Deploy standalone shindig on Quarry and an OAuth gadget demo

I got a virtual machine which I can log in as root. The virtual machine is pretty clean without any more packages besides CentOS.
I installed vim using yum install vim-enhanced. I also installed jdk1.5 and maven2.

Then I checked out the source code from shindig svn trunk. See instructions here http://incubator.apache.org/shindig/#tab-building.
Unfortunately, the test failed when I compiled and installed shindig. This kind of things always happens because of instability of trunk code. So I copied my previous checkout of shindig code which worked well from another machine. Then the compilation and installation succeeded.

OAuth gadget demo to retrieve google contact list

Now the sample demo is here:
http://gw11.quarry.iu.teragrid.org:9999/gadgets/files/samplecontainer/samplecontainer.html

Set field "Displaying gadget" to http://156.56.104.196:8888/oauth/gadgets/os_gadget.xml, Uncheck "use cache".
Click button "reset all". If everything works fine, you would see following in main panel:

Clieck "Personalize this gadget", a popup window would appear which prompts you to login to your google account. Then you can choose grant or deny the access request. If you grant the request, the popup window would be closed automatically, and the main panel would be populated with your google contact list.

Manipulate IFrame in Javascript

Create a iframe and set the content directly:

var frame = document.createElement('iframe');
parentElement.appendChild(frame);
frame.contentDocument.write(result);

According to Dom level 2 HTML specification, contentDocument is a property of HTMLIFrameElement.

Following code may also work. However I have not found the contentWindow property in W3C DOM specification.

var frame = document.createElement('iframe');
parentElement.appendChild(frame);
frame.contentWindow.document.write(result);

Integration of OpenSocial containers via OAuth

For OpenSocial gadgets,  OpenSocial containers are necessary to hold users' data (friends, profile, ...). In Javascript API, class opensocial.DataRequest can be used to get users' data from the container which renders the gadget.

But to integrate users' data from third-party OpenSocial containers, some additional steps are needed. opensocial.DataRequest does not allow gadget developers to specify which OpenSocial container would be used to serve the data. Also the gadgets can not send requests directly to third-party containers because of Same-Origin policy imposed by browsers.

Method gadgets.io.makeRequest can be used to send arbitrary HTTP GET/POST requests. These requests are sent to the original container first. The original container does some processing and relays the requests to the destination address.
http://code.google.com/apis/opensocial/docs/0.8/reference/gadgets/#gadgets.io.makeRequest
http://code.google.com/apis/opensocial/articles/makerequest-0.8.html
http://code.google.com/apis/gadgets/docs/remote-content.html

Both REST and RPC protocol specifications requires that compliant containers must be OAuth service provider:
http://www.opensocial.org/Technical-Resources/opensocial-spec-v081/restful-protocol (Section 4)
http://www.opensocial.org/Technical-Resources/opensocial-spec-v081/rpc-protocol
Also I found OAuth Consumer Request 1.0 Draft 1 (hosted at googlecode, not oauth.net) which standardizes two-legged authorization process without a User involvement. It is useful in server-to-server interaction.

How to use OAuth in gadgets
http://code.google.com/apis/gadgets/docs/oauth.html (Very useful)
http://sites.google.com/site/oauthgoog/oauth-proxy/social-oauthproxy

OpenSocial container list:
http://wiki.opensocial.org/index.php?title=Main_Page#Container_Information

Extensions:
Also, I found many OAuth extension drafts which are not listed in OAuth.net. I guess these extensions are implemented in Shindig and evaluated.
http://oauth.googlecode.com/svn/spec/ext/

Enable/Disabl Directory Listing in Tomcat

By default, directory listing (list content of a directory instead of render a web page) is forbidden in Tomcat.

To enable it globally, modified file <tomcat>/conf/web.xml.
Default setting for default servlet is:

    <servlet>
        <servlet-name>default</servlet-name>
        <servlet-class>org.apache.catalina.servlets.DefaultServlet</servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>0</param-value>
        </init-param>
        <init-param>
            <param-name>listings</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

Change the param-value for parameter listings to true.

To enable it for a specific web application, add following snippet to the web.xml of the application

    <servlet>
        <servlet-name>default_new</servlet-name>
        <servlet-class>
          org.apache.catalina.servlets.DefaultServlet
        </servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>0</param-value>
        </init-param>
        <init-param>
            <param-name>listings</param-name>
            <param-value>true</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!-- The mapping for the default servlet -->
    <servlet-mapping>
        <servlet-name>default_new</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

Note: servet-name can not be default because it is name of tomcat's default servlet . So you need to use a different name. Also servlet-mapping element is necessary to make it work.

Shindig server on Tomcat

Shindig can be run with built-in jetty server without problems. But after I deployed the war to Tomcat, there are some problems. I got a blank page when I tried to render a gadget. I searched for the problem, some other guys got this problem as well.

Other posts related to this problem:
http://mail-archives.apache.org/mod_mbox/incubator-shindig-dev/200805.mbox/%3C483C780B.6080802@oracle.com%3E

Finally I figured out how to make shindig work on Tomcat.
Why does not it work?
It ignores the context path. In other words, the implementation only considers the situation that the application is deployed as root application.

Two possible Solutions
(1) make shindig war the root application
Two alternative ways:
    (*) rename it to ROOT.war and deploy it to tomcat. (The original ROOT application cannot be used)
    (*) change conf/context.xml to set shindig application as root application
(2) Modify shindig configuration files <shindig>/java/common/conf/shindig.properties and <shindig>/config/container.js to add context path in all related urls.
It seems to work well. I am not sure whether there is any potential problem.