Importing and Consuming external Web Services

Being able to import and use services provided by other applications, be they home or third party built, is an essential aspect of Web application development. It is also one of the most fundamental tenets of a service oriented architecture. While other topics in this documentation focus on the creation of Web Services, this topic will focus exclusively on how they can be used from a Morfik application.

Morfik makes using Web Services which are external to your current application, very easy. The only thing you need to start, is to have the WSDL file of the service you wish to use. For the sake of simplicity, I have chosen to import the WSDL file which is generated by a very simple math sample, in this topic. In Figure 1 you can see the Web Services option, in the Home tab of the riboon, when in the Project View of the Morfik development environment.

Figure 1 Import Web Services menu option.

This wizard makes it extremely easy for you to import any web service you want (provided you have access to its WSDL definition file), into your project.

Once the wizard is started, it will ask for the WSDL file that describes the service to be imported, as can be seen in Figure 2.

Figure 2 Dialog for selecting the WSDL file to be imported.

Once you have selected the WSDL file the wizard will display all the methods found in the service description, with their respective parameters, as shown in Figure 3.

Figure 3 Methods (with parameters) available from the selected service.

Next you will be asked if you will want to invoke the imported methods directly from the browser. If the answer to that is yes and the service you are importing will not be running under the same domain name as the application you are coding, you should choose the option that enables the usage of a server side proxy. This proxy is handled automatically by the Morfik Framework and will allow you to code your application as if you were accessing these 3^rd party services as if they were running on your servers, despite the browser security restrictions.

Figure 4 Browser code generation and its options.

After you have completed the Import Web Service wizard, the IDE will have generated a dual module with the classes required to correctly call out to the imported methods in as easy a manner as possible from both the browser and server sides of your application. You can see the code for the server side portion of this module for these methods in Listing 1, and the browser side portion in Listing 2.

Listing 1 – Code for the automatically generated interface to the imported services

FX Code

Unit MathTestService;
 
Interface
 
Uses
    SystemClasses,
    SystemSerialiser,
    SystemXml;
 
Type
TMathTestServiceSoapIntf = Class(TSoapHttpClient)
    Procedure   MathProcessor (operand1 : double; operand2 : double; theOperator : string; 
                           Var theResult : double; Var Status_1 : longint); Virtual;
    Procedure   MathProcessor2(Operand1 : double; Operand2 : double; theOperator : string; 
                           Var theResult : double; Var Status_1 : longint); Virtual;
End;
 
Implementation
 
{.................... MathTestServiceSoapIntf ....................}
 
Procedure TMathTestServiceSoapIntf.MathProcessor(operand1 : double; operand2 : double; 
    theOperator : string; Var theResult : double; 
    Var Status_1 : longint);
Begin
    BeginInvoke('http://localhost:9119/?cls=soap',
        'MathProcessor xmlns="http://tempuri.org/"',
        'MathProcessorResponse xmlns="http://tempuri.org/"',
        'MathProcessor',ssDocumentWrapped);
    Try
        Try
            RequestBody.WriteDouble('operand1 xsi:type="xsd:double"', operand1);
            RequestBody.WriteDouble('operand2 xsi:type="xsd:double"', operand2);
            RequestBody.Writestring('theOperator xsi:type="xsd:string"', theOperator);
 
            Invoke();
 
            ReplyBody.ReadDouble('theResult xsi:type="xsd:double"', theResult);
            ReplyBody.Readinteger('Status xsi:type="xsd:int"', Status_1);
        Except
            Raise;
        End
    Finally
        EndInvoke();
    End
End;
 
