Use Javascript CustomActions because they're soooo easy
People have said that Javascript is the wrong thing to use for MSI CustomActions. Reasons given: hard to debug, hard to make it reliable. I don't agree. It's not hard to debug, certainly no harder than C++. Its just different. I found writing CustomActions in Javascript to be super easy, much easier than using C++. Much faster. And just as reliable.
There's just one drawback: Javascript CustomActions can be extracted via Orca, whereas a C/C++ CA would require reverse-engineering. If you consider your installer magic to be protected intellectual property, you will want to avoid script.
If you use script,
you just need to start with some structure. Here's some to get you started.
Javascript "boilerplate" code for CustomAction:
//
// CustomActions.js
//
// Template for WIX Custom Actions written in Javascript.
//
//
// Mon, 23 Nov 2009 10:54
//
// ===================================================================
// http://msdn.microsoft.com/en-us/library/sfw6660x(VS.85).aspx
var Buttons = {
OkOnly : 0,
OkCancel : 1,
AbortRetryIgnore : 2,
YesNoCancel : 3
};
var Icons = {
Critical : 16,
Question : 32,
Exclamation : 48,
Information : 64
};
var MsgKind = {
Error : 0x01000000,
Warning : 0x02000000,
User : 0x03000000,
Log : 0x04000000
};
// http://msdn.microsoft.com/en-us/library/aa371254(VS.85).aspx
var MsiActionStatus = {
None : 0,
Ok : 1, // success
Cancel : 2,
Abort : 3,
Retry : 4, // aka suspend?
Ignore : 5 // skip remaining actions; this is not an error.
};
function MyCustomActionInJavascript_CA() {
try {
LogMessage("Hello from MyCustomActionInJavascript");
// ...do work here...
LogMessage("Goodbye from MyCustomActionInJavascript");
}
catch (exc1) {
Session.Property("CA_EXCEPTION") = exc1.message ;
LogException(exc1);
return MsiActionStatus.Abort;
}
return MsiActionStatus.Ok;
}
// Pop a message box. also spool a message into the MSI log, if it is enabled.
function LogException(exc) {
var record = Session.Installer.CreateRecord(0);
record.StringData(0) = "CustomAction: Exception: 0x" + decimalToHexString(exc.number) + " : " + exc.message;
Session.Message(MsgKind.Error + Icons.Critical + Buttons.btnOkOnly, record);
}
// spool an informational message into the MSI log, if it is enabled.
function LogMessage(msg) {
var record = Session.Installer.CreateRecord(0);
record.StringData(0) = "CustomAction:: " + msg;
Session.Message(MsgKind.Log, record);
}
// http://msdn.microsoft.com/en-us/library/d5fk67ky(VS.85).aspx
var WindowStyle = {
Hidden : 0,
Minimized : 1,
Maximized : 2
};
// http://msdn.microsoft.com/en-us/library/314cz14s(v=VS.85).aspx
var OpenMode = {
ForReading : 1,
ForWriting : 2,
ForAppending : 8
};
// http://msdn.microsoft.com/en-us/library/a72y2t1c(v=VS.85).aspx
var SpecialFolders = {
WindowsFolder : 0,
SystemFolder : 1,
TemporaryFolder : 2
};
// Run a command via cmd.exe from within the MSI
function RunCmd(command)
{
var wshell = new ActiveXObject("WScript.Shell");
var fso = new ActiveXObject("Scripting.FileSystemObject");
var tmpdir = fso.GetSpecialFolder(SpecialFolders.TemporaryFolder);
var tmpFileName = fso.BuildPath(tmpdir, fso.GetTempName());
LogMessage("shell.Run("+command+")");
// use cmd.exe to redirect the output
var rc = wshell.Run("%comspec% /c " + command + "> " + tmpFileName, WindowStyle.Hidden, true);
LogMessage("shell.Run rc = " + rc);
// here, optionally parse the output of the command
if (parseOutput) {
var textStream = fso.OpenTextFile(tmpFileName, OpenMode.ForReading);
while (!textStream.AtEndOfStream) {
var oneLine = textStream.ReadLine();
var line = ParseOneLine(oneLine);
...
}
textStream.Close();
}
if (deleteOutput) {
fso.DeleteFile(tmpFileName);
}
return {
rc : rc,
outputfile : (deleteOutput) ? null : tmpFileName
};
}
Then, register the custom action with something like this:
<Fragment>
<Binary Id="IisScript_CA" SourceFile="CustomActions.js" />
<CustomAction Id="CA.MyCustomAction"
BinaryKey="IisScript_CA"
JScriptCall="MyCustomActionInJavascript_CA"
Execute="immediate"
Return="check" />
</Fragmemt>
You can, of course, insert as many Javascript functions as you like, for multiple custom actions. One example: I used Javascript to do a WMI query on IIS, to get a list of existing websites, to which an ISAPI filter could be installed. This list was then used to populate a listbox shown later in the UI sequence. All very easy.
On IIS7, there is no WMI provider for IIS, so I used the shell.Run() approach to invoke appcmd.exe to perform the work. Easy.
Related question: About Javascript CustomActions
