes that can be sent in a single request to the OPC UA Browse Service and the OPC UA server when browsing the OPC UA server.
  Note: If this value is too high, the 413 Payload Too Large error may occur. If this value is too low, the browsing and point creation performance will be affected.
• maxBrowseResultObjects: Enter the number of nodes that can be sent in a single response by the OPC UA Browse Service and the OPC UA server. If a request would return several nodes, multiple responses with OPC UA continuation points are returned.
  Note: If this value is too high, the 413 Payload Too Large error may occur. If this value is too low, the browsing and point creation performance will be affected.
  maxReadRequestObjects: Enter the number of nodes that can be sent in a single request to the OPC UA Browse Service and the OPC UA server when reading node attributes from the OPC UA server.

  Note: If this value is too high, the 413 Payload Too Large error may occur. If this value is too low, the browsing and point creation performance will be affected.

404 and 413 Error Workaround

If you encounter a 404 error, perform either of the following actions:

• Decrease the service limits for these parameters - maxReadRequestObjects, maxBrowseRequestObjects, maxBrowseResultObjects, and maxWriteRequestObjects.
• Increase the proxy_read_timeout parameter in the Web\exe\conf\nginx.conf file.

If you encounter a 413 error, perform either of the following actions:

• Decrease the service limits for these parameters - maxReadRequestObjects, maxBrowseRequestObjects, maxBrowseResultObjects, and maxWriteRequestObjects.
• Increase the client_max_body_size parameter in the Web\exe\conf\nginx.conf file.