How do I put a Monitor into CDF?

Question

I would like to keep track of progress of a database request in an Enterprise CDF, but it won't allow PrintTemporary or Monitor[] to add content.

When I use Dynamic[If[progress<1,Refresh[ProgressIndicator@progress,TrackedSymbols:>{progress},UpdateInterval->.5],Histogram[outputData,<various_options_here>]],TrackedSymbols:>{progress}], the ProgressBar doesn't update during VERY heavy operations, like SQLExecute or building a Histogram out of a large set of numbers (2 sets of about 10^6 values). In addition, since the end result of the output has to be without a semicolon, I cannot tag progress=1; onto its end. E.g. progress=0;long_SQL_request;progress=.5;Histogram[huge_data] progress=1; <- obviously can't do that last part. And progress=.5 never gets picked up by the ProgressBar.

Please help. Thank you!

Answer 1

Here is an example of using ProgressIndicator. I added Pause[] to simulate some blocking operation, and added Abort button. This is the pattern that I use when using this feature. It is simple and works for me. The idea is to pass the tracking symbol by reference.

Manipulate[(*example using progress monitor in Manipulate*)
 Module[{result},
  abort = False; track=0;
  result = solve[n, Unevaluated[track], Unevaluated[abort]];
  track = 0;
  If[abort, "Aborted", "success!"]],
 Grid[{
   {Control[{{n, 10, "size of problem?"}, 1, 1000, 1, Appearance -> "Labeled"}]},
   {Button["Abort", abort = True, ImageSize -> {40, 30}]},
   {Dynamic[ProgressIndicator[track, {0, 1}]]} }],
 {{track, 0}, None},
 {{abort, False}, None},
 TrackedSymbols :> {n},
 SynchronousUpdating -> False,
 ContinuousAction -> False,
 Initialization :>
  (
   solve[n_, track_, abort_] := Module[{k = 0, result = 1,i},
     Do[PrimeQ[i];
      Pause[0.1];
      k = k + 1;
      track = k/n;
      If[abort, result = -1; Break[]]
      , {i, n}
      ];

     result
     ]
   )
 ]

If you like to see position of progress, it is probably easier to use one of the new version 9 controls such as BulletGauge since those will automatically label the display. Here is example using [BulletGauge][2] and this works without Refresh even, so I removed the passing of the track symbol as in the first example above. I used reference 1 for this example just for now. Help has more information on how to set this control in more specific ways.

Manipulate[
 Module[{result}, abort = False; track = 0;
  result = solve[n]; 
  track = 0;
  If[abort, "Aborted", "success!"]],

 Grid[{{Control[{{n, 10, "size of problem?"}, 1, 1000, 1, Appearance -> "Labeled"}]}, 
     {Button["Abort", abort = True,ImageSize -> {40, 30}]}, 
     {Dynamic[BulletGauge[track, 1, Range[0, 1]]]} (*more options in help*)
   }
  ],     
 {{track, 0}, None},
 {{abort, False}, None},
 TrackedSymbols :> {n},
 SynchronousUpdating -> False,
 ContinuousAction -> False, Initialization :> (

   solve[n_] := Module[{k = 0, result = 1, i},
     Do[PrimeQ[i];
      Pause[0.1];
      k = k + 1;
      track = k/n;
      If[abort, result = -1; Break[]], {i, n}];
     result])
 ]