Stuff that's in my head

Tip of the Day #18: Dealing with data rounding issues

Colin Angus Mackay — Wed, 01 Sep 2010 17:34:41 GMT

If you have data coming in from a database, web service or other source external to your application and it contains, say for example, price information then do not round it. Don’t attempt to apply any form of formatting to it regardless of how much the client insists that the data will be in this form (e.g. all prices at go live will be in round pounds).

Yes, having whole rounded pounds, without having to display the pennies, on the front end looks nice and pretty. However, the display of whole rounded pounds on the front end is a rendering issue and should always be left to the code that is rendering the user interface. The rounding should never take place close to the point that the information is extracted from its source.

Why? Because eventually the client will want things displayed differently, to put prices with pennies in it, and you have to display those pennies. Now you don’t have to just update the rendering code to display the pounds and pence, but you also have to track down where that rounding occurs and stop it from happening in the first place.

But that’s not all. If you round data, effectively truncating it, early then subsequent calculations will be wrong. In fact, rounding isn’t just like truncating the data. Truncating is just removing precision. Rounding can change the value. That can cause even more havoc later on.

So, why round that early anyway, especially if the data is arriving in a certain way in the first place? Well, I can only guess that perhaps because back before anything went live, in the test system they weren’t. So, just to make the test system look like the eventual live system the prices were rounded the moment they arrived in the application just to be sure they were in round pounds.

The lesson, clients change their minds and business logic should always operate on the cleanest data, unsullied by rendering constraints wherever possible. This means that calculations based on that data will remain correct, even if other factors change.

Dime/Daim Bar Cake

Colin Angus Mackay — Mon, 30 Aug 2010 23:31:31 GMT

This is not so much a cake as a shortbread base with a sweet dairy topping. It serves many people and ideal as a party food. This recipe produces 20 servings.

Ingredients

250g of softened butter or margarine
150g granulated sugar
450g plain flour
500ml double (whipping) cream
250g Dime/Daim bars

Equipment

Baking tray (25cm x 35cm approx)
Grease proof paper (optional) cut to fit the baking tray
Large mixing bowl
Sieve
Rolling pin
Fork
Fan assisted oven (if not fan assisted, adjust cooking times accordingly)
Disposable food bag (e.g. a freezer bag)
Food mallet
Refrigerator
Whisk
Spatula

Instructions

1. Lightly grease or lay grease proof paper in the baking tray.

2. In a large mixing bowl, cream together the butter/margarine with the sugar until light and fluffy.

3. Sieve the flour into the mixing bowl. Mix everything together until a soft dough is formed.

4. Put the dough on centre of the the grease proof paper (or on a floured surface). Roll out the dough to roughly fit the baking tray. Place in the baking tray and push out to the sides to fill the tray.

5. Prick the surface of the dough evenly several times with a fork. Place the tray in a pre-heated oven at 160°C for approx 30 minutes until the shortbread is crisp and golden in colour.

6. Allow the shortbread time to cool naturally for about an hour or so. Do not refrigerate.

7. Unwrap the Dime/Daim bars and place in a food bag. Use the mallet to smash the Dime/Daim bars into small pieces of varying sizes (no more than about 1cm⊃;)

8. Pour the double (whipping) cream into a (new/cleaned) mixing bowl and whisk until the mix starts to firm up.

9. Add the smashed up Dime/Daim bars to the cream and mix together.

10. Using a spatula spread the cream mix over the shortbread base.

11. Place the baking tray in a refrigerator and allow to cool.

When ready to serve cut into rectangles of the desired size. You should expect to get about 20 pieces from the tray (4 x 5 grid)

Parser Error Message: Ambiguous match found

Colin Angus Mackay — Mon, 23 Aug 2010 17:05:52 GMT

Symptom

On deploying a newly precompiled web site, the error message as displayed by ASP.NET is as follows:

Server Error in '/' Application.

Parser Error

Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.

Parser Error Message: Ambiguous match found.

Source Error:

Line 1:  <%@ control language="C#" autoeventwireup="true" enableviewstate="false" inherits="WebSiteControls_Offers_TypeFilter, App_Web_typefilter.ascx.bd9a439f" %>

Line 2:  
Line 3:  <%--

Source File: /WebSiteControls/Offers/TypeFilter.ascx Line: 1

Version Information: Microsoft .NET Framework Version:2.0.50727.3053; ASP.NET Version:2.0.50727.3053

System Information

This may or may not be relevant, but it reflects my set up at the time I discovered this issue.

Web Site project
Visual Studio 2008
.NET 3.5
IIS 6.0

Reason

The reason for this is that a control, in this case a Repeater, in the User Control had a similar name as a field on the code behind. The only difference between the two the case. One was called “offerTypes” (in the code behind, an IEnumerable containing entities from the business layer), the other “OfferTypes” (a ASP.NET Repeater control).