 
Procedure TMathTestServiceSoapIntf.MathProcessor2(Operand1 : double; Operand2 : double; 
    theOperator : string; Var theResult : double; 
    Var Status_1 : longint);
Begin
    BeginInvoke('http://localhost:9119/?cls=soap',
        'MathProcessor2 xmlns="http://tempuri.org/"',
        'MathProcessor2Response xmlns="http://tempuri.org/"',
        'MathProcessor2',ssDocumentWrapped);
    Try
        Try
            RequestBody.WriteDouble('Operand1 xsi:type="xsd:double"', Operand1);
            RequestBody.WriteDouble('Operand2 xsi:type="xsd:double"', Operand2);
            RequestBody.Writestring('theOperator xsi:type="xsd:string"', theOperator);
 
            Invoke();
 
            ReplyBody.ReadDouble('theResult xsi:type="xsd:double"', theResult);
            ReplyBody.Readinteger('Status xsi:type="xsd:int"', Status_1);
        Except
            Raise;
        End
    Finally
        EndInvoke();
    End
End;
 
Begin
End.

/*
%MA STATIC
*/
Imports SystemClasses
Imports SystemSerialiser
Imports SystemXML
 
Namespace MathTestService
    Public Class TMathTestServiceSoapIntf
        Inherits TSoapHttpClient
        Public Overridable Sub MathProcessor(operand1 As Double, operand2 As Double, 
                                                               theOperator As String, ByRef theResult As Double, 
                                                               ByRef Status_1 As Longint)
            BeginInvoke("http://localhost:9119/?cls=soap", "MathProcessor xmlns=""http://tempuri.org/""", 
                               "MathProcessorResponse xmlns=""http://tempuri.org/""", 
                               "MathProcessor", ssDocumentWrapped)
            Try
                Try
                    RequestBody.WriteDouble("operand1 xsi:type=""xsd:double""", operand1)
                    RequestBody.WriteDouble("operand2 xsi:type=""xsd:double""", operand2)
                    RequestBody.WriteString("theOperator xsi:type=""xsd:string""", theOperator)
                    Invoke()
                    ReplyBody.ReadDouble("theResult xsi:type=""xsd:double""", theResult)
                    ReplyBody.ReadInteger("Status xsi:type=""xsd:int""", Status_1)
                Catch 
                    Throw 
                End Try
            Finally
                EndInvoke()
            End Try
        End Sub 
 
        Public Overridable Sub MathProcessor2(Operand1 As Double, Operand2 As Double, 
                                                                  theOperator As String, ByRef theResult As Double, 
                                                                  ByRef Status_1 As Longint)
            BeginInvoke("http://localhost:9119/?cls=soap", "MathProcessor2 xmlns=""http://tempuri.org/""", 
                               "MathProcessor2Response xmlns=""http://tempuri.org/""", 
                               "MathProcessor2", ssDocumentWrapped)
            Try
                Try
                    RequestBody.WriteDouble("Operand1 xsi:type=""xsd:double""", Operand1)
                    RequestBody.WriteDouble("Operand2 xsi:type=""xsd:double""", Operand2)
                    RequestBody.WriteString("theOperator xsi:type=""xsd:string""", theOperator)
                    Invoke()
                    ReplyBody.ReadDouble("theResult xsi:type=""xsd:double""", theResult)
                    ReplyBody.ReadInteger("Status xsi:type=""xsd:int""", Status_1)
                Catch 
                    Throw 
                End Try
            Finally
                EndInvoke()
            End Try
        End Sub 
 
    End Class
End Namespace

/*
$MA STATIC
*/
imports SystemClasses;
imports SystemSerialiser;
imports SystemXML;
 
namespace MathTestService
{
 
    public class TMathTestServiceSoapIntf : TSoapHttpClient
    {
        public virtual void MathProcessor(Double operand1, Double operand2, String theOperator, 
                                                        ref Double theResult, ref Longint Status_1)
        {
            BeginInvoke("http://localhost:9119/?cls=soap", "MathProcessor xmlns=\"http://tempuri.org/\"", 
                               "MathProcessorResponse xmlns=\"http://tempuri.org/\"", 
                               "MathProcessor", ssDocumentWrapped);
            try
            {
                try
                {
                    RequestBody.WriteDouble("operand1 xsi:type=\"xsd:double\"", operand1);
                    RequestBody.WriteDouble("operand2 xsi:type=\"xsd:double\"", operand2);
                    RequestBody.WriteString("theOperator xsi:type=\"xsd:string\"", theOperator);
                    Invoke();
                    ReplyBody.ReadDouble("theResult xsi:type=\"xsd:double\"", theResult);
                    ReplyBody.ReadInteger("Status xsi:type=\"xsd:int\"", Status_1);
                }
                catch
                {
                    throw;
                }
            }
            finally
            {
                EndInvoke();
            }
        }
 
