Enterprise Solution Patterns Jose Antonio Silva [email protected] [email protected] Lisboa...

Enterprise Solution PatternsEnterprise Solution PatternsJose Antonio [email protected]

Lisboa9.12.2003

mailto:[email protected]

22

AgendaAgenda

What are patterns?Where do they fit?What are pattern clusters?

Web presentation patterns Deployment patterns Distributed systems patterns Services patterns

Conclusion Resources

33

What Is A Pattern?What Is A Pattern?

ContextContext

ProblemProblem SolutionSolution

44

Singleton PatternSingleton Pattern

Context: Control access to a class by controlling

its instantiation process Problem:

Certain types of data need to be globally accessed and maintained

This data is often unique in the system E.G. counter class

55

Singleton PatternSingleton Pattern Solution:/// <summary>/// Counter Class (Singleton)./// </summary>public class Counter{

private static Counter _instance = null;private Counter() {}public static Counter getInstance() {

if (_instance==null) {

_instance = new Counter();}return _instance;

}

//... functions provided by Counter }

/// <summary>/// Class Counter (Singleton)/// </summary>public sealed class Counter{

private static readonly Counter instance = new Counter();

private Counter(){}

public static Counter Instance{

get {

return instance; }

}//....

}

/// <summary>/// Class Counter (Singleton)/// </summary>public sealed class Counter{

private static readonly Counter instance = new Counter();

private Counter(){}

public static Counter Instance{

get {

return instance; }

}//....

}

66

Layered Architecture PatternLayered Architecture Pattern

Context: You are designing a complex enterprise

application composed of a large number of components across multiple levels of abstraction

Problem: How do you structure an application to

support such operational requirements such as maintainability, reusability, scalability, robustness and security?

77

Layered Architecture PatternLayered Architecture Pattern

EMEAEMEA

88

Enterprise Solution PatternsEnterprise Solution PatternsUsing Microsoft .NETUsing Microsoft .NETVersion 2.0Version 2.0

David Trowbridge

99

Pattern Description FormatPattern Description Format

What to read next?Related Patterns

Benefits and LiabilitiesResulting Context

Refers to associated Impl. PatternExample

Solution Description & Picture How does it solve the problem? What else do I have to think about?

Solution

What issues do I need to consider?

What alternatives are there?

Forces

What problem does it solve?Problem

Is this pattern relevant to my work?Context

1010

What are Patterns?What are Patterns?

Description Dimension Recurring problem Context Solution

Tool Integration Dimension Collection of atomic elements Description of relationships Transformations

1111

Pattern Descriptions Help Pattern Descriptions Help Architects And Designers By…Architects And Designers By…

Documenting simple mechanisms that work

Providing a common vocabulary and taxonomy

Enabling solutions to be described concisely as combinations of patterns

Enabling reuse of architecture, design, and implementation decisions

1212

Integrating Patterns into ToolsIntegrating Patterns into Tools

1313

Tool Integration Helps Tool Integration Helps Architects and Designers by …Architects and Designers by …

Providing prepackaged “chunks” of design experience

Automated transformation result in: Enhanced reliability Reduced coding time Simplified testing Flexibility from interchangeable components

EMEAEMEA

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Where do they fit?Where do they fit?

1515

Where Do Patterns Fit?Where Do Patterns Fit?

Provide distilled design knowledgeThey describe transformationsPatterns are not source code filesPatterns are not distributable

componentsPatterns are not data structuresPatterns do not have a thread of

execution

1616

Building a House Analogy …….Building a House Analogy …….

GuidelinesGuidelines BlueprintsBlueprints

MaterialsMaterials

PatternsPatterns

ProcessProcess

Fir, #2 2”x4”x8’ boards412

ASTM4’x8’x ½” sheet rk120

20 psf load48’ Trusses24NM 12-212 Ga. Elec. Wire350’DWV½ “ copper pipe200’

SpecDescriptionQty.

Bill of Materials

PeoplePeople

TaxonomyTaxonomyTaxonomyTaxonomy

PeoplePeopleFoundation

Roofing

Flooring

Walls Electrical

Plumbing Heating

TrussTrussCeilingCeiling

JoistsJoistsCoveriCoveri

ngng

RebaRebarr

ConcreConcretete

High-rise

Tilt-up

Pole BuildingCape Cod

Stick Frame

Pre-hung doors

Truss Frame

Log Home

Post and Beam

Pre-fab trussesFraming patternsWiring patterns

Patterns

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Building an Application …….Building an Application …….

