Tech Talk

Ajax is getting a lot of tech buzz these days.  Making RPCs from client-side javascript is not a new technological innovation. Techniques such posting to hidden frames, posting to IFrames, and using Applets for server-side communication have been around for more than ten years.  

Back in 2000 I wrote a Web based Client Service Rep (CSR) application for a Appliance Warehouse.   It was a call center application used by CSRs to process customer orders for appliance rentals: washers, dryers, etc.  The application was designed to replace an existing client-server, windows-based application.  A key requirement was for the Web application to behave like the windows application it replaced (i.e. minimal or no screen refresh/browser form posts).

In 1999 Microsoft released an Applet-based RPC technique for javascript called Remote Scripting. This is the solution that I implemented for the CSR application. 

It's nice to see the resurgence of these javascript RPC methodologies albeit rebranded as "AJAX".  I now only use the XmlHttpRequest methodologies lauded by Ajax proponents, however; Remote Scripting can still be leveraged today.  An article posted by Peter Bromberg has some nice examples.

Here are some resources for Remote Scripting:

Microsoft Remote Scritpting

Brent Ashley's Remote Scripting Resources

Most software developers have either been asked a Fermi question in an interview or know of someone that has been asked this type of question.  Companies like Microsoft and Google are notorious for asking these questions. 

Why do interviewers ask this type of question?

Most developers I've talked to generalize the purpose of these questions as "They want to evaluate your critical thinking skills." Wikipedia's definition states that a Fermi problem:  is an estimation problem designed to teach dimensional analysis, approximation, and the importance of clearly identifying one's assumptions.

More specifically, the interviewer wants to determine how adept you are at creating quick, reasonably accurate estimations.   People who possess this skill augment a team's ability to quickly arrive at solutions when time and effort required to gather hard data is costly, impractical, or impossible. 

Here's a few links, so you can brush up on your Fermi skills:

http://www.soinc.org/events/fermiq/fermiguide.htm

http://www.vendian.org/envelope/dir0/fermi_questions.html

http://www.physics.uwo.ca/science_olympics/events/puzzles/fermi_questions.html

ASP.Net has various objects, properties, and methods manipulating and obtaining URL path information.  I did a search on Google for "asp.net paths". Rick Strahl's Web log had a nice breakdown of some of the common approaches for obtaining path information.  Reading through the threads that were posted at the end of his article made my head spin. I thought, "There's got to be a simple property built into ASP.Net Framework for obtaining the root Url path for a Web application."                        

After a lot of digging around on-line, I did not discover any built-in ASP.NET
functionality that would return a fully qualified domain name Uri for an
ASP.Net application.

I wrote some test code and iterated through some scenarios.  I discovered that the tilda "~" in front of Urls and HttpContext.Request.ApplicationPath both have problems and do not work in all usage scenarios. (i.e. Application hosted off the root of a Web site, certain scenarios involving the use of "#" in Anchor tags in User controls, etc).   

Conclusion: I will have to create my own bullet-proof methodology for generating Url paths for various links in ASP.Net applications.  I decided to write a simple class for this purpose, so it would be easy to use. The class is called App. Inserting it into the root of your Web project makes generating Urls simple and painless.

The Urls generated are not relative.  Each one is generated using the fully qualified domain name of the application instance, so paths always resolve properly.  (i.e. http://myapp/someFolder/someResource.aspx)

Here's some sample usage scenarios:

Url Redirection

Response.Redirect(App.Url + "/SomeFolder/SomePage.aspx" + "?idValue="
+ IdValue);

Javascript Reference

 <script language= "javascript"
src="<%=MyWebApp.App.Url%>/Common/Scripts/MyJavascriptFile.js" mce_src="<%=MyWebApp.App.Url%>/Common/Scripts/MyJavascriptFile.js"</script>

View Code Sample

I found this theme while browsing my friend's blog. It looked really slick, so I just had to use it.  (Sorry Sean.) It is a free template that he got from someone, but I still feel obligated to throw him some street cred. So, anyone that reads this post should go check out his blog at one on the links below.

-- Nuff said

http://www.alieninformatics.com/weblog/

http://www.cricketschirping.com/weblog