        public virtual void MathProcessor2(Double Operand1, Double Operand2, String theOperator, 
                                                          ref Double theResult, ref Longint Status_1)
        {
            BeginInvoke("http://localhost:9119/?cls=soap", "MathProcessor2 xmlns=\"http://tempuri.org/\"", 
                               "MathProcessor2Response xmlns=\"http://tempuri.org/\"", 
                               "MathProcessor2", ssDocumentWrapped);
            try
            {
                try
                {
                    RequestBody.WriteDouble("Operand1 xsi:type=\"xsd:double\"", Operand1);
                    RequestBody.WriteDouble("Operand2 xsi:type=\"xsd:double\"", Operand2);
                    RequestBody.WriteString("theOperator xsi:type=\"xsd:string\"", theOperator);
                    Invoke();
                    ReplyBody.ReadDouble("theResult xsi:type=\"xsd:double\"", theResult);
                    ReplyBody.ReadInteger("Status xsi:type=\"xsd:int\"", Status_1);
                }
                catch
                {
                    throw;
                }
            }
            finally
            {
                EndInvoke();
            }
        }
    }
}

This unit (Listing 1) has very little auxiliary and support code being primarily a wrapper around the necessary information serialization code. From that listing what should mainly interest the programmer, who is a user (consumer) of the web service, is a class that offers two methods, each tied to a "function" (a web method, by its own right) of the service. You can see this classes interface below:

FX Code

TMathTestServiceSoapIntf = Class(TSoapHttpClient)
    Procedure   MathProcessor (operand1 : double; operand2 : double; 
                           theOperator : string; Var theResult : double; 
                           Var Status_1 : longint); Virtual;
    Procedure   MathProcessor2(Operand1 : double; Operand2 : double; 
                           theOperator : string; Var theResult : double; 
                           Var Status_1 : longint); Virtual;
End;

    Public Class TMathTestServiceSoapIntf
        Inherits TSoapHttpClient
        Public Overridable Sub MathProcessor(operand1 As Double, operand2 As Double, 
                                                               theOperator As String, ByRef theResult As Double, 
                                                               ByRef Status_1 As Longint)
        End Sub 
 
        Public Overridable Sub MathProcessor2(Operand1 As Double, Operand2 As Double, 
                                                                  theOperator As String, ByRef theResult As Double, 
                                                                  ByRef Status_1 As Longint)
        End Sub 
 
    End Class

public class TMathTestServiceSoapIntf : TSoapHttpClient
    {
        public virtual void MathProcessor(Double operand1, Double operand2, String theOperator, 
                                                        ref Double theResult, ref Longint Status_1)
        {
        }
 
        public virtual void MathProcessor2(Double Operand1, Double Operand2, String theOperator, 
                                                          ref Double theResult, ref Longint Status_1)
        {
        }
    }

Careful observation of this code will undoubtedly reveal that this class’ methods are, in fact, an exact representation of what WebMethods we, originally, added to our application

Listing 2 – Code for the automatically generated browser side interface to the imported services

FX Code

Unit MathTestService;
['AutoSynchronize=None'];
 
Interface
 
Uses
    SystemUtilities,
    SystemClasses,
    SystemRPC,
    SystemCatalog,
    SystemWebMethod;
 
Type
TMathTestServiceMethod = Class(TSoapClient)
    Constructor Create(aMethodName : String);
End;
 
