ClickOnce
From Wikipedia, the free encyclopedia
ClickOnce is a Microsoft technology for deploying Windows Forms or Windows Presentation Foundation-based software, also called Smart clients. It is similar to Java Web Start for the Java Platform. ClickOnce is only available in .NET 2.0 and later. A less advanced technique can be obtained with the Microsoft Updater Application Block.
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[edit] Description
ClickOnce enables the user to install and run a Windows application by just clicking a link in a web page. The core principle of ClickOnce is to bring the ease of deployment of web applications to the Windows user. In addition, ClickOnce aims to solve three other problems with conventional deployment models: the difficulty in updating a deployed application, the impact of an application to the user's computer, and the need for administrator permissions to install applications.
ClickOnce-deployed applications are considered 'low impact', in that they are installed per-user, not per-machine. No administrator privileges are required to install one of these applications. Each ClickOnce application is isolated from the other. This means one ClickOnce application is not able to 'break' another.
ClickOnce employs CAS (Code Access Security) to ensure that system functions cannot be called by a ClickOnce application from the web, ensuring the security of data and the client system in general.
[edit] Applications
The ClickOnce model supports two flavors of applications: installed applications (akin to conventional Windows applications with start menu integration) and online applications (browser hosted applications that are not installed, only run and cached). ClickOnce applications can be deployed to a computer from a Web location, a network share, or even from a file location such as a CD.
The ClickOnce deployment technology is integrated into the Visual Studio 2005 project system and is also natively supported by MSBuild technology.
ClickOnce prior to .NET 3.5 only works with Internet Explorer, although the FFClickOnce extension allows Firefox to support it. See also this blog post discussing ClickOnce issues with Firefox.
[edit] Manifests
A ClickOnce deployment is controlled through the use of two XML manifest files: a deployment manifest and an application manifest. The deployment manifest file describes the deployment model: the current version, update behavior, publisher identity along with digital signature. This manifest is intended to be authored by administrators who handle deployment. The application manifest — a .exe.manifest file — describes the application assemblies, dependent libraries and lists permissions required by the application. This file is intended to be authored by the application developer. In order to launch a ClickOnce application, a user clicks on its deployment manifest file.
[edit] Updates
ClickOnce applications can be self-updating; they can check for newer versions as they become available and automatically replace any updated files. For its installed application flavor, ClickOnce presents several update options. Applications can be configured to check for updates on startup or after startup. ClickOnce also exposes programmatic APIs to customize update behavior. There is also support for required or mandatory updates for managing ongoing updates and ensuring that the entire user-base can be moved up to a new version in a timely manner.
[edit] Signatures
ClickOnce applications must be signed with an Authenticode Digital Certificate. You can create your own, but users will be prompted with security warnings that the signature cannot be verified. Certificates can be purchased from a number of Microsoft certified vendors for roughly $100-200 for a single year. After the year is over you must apply for a renewal of the certificate; however, this certificate has a new key. With a new key, the application will then not recognize the publisher and updates can no longer be sent to users. The application then has to be reinstalled with the new key. This issue will be fixed in Visual Studio 2008. Optionally, a 10 year certificate can be purchased.
[edit] See also
[edit] External links
- ClickOnce Introduction
- ClickOnce Deployment for Windows Forms Applications – ClickOnce content on MSDN
- ClickOnce In other than IE Browsers – MSDN Blog
- DevInstall's ClickOnce Page
- Article on ClickOnce configuration & usage
- Community Sites
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