Transcript EnterPrise2 - Syracuse University`s College of Engineering and

.NET Application
Design Considerations
Mark Sapossnek
CS 594
Computer Science Department
Metropolitan College
Boston University
A couple of additions
And many deletions
By
Jim Fawcett
CSE681 – Software Modeling and Analysis
Summer 2003
Agenda
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Design Model and Process
.NET System Architecture
.NET Design Patterns
Security
Scalability
Availability
Design Model and Process
 Microsoft Enterprise Services Framework
Services-Based Application Design Model
 Design Process
 Design Principles
Design Model and Process
Services-Based Application Model
Application 1
Application 2
User Services
Can be implemented
as Web Services
Business Services
Data Services
Design Model and Process
MSF Design Process Overview
Conceptual
Logical
Scenarios
Physical
Objects and Services,
UI, Logical DB
Components,
UI, Physical DB
http://
Design Model and Process
Conceptual Design
Conceptual
Logical
Scenarios
Physical
Objects and Services,
UI, Logical DB
Components,
UI, Physical DB
http://
The goal of conceptual design is to understand what the users do
and to identify business needs. The output is scenarios or use cases.
Design Model and Process
Logical Design
Conceptual
Logical
Scenarios
Physical
Objects and Services,
UI, Logical DB
Components,
UI, Physical DB
http://
The goal of logical design is to lay out the
structure of the solution and the
communication among elements.
The output is a set of objects and services,
high-level user interface design,
and logical database design.
Design Model and Process
Conceptual
Physical Design
Physical
Conceptual
Logical
Scenarios
Objects and Services,
UI, Logical DB
Components,
UI, Physical DB
http://
The goal of physical design is to apply real-world technology constraints to the logical
model, including implementation and performance considerations. The output is a set of
components, UI design for a particular platform, and physical database design.
Design Model and Process
Design Principles
 Understand and solve the business problem
 Communicate effectively with users and project teams
 Design based on a modular approach
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Consistent
Distributable (Web-centric)
Implementation language-independent
Flexible
Reusable
Reliable
 Balance innovation and discipline through each iteration
 Pay attention to the Enterprise Architecture and
Infrastructure
Agenda
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Design Model and Process
.NET System Architecture
.NET Design Patterns
Security
Scalability
Availability
.NET System Architecture
Distributed System Architecture
Rendering engine
Input/Output
Presentation logic
I/O Processing
Business logic
Data logic
Data engine
Everything Else
Data Management
Database
.NET System Architecture
Windows DNA Application Architecture
Rendering engine
HTML 3.2 Browser
Presentation logic
IIS/ASP (.asp)
Business logic
Data logic
Data logic
Data engine
COM Components
SQL Server Database
.NET System Architecture
.NET Application Architecture
Rendering engine
HTML 3.2 Browser
Presentation logic
IIS/ASP (.aspx, .ascx)
Business logic
Data logic
Data logic
Data engine
.NET Assemblies
Web
Services
SQL Server Database
.NET System Architecture
Web Service Architecture
Rendering engine
Presentation logic
Business logic
Data logic
Data logic
Data engine
SOAP Clients
Web Service (.asmx)
.NET Assemblies
SQL Server Database
.NET System Architecture
Web Services Application Model
Partner
Web Service
Web Services
Internet + XML
Partner
Web Service
YourCompany.com
Application
Business
Logic
Tier
Data Access and
Storage Tier
Other
Applications
Agenda
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Design Model and Process
.NET System Architecture
.NET Design Patterns
Security
Scalability
Availability
.NET Design Patterns
 Samples
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IBuySpy (http://www.ibuyspy.com/)
MSDN Sample: Duwamish 7.0
MSDN Sample: Fitch & Mather Stocks 7.0
 Using Uniform Modeling Language (UML)
 Discuss design patterns of each sample
application
IBuySpy Example
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E-Commerce Store Front
Selling fictional spy equipment
Shows how to build a portal site
Demonstrates use of ASP.NET applications
.NET Design Patterns
IBuySpy Portal Sample
.NET Design Patterns
IBuySpy Design Patterns
 Clean code/HTML content separation using
server controls
 Pages that are constructed from
dynamically-loaded User Controls
 Configurable output caching of portal page
regions
 Modular site layout defined by XML configuration
file
.NET Design Patterns
IBuySpy Design Patterns
 XML serialization that maps XML config file to
custom config classes
 Cached config settings automatically reloaded
when file changes
 Role-based security to control user access to
portal content
Duwamish Example
 A Sales and Inventory system for a book store.
