Accessing Attachments

As described in the Developer Guide, Xpress Insight allows files to be attached to an app or scenario. While the model is running within Xpress Insight, the Mosel interface will allow you to query, read and edit attachments of the scenario being run, as well as query and read (but not edit) attachments of the app to which that scenario belongs.

To demonstrate the use of an app and scenario attachments, in this example we have a Distances array that we want to populate with distances between cities. As this will not change, it would be very wasteful to store a copy of these in every scenario of the app, so we store them in a file distances.dat which is attached to the app. In the example, we call insightgetappattach to copy this file to the working directory and then populate the Distances array from this. (It is assumed that the app has a companion-file that configures the Distances array as unmanaged by Xpress Insight.)

To demonstrate the use of scenario attachments, we then save the model's results to a file decorated with today's date, and attach this file to the current scenario.

model RoutePlanner
 uses "mmxprs"                     ! Load the Xpress-Optimizer
 uses "mminsight"                  ! Load the Insight interface

 public declarations
  EvaluationDate: string
  Cities: set of string
  Distances: array(Cities,Cities) of real
  TrafficLevels: array(Cities,Cities) of real
  routetaken: array(Cities,Cities) of mpvar
 end-declarations

 ! Procedure to build and solve optimization problem
 procedure runproblem
  ! Download app attachment
  if insightgetmode <> INSIGHT_MODE_NONE then
   ! Model is running within Insight, so download distances.dat from Insight server
   insightgetappattach("distances.dat")
   if insightattachstatus<>INSIGHT_ATTACH_OK then
    writeln("Failed to download app attachment")
    exit(1)
   end-if
  else
   ! Model is running outside of Insight, attachments are not accessible
   ! so copy from some other location
   fcopy( '/Users/me/myfiles/distances.dat', 'distances.dat' )
  end-if
  ! Load into model
  initializations from "distances.dat"
   Distances
  end-initializations

  ! Perform optimization
  buildproblem
  optimizeproblem

  ! Capture results to file
  ROUTES_FNAME := "result-"+EvaluationDate+".dat"
  fopen(ROUTES_FNAME,F_OUTPUT)
  forall (s in Cities, d in Cities | routetaken(s,d).sol=1)
   writeln(s,"->",d)
  fclose(F_OUTPUT)

  ! Store as scenario attachment
  if insightgetmode <> INSIGHT_MODE_NONE then
   ! Model is running within Insight, so upload distances.dat to Insight server
   insightputscenattach(ROUTES_FNAME)
   if insightattachstatus<>INSIGHT_ATTACH_OK then
    writeln("Failed to upload scenario attachment")
    exit(1)
   end-if
  end-if
 end-procedure

 case insightgetmode of
  INSIGHT_MODE_LOAD: do
   loaddata
  end-do
  INSIGHT_MODE_RUN: do
   insightpopulate
   runproblem
  end-do
  INSIGHT_MODE_NONE: do
   loaddata
   runproblem
  end-do
 else
  writeln("Unknown execution mode")
 end-case

end-model

For clarity, the implementation of the loaddata, buildproblem and optimizeproblem procedures have been omitted from the example.