TMathProcessor = Class(TMathTestServiceMethod)
    operand1    : double;
    operand2    : double;
    theOperator : string;
    theResult   : double;
    Status_1    : longint;
    Constructor Create;
    procedure Execute; ['AutoSynchronize=Manual']; Override;
End;
 
TMathProcessor2 = Class(TMathTestServiceMethod)
    Operand1    : double;
    Operand2    : double;
    theOperator : string;
    theResult   : double;
    Status_1    : longint;
    Constructor Create;
    procedure Execute; ['AutoSynchronize=Manual']; Override;
End;
 
Implementation
 
{.................... MathTestServiceSoapIntf ....................}
 
Constructor TMathTestServiceMethod.Create(aMethodName : String);
Begin
    Inherited Create(aMethodName);
    UseProxyServer := True;
    ServiceURL     := 'http://localhost:9119/?cls=soap';
End;
 
Constructor TMathProcessor.Create;
Begin
    Inherited Create('MathProcessor');
    SoapAction := 'MathProcessor';
End;
 
Procedure TMathProcessor.Execute;
Begin
    With Self Do
    Begin
        Self.Bind('operand1',@operand1);
        Self.Bind('operand2',@operand2);
        Self.Bind('theOperator',@theOperator);
        Self.Bind('theResult',@theResult);
        Self.Bind('Status',@Status_1);
    End;
    Inherited Execute;
End;
 
 
Constructor TMathProcessor2.Create;
Begin
    Inherited Create('MathProcessor2');
    SoapAction := 'MathProcessor2';
End;
 
Procedure TMathProcessor2.Execute;
Begin
    With Self Do
    Begin
        Self.Bind('Operand1',@Operand1);
        Self.Bind('Operand2',@Operand2);
        Self.Bind('theOperator',@theOperator);
        Self.Bind('theResult',@theResult);
        Self.Bind('Status',@Status_1);
    End;
    Inherited Execute;
End;
 
 
Function MathTestService_CreateList(Name : String) : Pointer;
Begin
    Result := Nil;
End;
 
Procedure MathTestServiceSRLZRegister;
Begin
    With TSerializableMethodInfo.Create('MathProcessor') Do
    Begin
        RequestNameSpace := 'http://tempuri.org/';
        RequestNameSpaceAlias := '';
        AddField('operand1','double',ptIn);
        AddField('operand2','double',ptIn);
        AddField('theOperator','string',ptIn);
        AddField('theResult','double',ptOut);
        AddField('Status','longint',ptOut);
    End;
 
    With TSerializableMethodInfo.Create('MathProcessor2') Do
    Begin
        RequestNameSpace := 'http://tempuri.org/';
        RequestNameSpaceAlias := '';
        AddField('Operand1','double',ptIn);
        AddField('Operand2','double',ptIn);
        AddField('theOperator','string',ptIn);
        AddField('theResult','double',ptOut);
        AddField('Status','longint',ptOut);
    End;
 
End;
 
Begin
    MathTestServiceSRLZRegister;
End.

/*
%MA STATIC
*/
Imports SystemUtilities
Imports SystemClasses
Imports SystemRPC
Imports SystemCatalog
Imports SystemWebMethod
 
Namespace MathTestService
    Public Class TMathTestServiceMethod
        Inherits TSoapClient
        Public Sub New(aMethodName As String)
            MyBase.New(aMethodName)
            UseProxyServer = true
            ServiceURL = "http://localhost:9119/?cls=soap"
        End Sub 
 
    End Class
 
    Public Class TMathProcessor
        Inherits TMathTestServiceMethod
        Public operand1 As Double
        Public operand2 As Double
        Public theOperator As String
        Public theResult As Double
        Public Status_1 As Longint
 
        Public Sub New
            MyBase.New("MathProcessor")
            SoapAction = "MathProcessor"
        End Sub 
 
