I have been working on an BizSnap chapter for the Kylix Developer's Guide - adding more coverage of Kylix 2 to this book. The BizSnap chapter will be published on my website (in six weekly parts), covering XML Document Programming and Web Services support.

2. XML Data Binding
In the previous section you worked with the IXMLDocument interface as implemented by the TXMLDocument component. And although it's useful, the downside is that is doesn't offer you semantic support for the XML document. One typing mistake, and you didn't find the value of a child node, but accidentally added a new child node to the tree.
Fortunately, Kylix 2 also contains a way to perform XML Data Binding, whereby an XML Document is used to generate Object Pascal source code. The generated source code contains interfaces and class definitions that will help you make less mistakes by offering named methods as well as Code Insight support. Let's see how it works, and you'll get the idea.
The "work" is done by the XML Data Binding Wizard, which can be found in the Object Repository after you choose File | New (see Figure 2).

  {******************************************}
  {                                          }
  {             XML Data Binding             }
  {                                          }
  {         Generated on: 01/21/02 01:43:26  }
  {       Generated from: BizSnap.xml        }
  {                                          }
  {******************************************}
  unit BizSnap;
  interface
  uses
    xmldom, XMLDoc, XMLIntf;

  type

  { Forward Decls }

    IXMLChapterType = interface;
    IXMLSectionType = interface;

  { IXMLChapterType }

    IXMLChapterType = interface(IXMLNodeCollection)
      ['{8C1BC176-6C0E-D611-87C6-68D6D308EEFE}']
      { Property Accessors }
      function Get_Title: WideString;
      function Get_Section(Index: Integer): IXMLSectionType;
      procedure Set_Title(Value: WideString);
      { Methods & Properties }
      function Add: IXMLSectionType;
      function Insert(const Index: Integer): IXMLSectionType;
      property Title: WideString read Get_Title write Set_Title;
      property Section[Index: Integer]: IXMLSectionType read Get_Section; default;
    end;

  { IXMLSectionType }

    IXMLSectionType = interface(IXMLNode)
      ['{A42FC276-6C0E-D611-87C6-0072EC08EEFE}']
      { Property Accessors }
      function Get_Title: WideString;
      function Get_Components: WideString;
      function Get_Wizards: WideString;
      procedure Set_Title(Value: WideString);
      procedure Set_Components(Value: WideString);
      procedure Set_Wizards(Value: WideString);
      { Methods & Properties }
      property Title: WideString read Get_Title write Set_Title;
      property Components: WideString read Get_Components write Set_Components;
      property Wizards: WideString read Get_Wizards write Set_Wizards;
    end;

  { Forward Decls }

    TXMLChapterType = class;
    TXMLSectionType = class;

  { TXMLChapterType }

    TXMLChapterType = class(TXMLNodeCollection, IXMLChapterType)
    protected
      { IXMLChapterType }
      function Get_Title: WideString;
      function Get_Section(Index: Integer): IXMLSectionType;
      procedure Set_Title(Value: WideString);
      function Add: IXMLSectionType;
      function Insert(const Index: Integer): IXMLSectionType;
    public
      procedure AfterConstruction; override;
    end;

  { TXMLSectionType }

    TXMLSectionType = class(TXMLNode, IXMLSectionType)
    protected
      { IXMLSectionType }
      function Get_Title: WideString;
      function Get_Components: WideString;
      function Get_Wizards: WideString;
      procedure Set_Title(Value: WideString);
      procedure Set_Components(Value: WideString);
      procedure Set_Wizards(Value: WideString);
    end;

