Tài liệu Creating Applications with Mozilla-Chapter 6. Packaging and Installing Applications-P1 docx

The package inside the XPI has a manifest that is used to register the new Mozilla-based software with the Mozilla chrome registry.. When you install new packages or Mozilla-based softwa

Chapter 6 Packaging and Installing Applications-P1

The previous chapters covered the basic parts of building an application Now that you've seen how to create an application with XUL, CSS, and JavaScript that can be used on your local computer, we will show you how

to turn your program into something that can be installed by other users This chapter discusses the technologies Mozilla provides for packaging and installing applications

Until your project is packaged for distribution, it can't be fully considered a finished application (unless it was designed to work only on the computer where it was created) Making your application distributable, installable, and registrable allows others to use what you have created

This chapter is divided into four main sections It starts with a quick

overview of the basics of packaging and installing applications The second section provides details about how to get your application packaged and described so that Mozilla recognizes what it is The next section specifies how to put your package into a cross-platform installation file that can be installed over the Web onto other machines The last section provides tips for customizing how your application will look once it is installed

6.1 Packaging and Installing Overview

Several different pieces comprise Mozilla's distribution technology In fact, Mozilla may have a few more moving parts than other packaging systems because it needs a way to package and install new software uniformly across several different platforms Figure 6-1 shows the major components of

Mozilla's packaging system outlined in black

Figure 6-1 Mozilla packaging components

As you can see in Figure 6-1, the Cross-Platform Installer (XPI), pronounced zippy or X-P-I, is the archive format used to distribute Mozilla applications The XPI file contains a script that downloads and installs the application The package inside the XPI has a manifest that is used to register the new Mozilla-based software with the Mozilla chrome registry

When a XPI contains a Mozilla-based package such as the xFly sample discussed in Chapter 2 and the following chapters, the installation script also takes care of the package registration process, described in the Section 6.2.2 section later in this chapter Example 6-1 shows a simple installation script and the kind of information it contains The Section 6.3.2 section, also later

in this chapter, discusses other scripts that may need to be used in the

installation process, such as trigger scripts

Example 6-1 Package installation script

var myFile = "xFly.jar";

initInstall( // initialize the installation

"Install xFly", // display name

of installation

"xFly", // package name

"0.0.1", // version of install

1); // flags - an optional argument,

// reserved for future use

"content/xFly/"); // location of manifest in package

if (0 == getLastError( )) // if there have been no errors:

specified target directory Finally, packages in the installation are registered

At this point, the application is installed on a user's computer

When you install new packages or Mozilla-based software, the chrome registry on the Mozilla side brokers the deal reading the manifest,

executing the installation script(s), and updating the package information that it maintains internally (storing this information using RDF)

The relationship of the packaging, installation, and registration and all pieces involved may seem a little complex and idiosyncratic at first, but bear with it The upshot of this powerful but somewhat diffuse packaging technology is that you can bundle your software, put it on a server, and have users install it by simply clicking a link on a web page when using Mozilla

It is possible to use this packaging system to bundle any sort of application

or extension to an existing Mozilla application You can install a XPI that adds functionality to the Mozilla browser, such as Mouse Gestures

(http://optimoz.mozdev.org/gestures/ ), which enables the execution of common browser commands with mouse movements You can package new

Mozilla development tools and libraries like JSLib (see Chapter 5) You can also create installations for entirely new Mozilla applications

6.2 Packaging Mozilla Applications

Packaging simply means organizing your files into a Mozilla application

structure Packaging your application is required to make it installable and to make it something that Mozilla recognizes as one of its own Whether your Mozilla-based becomes a part of an existing Mozilla application, like Mouse Gestures, or will exist as a standalone application, like JabberZilla, you will need to package it

When you are done with this packaging section, package your Mozilla-based applications in the same way that we packaged the xFly example in Chapter

2 This chapter describes the manifests and other necessary files Then the Installation section shows how you can put your package in a XPI file and create installation script(s) so it can be distributed and installed

6.2.1 Package Manifests

All new packages must have manifests describing their contents, skin

information, and locale information These manifests are formatted in RDF, which makes them easy to combine with the RDF data that makes up the chrome registry and makes it easy to fit the package into the Mozilla

software There is some flexibility about where in the package the manifest must appear, but the registration process must find and read it regardless of where it is

The installation script points out the manifest locations so the package can

be registered properly Note that manifests appear in JARs, but they do not

appear in XPIs, since the latter is a temporary file that gets deleted once the files it contains, including JARs, are installed (see the Section 6.3 section later in this chapter for more information about XPI install files)

6.2.1.1 Theme package manifests

Example 6-2 shows a manifest for a new theme to be installed in Mozilla It

is simple because it describes only one type of package, the "fly skin," and the existing component it interacts with, the communicator the default Mozilla browser (the syntax and structure is the same for all manifests,

however) The manifest says, in effect, this is what I have here (the metadata about the theme its name, a description, etc.), and this is what it affects (the list of chrome:packages to which the theme should be applied)

Example 6-2 Simple theme package manifest

<?xml version="1.0"?>

<RDF:RDF rdf-syntax-ns#"

</RDF:Seq>

<! Fly Skin Information >

6.2.1.2 Language pack manifests

When you look at a package manifest that describes a new locale, as shown

in Example 6-3 (which is for a German language pack in Mozilla), you see a similar structure Again, the manifest describes the new package first and then lists the existing components to which this new package applies

Example 6-3 Locale package manifest

<?xml version="1.0"?>

<RDF:RDF rdf-syntax-ns#"

component

contents.rdf Type Manifests

Package manifests are an area where Mozilla browser itself may not be the best model for learning about the best application development practice Mozilla is such a large and modular application that it uses several manifests instead of one application-wide manifest.rdf file