        Public Overrides Sub Execute :{"AutoSynchronize=Manual"}
            With Me
                Me.Bind("operand1", Ref operand1)
                Me.Bind("operand2", Ref operand2)
                Me.Bind("theOperator", Ref theOperator)
                Me.Bind("theResult", Ref theResult)
                Me.Bind("Status", Ref Status_1)
            End With
            MyBase.Execute()
        End Sub
 
    End Class
 
    Public Class TMathProcessor2
        Inherits TMathTestServiceMethod
        Public Operand1 As Double
        Public Operand2 As Double
        Public theOperator As String
        Public theResult As Double
        Public Status_1 As Longint
 
        Public Sub New
            MyBase.New("MathProcessor2")
            SoapAction = "MathProcessor2"
        End Sub 
 
        Public Overrides Sub Execute :{"AutoSynchronize=Manual"}
            With Me
                Me.Bind("Operand1", Ref Operand1)
                Me.Bind("Operand2", Ref Operand2)
                Me.Bind("theOperator", Ref theOperator)
                Me.Bind("theResult", Ref theResult)
                Me.Bind("Status", Ref Status_1)
            End With
            MyBase.Execute()
        End Sub 
 
    End Class
 
 
    Private Function MathTestService_CreateList(Name As String) As Pointer
        result = Nothing
    End Function 
 
    Private Sub MathTestServiceSRLZRegister
        With New TSerializableMethodInfo("MathProcessor")
            RequestNameSpace = "http://tempuri.org/"
            RequestNameSpaceAlias = ""
            AddField("operand1", "double", ptin)
            AddField("operand2", "double", ptin)
            AddField("theOperator", "String", ptin)
            AddField("theResult", "double", ptout)
            AddField("Status", "longint", ptout)
        End With
        With New TSerializableMethodInfo("MathProcessor2")
            RequestNameSpace = "http://tempuri.org/"
            RequestNameSpaceAlias = ""
            AddField("Operand1", "double", ptin)
            AddField("Operand2", "double", ptin)
            AddField("theOperator", "String", ptin)
            AddField("theResult", "double", ptout)
            AddField("Status", "longint", ptout)
        End With
    End Sub 
 
    Initialization
        MathTestServiceSRLZRegister()
    End Initialization
End Namespace

/*
$MA STATIC
*/
imports SystemUtilities;
imports SystemClasses;
imports SystemRPC;
imports SystemCatalog;
imports SystemWebMethod;
 
namespace MathTestService
{
    public class TMathTestServiceMethod : TSoapClient
    {
        public TMathTestServiceMethod(String aMethodName)
        {
            base.Create(aMethodName);
            UseProxyServer = true;
            ServiceURL = "http://localhost:9119/?cls=soap";
        }
    }
 
    public class TMathProcessor : TMathTestServiceMethod
    {
        public Double operand1;
        public Double operand2;
        public String theOperator;
        public Double theResult;
        public Longint Status_1;
        public TMathProcessor()
        {
            base.Create("MathProcessor");
            SoapAction = "MathProcessor";
        }
 
        public override void Execute()        ["AutoSynchronize=Manual"]
        {
            with(this)
            {
                this.Bind("operand1", &operand1);
                this.Bind("operand2", &operand2);
                this.Bind("theOperator", &theOperator);
                this.Bind("theResult", &theResult);
                this.Bind("Status", &Status_1);
            }
            base.Execute();
        }
    }
 
    public class TMathProcessor2 : TMathTestServiceMethod
    {
        public Double Operand1;
        public Double Operand2;
        public String theOperator;
        public Double theResult;
        public Longint Status_1;
        public TMathProcessor2()
        {
            base.Create("MathProcessor2");
            SoapAction = "MathProcessor2";
        }
 
        public override void Execute()        ["AutoSynchronize=Manual"]
        {
            with(this)
            {
                this.Bind("Operand1", &Operand1);
                this.Bind("Operand2", &Operand2);
                this.Bind("theOperator", &theOperator);
                this.Bind("theResult", &theResult);
                this.Bind("Status", &Status_1);
            }
            base.Execute();
        }
    }
 