 Functions:
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Point of Sale
Order Entry
Shipping and Receiving
Catalog
.NET Design Patterns
Duwamish Sample Application
.NET Design Patterns
Duwamish Activity Diagram
.NET Design Patterns
Duwamish Sequence Diagram
.NET Design Patterns
Duwamish Design Patterns
 Move processing to the data rather than moving
data to the processing
 Pass all data back to the client in a method call
 Minimize the time that a database resource is
locked
 Use Binary/HTTP for remoting
.NET Design Patterns
Duwamish Design Patterns
 Use ASP.NET within its Web layer and utilize the
ASP.NET caching features
 Publish a single XML Web service named
CatalogService to expose its book catalog
search functions to the Internet
Fitch & Mather Example
 A Web-based expense reporting system for a
fictional company
 Original implementation was ASP and COM
 Ported to .NET and COM+
What is COM+ ?
 COM+ provides the following services:
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Transaction services
Security services
Synchronization services
Queued components
Event Service
JIT Activation and Object Pooling
In Memory Database
Load Balancing
 Many of these services are available administratively as
well as programmatically.
COM+ Application
COM+ Server
Application
(DLLHOST.EXE)
Component
Context
proxy manager
proxy
Component DLL
RPC channel
interceptor
stub
client
context
client
object
.NET Design Patterns
Fitch & Mather 7.0 Sample
 A port of the MSDN Fitch & Mather 2000 sample
to .NET technologies
 Not a complete deployable application
 Focus on
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Performance
Technology porting issues from the Windows DNA
architecture to the .NET Framework
Legacy integration and interoperability
Real-life deployment scenarios in a distributed
computing environment.
.NET Design Patterns
Fitch & Mather 7.0 Architecture
.NET Design Patterns
Fitch & Mather 7.0 Activity Diagram
.NET Design Patterns
Fitch & Mather 7.0 - Transactions
 Transaction Composability
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Transactions are composed
by a transaction root object
from individual transactional
or nontransactional objects
Transaction root objects are
located at a layer above the
data access layer
No objects in data access
layer marked for requiring
new transaction
Objects that perform write
operation must at least
support transactions
.NET Design Patterns
Fitch & Mather 7.0 - Security
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Use forms authentication with the combination of forms
and role-based security
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Show login page and verify user credentials on access to
restricted resources
Issue an authentication cookie as means of re-acquiring user
identity at a later stage.
Based on the user’s identity/roles, replace the principal object
on the current thread to reflect the identity of the user.
In the application OnAuthenticateRequest event handler of
Global.asax, automatically replace the principal on the
thread every time authentication happens.
On BLL and DAL components, place code segments into the
constructor of each class to verify the identity of the user and
whether they are authenticated. Throw an exception if they
are not.
.NET Design Patterns
UML Models
Agenda
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Design Model and Process
.NET System Architecture
.NET Design Patterns
Security
Scalability
Availability
Security
Overview
 Security is A PAIN:
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Authentication
Privacy
Authorization
Integrity
Nonrepudiation
Who‘s there?
No eavesdroppers
What are you allowed to do?
Did the data get changed?
Keep your promises
 As always: understand the requirements
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E.g. Search vs. bank account vs. news
Do you just need personalization?
Security
Questions to Ask
 Authentication
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How does the user provide their credentials?
Where are credentials stored?