Solution

Rename one or other so that the names differ by more that case alone. In my case, I renamed the field referring to the entities to offerTypeInformation.

Equator are Hiring Testers and Developers

Colin Angus Mackay — Mon, 23 Aug 2010 16:31:30 GMT

Due to continual expansion, Equator are currently looking for various people to join our Production team.

In return for this you will get to work for a dynamic and very talented development team. Equator has recently been voted the number 1 Digital Agency in Scotland and 15th in the UK for Design and Build by the NMA. We do more than just create web sites! We carry out CMS implementations, integration into third party systems including stock management, payment gateways and ecommerce solutions, create business application and we also lead the field in Google analytics and other tracking technologies.

On top of this we have just moved into our new Glasgow based head quarters which are truly unique and a really great place to work.

If you think you fit this job profile then please get in touch at devjobs@eqtr.com or call us on 0141 229 1800 and ask for Robert Graham.

The roles available:

Test Analyst

You must have at least 2-3 years experience in testing and have a proven track record testing web applications.

Key Role Skills

Create and manage test plans
Manage the execution and reporting of all test outcomes
Proof read web content
Ensure feedback to other production and client teams is timely and accurate
Provide feedback and suggestions to senior testers and wider company about improvements to the existing test processes
Be comfortable working in agile project methodologies

Senior Test Engineer

You must have at least 5 years experience in testing and have a proven track record testing web applications.

Key Role Skills

Create and manage test plans
Plan, develop and implement automated tests for web based projects
Experience of SQL Server investigation and data querying
Implementation of tests against ASP.Net web applications and C# based libraries
Manage the execution and reporting of all test outcomes
Ensure feedback to other production and client teams is timely and accurate
Create and recommend approaches to improve testing processes
Deliver presentations at monthly team meetings
Attend and represent the team at internal company meetings
Provide input and implement improvements in the development life cycle
Be comfortable working in agile project methodologies
Provide input into the recruitment process within Equator

Senior Interface Developer

You must have a genuine enthusiasm for development work, be committed, client facing, talented, fun and have at least five years experience in web based technologies.

As part of the team you will be expected to take on new projects, work on existing projects, provide mentoring for junior members of the team and help continually push the implementation of new technologies and best practice in every aspect of the development project life cycle.

Key Technical skills/Experience

5+ years HTML with an emphasis on clean, semantic markup and knowledge of HTML 5 techniques and practices
5+ years CSS with proven progressive enhancement techniques
5+ years of Javascript. Working with JS frameworks (e.g. jQuery) also an advantage
Knowledge and application of Ajax for enhancing user experience
Knowledge and application of usability and accessibility best practice.
Data integration from server-side technologies
Knowledge of C# and .NET an advantage
3 year + of working with CMS applications. Umbraco an advantage
Proven lead roles on projects
Produce accurate and well documented solutions
An eye for detail and an ability to work from design templates to produce excellent websites

Key Role Skills

Ability to teach and mentor others
Willingness to take full responsibility for design and development on client projects
Deliver presentations at monthly team meetings
Attend and represent the team at internal company meetings
Provide input and implement improvements in the development life cycle
Present ideas and solutions to clients
Undertake development reviews and buddy testing
Be comfortable working in agile project methodologies
Provide input into the recruitment process within the team

Senior Web Application Developer

You must have a genuine enthusiasm for development work, be committed, client facing, talented, fun and have at least five years experience in web based technologies.

Key Technical skills/Experience

5 years + ASP.Net
5 years + c#
5 years+ SQL Server
CSS, (X)HTML, JavaScript/ JQuery and Ajax experience
Web services and 3^rd party application integration experience
A good working knowledge of continuous integration technologies and proven implementation on projects
Knowledge of automated testing and load testing
An authoritative grasp of Object Oriented Design and techniques
Proven architectural roles on projects
Produce accurate and well documented solutions

Key Role Skills

Ability to teach and mentor others
Willingness to take full responsibility for design and development on client projects
Deliver presentations at monthly team meetings
Attend and represent the team at internal company meetings
Provide input and implement improvements in the development life cycle
Present ideas and solutions to clients
Undertake development reviews and buddy testing
Be comfortable working in agile project methodologies
Provide input into the recruitment process within the team

Web Application Developer

You must have a genuine enthusiasm for development work, be committed, client facing, talented, fun and have at least 2-3 years experience in web based technologies.

As part of the team you will be expected to take on new projects, work on existing projects, provide support to the senior members of the team, provide updates on progress and also support junior team members. You will also continually push for the implementation of new technologies and best practice in every aspect of the development project life cycle.

