chrome/common/extensions/docs/static/apps.html

<div id="pageData-name" class="pageData">Packaged Apps</div>
<div id="pageData-showTOC" class="pageData">true</div>

<p>
This page talks about packaged apps&mdash;how
you implement them,
and how they're different from
extensions and ordinary web apps.
</p>


<h2 id="overview">Overview</h2>

<p>
A packaged app is a web app
that's bundled into a <code>.crx</code> file
and can use Chrome extension features.
You build a packaged app just like you build an extension,
except that a packaged app can't include a
<a href="browserAction.html">browser action</a> or
<a href="pageAction.html">page action</a>.
Instead, a packaged app includes at least one HTML file
within its <code>.crx</code> file
that provides the app's user interface.
</p>

<p>
Packaged apps are a type of
<a href="http://code.google.com/chrome/apps/">installable web app</a>&mdash;a
web app that can be installed in Chrome.
The other type of installable web app is a
<a href="http://code.google.com/chrome/apps/docs/developers_guide.html">hosted app</a>,
which is an ordinary web app with a bit of additional metadata.
</p>

<p>
If you're developing a web app for the Chrome Web Store,
you might want to use a packaged app
instead of a hosted app if any of the following are true:
</p>

<ul>
  <li>
    You don't want to run a service to host your app.
  </li>
  <li>
    You want to build an app that works really well offline.
  </li>
  <li>
    You want tighter integration with Chrome,
    using the extension APIs.
  </li>
</ul>

<p>
The following articles can help you understand
the differences between web apps and websites,
extensions and packaged apps, and packaged apps and hosted apps:
</p>

<ul>
  <li> <a href="http://code.google.com/chrome/apps/articles/thinking_in_web_apps.html">Thinking in Web Apps</a> </li>
  <li> <a href="http://codesite-staging:29006/chrome/webstore/articles/apps_vs_extensions.html">Extensions, Packaged Apps, and Hosted Apps in the Chrome Web Store</a> </li>
</ul>


<h2 id="manifest"> The manifest </h2>

<p>
A packaged app's manifest can have any field
that's available to extensions,
except for "browser_action" and "page_action".
In addition, a packaged app's manifest <b>must</b>
have an "app" field.
Here is a typical manifest for a packaged app:
</p>

<pre>
{
  "name": "My Awesome Racing Game",
  "description": "Enter a world where a Vanagon can beat a Maserati",
  "version": "1",
  <b>"app": {
    "launch": {
      "local_path": "main.html"
    }
  },</b>
  "icons": {
    "16": "icon_16.png",
    "128": "icon_128.png"
  },
  "permissions": [
    "unlimitedStorage",
    "notifications"
  ]
}
</pre>

<p>
The "app" field has one subfield, "launch",
which specifies the <em>launch page</em> for the app&mdash;the
page (HTML file bundled into the <code>.crx</code> file)
that the browser goes to when the user clicks the app's icon
in the New Tab page.
The "launch" field can contain the following:
</p>

<dl>
  <dt>local_path:</dt>
    <dd><em>Required.</em>
    Specifies the launch page
    as a relative path referring to a file
    in the <code>.crx</code> package.
    </dd>
  <dt>container:</dt>
    <dd> The value "panel" makes the app appear
    in an app panel.
    By default, or when you specify "tab",
    the app appears in a tab.

    <!-- PENDING: In the overview
    (or somewhere else before here)
    we should show and define both app panels and tabs.
    We should link to that place from here. -->
    </dd>
  <dt>height:</dt>
    <dd>
    If the container is set to "panel",
    this integer specifies the height
    of the panel in pixels.
    For example, you might specify
    <code>"height":400</code>.
    Note that you don't use quotation marks in the value.
    This field specifies the height of the area
    to display contents in;
    window decorations add a few more pixels to the total height.
    If the container isn't a panel, this field is ignored.
    </dd>
  <dt>width:</dt>
    <dd>
    Similar to "height",
    but specifies the width of the panel.
    </dd>
  </dd>
</dl>

<p>
Packaged apps usually provide a 16x16 icon
to be used as the favicon for
tabs that contain app's pages.
They also should provide a 128x128 icon,
but not a 48x48 icon.
See the manifest documentation for the
<a href="manifest.html#icons">"icons" field</a>
for more information.
</p>

<p>
For further details on what a packaged app's manifest can contain, see the
<a href="manifest.html">manifest documentation</a>.
</p>

<h2 id="next">What next?</h2>

<p>
Read the <a href="overview.html">Overview</a> to learn
basic concepts about extensions.
</p>

<p class="backtotop"><a href="#top">Back to top</a></p>