 
    private Pointer MathTestService_CreateList(String Name)
    {
        result = null;
    }
 
    private void MathTestServiceSRLZRegister()
    {
        with(new TSerializableMethodInfo("MathProcessor"))
        {
            RequestNameSpace = "http://tempuri.org/";
            RequestNameSpaceAlias = "";
            AddField("operand1", "double", ptin);
            AddField("operand2", "double", ptin);
            AddField("theOperator", "String", ptin);
            AddField("theResult", "double", ptout);
            AddField("Status", "longint", ptout);
        }
        with(new TSerializableMethodInfo("MathProcessor2"))
        {
            RequestNameSpace = "http://tempuri.org/";
            RequestNameSpaceAlias = "";
            AddField("Operand1", "double", ptin);
            AddField("Operand2", "double", ptin);
            AddField("theOperator", "String", ptin);
            AddField("theResult", "double", ptout);
            AddField("Status", "longint", ptout);
        }
    }
 
    initialization
    {
        MathTestServiceSRLZRegister();
    }
}

This module (Listing 2) has a good quantity of auxiliary and support code which is not of much interest to the user of services. From that listing what should mainly interest the programmer, who is a user (consumer) of the web service, are two classes that embody the services definition. Each class is tied to a "functionailty" (a web method, by its own right) of the service. You can see the interface for these classes below:

FX Code

TMathProcessor = Class(TMathTestServiceMethod)
    operand1    : double;
    operand2    : double;
    theOperator : string;
    theResult   : double;
    Status_1    : longint;
    Constructor Create;
    procedure Execute; ['AutoSynchronize=Manual']; Override;
End;
 
TMathProcessor2 = Class(TMathTestServiceMethod)
    Operand1    : double;
    Operand2    : double;
    theOperator : string;
    theResult   : double;
    Status_1    : longint;
    Constructor Create;
    procedure Execute; ['AutoSynchronize=Manual']; Override;
End;

    Public Class TMathProcessor
        Inherits TMathTestServiceMethod
        Public operand1 As Double
        Public operand2 As Double
        Public theOperator As String
        Public theResult As Double
        Public Status_1 As Longint
 
        Public Sub New
        End Sub 
 
        Public Overrides Sub Execute :{"AutoSynchronize=Manual"}
        End Sub
 
    End Class
 
    Public Class TMathProcessor2
        Inherits TMathTestServiceMethod
        Public Operand1 As Double
        Public Operand2 As Double
        Public theOperator As String
        Public theResult As Double
        Public Status_1 As Longint
 
        Public Sub New
        End Sub 
 
        Public Overrides Sub Execute :{"AutoSynchronize=Manual"}
        End Sub 
 
    End Class

    public class TMathProcessor : TMathTestServiceMethod
    {
        public Double operand1;
        public Double operand2;
        public String theOperator;
        public Double theResult;
        public Longint Status_1;
 
        public TMathProcessor()
        {
        }
 
        public override void Execute()        ["AutoSynchronize=Manual"]
        {
        }
    }
 
    public class TMathProcessor2 : TMathTestServiceMethod
    {
        public Double Operand1;
        public Double Operand2;
        public String theOperator;
        public Double theResult;
        public Longint Status_1;
 
        public TMathProcessor2()
        {
        }
 
        public override void Execute()        ["AutoSynchronize=Manual"]
        {
        }
    }

Once the Web Service has been imported into your project, calling it up is not difficult, though calling it from the Server or Browser portions of your application work differently.

If you create a version of our WebMethod test class, renaming the WebMethod as MathRequester, you can import the .WSDL file from the project where those web services are declared and change the Execute method of the MathRequester version of the Web Method to call the original Web Service in its first implementation. The main difference between this new application and the original one is that the MathRequester WebMethod does not process the operations; it forwards the request to the original application, now running as a service provider.