  { Global Functions }

  function GetChapter(Doc: IXMLDocument): IXMLChapterType;
  function LoadChapter(const FileName: WideString): IXMLChapterType;
  function NewChapter: IXMLChapterType;

  implementation
  { Global Functions }

  function GetChapter(Doc: IXMLDocument): IXMLChapterType;
  begin
    Result := Doc.GetDocBinding('Chapter', TXMLChapterType) as IXMLChapterType;
  end;

  function LoadChapter(const FileName: WideString): IXMLChapterType;
  begin
    Result := LoadXMLDocument(FileName).GetDocBinding('Chapter', TXMLChapterType) as IXMLChapterType;
  end;

  function NewChapter: IXMLChapterType;
  begin
    Result := NewXMLDocument.GetDocBinding('Chapter', TXMLChapterType) as IXMLChapterType;
  end;

  { TXMLChapterType }

  procedure TXMLChapterType.AfterConstruction;
  begin
    RegisterChildNode('Section', TXMLSectionType);
    ItemTag := 'Section';
    ItemInterface := IXMLSectionType;
    inherited;
  end;

  function TXMLChapterType.Get_Title: WideString;
  begin
    Result := AttributeNodes['Title'].Text;
  end;

  procedure TXMLChapterType.Set_Title(Value: WideString);
  begin
    SetAttribute('Title', Value);
  end;

  function TXMLChapterType.Get_Section(Index: Integer): IXMLSectionType;
  begin
    Result := List[Index] as IXMLSectionType;
  end;

  function TXMLChapterType.Add: IXMLSectionType;
  begin
    Result := AddItem(-1) as IXMLSectionType;
  end;

  function TXMLChapterType.Insert(const Index: Integer): IXMLSectionType;
  begin
    Result := AddItem(Index) as IXMLSectionType;
  end;

  { TXMLSectionType }

  function TXMLSectionType.Get_Title: WideString;
  begin
    Result := AttributeNodes['Title'].Text;
  end;

  procedure TXMLSectionType.Set_Title(Value: WideString);
  begin
    SetAttribute('Title', Value);
  end;

  function TXMLSectionType.Get_Components: WideString;
  begin
    Result := ChildNodes['Components'].Text;
  end;

  procedure TXMLSectionType.Set_Components(Value: WideString);
  begin
    ChildNodes['Components'].NodeValue := Value;
  end;

  function TXMLSectionType.Get_Wizards: WideString;
  begin
    Result := ChildNodes['Wizards'].Text;
  end;

  procedure TXMLSectionType.Set_Wizards(Value: WideString);
  begin
    ChildNodes['Wizards'].NodeValue := Value;
  end;

  end.

  procedure TForm1.FormCreate(Sender: TObject);
  begin
    Chapter := GetChapter(XMLDocument1);
  end;

  procedure TForm1.FormCreate(Sender: TObject);
  begin
    Chapter := GetChapter(XMLDocument1);
    CurrentSection := 0; // first section
    btnNextClick(nil)
  end;

  procedure TForm1.btnPrevClick(Sender: TObject);
  begin
    if CurrentSection > 0 then Dec(CurrentSection);
    Memo1.Lines.Clear;
    Memo1.Lines.Add(Chapter.Section[CurrentSection].Title);
    Memo1.Lines.Add(Chapter.Section[CurrentSection].Components);
    Memo1.Lines.Add(Chapter.Section[CurrentSection].Wizards);
    btnNext.Enabled := (CurrentSection < Pred(Chapter.Count));
    btnPrev.Enabled := (CurrentSection > 0)
  end;

  procedure TForm1.btnNextClick(Sender: TObject);
  begin
    if CurrentSection < Pred(Chapter.Count) then Inc(CurrentSection);
    Memo1.Lines.Clear;
    Memo1.Lines.Add(Chapter.Section[CurrentSection].Title);
    Memo1.Lines.Add(Chapter.Section[CurrentSection].Components);
    Memo1.Lines.Add(Chapter.Section[CurrentSection].Wizards);
    btnNext.Enabled := (CurrentSection < Pred(Chapter.Count));
    btnPrev.Enabled := (CurrentSection > 0)
  end;

Next Time, Dr.Bob says...
In the next section, we'll use the XML Mapping Tool to produce source code that can transform an XML document to a DataSet (and back) for even more powerful functionality. All this and more next week, so stay tuned...