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* [[lNet|lNet]] - composants de gestion de reseau Léger | * [[lNet|lNet]] - composants de gestion de reseau Léger | ||
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+ | * [[XML Tutorial|XML Tutorial]] - XML est souvent utilisé avec les communications de réseau | ||
== Le protocole TCP/IP == | == Le protocole TCP/IP == |
Revision as of 01:34, 27 June 2007
│
Deutsch (de) │
English (en) │
español (es) │
français (fr) │
日本語 (ja) │
한국어 (ko) │
polski (pl) │
português (pt) │
русский (ru) │
slovenčina (sk) │
中文(中国大陆) (zh_CN) │
Cette page sera le début de tutoriels en rapport avec la programmation de reseaux avec Lazarus. Je ne suis pas un expert en programmation de gestion de réseau et je complèterais si j'en apprend davantage. J'invite d'autres gens à aider à la création d'articles sur la gestion de réseau . Ajouter juste un lien vers la prochaine section , ajouter une page et créer votre propre article WiKi . Sur cette page quelques informations générales seront données.
D'autres tutoriels sur la gestion de réseaux
- Sockets - composants permettant une interface logicielle(Sockets) avec les services du système d'exploitation pour utiliser le protocole reseau TCP/IP
- lNet - composants de gestion de reseau Léger
- XML Tutorial - XML est souvent utilisé avec les communications de réseau
Le protocole TCP/IP
XML
L'eXtensible Markup Language(XML) est un langage recommandé par W3C et créé pour échanger de l'information entre différents systèmes. C'est une manière basée sur le texte pour stocker l'information. Les langages modernes d'échange de données comme XHTML, aussi bien que la plupart des technologies de WebServices, sont basés sur le XML.
Il y a actuellement un ensemble d'unités qui fournissent un support pour XML sur Lazarus. Ces unités s'appellent "XMLRead", "XMLWrite" et "DOM" et elles font partie de la bibliothèque de composants libre (FCL) du compilateur Free Pascal. La bibliothèque FCL est déjà dans le chemin de recherche par défaut du compilateur sur Lazarus, ainsi vous devez seulement ajouter les unités à votre clause uses afin d'obtenir le support de XML . La bibliothèque FCL n'est pas documenté actuellement(Octobre / 2005), ainsi ce court tutoriel vise à présenter l'accès à XML en utilisant ces unités .
The XML DOM (Document Object Model) is a set of standarized objects that provide a similar interface for the use of XML on different languages and systems. The standard only specifies the methods, properties and other interface parts of the object, leaving the implementation free for different languages. The FCL currently supports fully the XML DOM 1.0.
Exemple de base
Pour les programmeurs en Delphi : Note that when working with TXMLDocument, the text within a Node is considered a separate TEXT Node. As a result, you must access a node's text value as a separate node. For instance, consider the following XML:
<?xml version="1.0" encoding="utf-8"?>
<request>
<request_type>PUT_FILE</request_type>
<username>123</username>
<password>abc</password>
</request>
Consider also the following code example:
var
PassNode: TDOMNode;
Doc: TXMLDocument;
begin
Doc := TXMLDocument.Create;
// Read in xml file from disk
ReadXMLFile(Doc, 'c:\xmlfiles\test.xml');
// Retrieve the "password" node
PassNode := Doc.DocumentElement.FindNode('password');
// Write out value of the selected node
WriteLn(PassNode.NodeValue); // will be blank
// The text of the node is actually a separate child node
WriteLn(PassNode.FirstChild.NodeValue); // correctly prints "abc"
Let´s say you want to access a XML file called 'C:\Programas\teste.xml'. Here is the file content:
<?xml version="1.0" encoding="ISO-8859-1"?>
<images directory="mydir">
<imageNode URL="graphic.jpg" title="">
<Peca DestinoX="0" DestinoY="0">Pecacastelo.jpg1.swf</Peca>
<Peca DestinoX="0" DestinoY="86">Pecacastelo.jpg2.swf</Peca>
</imageNode>
</images>
The following code can write the Node´s names to a TMemo placed on a form:
var
Documento: TXMLDocument;
i, j: Integer;
begin
Documento := TXMLDocument.Create;
ReadXMLFile(Documento, 'C:\Programas\teste.xml');
Memo.Lines.Clear;
with Documento.DocumentElement.ChildNodes do
begin
for i := 0 to (Count - 1) do
begin
Memo.Lines.Add(Item[i].NodeName + ' ' + Item[i].NodeValue);
for j := 0 to (Item[i].ChildNodes.Count - 1) do
begin
Memo.Lines.Add(Item[i].ChildNodes.Item[j].NodeName + ' '
+ Item[i].ChildNodes.Item[j].NodeValue);
end;
end;
end;
Documento.Free;
end;
Populating a TreeView with XML
One common use of XML files is to parse them and show their contents in a tree like format. You can find the TTreeView component on the "Common Controls" tab on Lazarus.