Only the name of the WebMethod was changed and its server side code. The code you see in Listing 3 is that of the Server side of the MathRequester Web Method.

Listing 3 – Server side code calling out to the imported Web Service.

FX Code

Unit MathRequester;
 
Interface
 
Type
MathRequester=Class(WebMethod)
    Operand1    : Double;
    Operand2    : Double;
    theOperator : String;
    theResult   : Double;
    Status      : Integer;
  Private
    { Private declarations }
  Public
    { Public declarations }
    Procedure Execute; override;
End; ['WSPublished=False'];
 
Implementation
 
Uses
  MathTestService;
 
Procedure MathRequester.Execute;
Var
  MathInt: TMathTestServiceSoapIntf;
Begin
   MathInt := TMathTestServiceSoapIntf.Create;
   Try
     MathInt.MathProcessor (Operand1, Operand2, theOperator, theResult, Status);
   Finally
     MathInt.Free;
   End;
End;
 
End.

/*
%MA STATIC
*/
Imports SystemWebMethod
Imports MathTestService
 
Namespace MathRequester
    Public Class MathRequester
        Inherits WebMethod
        Public Operand1 As Double
        Public Operand2 As Double
        Public theOperator As String
        Public theResult As Double
        Public Status As Integer
 
        ' Public declarations
        Public Overrides Sub Execute
            Dim MathInt As TMathTestServiceSoapIntf
            MathInt = New TMathTestServiceSoapIntf()
            Try
                MathInt.MathProcessor(Operand1, Operand2, theOperator, theResult, Status)
            Finally
                MathInt.Free()
            End Try
        End Sub
 
    End Class
    :{"WSPublished=False"}
End Namespace

/*
$MA STATIC
*/
imports SystemWebMethod;
imports MathTestService;
 
namespace MathRequester
{
    public class MathRequester : WebMethod
    {
        public Double Operand1;
        public Double Operand2;
        public String theOperator;
        public Double theResult;
        public Integer Status;
        //' Public declarations
        public override void Execute()
        {
            TMathTestServiceSoapIntf MathInt;
            MathInt = new TMathTestServiceSoapIntf();
            try
            {
                MathInt.MathProcessor(Operand1, Operand2, theOperator, theResult, Status);
            }
            finally
            {
                MathInt.Free();
            }
        }
    }
    ["WSPublished=False"]
}

You will notice that this service (MathRequester) has the same parameters as the remote target service (MathProcessor). This is necessary since the information is just going through this service, but it also makes it quite easy to handle the remote call and the return of the result (out) values to the browser side of your applications.

As mentioned in the first part of this post, Morfik makes it possible for the developer to write client side code that makes direct references to a Web Service, even if it is published by a 3^rd party. This is handled by the Morfik Framework that implements a transparent proxy on the server side portion of your application.

This leads to greater simplicity in writing applications that rely on such services as it is not necessary to create a new layer of web method code to transfer execution to the server and then relay the response. All this is handled transparently by the Morfik Framework without the need of any additional coding.

Listing 4 shows an example of what direct browser access to our MathProcessor sample Web Method would look like.

FX Code

Unit Content;
 
Interface
 
Uses SystemRPC;
 
Type
Content=Class(Form)
    TextLabel1       : TextLabel;
    TextLabel2       : TextLabel;
    btnExecuteMathOp : Button;
    Op1Edit          : TextEdit;
    Op2Edit          : TextEdit;
    Procedure btnExecuteMathOpClick(Event: TDOMEvent); Message;
  Private
    { Private declarations }
    Procedure GetMathOpResult(SoapClient : TSoapClient);
  Public
    { Public declarations }
End;
 
Implementation
 
Uses MathTestService;
 
Procedure Content.GetMathOpResult(SoapClient : TSoapClient);
Var
   MathOp: TMathProcessor;
Begin
     MathOp := TMathProcessor(SoapClient);
     Try
        TextLabel1.Caption := MathOp.theResult.ToString;
     Finally
        MathOp.Free;
     End;
End;
 