Key Technical skills/Experience

2/3 years + ASP.Net
2/3 years + c#
2/3 years+ SQL Server
CSS, (X)HTML, JavaScript/ JQuery and Ajax experience
An understanding of web services and application integration
Knowledge of and a desire to use continuous integration technologies
Knowledge of automated testing and load testing
A good grasp of Object Oriented Design and techniques
Produce accurate and well documented solutions

Key Role Skills

Willingness to teach and mentor others
Take responsibility for design and development on client projects
Provide input and implement improvements in the development life cycle
Present ideas and solutions to clients
Undertake buddy testing
Be comfortable working in agile project methodologies

Equator are hiring - looking for a Marketing Manager

Colin Angus Mackay — Wed, 07 Jul 2010 11:30:07 GMT

Marketing Manager – Online

Equator is Scotland’s largest full service digital agency. Established in 1999, Equator has grown to be a team of over 60 talented online enthusiasts, positioning us as a top 20 UK design & build agency. Equator’s marketing team currently delivers successful SEO, PPC, affiliate, media and social media campaigns for big names including AllSaints, RSPCA, SSE and AXA. Within Marketing we are recruiting a Marketing Manager to support the Marketing Director and manage operations within the department.

Marketing Manager - The Overview:

Location - Glasgow (G3 8EX) with occasional travel
Career development within the dynamic online marketing sector
Platform to deliver in a growing marketing team.
Competitive salary dependent on experience and skills

Marketing Manager - The Vacancy:

Marketing is one of the business units at the heart of what Equator does with responsibilities for developing, launching and managing paid search, natural search optimisation, affiliate marketing, media and social media campaigns. As a Marketing Manager, your focus will be to support the Marketing Director in developing and delivering campaigns for our 20+ marketing clients.

Help deliver strategic planning for all current clients
Support Marketing Director in development and expansion of function
Support and manage functional team managers within department
Maintain and develop client job management
Coordinating the delivery of new propositions and assist in identifying and developing new business streams
Identify, monitor and manager key business measures within the function to validate success of departmental works

Marketing Manager - The Person:

To operate successfully in this marketing role, you will need to demonstrate the following experience and have these points clearly presented in your CV.

Experience within an online marketing environment, with experience of managing a small team
Sound commercial experience (marketing) supporting delivery of ‘bottom line’ profit performance within a business.
Experience of driving and implementing business change
Evidence of both strategic and short-term planning experience
Ability to work as part of a team, and within a matrix organisation
Communicate effectively and influence at all levels in the business
Confidence, presence and determination to succeed in a dynamic and demanding business environment with a passion for producing results that have an impact.

Please apply online to martin.jordan@eqtr.com. Please send your letter and CV as one document. This role will be shortlisted in mid-late July.

32bit ASP.NET App on 64bit Windows 7

Colin Angus Mackay — Tue, 06 Jul 2010 17:28:25 GMT

Recently we all moved to Windows 7 (64bit) on our development machines. With that, we moved also to IIS7. So that meant that development copies of websites that we are working on have to be moved to IIS7. This should be simple. Right?

When I attempted to get the first site up and running I got hit by the error "Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.". (The full error message is below.) After searching around I eventually managed to piece together that the reason was that IIS was trying to run in 64 bit mode and this application was compiled as a 32 bit application. Okay.... So how do you fix this?

It turns out the fix is rather easy. In the IIS Manager, open up the list of Application Pools and select the pool for your application. Right-click and select "Advanced Settings". From that point you get this dialog:

Just set "Enable 32-bit applications" to "True", then Okay the dialog. You then have to recycle the Application Pool for the change to take effect.

Server Error in '/' Application.

Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.BadImageFormatException: Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Source Error:



An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Assembly Load Trace: The following information can be helpful to determine why the assembly 'System.Web' could not be loaded.


WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

Stack Trace:


[BadImageFormatException: Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
   System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
   System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +416
   System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +166
   System.Reflection.Assembly.Load(String assemblyString) +35
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +190

[ConfigurationErrorsException: Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11207304
   System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +388
   System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +232
   System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +48
   System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +210
   System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +76
   System.Web.Compilation.CodeDirectoryCompiler.GetCodeDirectoryAssembly(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories, Boolean isDirectoryAllowed) +11196482
   System.Web.Compilation.BuildManager.CompileCodeDirectory(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories) +185
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +551

[HttpException (0x80004005): Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
   System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +76
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +1012
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +1025

[HttpException (0x80004005): Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11301302
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +88
   System.Web.HttpRuntime.ProcessRequestInternal(HttpWorkerRequest wr) +11174792

Version Information: Microsoft .NET Framework Version:2.0.50727.4927; ASP.NET Version:2.0.50727.4927

Tip of the Day #18: Storing User Input in XML

Colin Angus Mackay — Thu, 24 Jun 2010 09:12:44 GMT

If you are going to dump user generate input into XML please remember to escape appropriately. For example, the ampersand symbol has special meaning in XML and you must escape it. e.g. & becomes &