The function below will take a XML document previously loaded from a file or generated on code, and will populate a TreeView with it´s contents. The caption of each node will be the content of the first attribute of each node.
procedure TForm1.XML2Tree(tree: TTreeView; XMLDoc: TXMLDocument); var iNode: TDOMNode; procedure ProcessNode(Node: TDOMNode; TreeNode: TTreeNode); var cNode: TDOMNode; begin if Node = nil then Exit; // Stops if reached a leaf // Adds a node to the tree TreeNode := tree.Items.AddChild(TreeNode, Node.Attributes[0].NodeValue); // Goes to the child node cNode := Node.ChildNodes.Item[0]; // Processes all child nodes while cNode <> nil do begin ProcessNoDe(cNode, TreeNode); cNode := cNode.NextSibling; end; end; begin iNode := XMLDoc.DocumentElement.ChildNodes.Item[0]; while iNode <> nil do begin ProcessNode(iNode, nil); // Recursive iNode := iNode.NextSibling; end; end;
Modifying a XML document
The first thing to remember is that TDOMDocument is the "handle" to the DOM. You can get an instance of this class by creating one or by loading a XML document.
Nodes on the other hand cannot be created like a normal object. You *must* use the methods provided by TDOMDocument to create them, and latter use other methods to put them on the correct place on the tree. This is because nodes must be "owned" by a specific document on DOM.
Below are some common methods from TDOMDocument:
function CreateElement(const tagName: DOMString): TDOMElement; virtual; function CreateTextNode(const data: DOMString): TDOMText; function CreateCDATASection(const data: DOMString): TDOMCDATASection; virtual; function CreateAttribute(const name: DOMString): TDOMAttr; virtual;
And here an example method that will located the selected item on a TTreeView and then insert a child node to the XML document it represents. The TreeView must be previously filled with the contents of a XML file using the fonction XML2Tree.
procedure TForm1.actAddChildNode(Sender: TObject); var Posicao: Integer; NovoNo: TDomNode; begin {******************************************************************* * Detects the selected element *******************************************************************} if TreeView1.Selected = nil then Exit; if TreeView1.Selected.Level = 0 then begin Posicao := TreeView1.Selected.Index; NovoNo := XMLDoc.CreateElement('item'); TDOMElement(NovoNo).SetAttribute('nome', 'Item'); TDOMElement(NovoNo).SetAttribute('arquivo', 'Arquivo'); XMLDoc.DocumentElement.ChildNodes.Item[Posicao].AppendChild(NovoNo); {******************************************************************* * Updates the TreeView *******************************************************************} TreeView1.Items.Clear; XML2Tree(TreeView1, XMLDoc); end else if TreeView1.Selected.Level >= 1 then begin {******************************************************************* * This function only works on the first level of the tree, * but can easely modifyed to work for any number of levels *******************************************************************} end; end;
Create a TXMLDocument from a string
Given al XML file in MyXmlString, the following code will create it's DOM:
Var S : TStringStream; XML : TXMLDocument; begin S:= TStringStream.Create(MyXMLString); Try S.Position:=0; XML:=Nil; ReadXMLFile(XML,S); // Complete XML document // Alternatively: ReadXMLFragment(AParentNode,S); // Read only XML fragment. Finally S.Free; end; end;
WebServices
According to the W3C a Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface that is described in a machine-processable format such as WSDL. Other systems interact with the Web service in a manner prescribed by its interface using messages, which may be enclosed in a SOAP envelope, or follow a REST approach. These messages are typically conveyed using HTTP, and are normally comprised of XML in conjunction with other Web-related standards. Software applications written in various programming languages and running on various platforms can use web services to exchange data over computer networks like the Internet in a manner similar to inter-process communication on a single computer. This interoperability (e.g., between Windows and Linux applications) is due to the use of open standards. OASIS and the W3C are the primary committees responsible for the architecture and standardization of web services. To improve interoperability between web service implementations, the WS-I organisation has been developing a series of profiles to further define the standards involved.
Web Service Toolkit for FPC & Lazarus
Web Service Toolkit is a web services package for FPC and Lazarus.
External Links
XML
- W3Schools Xml Tutorial
- Thomas Zastrow article FPC and XML