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Temporary or persistent
Security
Authentication Approaches
 IIS/Windows
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Basic, Digest, NTLM, Kerberos, Certificates
 ASP.NET
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Windows
Forms-based (cookie) authentication
Microsoft Passport authentication
Custom authentication
Security
Forms-Based Authentication
 Easy to implement
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ASP.NET provides redirection
Custom Login UI (no popup dialogs)
Custom credential verification
Custom application roles
Support for advanced usage
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Application defined data
Control over cookie lifetime, paths
Security
Authorization Strategies
 ASP.NET
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Windows Security & ACLs
URL Authorization
Custom Authorization
 All applications
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Declarative Method Authorization
Explicit Authorization
Agenda
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Design Model and Process
.NET System Architecture
.NET Design Patterns
Security
Scalability
Availability
Scalability
How Do You Handle Success?
…
Scalability
Approach 1 – Scale Up
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 SMP:
Symmetric
MultiProcessor
 Can only get so big
 Expensive
Scalability
Approach 2 – Scale Out
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 Less expensive, though more to manage
 Symmetric (load balancing) or asymmetric
(partitioning)
Scalability
Approach 3 – Partition Database
 Scale out with database
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 Scale up database
 Partition database
Scalability
Design for Scalability
 Design a stateless application if possible
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Use a database for state management
Run on a cluster of Web servers
Use caching or offline content generation
Partition the database tier or the Web tier
Use stored procedures
Use transactions intelligently
Use asynchronous programming techniques
Benchmark your application – performance
measurement and tuning
Scalability
Use a Database for State Management
 Design your Web application to run on a cluster
of Web servers
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Shared nothing, stateless
 This means you must manage user session
state somewhere other than the Web server
 Use a database
Scalability
Single Stateless Application Server
 A single stateless server running your
application code
Application
Code
Scalability
Multiple Identical Stateless
Application Servers
 The application code is cloned across a set of
identical servers
Application
Code
Application
Code
Application
Code
Scalability
Partition the Database Tier
 Functional
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Each functional area of the site gets its own DB
This allows you control over how you deploy into the
production environment
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Dedicated hardware to certain functions
Class of hardware per function
 Table
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Takes some planning
SQL Server 2000 makes this easier than ever before
Huge scale opportunity for large tables
Scalability
Partition the Web Tier
 Just like database functional partitioning, you
can dedicate clusters to application functions
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WWW.mydomain.com is handled by one cluster
SEARCH.mydomain.com is handled by another
cluster
You can also create clusters of clusters
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Use DNS Round Robin to distribute traffic across multiple
load balanced clusters that serve one function
Scalability
Partition the Web Tier
 Use DNS Host names or hardware solutions to
distribute traffic to dedicated clusters
 Once you have a stateless application, this is
how you achieve huge scale
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Scalability throttling with inexpensive hardware
Scalability
Benefits of Partitioning
 More control over traffic flow through the
application
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Users who are searching or registering are moved off
of the WWW cluster to keep the response time of the
WWW cluster snappy
 Application and server tuning can be different for
each function
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Search servers may have more memory, more CPUs
than the servers handling WWW
Scalability
Benefits of Partitioning
 Different content management techniques can be used
on different functions
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WWW may be primarily static content or dynamically generated
offline. WWW may use XML and XSL for high performance UI
formatting and internationalization
Registration requires real-time database access and custom
code
 Administration of the clusters can be handled separately
 Database partitioning gives you scale-out capabilities at
the database tier
Scalability
Using Stored Procedures
 There is a real performance benefit to stored
procedures
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Compiled code in the database
 DBA can tune stored procedures
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Can’t tune embedded SQL
 Good separation (API) between table structure
and application code
 Tradeoff is database portability
Scalability
Using Transactions Intelligently
 Transactions are powerful but they do have overhead
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Use them intelligently
 Not every COM component ‘requires’ a transaction
 Design your components with your transactions in mind
