Categories
Axis2 C# Java Programming Technology Uncategorized Web Development

Building a JSON Axis2 REST Client for a WCF Service.

Using JSON as the message format for a WCF REST service has some advantages
if you are building a backend service for a purely browser based application.

For instance, JSON is natively supported in all of the major web browsers.

I had to build a REST client using Axis2 that uses the JSON message format.

The blog post Enabling JSON in Apache Axis2 explains the conventions that are used to map XML to JSON and how to configure axis2.xml so that your client application can use the XML/JSON mapping convention of your choice.

I chose the mapped namespace convention which can be configured by adding the two lines to your axis2.xml

<messageFormatter contentType="application/json"
class="org.apache.axis2.json.JSONMessageFormatter"/>

<messageBuilder contentType="application/json"
class="org.apache.axis2.json.JSONOMBuilder"/>

If you choose the mapped namespace convention you may get an exception that says “JSON mapped namespaces are not supported in Axis2”. If you see the above Axis2 exception then you need to patch jettison.

Instructions on the exception and the patch are in the “Building a JSON web service with Java and Axis2” post by Marcus Schiesser.

The ServiceClient (org.apache.axis2.client.ServiceClient) object can be used to make REST API calls in Axis2.

The ServiceClient can be configured using the Options (org.apache.axis2.client.Options) object.

For a REST style service invocation you need the following options,


Options options = new Options();
options.setTo(new EndpointReference("http://your.service.endpoint.url"));
options.setProperty(Configuration.MESSAGE_TYPE, "application/json");
options.setProperty(Configuration.ENABLE_REST, Constants.VALUE_TRUE);

//reuse HTTP clients
options.setProperty(HTTPConstants.REUSE_HTTP_CLIENT, Constants.VALUE_TRUE);
options.setProperty(HTTPConstants.CACHED_HTTP_CLIENT, httpClient);

The httpClient object is created via the MultiThreadedHttpConnectionManager. This is needed for managing the HTTP connections if your client is used in a multithreaded application. See the post “Improving Axis2 Client HTTP Transport Performance”

Finally, you have to engage the addressing module and set the ServiceClient options


client = new ServiceClient();
client.engageModule("addressing");
client.setOptions(options);

The ServiceClient sendReceive call takes an OMElement which I created using custom XML serialization on the message objects.

Make sure you cleanup the http connections via the httpconnectionManager used to create the httpClient. Again. see the post “Improving Axis2 Client HTTP Transport Performance” on how to do this correctly.

The sendReceive call can be made non-blocking if you are looking for further improvements in performance.

The response returned by the sendReceive call is an OMElement again and can be de-serialized using custom XML de-serialization on your message objects.

If you are looking for pure SOAP interoperability between WCF .NET SOAP client and an Axis2 service be sure to chek out my other post Axis2 and WCF .Net Interoperability (Interop)

Categories
Facebook Technology Uncategorized

How to Add Music Player to your Facebook Page

Update (Sept 7th, 2012):
The instructions in this post are no longer valid. However, I am leaving this post as it contains some useful information and comments.
Facebook tools/apis have been constantly changing. If you want to use their tools going to their website directly is your best bet.

If  you maintain a Facebook page for your band, Facebook provides an application called the Music Player that you can use to upload songs to your band’s page.

When you upload a new song it is automatically published into the news feed of all your fans. You don’t have to send out fan updates to publicize new songs. Publishing into your fan’s news feed is currently the best way to get the attention of Facebook users.

Here are the steps to add Music Player to your Facebook band page :

Login to Facebook. Make sure you are the page admin for the page you are editing.

Ads and Pages
Ads and Pages

Click on “Ads and Pages” on the left menu.

Update: If you don’t see the “Ads and Pages” link on the left menu simply go to this link to edit pages http://www.facebook.com/pages/manage.

Edit Pages
Edit Pages

Click on “Edit Page” link at the bottom of the page you want to edit.

More Applications
More Applications

Click on “Browse More”  which will take you to the application search page.

Search Music Player
Search Music Player

Type music player in the search box and hit enter. This should take you to the Search Results page.

Music Player application
Music Player application

You should be able to see the “Music Player by Facebook” application in the search results.

Click on it.

Add Music Player to Page
Add Music Player to Page

Click on Add to my page. This should pop-up a dialog.  Select the page.

Thats it.

You should now be able see the “Music Player” application on your page.

You can edit the “Music Player” application to upload and display albums on your fan page.

Tip: You can add the “Music Player” to any page in general, not just a Band page.

Categories
Gadgets Technology Uncategorized

Virtual Box – Access host [Mac OS X] physical ethernet port from guest OS [Windows 7].

