Archives
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Browse internet faster and save power using a smart HOSTS file
Internet is full of flash ads nowadays that make page load slower, render slower and consumes more CPU, thus power. If you can browse without having any flash ads or in fact any ads loaded and without any of the tracking scripts - you can browse much faster, scroll through pages much smoother and have more hours from your battery. Nowadays, most websites use scripts from various analytics sites that track your browsing habit, use IFRAME to load tracking and social networking widgets. All of these add considerable delay to page loading and make browser consume more CPU and bandwidth. If you can turn all of them off, browsing internet feels a lot smoother, faster and you get more work hours while running on battery.
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Get Dropthings license by donating to charity
Now you no longer pay me for Dropthings license instead you donate the money to a charity and I will give you the license. In case you don’t know what Dropthings is, it is a Web 2.0 Personalizable Dashboard framework that you can use to build Web 2.0 personalizable websites and enterprise dashboards. It is built using ASP.NET AJAX, jQuery, Silverlight, .NET 3.5, Entity Framework, SQL Server. It is in use in big companies like BT, Intel, Microsoft, Thomson Reuters; many government organizations like State Police, Canada Border Protection etc. Since it is a state of the art .NET 3.5 codebase, it is sometimes used as a starting point for an application with all the best practices already in place in order to build an N-tier web app using popular technologies, design patterns and testing methods. Dropthings helps you build web app utilizing extensive performance and scalability research that I have done to scale websites to millions of users. It also helps you build a codebase that is highly testable. It shows you how to test AJAX applications using automated test tools like WatiN. It has a business layer and a data access layer that is fully unit testable, nearly 100% test coverage and uses Inversion of Control pattern to the fullest.
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MVP Open Day 2011 at Cambridge
Microsoft Research arranged MVP Open Day 2011 at Cambridge on Oct 24, 2011. Beautiful university, made me feel like giving up my job and going back to study. Amazing research work going there, very thought provoking. The session on DNA programming was out of the world. The most surprising thing I learnt that a 10cm long DNA strand can hold 10TB digitally encoded data and cells are thousand times more robust computing system than silicon based chips. Moreover, cells are self-powered, super energy efficient micro processors, hundred years ahead of Intel processors.
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Prevent ASP.NET cookies from being sent on every css, js, image request
ASP.NET generates some large cookies if you are using ASP.NET membership provider. Especially if you are using the Anonymous provider, then a typical site will send the following cookies to every request when a user is logged in, whether the request is to a dynamic page or to any static resource:
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Tweaking WCF to build highly scalable async REST API
At 9 AM in the morning, during the peak traffic for your business, you get an emergency call that the website you built is no more. It’s not responding to any request. Some people can see some page after waiting for long time but most can’t. So, you think it must be some slow query or the database might need some tuning. You do the regular checks like looking at CPU and Disk on database server. You find nothing is wrong there. Then you suspect it must be webserver running slow. So, you check CPU and Disk on webservers. You find no problem there either. Both web servers and database servers have very low CPU and Disk usage. Then you suspect it must be the network. So, you try a large file copy from webserver to database server and vice versa. Nope, file copies perfectly fine, network has no problem. You also quickly check RAM usage on all servers but find RAM usage is perfectly fine. As the last resort, you run some diagnostics on Load Balancer, Firewall, and Switches but find everything to be in good shape. But your website is down. Looking at the performance counters on the webserver, you see a lot of requests getting queued, and there’s very high request execution time, and request wait time.
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Build truly RESTful API and website using same ASP.NET MVC code
A truly RESTful API means you have unique URLs to uniquely represent entities and collections, and there is no verb/action on the URL. You cannot have URL like /Customers/Create or /Customers/John/Update, /Customers/John/Delete where the action is part of the URL that represents the entity. An URL can only represent the state of an entity, like /Customers/John represents the state of John, a customer, and allow GET, POST, PUT, DELETE on that very URL to perform CRUD operations. Same goes for a collection where /Customers returns list of customers and a POST to that URL adds new customer(s). Usually we create separate controllers to deal with API part of the website but I will show you how you can create both RESTful website and API using the same controller code working over the exact same URL that a browser can use to browse through the website and a client application can perform CRUD operations on the entities.
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Automatic Javascript, CSS versioning to refresh browser cache
When you update javascript or css files that are already cached in users' browsers, most likely many users won’t get that for some time because of the caching at the browser or intermediate proxy(s). You need some way to force browser and proxy(s) to download latest files. There’s no way to do that effectively across all browsers and proxies from the webserver by manipulating cache headers unless you change the file name or you change the URL of the files by introducing some unique query string so that browsers/proxies interpret them as new files. Most web developers use the query string approach and use a version suffix to send the new file to the browser. For example,
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WCF does not support compression out of the box, so fix it
WCF service and client do not support HTTP Compression out of the box in .NET 3.5 even if you turn on Dynamic Compression in IIS 6 or 7. It has been fixed in .NET 4 but those who are stuck with .NET 3.5 for foreseeable future, you are out of luck. First of all, it’s IIS fault that it does not enable http compression for SOAP messages even if you turn on Dynamic Compression in IIS 7. Secondly, it’s WCF’s fault that it does not send the Accept-Encoding: gzip, deflate header in http requests to the server, which tells IIS that the client supports compression. Thirdly, it’s again WCF fault that even if you make IIS to send back compressed response, WCF can’t process it since it does not know how to decompress it. So, you have to tweak IIS and System.Net factories to make compression work for WCF services. Compression is key for performance since it can dramatically reduce the data transfer from server to client and thus give significant performance improvement if you are exchanging medium to large data over WAN or internet.
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Safely deploying changes to production servers
When you deploy incremental changes on a production server, which is running and live all the time, you some times see error messages like “Compiler Error Message: The Type ‘XXX’ exists in both…”. Sometimes you find Application_Start event not firing although you shipped a new class, dll or web.config. Sometimes you find static variables not getting initialized and so on. There are so many weird things happen on webservers when you incrementally deploy changes to the server and the server has been up and running for several weeks. So, I came up with a full proof house keeping steps that we always do whenever we deploy some incremental change to our websites. These steps ensure that the web sites are properly recycled , cached are cleared, all the data stored at Application level is initialized.