web services with delphi, sep, 2008

Oregon Delphi User GroupSeptember, 2008

What are web services—very brieflyRemotely invokable methods with a pre-defined

APIParameters (object with properties)Return values (object with properties)SOAP XML via HTTP

Another way of saying it…“Web Services, in the general meaning of the term, are processes offered via the Web. In a typical Web Services scenario, a business application sends a request to a service at a given URL using the SOAP protocol over HTTP. The service receives the request, processes it, and returns a response.” –Harms Software

2ODUG - Web Services, Sep 2008

Single store, one database, simple accounting.


Add an ecommerce web site.

Two databases—accountant is not happy.Shipping department confused.Customers can “buy” out-of-stock items.


Need to merge—but how?


The answer of course for today:Web Services!


What is needed here?Web site needs to know what inventory is

availableStore needs to collect order informationStore needs to adjust inventory levelsStore needs to ship productsStore needs to notify web site of order statusWeb site needs to display order status


Possible web service methods:UpdateInventory

Adds or updates items to web databaseGetPendingOrders

Get list of orders pending from webGet single order details from web

UpdateOrderStatusUpdate status field and tracking number on web


File > NewOther > Web Services > SOAP Server

ApplicationThree types

ISAPI .DLLCGI Stand-alone .EXEWeb App Debugger

Create an interfaceFile > new

Other > Web Services > SOAP Server Interface


Four modules created__Intf.pas

Exposed methods for the web servicesIMyWebClass = class(Invokable)

__Impl.pasDelphi implementation of web servicesTMyWebClass = class(TInvokableClass,

IMyWebClass)Here’s the meat!

Data module – web service work horseMain Form – standard application


Add interface and implementationIntf and Impl units

Build/Run once to register COM objectRun Web App Debugger, start serverVerify new web service available in browserView WSDL automatically created for us

What’s a WSDL?Web Service Description LanguageXML document describing the web service

We’ve Created a Web Service!


Questions?

Now on to the Client…


New standard VCL applicationFile > New

Other > Web Services > WSDL ImporterURL of web service’s WSDLNew unit created

Full Interface to web service methods!


Call a method—see the answer—SUCCESS!Web App Debugger

View the logSee the XML packets

Get/Response – general web page requestsPOST – web service method calls


Web Apps –vs- Windows AppsNo formStatelessMulti-user

AcronymnsHTTP – HyperText Transfer ProtocolXML – eXtended Markup LanguageSOAP – Simple Object Access ProtocolRIO – Remote Invokable ObjectWSDL – Web Service Description LanguageUDDI – Universal Description, Discovery, and

Integration


Web ServiceAdd(a, b: Double): Double;Subtract(a, b: Double): Double;

ClientTwo edit fields, two buttons, display answer


Database queriesArraysTRemotable class


Packet SizeServer speedBandwidth bottleneck

Trapping XMLLogging/modifying XML on-the-fly

Use HTTPRIO from WebServicesUse TXMLDocument from Internet

Tutorial Referencehttp://exposureroom.com/members/skumar.aspx/tutorials/post/1


eCommerceSample packetsXML Notepad

GoogleeBayAmazonFedExCDDBMapPointMore!


web services with delphi, sep, 2008

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