TaxonomyTaxonomy

GuidelinesGuidelines BlueprintsBlueprints

ElementsElements

PatternsPatterns

PeoplePeopleProcessProcess

Guidelines

Local – within enterpriseIndustry - principles Elements

Application Controller (Custom)1

PAG Data Access Component1Microsoft SQL Server1

Microsoft Windows Server 20033Microsoft ASP.NET1DescriptionQty.

Layered Application

BrokerObserver

Implementing Singleton with C#

Model-View-ControllerFacade

Implementing MVC with ASP.NET

Patterns

Tiered Distribution

Gateway

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Patterns Do Not Live In IsolationPatterns Do Not Live In Isolation

1919

Organizing Our ThinkingOrganizing Our Thinking

DesignDesign

ArchitectureArchitecture

Impl.Impl.

DataData AppApp DeployDeploy InfrastructureInfrastructure

2020


DesignDesign

ImplementatiImplementationon

InfrastructurInfrastructuree

DeploymentDeploymentApplicationApplicationDataData

The Pattern GraphThe Pattern Graph

2121


DesignDesign




Patterns – Solutions LanguagePatterns – Solutions Language

ThreeThreeLayeredLayered

ApplicationApplication

Layered Layered ApplicationApplication

Simple Simple WebWeb

Complex Complex WebWeb

Rich ClientRich Client

Ext. EnterpriseExt. Enterprise

4-Tier4-Tier3-Tier3-Tier

TieredTieredDistributionDistribution

LayeredLayeredServicesServices

ApplicationApplication

2222

ArchitectureArchitectureApplication InfrastructureDeploymentDeployment

Tiered Distribution

• Scalability• Availability• Performance• Secure

Discrete Logical Layers Data & Functional Analysis

• Design Flexibility • Maintainability• Loose Coupling

Complex Web App

• Security• Component Reuse• Manageability• Performance Tradeoff

Complex Web App

• Security• Component Reuse• Manageability• Performance Tradeoff

D A D I

A

D

I

2323

DesignDesignApplication InfrastructureDeploymentDeployment

• Clusters• Zones• Policies • Protocols• Links

Design Classes & Mechanisms – eg:

• Security• Communication• Data Access• Exception Handling• Logging

Runtime Dependencies

Map Processes to Processors

Runtime Dependencies

Map Processes to Processors

D A D I

A

D

I

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ImplementationImplementation

Application InfrastructureDeploymentDeployment

• Hardware Spec & Configuration

• IP Addressees • Ports • Server & Files Names

Implementation Classes & Mechanisms

Product usage – eg: .NET remoting

Configuration Dependencies

Distribution Manifest – Components, Machines, Files…

Configuration Dependencies

Distribution Manifest – Components, Machines, Files…

D A D I

A

D

I

EMEAEMEA

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What are patterns clusters?What are patterns clusters?

2626


DesignDesign




The Pattern Graph - ClustersThe Pattern Graph - Clusters

ComponentsComponents

PresentationPresentation

FrameworkFramework

SecuritySecurity

Smart ClientSmart Client

2727

Current Area Of FocusCurrent Area Of Focus

Cluster Problem

Web Presentation How do you create dynamic Web applications?

Deployment How do you divide an application into layers and then deploy them onto a multi-tiered hardware infrastructure?

Distributed Systems How do you communicate with objects that reside in different processes or different computers?

Services How do you use functionality available remotely?How do you expose your application’s functionality over a network?

Performance and Reliability How do you create a systems infrastructure that can meet critical operational requirements?

