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Walkthrough: Create a custom installer for a ClickOnce application

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Any ClickOnce application based on an .exe file can be silently installed and updated by a custom installer. A custom installer can implement custom user experience during installation, including custom dialog boxes for security and maintenance operations. To perform installation operations, the custom installer uses the InPlaceHostingManager class. This walkthrough demonstrates how to create a custom installer that silently installs a ClickOnce application.

Note

The ApplicationDeployment class and APIs in the System.Deployment.Application namespace are not supported in .NET Core and .NET 5 and later versions. In .NET 7, a new method of accessing application deployment properties is supported. For more information, see Access ClickOnce deployment properties in .NET. .NET 7 does not support the equivalent of ApplicationDeployment methods.

Prerequisites

To create a custom ClickOnce application installer

  1. In your ClickOnce application, add references to System.Deployment and System.Windows.Forms.

  2. Add a new class to your application and specify any name. This walkthrough uses the name MyInstaller.

  3. Add the following Imports or using directives to the top of your new class.

    using System.Deployment.Application;
using System.Windows.Forms;

  4. Add the following methods to your class.

    These methods call InPlaceHostingManager methods to download the deployment manifest, assert appropriate permissions, ask the user for permission to install, and then download and install the application into the ClickOnce cache. A custom installer can specify that a ClickOnce application is pre-trusted, or can defer the trust decision to the AssertApplicationRequirements method call. This code pre-trusts the application.

    Note

    Permissions assigned by pre-trusting cannot exceed the permissions of the custom installer code.

    InPlaceHostingManager iphm = null;

public void InstallApplication(string deployManifestUriStr)
{
    try
    {
        Uri deploymentUri = new Uri(deployManifestUriStr);
        iphm = new InPlaceHostingManager(deploymentUri, false);
    }
    catch (UriFormatException uriEx)
    {
        MessageBox.Show("Cannot install the application: " + 
            "The deployment manifest URL supplied is not a valid URL. " +
            "Error: " + uriEx.Message);
        return;
    }
    catch (PlatformNotSupportedException platformEx)
    {
        MessageBox.Show("Cannot install the application: " + 
            "This program requires Windows XP or higher. " +
            "Error: " + platformEx.Message);
        return;
    }
    catch (ArgumentException argumentEx)
    {
        MessageBox.Show("Cannot install the application: " + 
            "The deployment manifest URL supplied is not a valid URL. " +
            "Error: " + argumentEx.Message);
        return;
    }

    iphm.GetManifestCompleted += new EventHandler<GetManifestCompletedEventArgs>(iphm_GetManifestCompleted);
    iphm.GetManifestAsync();
}

void iphm_GetManifestCompleted(object sender, GetManifestCompletedEventArgs e)
{
    // Check for an error.
    if (e.Error != null)
    {
        // Cancel download and install.
        MessageBox.Show("Could not download manifest. Error: " + e.Error.Message);
        return;
    }

    // bool isFullTrust = CheckForFullTrust(e.ApplicationManifest);

    // Verify this application can be installed.
    try
    {
        // the true parameter allows InPlaceHostingManager
        // to grant the permissions requested in the applicaiton manifest.
        iphm.AssertApplicationRequirements(true) ; 
    }
    catch (Exception ex)
    {
        MessageBox.Show("An error occurred while verifying the application. " +
            "Error: " + ex.Message);
        return;
    }

    // Use the information from GetManifestCompleted() to confirm 
    // that the user wants to proceed.
    string appInfo = "Application Name: " + e.ProductName;
    appInfo += "\nVersion: " + e.Version;
    appInfo += "\nSupport/Help Requests: " + (e.SupportUri != null ?
        e.SupportUri.ToString() : "N/A");
    appInfo += "\n\nConfirmed that this application can run with its requested permissions.";
    // if (isFullTrust)
    // appInfo += "\n\nThis application requires full trust in order to run.";
    appInfo += "\n\nProceed with installation?";

    DialogResult dr = MessageBox.Show(appInfo, "Confirm Application Install",
        MessageBoxButtons.OKCancel, MessageBoxIcon.Question);
    if (dr != System.Windows.Forms.DialogResult.OK)
    {
        return;
    }

    // Download the deployment manifest. 
    iphm.DownloadProgressChanged += new EventHandler<DownloadProgressChangedEventArgs>(iphm_DownloadProgressChanged);
    iphm.DownloadApplicationCompleted += new EventHandler<DownloadApplicationCompletedEventArgs>(iphm_DownloadApplicationCompleted);

    try
    {
        // Usually this shouldn't throw an exception unless AssertApplicationRequirements() failed, 
        // or you did not call that method before calling this one.
        iphm.DownloadApplicationAsync();
    }
    catch (Exception downloadEx)
    {
        MessageBox.Show("Cannot initiate download of application. Error: " +
            downloadEx.Message);
        return;
    }
}

/*
private bool CheckForFullTrust(XmlReader appManifest)
{
    if (appManifest == null)
    {
        throw (new ArgumentNullException("appManifest cannot be null."));
    }

    XAttribute xaUnrestricted =
        XDocument.Load(appManifest)
            .Element("{urn:schemas-microsoft-com:asm.v1}assembly")
            .Element("{urn:schemas-microsoft-com:asm.v2}trustInfo")
            .Element("{urn:schemas-microsoft-com:asm.v2}security")
            .Element("{urn:schemas-microsoft-com:asm.v2}applicationRequestMinimum")
            .Element("{urn:schemas-microsoft-com:asm.v2}PermissionSet")
            .Attribute("Unrestricted"); // Attributes never have a namespace

    if (xaUnrestricted != null)
        if (xaUnrestricted.Value == "true")
            return true;

    return false;
}
*/

void iphm_DownloadApplicationCompleted(object sender, DownloadApplicationCompletedEventArgs e)
{
    // Check for an error.
    if (e.Error != null)
    {
        // Cancel download and install.
        MessageBox.Show("Could not download and install application. Error: " + e.Error.Message);
        return;
    }

    // Inform the user that their application is ready for use. 
    MessageBox.Show("Application installed! You may now run it from the Start menu.");
}

void iphm_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
    // you can show percentage of task completed using e.ProgressPercentage
}

  5. To attempt installation from your code, call the InstallApplication method. For example, if you named your class MyInstaller, you might call InstallApplication in the following way.

    MyInstaller installer = new MyInstaller();
installer.InstallApplication(@"\\myServer\myShare\myApp.application");
MessageBox.Show("Installer object created.");

Next steps

A ClickOnce application can also add custom update logic, including a custom user interface to show during the update process. For more information, see UpdateCheckInfo. A ClickOnce application can also suppress the standard Start menu entry, shortcut, and Add or Remove Programs entry by using a <customUX> element. For more information, see <entryPoint> element and ShortcutAppId.

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