 
Procedure Content.btnExecuteMathOpClick(Event: TDOMEvent);
Var
   MathOp: TMathProcessor;
Begin
   MathOp := TMathProcessor.Create;
   MathOp.operand1 := Op1Edit.Text.ToInteger;
   MathOp.operand2 := Op2Edit.Text.ToInteger;
   MathOp.theOperator := 'ADD';
   MathOp.OnWebMethodReturn := @GetMathOpResult;
   MathOp.Execute;
End;
 
End.

/*
%MA DYNAMIC
*/
Imports SystemRPC
Using MathTestService
 
Namespace Content
    Public Class Content
        Inherits Form
        Published TextLabel1 As TextLabel
        Published TextLabel2 As TextLabel
        Published btnExecuteMathOp As Button
        Published Op1Edit As TextEdit
        Published Op2Edit As TextEdit
 
        ' Private declarations 
        Private Sub GetMathOpResult(SoapClient As TSoapClient)
            Dim MathOp As TMathProcessor
            MathOp = Ctype(SoapClient, TMathProcessor)
            Try
                TextLabel1.Caption = MathOp.theResult.ToString()
            Finally
                MathOp.Free()
            End Try
        End Sub 
 
        Published Message Sub btnExecuteMathOpClick(Event As TDOMEvent)
            Dim MathOp As TMathProcessor
            MathOp = New TMathProcessor()
            MathOp.operand1 = Op1Edit.Text.ToInteger()
            MathOp.operand2 = Op2Edit.Text.ToInteger()
            MathOp.theOperator = "ADD"
            MathOp.OnWebMethodReturn = Ref GetMathOpResult
            MathOp.Execute()
        End Sub 
 
    End Class
End Namespace

/*
$MA DYNAMIC
*/
imports SystemRPC;
using MathTestService;
 
namespace Content
{
    public class Content : Form
    {
        published TextLabel TextLabel1;
        published TextLabel TextLabel2;
        published Button btnExecuteMathOp;
        published TextEdit Op1Edit;
        published TextEdit Op2Edit;
        //' Private declarations
        private void GetMathOpResult(TSoapClient SoapClient)
        {
            TMathProcessor MathOp;
            MathOp = (TMathProcessor)(SoapClient);
            try
            {
                TextLabel1.Caption = MathOp.theResult.ToString();
            }
            finally
            {
                MathOp.Free();
            }
        }
 
        published message void btnExecuteMathOpClick(TDOMEvent Event)
        {
            TMathProcessor MathOp;
            MathOp = new TMathProcessor();
            MathOp.operand1 = Op1Edit.Text.ToInteger();
            MathOp.operand2 = Op2Edit.Text.ToInteger();
            MathOp.theOperator = "ADD";
            MathOp.OnWebMethodReturn = &GetMathOpResult;
            MathOp.Execute();
        }
    }
}

The code that is presented in Listing 4 has two methods that exemplify the fundamentals of Web Service usage from the browser portion of a Morfik application. The first method is the btnExecuteMathOpClick method which is associated to the OnClick event of a button so that the user can directly trigger the execution of the request. This method instantiates the appropriate WebMethod class and sets its parameters before calling its Execute method.

Event though the Execute method will immediately return, it is important to remember that the actual Web Service call is asynchronous and will not return immediately. In order to receive a notification that the underlying Web Service being requested has returned the OnWebMethodReturn property of the Web Method that was instantiated is set to point to another method that takes a TSoapClient parameter.

In the case show in listing 4 this is the GetMathOpResult method. Inside this method the parameter is typecast into the type of the Web Method that was originally invoked and after its output parameters are read, the corresponding object is freed.

• What are Web Services and why do I need to use them?
• Understanding the way Web Services are used in Morfik
• Creating Web Methods and using them in your application
• Non-visual Web Methods