What is Java Web Start?

Introduction
Java Web Start is a new technology used to deploy applications based on Java TM technology. It is a convenient channel for connecting computers and the Internet, allowing users to run and manage applications on the web.
Java Web Start provides a simple way to activate an application and ensures that the latest version is always running to eliminate complicated installation or upgrade processes.
Traditionally, You need to search, download, locate, and execute the installation program on the web to publish software through the Web. After the installation program is executed, you are prompted to specify the installation path and installation options, such as full, typical, or minimum installation. This is usually a time-consuming and complex task, and each new version of the software must be repeated.
　　
On the contrary, applications deployed on the web, such as the Popular HTML-based email client software and calendar, and auction sites, are easy to install and use. Web browsers automate the entire process. There is no complicated process of downloading, installing, and configuring, and make sure you always use the latest version.
　　
Java Web Start provides the same benefits for full-featured applications as the preceding HTML applications. Java Web Start is a Web-Oriented Application Deployment Solution. Using full-featured applications to replace HTML-based customer software offers the following benefits:
　　
Highly Interactive user interfaces, comparable to traditional applications (such as text processing and spreadsheet software.
　　
Low bandwidth requirements. The application does not need to connect to the Web server every time it is clicked. It can cache downloaded information. In this way, it can achieve better interaction on low-speed connections.
　　
　　 Supports offline use
In exchange, you must download the application for the first time. The initial activation cost of HTML-based applications is very low. Generally, it takes several seconds to open a Web page. It may take several minutes for Java TM-based applications to be downloaded over a typical modem. Java Web Start caches all downloaded files on the local computer. In this way, although the first activation cost of the application is higher than that of the HTML page, the next step is to run the application almost immediately because the required resources are already on the local computer.
At each startup, Java Web Start checks whether the Web server has an updated version of the application and can be automatically downloaded and started. In this way, the application is automatically updated. There is no complicated upgrade process.
　　
　　 Security
Java Web Start is built on the Java 2 platform, which provides a complete security architecture. By default, applications started using Java Web Start will run in a controlled environment ("sandbox") and only have limited access to files and networks. Therefore, starting an application through Java Web Start can ensure the security and integrity of the system.
Applications can request unrestricted access to the system. In this case, the Java Web Start dialog box is displayed when the application is started for the first time. The security warning displays source information about the application, such as the vendor that develops the application. If you select to trust the supplier, the application will be started. The source information of the application depends on the digital code signature.
　　
　　 Installation instructions
For installation instructions and system requirements for this release, see the installation guide.
Use Java Web Start
Java Web Start allows you to start Java-based applications directly through the Web. Applications can be started in the following three ways:
Start the web browser by clicking the link.
Start from the built-in "Application Manager" of Java Web Start. The manager will track recently used applications and provide quick access to preferred applications.
Start from the desktop icon or the Start menu (for Windows only.
Regardless of the startup method selected, the running effect of the application is the same. Specifically, Java Web Start
　　
It is often connected to the Web server to check the updated version of a specific application.
　　
　　 Start from Web Browser
On the Java Web Start product page (http://java.sun.com/products/javawebstart), there are some applications that can be directly clicked to start. Click the start button to start different applications. The Web browser starts Java Web Start, which downloads, caches, and executes the specified application. You will notice that the second time you start the application, the speed is significantly faster, because it already exists locally and does not need to be downloaded again.
Most demo programs on the page can be directly downloaded and executed without user intervention. These applications run in a controlled environment and do not have access to local disks or networks, and do not install any viruses on your computer.
　　
Some demo programs require additional permissions, such as accessing the local hard disk. For these applications, a security dialog box is displayed, showing the source information about the application based on the digital signature of the Code. The application runs only when you decide to trust the supplier.
　　
This is indeed all the requirements for using Java Web Start, but how does it work? The HTML link for starting an application is actually a standard HTML link. However, it does not point to other web pages, but is linked to a special configuration file called the JNLP file. The Web browser checks the file extension and/or MIME type and determines that it belongs to Java Web Start. Start Java Web Start With the downloaded JNLP file as the parameter. Java Web Start displays a flashing screen and processes the download, cache, and run applications as instructed by the JNLP file.
　　
　　 Start from the built-in "Application Manager"
"Application Manager" is the built-in part of Java Web Start. It allows you to quickly and easily start applications that have been started through Java Web Start. The manager is a single-phase combination of the "History" menu and the "Start/Program" menu, providing corresponding functions for Java applications deployed on the web. "Application Manager" also allows you to view additional application information and jump to the home page of a specific application.
　　
You can double-click the application icon or click the start button to start the application from the application manager.
　　
Another important feature of "Application Manager" is the "Preferences" dialog box, which allows you to view and modify the settings used by Java Web Start. For example, it includes tabs that enable you to perform the following settings:
　　
Specify the HTTP proxy (or tell Java Web Start to use the default browser settings ).
Clear the downloaded application cache.
Specifies the location of different Java runtime environments (jres) versions.
Specifies whether to display the Java console.
View the root certificate set.
"Application Manager" can be started by clicking the Java Web Start icon on the desktop or the icon in the Windows "start" menu. On Solaris/Linux, start by calling the javaws command in the Java Web Start installation directory. The application manager can also be started through a web browser. The product page (http://java.sun.com/products/javawebstart) shows such an example.
　　
　　 Start from the desktop icon or "start" menu (Windows only)
Java Web Start automatically creates shortcuts on the Windows desktop and the "Start" menu for Java-based applications deployed on the web. By default, if you want to create a shortcut, Java Web Start will prompt you when you start the application for the second time. This parameter can be changed through the "Preferences" panel.
You can also use the "Application Manager" to add or delete shortcuts and shortcut menu items by using the application/create shortcuts and applications/delete shortcuts.
　　
　　 Use Java Web Start after Proxy Server/Firewall
Java Web Start must be configured with the correct proxy settings to start applications outside the firewall. Java Web Start will automatically try to check the agent settings of the default browser of the system (ie or Netscape on Windows, and Netscape on Solaris/Linux ). Java Web Start supports automatic script configuration for most web proxies. It can detect agent settings in almost all environments. If the proxy settings cannot be automatically detected, you are prompted to specify the proxy settings when you use Java Web Start for the first time. Java Web Start also prompts you to enter the username and password required to access the Authentication Proxy Server. The user name and password are stored as the current entry information of Java Web Start. However, when calling a new Java virtual machine, if you visit a secure web site, you will be prompted to enter the user name and password, because this information is stored with the Java Virtual Machine instance.
　　
You can also use the Java Web Start "Preferences" Panel to view or edit the proxy configuration. By clicking the icon on the (Windows) desktop or in the Java Web Start installation directory (Solaris/Linux), type. /javaws command to start "Application Manager" and then select "Edit/preference ". Check whether the settings are correct.