If you are in a hurry here is the quick summary :

To access the host machine’s ethernet adapter/port from your guest os, you need to create a bridged adapter on the virtual machine. The bridged adapter maps a virtual interface on the guest os to the physical ethernet adapter/port on the host machine.

Got some time ? Then read on…

I got  a new TRENDnet  Gaming Adapter TEW-647GA (Wireless Bridge) to connect my 20 GB PS3 to the Internet and also to explore the Internet@TV features of my Samsung LED TV.

TRENDnet TEW-647GA
TRENDnet TEW-647GA

The wireless bridge comes with a setup utility on a CD. If you are on a Windows machine then setup is a breeze. But if you are on a Macbook/Macbook Pro/Mac you may not be so lucky. Fortunately, for me I had  Virtual Box with Windows 7 set up as a guest instance.

How to Access the host ethernet port from the guest OS ?

Connect the wireless bridge to the built-in ethernet port on the host and power up it up.

From your guest OS, mount the host CD drive  and run the setup.exe utility.

By default virtual box sets up the guest os to use NAT networking, running the setup utility with the default (NAT) virtual machine networking configuration will fail. The wireless bridge will not be recognized by the setup utility.

Reconfigure the guest virtual machine with a bridged adapter and map this new adapter to the physical built-in ethernet network adapter.

Run setup utility again from the guest os.

Setup.exe should now discover the wireless bridge connected to the ethernet port on the host machine.

Follow the instructions on the TRENDnet  installation guide. On my Window 7 guest OS I had to ignore the error messages that said configuration had failed. The configuration had in fact completed successfully and I was able to connect to my Netgear WGR614 router and the internet.

Disconnect the wireless bridge from the ethernet port and connect it to the gaming console. The gaming console should automatically pick up an IP via DHCP and your gaming console should be connected to the net.

Have fun!

Additional Notes :

You can configure an extra adapter (adapter 2) on your virtual machine if adapter 1 is configured with NAT networking already. TRENDnet Setup utility will still recognize the wireless bridge connected to the ethernet port.

Categories
Facebook Technology Uncategorized Web Development

How to Post to a Facebook Fan Page on Behalf of the Page.

Quick Summary

Use the Facebook.showPermissionDialog FBJS api call to authorize the Page for which you are an admin. Set the enableProfileSelector to true and include the page id in the profileSelectorIds. Once  the app user has authorized and given the extended permissions, You can use the Stream.publish api call with the page id as the target id and publish on behalf of the page.

The Details – Posting to the Facebook Fan Page on behalf of the page.

Facebook allows you to create pages aka fan pages for your website, business, product, or almost just about anything. Page admins can customize their pages by adding facebook applications from the app directory to their pages. Using Facebook applications for fan pages allows you to integrate into the social connections of your fans better.

Applications with extended permissions can publish to a user’s wall, news feed stream or profile. In addition, applications can now publish to a Page wall.

Publishing to a Page as a user is fairly simple with Stream.publish facebook api, the Facebook developer api covers this well. You can prompt the user for  ‘publish_stream’ extended permissions using the  fb:prompt-permission FBML tag, preferably during an initial set up workflow.

Once the user has authorized your app and given the extended permission, You just have to set the target id to the page id in your Stream.publish api call.  See the sample php api call below,

$facebook->api_client->stream_publish($message, $attachment,$action_links, $target_id);

Publishing on behalf of  a page is trickier.  Page admins have to authorize the app to publish on behalf of a page. You can do this by using

the Facebook.showPermissionDialog FBJS api call.

Facebook.showPermissionDialog('publish_stream, read_stream', ondone, showProfileSelector, [1234,2345]);

Just replace the profileSelectorIds ( [1234, 2345]) and include the page id in the FBJS call above. This should bring up a permission dialog and show

a “profile  selector” including the page for which you are an admin.

You should now be able to use the Stream.publish api call with the page id as the target id and publish on behalf of the page.

Categories
Programming software Technology Uncategorized Web Development

UI Programming Models

I found this excellent post Toward a better UI programing model with pointers to various UI programming models.

Web designers are forced to think within the constraints of the web browser when it comes to user interaction design.

The post above discusses more general approaches to user interaction design and not just within the context of the web browser.

Since I am mostly involved in web UI interactions these days this post was very refreshing as it brought a new perspective to me.

While developing the UI for a web app recently I realized that the web design world is in the search-discovery cycle of  “patterns” that guide user interactions.  Patterns in user interactions has the dual benefit of helping both designers and users. Much like the “guidelines” on Windows ( Windows User Experience Interaction Guidelines ) or Mac (Apple Human Interface Guidelines ) development platforms that help Windows or Mac application developers respectively while standardizing the user interactions of the applications developed on those platforms. These guidelines ensure strict quality, improves user experience and makes the life of designers easier.