ClustersClusters

OLTP No embedded systems, data warehouse

Object-Oriented Application No procedural or AOP Layered Application No monoliths Tiered Distribution No stand-alone desktop apps

Root ConstraintsRoot Constraints

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Web Presentation ClusterWeb Presentation Cluster

Model-View-Controller

Front Controller

Page Cache Intercepting Filter

ImplementingMVC

with ASP.Net ImplementingFront Controller with ASP.Net

ImplementingIntercepting Filter

with ASP.Net

ImplementingPage Cache

with ASP.Net

ImplementationImplementation

DesignDesign

Page Controller

ImplementingPage Controller with ASP.Net

2929

Model-View-ControllerModel-View-Controller How do you modularize the user interface

functionality of a Web application so that you can easily modify the individual parts? User Interface changes more frequently Same data displayed different ways Different skill sets required for UI design and App dev

Separate the modeling of the domain, the presentation, and the actions based on user input into separate classes

Model - manages the behavior and data of the application domain

View - display of information Controller - interprets the

mouse and keyboard inputs

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Implementing MVC InImplementing MVC InASP .NETASP .NET

public class DatabaseGateway{ public static DataSet GetRecordings() {…} public static DataSet GetTracks(…) {…}}

public class DatabaseGateway{ public static DataSet GetRecordings() {…} public static DataSet GetTracks(…) {…}}

public class Solution : System.Web.UI.Page{private void Page_Load(…) {…} void SubmitBtn_Click(Object sender, EventArgs e) { DataSet ds = DatabaseGateway.GetTracks (…) MyDataGrid.DataSource = ds; MyDataGrid.DataBind … }}

public class Solution : System.Web.UI.Page{private void Page_Load(…) {…} void SubmitBtn_Click(Object sender, EventArgs e) { DataSet ds = DatabaseGateway.GetTracks (…) MyDataGrid.DataSource = ds; MyDataGrid.DataBind … }}

ModelModel

ControllerController

<%@ Page language="c#" Codebehind="Solution.aspx.cs"

AutoEventWireup="false" Inherits="Solution" %>

<html>

<body>

<form id="Solution" method="post" runat="server">

<asp:dropdownlist id="recordingSelect“… />

<asp:button id="submit" … />

<asp:datagrid id="MyDataGrid" … />

</form>

</body>

</html>

<%@ Page language="c#" Codebehind="Solution.aspx.cs"

AutoEventWireup="false" Inherits="Solution" %>

<html>

<body>

<form id="Solution" method="post" runat="server">

<asp:dropdownlist id="recordingSelect“… />

<asp:button id="submit" … />

<asp:datagrid id="MyDataGrid" … />

</form>

</body>

</html>ViewView

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Page ControllerPage Controller

How do you best structure the controller for moderately complex Web applications so that you can achieve reuse and flexibility while avoiding code duplication? MVC focuses primarily on the separation between the

model and the view Many dynamic Web pages involve similar steps: verifying

user authentication, extracting query string parameters etc. Testing user interface code is time-consuming

Use the Page Controller pattern to accept input from the page request, invoke the requested actions on the model, and determine the correct view to use for the resulting page

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Implementing Page Controller Implementing Page Controller in ASP.NETin ASP.NET

public class BasePage : Page{ virtual protected void PageLoadEvent(object

sender, System.EventArgs e) {} protected void Page_Load(…) { … string name = Context.User.Identity.Name; eMail.Text = DBGateway.RetrieveAddress(name); siteName.Text = "Micro-site"; … PageLoadEvent(sender, e); }}

BenefitsBenefits SimplicitySimplicity Leverages Framework featuresLeverages Framework features Increased reuseIncreased reuse

LiabilitiesLiabilities One controller per pageOne controller per page Deep inheritance treesDeep inheritance trees

3333

Front ControllerFront Controller

How do you best structure the controller for very complex Web applications so that you can achieve reuse and flexibility while avoiding code duplication? Page controller can lead to overburdened base classes Inheritance hierarchy is static Might need to coordinate processes across pages Might deal with dynamic navigation paths,

e.g. a ‘Wizard’ that includes optional pages

Front Controller solves the decentralization problem present in Page Controller by channeling all requests through a single controller

3434

Implementing Front Controller In Implementing Front Controller In ASP .NET Using HTTP HandlerASP .NET Using HTTP Handler

public class Handler : IHttpHandler

{

public void ProcessRequest(HttpContext context)

{

Command command =

CommandFactory.Make(context.Request.Params);

command.Execute(context);

}

…

}

public class CommandFactory

{

public static Command Make(NameValueCollection parms)

{

string siteName = parms["site"];

Command command = new UnknownCommand();

if (siteName == null || siteName.Equals("micro"))

command = new MicroSite();

else if(siteName.Equals("macro"))

command = new MacroSite();

return command;

