Transcript ASP.NET Best Practices

Best Practices for
ASP.NET Development
Ammar Abuthuraya
Developer & Platform Lead
Microsoft Corporation
What we will cover
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Designing ASP.NET Web forms
Use code-behind for best performance
and scalability
ASP.NET caching techniques
State management options
Recommendations for communicating
with COM components from ASP.NET
Session Prerequisites
 Understand
.NET architecture
 Working knowledge of either VB.NET or
C#
 Knowledge of ASP.NET application
architecture
 Knowledge of ASP
Level 300
So Why This Presentation?
 You
know how to build ASP applications
and use the same techniques to build
ASP.NET applications
 You want to leverage the power and
capabilities of ASP.NET
 You want to use ASP.NET to build highperformance, scalable, web-based
applications
Demonstrations
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Language best practices
Server Control design practices
Component & user control design
State management recommendations
Caching techniques
Measuring performance
Agenda
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Deployment Best Practices
Measurement Techniques
Language and Code Practices
Code Performance
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.NET Common Language Runtime (CLR)
provides big runtime performance wins
Further optimize by native code
generation using NGEN.EXE
No perf difference in .NET languages
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Equivalent code written in VB and C#
provides equivalent performance at runtime
Language and Code Practices
Binding in VB.NET
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Early binding in VB performs better than
late binding
‘ VB Late Binding Example
Dim j, obj
obj = New System.Collections.ArrayList()
for j = 0 To i
obj.Add(j)
Next
‘ VB Early Binding Example
Dim j as integer, obj As ArrayList
obj = New System.Collections.ArrayList()
for j = 0 To i
obj.Add(j)
Next
Language and Code Practices
Language Recommendations
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Avoid using late binding in VB
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Use <%@ Page Language=“VB” Explicit=“true”
%>
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Explicitly declare all variable types (Dim a as Long)
Avoid late bound methods on Object type
Requires all variables to be declared (DIM required)
Still enables late bound code to exist though
<%@ Page Language=“VB” Strict=“true” %>
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Disallows any late bound code to be used
Language and Code Practices
COM interop Issues
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Apartment threaded components are
particularly expensive in ASP.NET
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ASP.NET now uses MTA thread pool by default that
has very bad perf side effects when running STA
components
This affects all VB6( STA) components!
Language and Code Practices
interop Recommendations
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Ideally migrate COM code to .NET
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Alternatively structure APIs to be less “chatty” and
more “chunky” in usage
Use COM interop through
System.Runtime.interopServices
If using apartment components, mark page to
run in STA compat mode:
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<%@ Page ASPCompat=“true” %>
Language and Code Practices
interop Recommendations
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Be careful not to declare any STA
component in “constructor” of page:
<%@ Page Language=“VB” ASPCompat=“true” %>
<script language=“VB” runat=server>
Dim MyComponent as New MySTAComponent() 'Bad!
</script>
<%@ Page Language=“VB” ASPCompat=“true” %>
<script language=“VB” runat=server>
Dim MyComponent as MySTAComponent
Sub Page_Load(Sender as Object, E as EventArgs)
MyComponent = New MySTAComponent()
End Sub
</script>
Demonstration 1
Language Best Practices
Early binding vs. Late Binding Using
COM objects in ASP.NET
Agenda
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Deployment Best Practices
Measurement Techniques
Server Control Design Practices
Optimizing Server Control Rendering
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Server controls provide a very clean
programming model abstraction
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Server controls do more rendering/postback
work than old-style <%= %> code
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Recommended way to build ASP.NET pages
Should understand what this work is and optimize for
it accordingly
Two areas to think about and optimize:
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Rendering Content
ViewState Postback
Server Control Design Practices
Optimizing Server Control Rendering
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Server controls encapsulate rendering markup logic at
runtime
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individual server controls each add slight additional
rendering cost
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Handle style and automatic uplevel/downlevel functionality
management
Additional allocations for style management
Additional allocations for control itself
Net take: the more individual server controls on page,
the more this overhead can be noticed
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Need to be especially aware of this w/ composite list controls
that generate multiple controls per data row
Server Control Design Practices
Optimizing Use of Viewstate
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ASP.NET allows pages/controls to maintain state across
round trips by storing state within hidden “viewstate”
field
Disabled with “EnableViewState” attribute
Some downsides:
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increases network payload
Performance overhead to serialize this
Recommendation:
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Always review your usage of this feature
Always disable if you are not doing postback
Disable on per control basis if possible
Use <%@ Page Trace=“true” %> to track usage size
Server Control Design Practices
Data Validation Techniques
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Leverage client side scripting capabilities
to perform validations
Perform validation on both server & client
side to avoid validation bypass
Make appropriate use of the
RequiredFieldValidator
Use RegularExpressionValidator for
validating complex field types like Credit
Card
Server Control Design Practices
Data Binding Best Practices
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Multiple ways to do data access with .NET
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SQL vs. OLEDB ADO.NET Provider
DataReaders vs. DataSets
Recommendations:
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Always use SQL Data Provider for Microsoft®
SQL Server™ data access
Use DataReaders for ASP.NET data access
and use DataSets only when data caching or
with web services
Demonstration 2
Server Control Design Practices
Optimizing Server Control Rendering
Optimizing Use of Viewstate
Data Validation Best Practices
Data Binding Best Practices
Agenda
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Deployment Best Practices
Measurement Techniques
Component & User Control Practices
Improving User Experience
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ASP.NET built-in caching features
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Output Caching
Fragment Caching
Caches the static result of an ASP.NET
page
Use the <%@ OutputCache %> directive
to control caching behavior
Component & User Control Practices
Improving User Experience
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Caching Options:
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Duration - Time item exists in the cache
VaryByParam - Varies cache entries by
Get/Post params. Name param, separate by
semi-colons, supports *
VaryByHeader - Varies cache entries by Http
header
VaryByCustom - Override method within
Global.asax to custom vary by whatever you
want (you control the cache key)
Component & User Control Practices
Improving User Experience
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Caching the entire page isn’t always
possible
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Partial page personalization, etc.
