The Remote Solving Configuration file

This configuration file allows the user to control some of the ways the Xpress solver interacts with the remote Insight Compute Interface. It contains advanced configuration settings; its expected that most users will not need to use these configuration options.

To use the configuration file, set the environment variable XPRESS_COMPUTE_CONFIG to the full path of the file including the file name itself; you must also set the XPRESS_COMPUTE and XPRESS_COMPUTE_URL environment variables to activate remote solving in the usual way. Changes to the configuration are only read when the Optimizer is first initialized with XPRSinit.

The configuration file must be a valid JSON document, containing a single object with key-value pairs. All keys are optional and Xpress will use sensible defaults for anything you do not specify. For example:

{
  "logLevel": 101,
  "caCertsPath": "C:/xpressmp/ssl/ca-bundle.crt"
}

The remainder of this section details the individual keys that can be set.

caCertsPath

This field can be set to the absolute path of the certificate bundle file to use for authenticating SSL certificates when communicating with a remote server using HTTPS. If unspecified, Xpress will look for a file ca-bundle.crt in the path specified by the MOSEL_SSL environment variable (if set), or the .mmssl folder of the user's home directory (if not). If this file does not exist, it can be created in the default location by executing the command mmssl setup

For example:

{
  "caCertsPath": "C:/xpressmp/ssl/ca-bundle.crt"
}

cleanupJobs

This field controls whether Xpress should delete a compute job from the remote server when it successfully completes or is interrupted. The default is true. Set to false to retain each compute job in the remote Insight Compute Interface.

For example:

{
  "cleanupJobs": false
}

logLevel

This field controls additional lines written to the problem's log that describe communication between the local Xpress application and the remote Insight Compute Interface. (Note it doesn't affect lines written by the remote Insight Compute Interface itself.) Supported levels are:

• 0 - write no extra log lines
• 1 - write error and warning messages only
• 2 - write error, warning and notification messages (the default)
• 101 - as 2, but also write lines for every HTTP request made and event message received from the server
• 102 - as 101, but include extra debugging output. Should be set on the advice of FICO product support only.

For example:

{
  "logLevel": 0
}

maxRetries

This field controls how many times a failed request to the remote server will be retried before we show an error to the user. There will be an exponentially increasing delay before each retry (200ms, 400ms, 800ms, etc) - the default setting of 8 means we try each request for about 51 seconds before the user is informed of an error. Set to a lower value if you want to see errors quicker, or 0 to disable retries entirely.

For example:

{
  "maxRetries": 2
}

trustSrv

This field controls whether Xpress should trust the remote server without checking its certificate, when an HTTPS URL is used. If set to false, the authenticity of the remote server is checked using the list of trusted certification authorities and the operation will be aborted if the verification fails. Set to true if you want to use a server that has a known invalid or self-signed certificate, and acknowledge the security risks this brings. Default is false.

For example:

{
  "trustSrv": true
}