}

}

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Implementing Front Controller In Implementing Front Controller In ASP .NET Using HTTP HandlerASP .NET Using HTTP Handler

Benefits Flexibility Simplified Views Open for extension, but

closed to modification (open-closed principle)

Supports URL mapping Thread-safety

Liabilities Performance Implications

(object creation) Additional complexity

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Deployment ClusterDeployment Cluster

Key Points Layers – Logical application structure Tiers – Physical distribution onto

server infrastructure Deployment – Application and

infrastructure teams map components to tiers

Pattern Problem

Layered Application

How do you structure an application to support such operational requirements as maintainability, reusability, scalability, robustness, and security?

Three-Layered Services Application

How do you layer a service-oriented application and then determine the components in each layer?

Tiered Distribution How should you structure your servers and distribute functionality across them to efficiently meet the operational requirements of the solution?

Three-Tiered Distribution

How many tiers should you have, and what should be in each tier?

Deployment Plan How do you determine which tier you should deploy each of your components to?

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Layered ApplicationLayered Application

Problem How do you structure an application to support such operational

requirements as maintainability, reusability, scalability, robustness, and security?

Forces Impact of change Separation of concerns Independent components Operational requirements

Solution Separate the components of your solution into layers. The

components in each layer should be cohesive and at roughly the same level of abstraction; Each layer should be loosely coupled to the layers underneath

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Layered ApplicationLayered Application

Discussion Points Dependency management Strict versus relaxed Top down versus bottom up Custom Reuse existing scheme Testing considerations

Benefits Easier maintenance and

enhancement Reuse Support for distributed dev Enables tiered distribution Testability

Liabilities Layer overhead Bound data Complexity Custom Change propagation

3939

Three Layered Services Three Layered Services ApplicationApplication

Problem How do you layer a service-oriented application

and then determine the components in each layer?

Forces Minimize impact of adding service to an application Differing operational requirements by

component type Separation of concerns

Solution Base your layered architecture on three layers –

presentation, business, and data

4040

4-Layered Services Application4-Layered Services Application

Discussion Points Presentation layer Business layer Data layer Foundation services

Benefits Separation of concerns Minimal layers Liabilities

Complex business logic may require more business layers

Complex UI apps may require additional UI layers

4141

Tiered DistributionTiered Distribution

Problem How should you structure your servers and distribute functionality

across them to efficiently meet the operational requirements of the solution?

Forces Resource Consumption Server Optimization Security Requirements Geographic and licensing constraints

Solution Structure your servers and client computers into a set of physical

tiers; A tier is composed of one or more computers that share one or more of the following characteristics System resource consumption profile Operational requirements Design constraints

4242

Tiered DistributionTiered Distribution

Benefits Tiers optimized for

specific task Different security needs Operational

requirements Admin and deployment

overhead

Liabilities Performance Admin overhead Complexity

4343

Three-Tiered DistributionThree-Tiered Distribution

Problem How many tiers should you have, and what should be in

each tier?

Forces Database load Security policies Reuse Scalability

Solution Structure your application around three physical tiers:

Client, application, and database

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Three-Tiered DistributionThree-Tiered Distribution

Benefits Scalability and fault

Tolerance Support thin client

solutions Security Collocated app & web

server performance

Liabilities Business logic exposed

to client tier Incremental cost of

adding web server

Discussion Points Server optimization Security Server farms Clustering

4545

Deployment PlanDeployment Plan

Problem How do you determine which tier you should deploy each of

your components to?

Forces Layers != Tiers Different Skill Sets Impact of adding tiers Resource Consumption Constraints, security and operational requirements Performance Impact of distribution

Solution The application architects must meet with the system

architects to create a deployment plan that describes which tier each of the application's components will be deployed to

4646

Deployment PlanDeployment Plan

Discussion Points Importance of testable

requirements Define Tiers and Components Map Components to tiers Models

Simple Web App Complex Web App Extended Enterprise App Smart Client App

Benefits Equal emphasis on both

operational and functional requirements

Increased communication

4747

Distributed Systems ClusterDistributed Systems Cluster

Key Points Distributed Computing Challenges Layered Applications Coarse Grained Interfaces Client versus Server Activation

Pattern Problem

Broker How can you structure a distributed system so that application developers don’t have to concern themselves with the details of

remote communication? Implementing Broker with .Net Remoting (Server Activated)

How do you Implement Broker in .Net?