Fragment Caching allows caching regions
of a page by using user controls (.ascx)
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User controls define <%@ OutputCache %>
directive
Component & User Control Practices
Coding Patterns in ASP.NET
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Common coding patterns:
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Spaghetti – include all presentation logic and code in
the same page like classic ASP
Code behind – all presentation logic is in the aspx
file, which is linked to a separate code behind file
Component – business logic is present in a compiled
component, which is invoked for providing various
services
There is no perf difference between a
dynamically compiled .aspx (“spaghetti”) and
“code behind” style page
Component & User Control Practices
Optimizing Data Flow Across Tiers
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Data exchange across tiers has to be optimized
for the deployment scenario
Avoid passing datasets across tiers
Use DataReaders for fast, forward-only access
to the data stream
XML is very verbose; suitable for
communications with unknown systems
Component & User Control Practices
Optimizing Data Flow Across Tiers
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Minimize the number of post backs
Leverage client side capabilities to avoid post
backs
Control the amount of view state information
passed during a post back
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Use EnableViewState at page or control level to
configure view state usage.
Demonstration 3
Component & User Control Best
Practices
Buffered Output
Fragment Caching & Custom Caching
Code Behind, User Controls & Components
Data Flow Across Tiers
Optimizing Postback
Agenda
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Deployment Best Practices
Measurement Techniques
State Management Recommendations
in Proc Session State
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Session state is stored in the ASP.NET
worker process
Recycling the process will cause all
session state to be lost
Session state performance is maximum in
this mode
State Management Recommendations
Out of Proc Session State
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Session state can be stored in a State
server process running on the same
machine or a different machine
State can also be stored in a SQL Server
database
Restarting the web server does not cause
the session state to be lost
More reliable than in process session
state but less performant
State Management Recommendations
Configuring Session State
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Session state can be configured via the
<sessionState> element in the web.config
file
Change causes ASP.NET application to be
restarted, all new sessions will be stored
as per the updated session configuration
Out of process session state stores like
State Server or SQL Server must be
started & configured properly
Demonstration 4
State Management Best Practices
State Management
Session State in A State Server
Agenda
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Deployment Best Practices
Measurement Techniques
Deployment Best Practices
Logical Design
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Design your applications using logical 3-Tier
Design Practices:
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Pages (.aspx) and User Controls (.ascx)
Reusable Biz Classes in \bin dir (.vb + .cs)
Data within a SQL Database
Design your Web application so that it can be
distributed across a Web farm
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Your code shouldn’t assume that a client will always
return to the same machine
Be careful of assumptions regarding statics and
application state
Deployment Best Practices
Physical Deployment
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Deploy your applications such that the pages
and components run in same process
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Deploying onto remote servers connected via DCOM
or Web Services will almost always hurt your
performance/scalability
Leverage Web services only for application to
application communication -- not intra app calls
Leverage ISA Server for configurations where a
DMZ security zone is required
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Enables you to restrict app server access from
browser clients
Deployment Best Practices
ISA for DMZ Configurations
DMZ (firewalled)
Browsers
ISA
ASP.NET
SQL
Agenda
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Deployment Best Practices
Measurement Techniques
Measurement Techniques
Overview of Application Center Test
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Application Center Test (ACT) is a tool designed
for stress testing web servers
The tool assists in determining performance
and scalability of a given web site
The tool also collect useful statistical
information during the stress test
ACT also exposes a programming interface,
which can be used for creating stress test
scripts
Measurement Techniques
Key Performance indicators
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The key performance indicators of a web
application are:
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Processor utilization
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ASP.NET
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Low value indicates blocking on other resources
Requests/Sec & Requests Queued
Memory
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Pages Faults/Sec – lower the better, high numbers
indicate insufficient memory condition
Measurement Techniques
Stress Testing
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Stress testing is a defensive mechanism to
creating scalable web sites
Stress runs will indicate the scalability of the
application
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Can be used to determine scale of operation, when to
add new hardware etc
Stress testing should not be the final step in
building a web application. It should be
integrated into the development life cycle
Narrow the scope of a stress run to get more
accurate, actionable results
Measurement Techniques
Stress Testing
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Use the web site logs to determine
operational load
Stress tools like WAS (“Homer”) allow log
files to be “replayed” on a web site and
record statistical performance information
Run performance monitoring tools on the
live servers to identify scalability issues
Measurement Techniques
Designing Scalable Applications
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Two ways to quantify Web performance:
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Measure performance by stressing server
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Machine Throughput (requests/sec)
Response Time (time to first/last bytes)
Utilize multiple client stress machines
Use Application Center Test tool
Measure multiple scenarios:
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Simulate end to end scenario walkthroughs of site
Measure individual page performances
Demonstration 5
Measurement Techniques
Performance Measurement
Session Summary
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in this session we discussed:
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Language and Code Practices
Server Control Design Practices
Component and User Control Usage
Practices
State Management Recommendations
Caching Techniques
Deployment Best Practices
Measurement Techniques
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