ASP.NET Don'ts And Dos

ASP.NET Don’ts and Do's

Some folks may keep falling into a trap and are unaware of what they are doing. This article highlights the Dos and the Don’ts in general regarding ASP.NET. The majority of the items listed are taken from the ASP.NET team recommendations. Though this may not be a complete checklist, it covers some of the most common “gotchas” folks run into.

If you know other tips about the Dos and Don’ts in ASP.NET in general, feel free to drop a comment so I can update the list.

Control Adapters

If some of you are still using Control Adapters, especially those WebForms folks- you should avoid it, as much as possible.

Avoid: Control Adapters, as these were created to support mobile controls rendering different markups for different devices.

Prefer: CSS media queries, responsive design and mobile specific views.

Style Properties on Controls

Try to Avoid


• The four thousand specific control style properties, e.g.


• EditItemTemplate-AlternateItem-Font-ForeColor-SomeStyle-Blah-Blah :S
  
  
• Using inline CSS styles, e.g.
  

  style=“color:yellow;text-align:center;”

Prefer: CSS stylesheets. You can create your own or use Bootstrap or a combination of your own CSS.

JavaScript Frameworks and AjaxControlToolkit

Try to Avoid: Mixing your jQuery code or other JS frameworks code with WebForm's AjaxControlToolkit controls to avoid functionality issues.

Prefer: Stick to the specific control libraries.

UpdatePanel Control

Do Not: Over use it (Think about performance and maintainability)

Do: Use it, when necessary and if it makes sense to use it.

Try to Avoid: It doesn’t help you to become a better web developer.

Prefer: AJAX e.g jQuery AJAX can be used to do asynchronous updates.

Page and Control Callbacks

Try to Avoid: Page callbacks or control callbacks.

Prefer: Anything else, e.g. Page Method,Web Service, AJAX, Web API.

Scripts and CSS Files

Do: Minify, bundle your CSS and Script files when deployed on production.
Try to Avoid: Deploying unminified scripts and CSS when you can minify them.

Static Script References

Try to Avoid: Referencing local script references (e.g jQuery)
Prefer: Use CDN (Content Delivery Network), when referencing is done on static files 
But Always: Do a fallback local reference, in case CDN fails

Capability Detection

Try to Avoid: BrowserCaps, as it has a history of breaking as new browser versions are released
Prefer: Client-side feature detection and lightup, such as via Modernizr.

SQL Queries

Do Not: Append input values directly into your SQL statement because it can lead you to SQL Injection attacks. It’s a big NO NO!

Do:

(1) Use parameter queries
(2) Stored Procedures
(3) ORM e.g. Entity Framework, NHibernate etc.

This article highlights preventing SQL Injection. Protect Your Data: Prevent SQL Injection

Displaying of Data

Do Not: Display huge amounts of data in your page as it can affect the performance of your App and it is not user-friendly.

Do: Limit the amount of data to be displayed.

(1) Filter out items and load the associated data.
(2) Apply paging (e.g using custom paging with LINQ or using SQL paging).
(3) Apply data caching (but be careful: use it only where it makes sense).

Request Validation

Do Not: Depend on the request validation to protect your site against XSS attacks.

Do: 

(1) Validate well-formedness of the data 

“Is this user-submitted value, a valid System.Uri whose scheme is http: or https:?”


(2) Encode data on the way out.



CSHTML: @foo ● ASPX: <%: foo %>


(3) Don’t forget about JavaScriptStringEncode, UrlEncode, etc.

 

Cookieless Forms Auth& Session

Do Not: Enable cooki less forms authentication or session, as they could make your users victim to malicious attacks.

Do: 

(1) Enable “require cookies” for these features.
(2) Consider using only secure (SSL) cookies for the sites serving sensitive information.

EnableViewStateMac

For the developers who use ASP.NET runtime <= 4.5.2

Do Not: Set EnableViewStateMac = false

Not ever: Not even on a single page.

“But I’m not using ViewState!” is not a valid excuse.

Do: Tease Microsoft for even allowing this as an option in the first place.

Well MS already forbids it when they released ASP.NET 4.5.2.

Medium Trust

Do Not: Depend on Medium Trust (or any other <trust> level) as a security boundary.

Do:

(1) Place untrusted Applications into their own Application pools.
(2) Run each Application pool under its own unique identity.
(3) You can follow some guidance.

<appSettings>

Do Not: Use <appSettings> to disable Microsoft security fixes for any lengthy time in production.

Do: Use Microsoft security-sensitive <appSettings>config as temporary compatibility that shims while rolling out Server upgrades or patches

Consult the list.

UrlPathEncode

Do Not: Use UrlPathEncode to encode the arbitrary user-provided strings.

Do: 

(1) Sanitize inputs instead, checking submitted URL for well-formation.
(2) Use UrlEncode to encode the user input meant to appear as a query string parameter in the URL.

PreSendRequestHeaders&PreSendRequestContent

Try to Avoid: Registering for these events from within managed IHttpModule instances.

Prefer: Using native IIS modules, if you need to hook these asynchronous pipeline events.

Asynchronous Page Events

Try to Avoid: Writing async void methods [like Page_Load] for page lifecycle events.
Prefer: Using Page.RegisterAsyncTask() instead, if you need to register asynchronous work.
Do: Set <httpRuntimetargetFramework=“4.5” /> if using Task.

Response.Redirect& End

Be Aware: Reponse.Redirect(String) calls Response.End(), which aborts the current thread in synchronous requests and halts the code execution.

For asynchronous handlers, Response.End() does not abort the current thread, so code execution continues.

If you need to redirect the response, use the method appropriate for the framework you’re using. For example, in MVC, return a RedirectResult instead of calling Response.Redirect.

EnableViewState&ViewStateMode

Try to Avoid: Using EnableViewState.
Prefer: 

(1) Set ViewStateMode=“Disabled” at page directive level.
(2) Set ViewStateMode=“Enabled” only on the controls that require state.

SQLMembershipProvider

Be Aware: Replaced by the UniversalProviders and ASP.NET. identity which works with all the databases and the Entity Framework supports including SQL, Azure SQL, SQL Compact, MySQL and more.

Long-Running Request

Try to Avoid

Session, as ASP.NET will forcibly release the session object lock at a potentially inopportune time
Blocking I/O operations.

Prefer

WebSockets, if possible, has much lower per-request memory overhead.

Real-Time Updates

Try to Avoid

The traditional way of pinging the Server for the updates with AJAX.

Prefer

ASP.NET SignalR. It provides a simple and clean API that allows you to create real-time web apps. HTML5 is also worth trying.

WebForms

Do Not

Stick to use Web Forms.

Do

• Learn other technologies that ASP.NET offers such as MVC, Web API, SignalR and ASP.NET Mobile.
• Learn JavaScript frameworks (e.g Angular, Knockout, React etc..).
• Keep up to date with what’s the latest and know the new features it offers.