Singleton How do you make an instance of an object globally available and guarantee that only one instance of the class is created?

Implementing Singleton in .Net

How do you Implement Singleton in .Net

5454

Services PatternsServices Patterns

Pattern Problem

Service Interface How do you make pieces of your application's functionality available to other applications, while ensuring that the interface mechanics are decoupled from the application logic?

Implementing Service Interface using .NET

How do you Implement Service Interface in .Net?

Service Gateway How do you decouple the details of fulfilling the contract responsibilities defined by the service from the rest of your application?

Implementing ServiceGateway with .NET

How do you Implement Service Gateway in .Net

Key Points Service vs. Instance interfaces Far Links Web Services are About Interop

5555

Service InterfaceService Interface

Problem How do you expose your application’s functionality over a

network so it can be consumed by disparate applications?

Forces Separation of concerns – business logic and service contract

issues Consuming applications may require different channels for

optimization

Solution Design your application as a collection of software

services, each with a service interface through which consumers of the application may interact with the service.

5656

Service InterfaceService Interface

Discussion Points Service vs. instance Specialized kind of

Remote Façade May want to aggregate

in to Service Layer

Benefits Application flexibility Optimized performance Interoperable

Liabilities Adds complexity

5757

Implementing Service InterfaceImplementing Service Interfaceusing .NETusing .NET

5858

Service GatewayService Gateway Context

You are designing an application that consumes services provided by another application. The use of this service is governed by a contract indicating communication protocols, msg formats, etc.

Problem How do you decouple the contract implementation

responsibility from the rest of your application?

Forces Communication and message details often change at a

different rate than business logic Your application may use a different data format than an

external service, therefore the data may need transformation

If the contract changes, you want to localize the impact of the change within your application

Solution Encapsulate contract implementation code in to a Service

Gateway component

5959

Implementing Service GatewayImplementing Service Gatewaywith .NETwith .NET

Key Points RecordingCatalog is

the Gateway

Recording and Trackare Data Transfer

Objects

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Implementing Service GatewayImplementing Service GatewayIn .NETIn .NET

EMEAEMEA

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Enterprise Solution PatternsEnterprise Solution PatternsUsing Microsoft .NETUsing Microsoft .NETVersion 2.0Version 2.0

David Trowbridge

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ConclusionConclusion

Patterns contain atomic chunks of design information

They enable reuse of architecture, design and implementation decisions

Provide a common vocabulary and taxonomy

Strong potential for tool integration

EMEAEMEA

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E S Patterns at TechEd 2003E S Patterns at TechEd 2003By David Trowbridgehttp://microsoft.sitestream.com/DEV/DEV361_files/default.htm

Last year’s EMEA Architect Tour Last year’s EMEA Architect Tour (Finland)(Finland)http://www.dotnetmaailma.com/dotnetmaailma/seminaarit/online/EMEA+Architects+Tour.htm

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Patterns catalog online (Patterns catalog online (complete complete listlist))Enterprise Solution Patterns (book;

v2.0)http://msdn.microsoft.com/practices/type/Patterns/Enterprise/

27+5

Data Patterns (book)http://msdn.microsoft.com/practices/type/Patterns/Data/ 12

Patterns community: http://www.gotdotnet.com/team/archticture

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Longhorn Developer PreviewLonghorn Developer PreviewLisboa, 9 FevereiroLisboa, 9 Fevereiro

The road to “Longhorn” David Chappell

“Avalon”: The Longhorn User Experience Lester Madden, Microsoft EMEA

“Indigo”: The Longhorn Communications Clemens Vasters, newtelligence AG

“WinFS”: The Longhorn File System Hans Verbeeck, Microsoft EMEA

“Whidbey”: Get ready for Longhorn Nigel Watling, Microsoft EMEA

6666

Connected Applications TourConnected Applications TourApril 2004April 2004

Web Services, Biztalk & Indigo

EMEAEMEA

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Obrigado

José António [email protected]://canoas.com/blog/

Obrigado

José António [email protected]://canoas.com/blog/

Enterprise Solution Patterns Jose Antonio Silva [email protected] [email protected] Lisboa...

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