DEV386Best Practices for .NET Smart Clients and Web Services DevelopmentMarc Ghys & Bart Debeuckelaere.NET architects, Euricom

Agenda

Smart clients and web servicesCustom user controlsOffline business logicError handling over SOAPNo touch deploymentDemo of a real-life example

Smart clients & web servicesOverview

Web ServicesWeb Services

SOAP over LANSOAP over LAN

SOAP over WAN (ADSL)SOAP over WAN (ADSL)

SOAP over InternetSOAP over Internet

BackofficeBackofficeSOAPSOAPWinFormWinFormApplicationApplication

Smart clients & web services Performance

Design to performancePerformance ≠ ScalabilityFocus on user experience

Limit number of roundtripsDo web service calls when users expect it, e.g. not in the middle of a page in an OnLeave event

Cache data to the max in your winform clientCompress SOAP messages

I.I.S. compressionCustom compression

Use Windows Server 2003 !!!

Smart clients & web services Security

Windows built-in authentication mechanismBasicBasic over SSLDigestIntegrated Client certificates

SOAP headersCustom handling of authentication

WS-Security (new in WSE)Set authentication mode in web.config file

// Fragment of a Web.config file.<authentication mode= "Windows"></authentication>

Smart clients & web services Windows integrated authentication

Uses credentials of logged on userTransparent to user

myWebService.Credentials = System.Net.CredentialCache.DefaultCredentials;

Authentication bug causes repeated authentication roundtrips with every web service call in .NET framework 1.0

solved by QFExxxx

codeTableManager.Credentials = new System.Net.NetworkCredential(“Marc",“pwd");

Can also be set manually

Smart clients & web services Client certificates

Stronger Public Key cryptographyUses SSL 3.0 or TLS 1.0 protocolMany ways to manage access

X509Certificate x509 = X509Certificate.CreateFromCertFile(@"c:\Marc.cer");myPRoxy.ClientCertificates.Add(x509);

Get certificate from store (new in WSE)store = WSE.X509CertificateStore.LocalMachineStore(WSE.X509CertificateStore.MyStore);store.OpenRead();certificates = store.FindCertificateBySubjectString(“euricom"));

Get certificate from a file

Securing a web service• Using Windows integrated security• Using a client certificate

demodemo

Agenda

Smart clients and web servicesCustom user controlsOffline business logicError handling over SOAPNo touch deploymentDemo of a real-life example

Custom user controlsOverview

Easy to add extra functionalityTranslation, security

Force specific property valuesFont type & size, styling

Encapsulation of 3rd party controlsTransparent work-arounds for bugsRenaming properties & methods

3 possible approachesInherit, wrap or extend

Custom user controlsDeriving from an existing control

Fastest way to create a custom controlDerive from any existing control

All standard functionality immediately availableAutomatically reuses designer of inherited control

No real encapsulationDifficult to hide and/or rename properties and methodsVery difficult to create a custom designer

Custom user controlsDeriving from an existing control

No multiple inheritance in .NETImpossible to derive from a ‘basecontrol’ that contains shared functionality for a set of controls (e.g. validation, formatting, ...)

System.Windows.Forms.TextBox

Euricom.Toolkit.BaseControlEuricom.Toolkit.ListBox

Solution:instantiate BaseControl in the custom control and delegate properties, methods and events

Custom user controlsWrapping an existing control

User control derives from a ‘BaseControl’Contains generic properties, methods and events used by all custom controls

Reuse the functionality of an existing control by placing it on the user control

Expose control’s features by delegating properties, methods and eventsReuse of designer

Custom user controlsIssues with wrapping controls

Problem with delegating leave eventFires multiple times or not at allSolved in .NET framework 1.1

Performance issue in .NET framework 1.0Solved with QFExxxx

Custom user controlsUsing extenders

Loosely coupled way to add functionality to any existing control

Implement the IExtenderProvider interfaceBuilt-in tooltip control is an extender

Adds extra properties to existing controlsAt design-time, properties are added to the property windows of controlsAt run-time, properties are accessed through the extender

toolTipExtender.SetToolTip(txtFirstName, “Name of the person”);

Custom user controlsUsing GDI+ to draw your control

Gives you pixel-level control over how the control is shownOnPaint event provides GDI+ Graphics object

protected override void OnPaint(PaintEventArgs p){

// Draw border around controlp.Graphics.DrawRectangle(myPen, 0, 1, 300, 100);

