Engwar

What the Buzz!

Chintana — Thu, 18 Feb 2010 16:22:46 +0000

No wonder Google Buzz has created so many mixed reaction. Besides being one of the — if not the most — coolest and elegant social media service to date, it’s a good example of a non intrusive design. Integration with Gmail is one huge selling point to begin with. Connecting with a handful of other social media sites is again done wonderfully. The list will increase in future no doubt. It’s one of those things that you’ve always wondered what’s wrong with all the social media sites out there and boom someone comes with a solution having everything exactly the way you want. I am hooked!

Understanding OpenNebula

Chintana — Wed, 17 Feb 2010 14:04:27 +0000

OpenNebula is a platform providing the ability to manage a pool of virtual resources. You can create virtual machines and configure them as you would configure a physical machine connected your network. Difference between OpenNebula and Amazon EC2 (and other public cloud providers) is that Amazon EC2 is a public service. Amazon is having an infrastructure management tool like OpenNebula which they use to provide those virtual resources to people in a pay-as-you-go scheme. You can use OpenNebula to provide similar kind of service to users inside your network. If you want to be another cloud service provider like Amazon, you can easily adapt OpenNebula to do that too. You only have to write a frontend which restricts creation of virtual machines only after a payment is made (on a very high level ). OpenNebula has an XMLRPC interface through which you can interface with from another program written in a different programming language. Also, OpenNebula provide a driver which expose it’s functionality through the libvirt API.

What is libvirt? Libvirt is an effort to come up with an API for all virtualization platforms. Plus, it does have an implementation (libvirtd) which other management programs can talk to. For example virsh and virt-manager are couple of tools which can talk to underlying virtualization platforms such as Xen and KVM through libvirt.

Going a step further than libvirt, OpenNebula eases the creation of networks, adding cluster nodes and deploying virtual machines. Also, OpenNebula comes with a scheduler which will deploy a given virtual machine on the cluster. Scheduling policies can be configured and if more complex policies are needed those can be created through Haizea. Haizea is a scheduler which can be plugged into OpenNebula. OpenNebula stores all these information in an SQLite database that can be accessed from any other programming language if those information needs to be pulled out. A nice to have feature would be an API that gives all kinds of information stored in the SQLite database.

Using WSAS business service with .Net trader client

Chintana — Thu, 11 Feb 2010 06:29:03 +0000

Stonehenge is an Apache project started to demonstrate interoperability between different Web services platforms. Until we get this into the Stonehenge documentation, this is to record how to configure .Net trader client (a web interface written in .Net and is operating in the presentation layer) to talk to business service written using Java and is hosted in WSAS. Prerequisites and installation steps can be found in the Stonehenge wiki.

IMO (also I’ve raised this issue numerous times in the Stonehenge mailing list) problem with .Net WCF code we have now in Stonehenge defines bindings to each and every endpoint. Currently Stonehenge .Net trader client program can talk to business services implemented in .Net, Java (deployed in WSO2 WSAS and Sun Metro) and PHP (implemented using WSF/PHP). Each of these implementations runs on a different port and is having their own URL that they’re exposing the services. When there is a new implementation of the business service using a different framework, in order to point the .Net trader client program to talk to this new business service we have to add a binding into the trader client configuration with a binding specific to that. This, IMHO, defeats the whole purpose of Web services. When you compare .Net WCF to WSO2 Web services frameworks, in the WSO2 family of open source frameworks for many languages, only need the end point. When you want to talk to a different service with similar semantics, you just change the end point URL and everything else just work. There’s no “boilerplate” configuration necessary. That’s loose coupling. Anyhoo, back to the steps,

Open SQL Management Studio
Connect to your StockTraderDB database
Open up ClientToBs table and make sure DOTNET_CLIENT is using DOTNET_BS
Open up Service table and change the URL of DOTNET_BS to http://localhost:9763/services/TradeServiceWsas
Open Web.config in \dotnet\trader_client\Trade and add requireSignatureConfirmation="false" to line 99. After the change the line should look like the following,
messageSecurityVersion="WSSecurity11WSTrust13WSSecureConversation13WSSecurityPolicy12BasicSecurityProfile10" requireSignatureConfirmation="false">
Build WSAS trunk
Start WSAS by running \bin\wso2server.bat
Import BS.jks and OPS.jks in \stocktrader\wsas\resources\conf. Go to https://localhost:9443/carbon and login as admin. Username: admin, password: admin.
Click on Key Stores -> Add New Key Store. For BS.jks password is ‘yyy’. For OPS.jks password is ‘password’.
Start .Net services by running RunServices.bat
Login to .Net trader client by going to http://localhost/trade and tryout the operations

Yahoo Traffic Server

Chintana — Fri, 05 Feb 2010 05:57:14 +0000

Yahoo has donated the caching proxy server they use internally to Apache Foundation. This, apart from acting as a high performance proxy server has many other cool features. If you’re trying it out here’s the minimum required settings that you should set in order it to act as a caching proxy server.

First you have to compile it from svn, or git. Info on doing this is available in the README file. After doing make install, by default it’ll be installed into /usr/local. Configuration directives are broken down into a series of files in order to make it easy to find and change aspects of the system. Main configuration file reside in /usr/local/etc/trafficserver/records.config. Open it up with a text editor and make sure that proxy.config.reverse_proxy.enabled and proxy.config.url_remap.remap_required are set to 0. Then open up /usr/local/etc/trafficserver/storage.config and configure a simple file cache. Uncomment the respective entries and make sure a folder with the name exists that the traffic server user can write to.

