Report variables can be assigned on the server before rendering — the onPrepareVariables event supplies values that flow into the report generator.

Set variable values in PHP.
$viewer = new StiViewer();
$viewer->javascript->relativePath = '../';

$viewer->onPrepareVariables = function (StiVariablesEventArgs $args) {
    if (count($args->variables) > 0) {
        $args->variables['Name']->value = 'Maria';
        $args->variables['Surname']->value = 'Anders';
        $args->variables['BirthDay']->value = '1982-03-20 00:00:00';
    }
};

$viewer->process();
$report->loadFile('../reports/Variables.mrt');
$viewer->report = $report;

How it works. Values chosen on the server are injected into the report generator, so the client renders with data it never had to supply.
На скриншоте ниже Вы можете увидеть результат выполнения данного кода:

Setting Report Variables on the Server-Side