Problem with VF contentType and content-disposition causing IE8+ not to execute a downloaded file

Question

Scenario: User visits a visualforce page and a few parameters are fed into the page markup to dynamically populate a "plain text" body. This plain-text file is downloaded & executed by the user's browser - launching the local app which handles the named file's extension.

Specifically, I am delivering an SAP shortcut which will open the SAP GUI client installed on the user's local machine. The following code behaves properly in all browsers except for Internet Explorer (8+) which is the environment I am trying to solve for.

The body of the text file is as follows:

[System]
Name=ABC
Description=ABC Development
Client=100
[User]
Language=EN
[Function]
Title=Create Sales Order: Step 1
Command=VA01 VBAK-AUART={param};VBAK-VKORG=US01; VBAK-VTWEG=01;
[Options]
Reuse=1

I came across quite a few articles similar to this one which specifically IE8's file handling behavior from VF but so far I have been unsuccessful in getting the file to launch with the registered application handler for the "*.sap" file type. How do I use Visualforce to generate a CSV file that can be downloaded using IE8?

My controller looks like this - attempting to set the content-disposition header to force the browser to download the file rather than opening it as a page:

public with sharing class myTestController {
    public myTestController() {
            // modified casing per Daniel's commment
        ApexPages.currentPage().getHeaders().put('Content-Disposition', 'attachment; filename=CoolFileName.sap');
    }
}

My page markup (currently) looks like this:

<apex:page controller="myTestController" showHeader="false" sidebar="false" contentType="text/plain#SomeCoolFileName.sap" cache="true" standardStylesheets="false">[System]
Name=ABC
Description=ABC Development
Client=100
[User]
Language=EN
[Function]
Title=Create Sales Order: Step 1
Command=VA01 VBAK-AUART={!$CurrentPage.Parameters.OrderType};VBAK-VKORG=US01; VBAK-VTWEG=01;
[Options]
Reuse=1
</apex:page>

The problem that I run into is that no matter the value that is in the contentType attribute on the page tag, IE8 will always render it as plain text directly in the browser rather than opening it with the application which has been registered with the OS to open ".sap" files. Chrome and Firefox both download and execute the file using the registered handler and the SAP GUI app is launched as desired.

I've attempted to use contentType value of: text/plain, application/octet-stream, application/x-sapshortcut, application/x-msdownload, application/pdf, and a few others for the fun of it.

Microsoft's documentation about mime type detection in IE 4+

Anyone dealt with a similar scenario and have any tips?

Answer 1

Using a contentType of "application/x-unknown" and specifying the desired filename via setting the Content-Disposition header in the controller was key to making this work.

The working solution was the following code:

Controller

public with sharing class SAPGUILauncher {

    public SAPGUILauncher() {
        Apexpages.currentPage().getHeaders().put('Content-Disposition', 'attachment; filename="SAPGUILauncher.sap"');
    }
}

VF

<apex:page controller="SAPGUILauncher" cache="true" contentType="application/x-unknown">[System]
Name={!$Setup.SAPLauncherSettings__c.SAPName__c}
Description={!$Setup.SAPLauncherSettings__c.SAPDescription__c}
Client={!$Setup.SAPLauncherSettings__c.SAPClient__c}
[User]
Language={!$Setup.SAPLauncherSettings__c.SAPLanguage__c}
[Function]
Title={!$Setup.SAPLauncherSettings__c.SAPTitle__c}
Command=ZSFDCVA01_2 P_AUART={!$CurrentPage.Parameters.OrderType}; P_VKORG={!$CurrentPage.Parameters.SalesOrg}; P_VTWEG={!$CurrentPage.Parameters.DistributionChannel}; P_KUNNR={!$CurrentPage.Parameters.SoldToParty}; P_KUNWE={!$CurrentPage.Parameters.ShipToParty}; P_BSTKD={!$CurrentPage.Parameters.PONumber}; P_MATNR={!$CurrentPage.Parameters.MaterialNumber}; P_KWMENG={!$CurrentPage.Parameters.Quantity};
[Options]
Reuse={!$Setup.SAPLauncherSettings__c.SAPReuse__c}
</apex:page>