Microsoft Report Viewer is the lightweight reporting engine used by generated apps to produce data reports in PDF, Word, Excel, and TIFF format. A generated app creates an in-memory table of data sorted and filtered according to the end user criteria. The data table is passed to Report Viewer to produce a report. The design template of the report is either created on-the-fly by the application framework or supplied by a developer at design time.
Report Viewer allows including formulas written in Visual Basic in the definitions of property expressions in various elements of a report template. The report formulas from the template are compiled to executable code by Report Viewer. If an ASP.NET web application tries to create a report with the help of Microsoft Report Viewer, then certain security requirements must be satisfied. The formulas compiled by Report Viewer must run in “sandbox” environment.
ASP.NET security configuration has changed starting with ASP.NET 4.0. Now the sandbox of Report Viewer is required to jump through many hoops in order to produce a report. This results in poor performance of reports on large datasets requiring significantly more time to complete rendering.
A simple solution exists to overcome this problem in an app created with Code On Time.
1) Select the project name on the start page of the app generator and choose Settings.
2) Proceed to Web Server Configuration and paste the following snippet into Web.Config modification instructions box:
3) Click Finish and regenerate the project. A new <trust…/> entry will be created in the configuration file of application.
Now the reporting performance will become significantly improved.