Start the traffic server by trafficserver start. Configure your browser to use :8080 and you’re all set. Now you can test with the bazillion other options available in the config files.

Web site lead generation pages

Chintana — Tue, 02 Feb 2010 11:35:02 +0000

This article explains some worthy insights into making lead generation pages. An interesting idea that’s new to me was to make the page a dead-end. Having no links on the lead generation page that links back to the main site. Making it “harder” for the user to click something and navigate away from the lead gen page. Hmm … Also the article has some intriguing example designs of lead generating pages.

Browsers, browsers and more browsers

Chintana — Mon, 01 Feb 2010 17:53:41 +0000

No matter how many browsers are out there I still haven’t found the one true browser that rule ‘em all. This has the awkward situation where there has to be multiple browser instances running at any given time. All the memory that these fellows eats up is not much of a bigger deal because memory is not a problem these days.

For general browsing Firefox is ideal with Adblock Plus and Noscript. Safe and sound. For email (mostly Gmail and Gmail hosted these days) and other Google apps, Chrome fits nicely. Albeit you can’t use Google Chrome because of the annoying user tracking which cannot be turned off. Fixing that is easy, you just have to forget about Google Chrome and use Chromium nighty. Since I’m logged into Gmail no searching on Chrome. Can use the Firefox instance that’s there for general use. Next problem comes when opening up random links that include blogger and other sites with Google analytics. Gah, copy and paste those links to Firefox. My laziness prevent this from happening. Firefox is having Noscript so login to Gmail in that. Now have to use Opera for searching Google. This becomes irritating and I just use Firefox and search on Yahoo.

Using proprietary browsers is an unacceptable solution. You just don’t know what the hell is going on. There are other annoyances as well. A good candidate is Maxthon. Maxthon 3 interface looks like a step in the right direction but has a long way to go to become functional. For the life of me, I can’t figure out how to change Maxthon proxy settings without it being changing the IE proxy settings.

When you go beyond Firefox, searching for a better browser, quite frankly there is none.

Bill Gates’ vision

Chintana — Thu, 21 Jan 2010 03:45:54 +0000

This is not about Bill Gates’ move into social media, twitter, the micro blogging craze for the cool kids. No. Nor this is about The Gates Notes where he write about his thoughts. After reading The Internet Tidal Wave [PDF] again, it’s fascinating to take a peek at Bill Gates vision for the company, 15 years ago!

Later in 2005, the leaked memos about services disruption is also insightful. Bill Gates memo as well as Ray Ozzie’s one.

While digging a few links, came across this interesting analysis of the Microsoft anti trust case by Thimothy F. Bresnahan [PDF].

Taking a break from social media

Chintana — Thu, 24 Dec 2009 03:59:55 +0000

It’s been a few weeks that I’ve completely stopped using social media services Facebook and Twitter. I don’t think I’m missing that much. Well, may be a few tea time laughs and giggles, a few emails/IMs/a face-to-face chat that’s about not being able to understand tweets I can recall a very few birthdays and even less number of phone numbers from my memory. Now that the Facebook account is gone birthday calendar is no more.

Twitter, being the 140 char twat it is, forcing me to come up with less words as possible was slowly making my blog defunct. I wanted to blog more and this twat was getting in the way. Bye bye.

With Facebook, I was logged into find out that a number of my friends are “at work”, “bored”, “had lunch”, “saw a parakeet”, “just farted”, “still at work ” etc… along with a number of silly youtube videos. An hour or so later when I hit the logout button, I’ve gathered invaluable information about the online presence of five hundred odd people. I know many of you love Facebook to keep in touch with old friends. It’s great if you like it. One of those things that just not for me. Too much information.

More time to spend with dead and not so dead trees. Books and ebooks. A lot of people I know prefer books over ebooks. I prefer reading PDFs more than a book in my hands. Partly maybe, the effort you have to take for turning a page is far far far more less! Convenience being the other major factor where you can have hundreds of books without every taking an inch on your desk! Speaking of which I wonder whether Sony has released the Daily Edition …

External user stores in Identity Server

Chintana — Fri, 18 Dec 2009 15:03:04 +0000

Pointing WSO2 Identity Server to use user data stored in an external database has never been this easy. Once you complete the following it just works without having to do any other configuration or editing config files. All this can be done in few seconds using the excellent, intuitive web based management interface. In this case I wanted to point the Identity Server to talk to a Microsoft SQL Server database. More specifically this is how the Identity Server is configured in Apache Stonehenge project so that the .Net client program can authenticate via the Identity Server passive STS against users stored in a Microsoft SQL Server database. If you’re talking via JDBC this can be any database.

You need to download the jTDS driver that can talk to Microsoft SQL. Get the latest driver here.
Copy the jTDS jar file to \repository\components\lib and restart the server.
Now, login to Identity Server web based administration console by going to http://localhost:9443/carbon. Default username: admin and password: admin.
Goto User Management > Add External User Store and fill up with the following values
Connection URL: jdbc:jtds:sqlserver://localhost:1433/stocktraderdb
Connection user name: trade
Connection password: yyy
Connection password repeat: yyy
Driver name: net.sourceforge.jtds.jdbc.Driver

SQL for retrieving a given user’s password: select password from accountprofile where userid = ?
SQL for listing users using “like”: select userid from accountprofile where userid like ?
SQL for selecting a single user given the user name: select userid from accountprofile where userid = ?
SQL for retrieving a user list: select userid from accountprofile

and click Finish.
Now, click Test Connection to make sure the connection to the database is working fine.

That’s all you need to do. Now whenever your application point you to the Identity Server passive STS, you’ll be authenticated against users in the Microsoft SQL database.