There are plenty of resources that discuss “web ui interaction patterns” .

Designing Interfaces is a good resource if you are designing web user interactions. Rob Adams one of the core developers of Adobe’s Flex  has an excellent set of introductory articles which not only apply to designing user interfaces using Adobe’s Flex but applies to user interface design in general. I especially liked the Structuring your Application part.

Everyone loves the web, even if there are a few frustrations that we still have to overcome 🙂

Happy Surfing !

Categories
git Programming repository software Uncategorized

Git Fast Forward

git fast forward merge is a special case of a git merge.

Check the Basic Branching and Merging section of the git community book for the definition.

Here I present a case where non-fast forward merges were rejected by git and I had to fast forward a local branch to merge remote changes.

>git branch -a

* development

mylocal-branch

origin/development

>git status

# On branch development
nothing to commit (working directory clean)
>git merge mylocal-branch (you want to merge from mylocal-branch to development branch )

> git push <repository | origin> development

Works if the remote branch ‘development’ has no simultaneous commits from a co-worker, say.

But fails with the following messages if there were simultaneous commits on the remote branch ‘development’

! [rejected]        development -> development (non-fast forward)
error: failed to push some refs to ‘<your repository name>’

Here is how to fix this scenario,

> git pull <repository | origin> +development:development

The ‘+’ option fast forwards the local ‘development’ branch to the remote ‘development’ branch

> git merge mylocal-branch

At this point you have changes from the remote and local ‘development’ branches merged

> git push <repository | origin> development

The changes were now pushed to the repository without being rejected. This is one scenario where you can use fast forward to merge changes and synchronize local and remote branches.

Categories
PHP Programming Uncategorized

newline characters in PHP error log or debug output

There is a PHP Predefined constant PHP_EOL that allows you to print a newline character if you are running php CLI or if you are outputting text to an error log file.

Apparently, it is also cross platform compatible.

For a long time I was using print statements to throw debug output and had a hard time reading the blob of text output that was getting spit out.

Now my log output and debug output are much more readable 🙂

Categories
software Uncategorized

Some useful and common regular expressions (regex)

Regex for URI

 var uri_re = /^(?:(?:[^:\/?#]+):)?(?:\/\/(?:[^\/?#]*))?([^?#]*)(?:\?([^#]*))?(?:#(.*))?/;
Categories
Microsoft Technology Uncategorized

MPLS ALT.NET – The first get together.

MPLS ALT .NET
MPLS ALT .NET

Yesterday was the first ever MPLS ALT.NET get together at the Bulldog N.E Thanks Ira Mitchell and Jim Swanson for hosting. Judging by the turnout at the initial meet one can easily tell that there is a great enthusiasm for alt .net in Minneapolis.

Jim and Ira do a better job of explaining What ALT .NET is all about.

The folks at Redmond, WA do a great job trying to build awesome tools for developers but often times committing resources to every available tool in the open source community is not possible. Filling this gap is where a community like ALT .NET can help.

The state of Microsoft and the OSS community is better explained by Ayende Rahien.

I hope that this community becomes successful and brings in the best of the OSS, Java and RoR communities into the .NET world.

Categories
physics science Uncategorized

Is this a Revolution ?

A cool rap video about the Large Hadron Collider (LHC) caught my attention and I shared it with some of my old buddies.

I received a few encouraging words mostly in jest about how I should be involved with something revolutionary like the LHC project and drew a few sarcastic comments too.

The email responses from my friends inspired me to write this post and made me understand the significance of the LHC project a little better and also made me realize how we may be overlooking great revolutions happening around us.

Here is my email response,

Dear XYZ,

Thanks for the encouraging words and I enjoyed the sarcasm too…

Revolutions don’t happen overnight… rather they reach a crescendo at the right moment or they erupt from their simmering state into an eruption almost overnight. The trouble with revolutions, too is that you don’t know when they are happening.

The point of sharing that video was to show, how serious research can be presented in a light manner.

And personally, it had a context to me since I recently read this article, Surfer dude rewrites Physics ?that made references to the Large Hadron Collider.
If you do not have the time to read the whole article , here is a snippet that references the Large Hadron Collider,

“…The ultimate proof, or disproof, could then come when the world’s most powerful particle accelerator, the Large Hadron Collider, begins operating later this year in Switzerland. It is widely anticipated that the LHC will lead to the discovery of new subatomic particles, and string theorists are also betting on it to validate some of their ideas…”

In short, the assumptions we are making about how we are held together in one piece can be shattered by this collider.

This my friend is an example of a revolution in progress since it can explain among other truths the beginning(s) and the end of time…

-Senthil