 Be aware of the transactional semantics of the
underlying database
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Long-lived locks in the DB will kill application performance
Look for blocking and deadlocks when testing
Scalability
Using Messaging
 Use store and forward where applicable
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Can provide a high degree of scalability by
decoupling the user experience from the backend
processing
 MSMQ
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Underlying messaging technology on Windows
 COM+ Queued Components
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Combines ease of COM programming with MSMQ
 Tradeoffs
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Manual implementation of 2 phase commit semantics
(Compensating Transactions)
Scalability
Performance Tuning
 Performance Tuning is the process by which you
measure individual operations on your site
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Still a bit of a black art
Need to measure for detail but analyze with a holistic view of the
system
Database performance is key; focus there first
 Know your tools
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PerfMon
WAST
SQL Server Profiler
SQL Server Index Tuning Wizard
SQL Server Query Analyzer
Scalability
Framework/CLR Best Practices
 Enable Web Garden: run applications in
multiple worker processes (with processor
affinity)
 Use Early Binding: Late Binding requires work at
runtime
 “Pre-JIT” to start up faster (available in beta 2)
 Make chunky and not chatty calls
 Implement Dispose method on the object that
cleans up your resources and release the
reference (set to null) once you are done
Scalability
Framework/CLR Best Practices
 Use value type for small data
 Do not cache strings or arrays length: Strings
are immutable
 For best inlining performance
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Minimize the use of virtual methods
Use sealed types if possible
Scalability
ASP.NET Best Practices
 Disable “ViewState” if you are not doing Postback
 Disable session state for all pages or Web Methods that
don’t require/need session data
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Set to “readonly” if you read but do not update session state
 Design pages around these ASP.NET built-in caching
features
 Always use System.Data.SqlClient for SQL Server
Access
 Use DataReaders for ASP.NET data access
Scalability
ASP.NET Best Practices
 Avoid apartment threaded COM components
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Migrate apartment threaded components to .NET
Alternatively, enable the <%@ AspCompat=“true” %> directive
for pages that utilize apartment COM objects
Always generate early-bound managed wrappers for COM
components (avoid late bound hit)
 Recommend UI Logic in ASP.NET Pages
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Business and data logic in re-usable components
User Controls for UI reuse
 Recommend web pages & components run in same
process
 Leverage web services only for application to application
communication (not intra application)
Agenda
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Design Model and Process
.NET System Architecture
.NET Design Patterns
Security
Scalability
Availability
Availability
What Is High Availability?
 The question you must ask yourself is:
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How much downtime can my organization afford
without losing productivity, profits, sales, etc.?
 It is a combination of people, process, AND
technology
Availability
How Much Availability Do I Need?
 Understand the business need
 Five nines (99.999% uptime) is 5 minutes of
downtime per year
 Formulas for downtime:
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% Uptime/year = (8760 - # of total hours down per
year)/8760
% Uptime/month = ((24 * # of days in the month) - #
of total hours down in that calendar month)/(24 * # of
days in the month)
% Uptime/week = (168 - # of total hours down in that
week)/168
Availability
How Do I Achieve High Availability?
 It’s deceptively simple …
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Plan and prepare
Deploy systems to create redundancy – this is the key
to high availability from a technology standpoint
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Use more than one method – avoid a single point of failure
Test, test, test
Monitor on a continuous basis
Availability
Improved Availability with ASP.NET
 ASP.NET has been designed with assumption
that failures will occur on systems
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Designing for failure reduced fragility
 Detects/recovers from common problems
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Access violations, memory leaks, deadlocks
 Preemptive cycling of applications
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Time- and request-based settings
 Net Result: Users should never think that an
ASP.NET application is down or unavailable
Conclusion
 Follow design process
 Understand the architecture and design
trade-offs
 Study design patterns of other .NET applications
 Build security into the overall design
 Chose appropriate design patterns for scalability
and availability
Resources
 Microsoft Solutions Framework
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http://www.microsoft.com/business/micro
soft/mcs/msf.asp
 Microsoft Operations Framework
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http://www.microsoft.com/business/micro
soft/mcs/mof.asp
 General .NET information
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http://msdn.microsoft.com/net
 .NET Framework SDK