}

Use Invalidate() to force redrawe.g. When a property has changed

Custom user controlsDesign-time support

Reuse and improve built-in designersE.g adding extra markers using GDI+ by overriding OnPaintAdornments()

Use TypeConverter class to improve generated code

e.g. show ‘subproperties’ by deriving from ExpandableObjectConverter

Creating custom controls• Wrapping an existing control• Using an extender• Inheriting an existing control• Drawing the control with GDI+• Using the TypeConverter class

demodemo

Agenda

Smart clients and web servicesCustom user controlsOffline business logicError handling over SOAPNo touch deploymentDemo of a real-life example

Treating offline situationsExecuting business logic offline

Need for business logic on the client E.g. validation of input data

Put shared business logic in BusinessRules class and deploy to clientBusinessObject class inherits from BusinessRule and adds persistence functionality

Treating offline situationsExecuting business logic offline

MyApp.BusinessRules.Customer

MyApp.BusinessObjects.Customer

Server Client

Data

MyApp.DataAccess.Customer

Customer.ValidateEmail(john@doe.com);

Agenda

Smart clients and web servicesCustom user controlsOffline business logicError handling over SOAPManaging stateNo touch deploymentDemo of a real-life example

Error handling over SOAPOverview

Standard Exception over SOAPLimited to one exception and standard properties

Returning serialized custom exceptionsCreate a custom exception classe.g. containing multiple ‘sub-exceptions’Throw a new SOAP exception and put serialized custom exception in XML node

Error handling over SOAPOverview

Using SOAP headers to transfer exceptions

Define SOAP header class containing CustomException propertyType can be anything (e.g. DataSet)Convert Exception data to CustomException type in WebService layer

Custom Exceptions• Using SOAP headers to send a

custom exception to a client

demodemo

Agenda

Smart clients and web servicesCustom user controlsOffline business logicError handling over SOAPNo-touch deploymentDemo of a real-life example

No-touch deploymentAppUpdater component

Three ways to check versionsDirect file check

Check on last modified dateManifest Check

XML web service checkWeb service not included in AppUpdater, has to be developed seperately

<VersionConfig><AvailableVersion>1.1.5.2</AvailableVersion><ApplicationUrl>http://appserver/crm/versions/V1152/</ApplicationUrl>

</VersionConfig>

No-touch deploymentAppUpdater component

Files are downloaded using HTTP-DAVIncludes directory and file enumeration

Free source downloadCan be adapted to your needs

No-touch deploymentCustom updater

Written from scratchFlexibility in features, coding style, etc...

Support for zone based deploymentDeploying a new version to 4.500 clients is not done in 5 minutes!Deploy to zones of 500 clients in different timeframesAssemblies are compressed and sent as DIME attachments using WSE

No-touch deploymentCustom updater

Peach.exePeach.exe Versions.xmlVersions.xml

Main formMain form

WithdrawalWithdrawal form form

InsuranceInsurance form form

Version 2.0.1.28Version 2.0.1.28

Get version info through web serviceGet version info through web service

Download new versionDownload new versionMain formMain form

WithdrawalWithdrawal form form

InsuranceInsurance form form

as DIME attchmentas DIME attchment

No-touch deploymentBITS

Downloads software in backgroundUsed by Windows 2000, Windows XP and Windows 2003 for autoupdate

Uses idle network bandwidthResumes after network disconects, reboots

Version 1.5 now available in Windows Server 2003, as upgrade for Win2000, XP

Download an updated assembly• As a DIME attachment using WSE• Using BITS

demodemo

Agenda

Smart clients and web servicesCustom user controlsOffline business logicError handling over SOAPNo touch deploymentDemo of a real-life example

Peach GUI Framework

Peach GUI FrameworkPeach GUI Framework

GUI ControlsGUI ControlsWizard ControlWizard Control

Error HandlingError HandlingTranslationTranslation

SecuritySecurityCachingCaching

ConfigurationConfiguration

PeachPeachTodayToday My OfficeMy Office CustomersCustomers InsuranceInsurance BankingBanking

MultipleMultipleapplication application

supportsupport

Peach GUI FrameworkAdvantages

Allows seperated development teams to develop independent plug-in applications

Framework handles inter-application communicationFramework can be improved seperately

Forces consistent look & feelForm & Wizard controlsQuickstep

Peach GUI FrameworkAdvantages

Provides numerous technical facilitiesError HandlingTranslationSecurityCaching

demodemo

Peach GUI framework

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