Although they have the same format, these distributed manifests are found in

several contents.rdf files In a single theme (e.g., the modern.jar), you can see as many as eight manifests (for major component to which the theme applies)

These two types of manifests the contents.rdf file, which typically describes a single package-component relationship; and the

manifest.rdf file, which describes the package's relationship to all affected components are functionally equivalent In both cases, the

chrome registry reads all RDF/XML data and registers the package

Because the manifest data format is RDF/XML, you can use either type of manifest in your own package development, although using a single

manifest.rdf is generally much easier, especially if you want to

change the list of affected components of any other metadata later

The package manifests for content and new applications which may

include new content, skin, and locale information have an identical syntax and a very similar structure, as you will see in the following sections The manifest for a full Mozilla-based application like xFly describes the content, the skin, and the locale in a single file that sits at the top of that package

Example 6-4, the package manifest from the XMLTerm Mozilla extension, describes the contents, skin, and locale in a single file, which is most

common for Mozilla-based applications

Example 6-4 manifest.rdf describing the XMLTerm extension

<?xml version="1.0"?>

<RDF:RDF rdf-syntax-ns#"

</RDF:Seq>

<RDF:Seq

about="chrome://communicator/content/tasksOverlay.xul">

chrome:name="en-US"

chrome:previewURL="http://www.mozilla.org/locales/en-US.gif">

<chrome:packages>

<RDF:Seq

about="urn:mozilla:locale:en-US:packages">

<RDF:li US:xmlterm"/>

Note that the overlay section in the middle of the example is part of the content description It tells the chrome registry that the contents of the file xmltermOverlay.xul should be overlaid into the

tasksOverlay.xul file in Mozilla, in which much of the Tools menu is defined The package manifest for the xFly sample application that we

discuss here, also a single file, is very similar to the manifest in Example

6-4

6.2.2 Registering Packages

Typically, registration occurs during installation, which is why the Section 6.3 section of this chapter goes into more detail about the specific methods and objects available for package registration The registration process deals

with packages and package manifests, however, so the following two

sections describe the two types of package registration that are possible in Mozilla The first provides an overview of how to register a package on installation, as is typically done, and the second describes how to use a special file to register your work with Mozilla as you develop it so that you can view your work as it progresses

6.2.2.1 Registering packages on installation

Generally, the registration process is a transaction that takes place between your installation scripts, the chrome registry, and the manifests that describe the package Usually, registration happens upon installation You can

approach this transaction in many ways, but the general relationship is shown in Figure 6-2

Figure 6-2 Package interaction overview

In this relationship, the install script is responsible for managing the transfer

of files to a specified location on the local disk and alerting the chrome registry to the new files and their manifests The chrome registry then finds and reads those manifests If the information there is formatted correctly, then that information is added to the sum of package information that the chrome registry manages a single, overarching datasource of all packages

in Mozilla, including skins, locales, overlays, and other software In this way, the package is added to Mozilla The major players in this interaction between the packages, the package descriptions, and the chrome registry are shown in the following list

• Manifests in the archives themselves

• XPInstall, the technology that performs the downloading and resource installation

• The chrome registry, the database of packages, and user information that is read and written to when new software is installed

6.2.2.2 Registering packages as you develop them chrome.txt)

(installed-The file installed-chrome.txt is a convenience for developers who want to create and test new packages without having to install them with installation scripts and manifests Some earlier xFly examples in this book already used this method The installed-chrome.txt file is a list of entries that point to package manifests Each line provides the chrome

registry with a pointer to a manifest in which new software is described: new skin information, new packages, and new locales

In the following snippet from the installed-chrome.txt file in the Mozilla chrome directory, five entries point to contents.rdf type manifests that describe the modern skin resources particular to the

application's major components The first line in this list, for example, tells the chrome registry to find a contents.rdf file in the subdirectory

skin/modern/communicator contained in the modern.jar file, which describes the resources present there to skin the communicator

component When the chrome registry reads this line, it uses those resources

to skin the communicator component, shown here:

skin,install,url,jar:resource:/chrome/modern.jar!/skin/modern/communicator/

skin,install,url,jar:resource:/chrome/modern.jar!/skin/modern/editor/

skin,install,url,jar:resource:/chrome/modern.jar!/skin/modern/global/

skin,install,url,jar:resource:/chrome/modern.jar!/skin/modern/messenger/

skin,install,url,jar:resource:/chrome/modern.jar!/skin/modern/navigator/

Instead of installing your package with installation scripts, you can add the appropriate entries to this file, as seen in the following examples Adding these entries only registers local content on your machine When you use the installed-chrome.txt file, you neither install a new package nor make that package installable by others Editing the installed-

chrome.txt file directly is a shortcut for making Mozilla aware of

packages so that you can check your progress as you develop You probably need to create an installer for packages you want to distribute and install on other systems

To register a local copy of the xFly application with the Mozilla chrome directory, you would add the following three entries, where the xFly

directory and the appropriate subdirectories sit directly under the chrome directory:

content,install,url,resource:/chrome/xfly/content/

skin,install,url,resource:/chrome/xfly/skin/

US/

locale,install,url,resource:/chrome/xfly/locale/en-The first line tells the chrome registry that the content is found in the

directory chrome/xfly/content The next line points to the skin

resources at chrome/xfly/skin, and so on Note that creating a single entry for the xFly skin and locating its resources underneath the xFly

application directory (as opposed to a subdirectory in the modern and/or classic JARs) means that the xFly skin will not change when the user

changes skins

If we had the same structure archived in a JAR file called xfly.jar rather than in a directory, the installed-chrome.txt entries would look like this:

content,install,url,jar:resource:/chrome/xfly.jar!/content/