Quick (hopefully easy) question for you guys.


What is going to be the quickest/easiest way to generate XML from VB.NET?


Note: I don't mean an XML file, but XML in memory somehow (an XML-related
object, but one that would have a method for getting the fully-formed XML
back out again).


For example, what will be my easiest way to build the following in memory:

<CommandXML>
    <cmd name="1" action="2">
        <arg name="3" value = "4"/>
        <arg name="5" value = "6"/>
    </cmd>
    <cmd name="7" action="9">
        <arg name="9" value = "0"/>
    </cmd>
</CommandXML>



Basically, the reason I need this in memory, is I need to build this XML,
then send it (as a string) to a server component.


Thanks!
-Scott

You'll be delightfully surprised how easy it is. You basically use the
XMLserialization object to create an object or series of nested objects
that can read in or write out XML to a text file or other output
source.

The WROX Visual Basic for Beginners book cover this in detail.

Scott,
As Bingomanatee suggests XML Serialization is one of the easier ways,
especially if you can represent your data as Objects. The trick is getting
the "arrays" correct (the list of commands & the list of arguments).

Something like (note the sample only supports a single cmd & a single arg):

Imports System.Xml.Serialization

        Dim writer As New System.Xml.XmlTextWriter("CommandXml.xml",
System.Text.Encoding.UTF8)
        writer.Formatting = Xml.Formatting.Indented
        writer.Indentation = 1
        writer.IndentChar = ControlChars.Tab

        Dim serializer As New
System.Xml.Serialization.XmlSerializer(GetType(CommandXml))

        Dim command As New CommandXml
        command.Command = New command
        command.Command.Name = "1"
        command.Command.Action = "2"
        command.Command.Argument = New Argument
        command.Command.Argument.Name = "3"
        command.Command.Argument.Value = "4"

        serializer.Serialize(writer, command)
        writer.Close()


Public Class CommandXml

    Private m_command As Command

    <XmlElement("cmd")> _
    Public Property Command() As Command
        Get
            Return m_command
        End Get
        Set(ByVal value As Command)
            m_command = value
        End Set
    End Property

End Class

Public Class Command

    Private m_name As String
    Private m_action As String
    Private m_argument As Argument

    <XmlAttributeAttribute("name")> _
    Public Property Name() As String
        Get
            Return m_name
        End Get
        Set(ByVal value As String)
            m_name = value
        End Set
    End Property

    <XmlAttributeAttribute("action")> _
    Public Property Action() As String
        Get
            Return m_action
        End Get
        Set(ByVal value As String)
            m_action = value
        End Set
    End Property

    <XmlElement("arg")> _
    Public Property Argument() As Argument
        Get
            Return m_argument
        End Get
        Set(ByVal value As Argument)
            m_argument = value
        End Set
    End Property

End Class

Public Class Argument

    Private m_name As String
    Private m_value As String

    <XmlAttributeAttribute("name")> _
    Public Property Name() As String
        Get
            Return m_name
        End Get
        Set(ByVal value As String)
            m_name = value
        End Set
    End Property

    <XmlAttributeAttribute("value")> _
    Public Property Value() As String
        Get
            Return m_value
        End Get
        Set(ByVal value As String)
            m_value = value
        End Set
    End Property

End Class



I find using System.Text.XmlTextWriter to be equally easy. Something like:

        Dim writer As New System.Xml.XmlTextWriter("CommandXml.xml",
System.Text.Encoding.UTF8)
        writer.Formatting = Xml.Formatting.Indented
        writer.Indentation = 1
        writer.IndentChar = ControlChars.Tab
        writer.WriteStartDocument()

        ' <CommandXML>
        writer.WriteStartElement("CommandXML")

        '    <cmd name="1" action="2">
        writer.WriteStartElement("cmd")
        writer.WriteAttributeString("name", "1")
        writer.WriteAttributeString("action", "2")

        '        <arg name="3" value = "4"/>
        writer.WriteStartElement("arg")
        writer.WriteAttributeString("name", "3")
        writer.WriteAttributeString("value", "4")
        writer.WriteEndElement() ' arg

        '        <arg name="5" value = "6"/>
        writer.WriteStartElement("arg")
        writer.WriteAttributeString("name", "5")
        writer.WriteAttributeString("value", "6")
        writer.WriteEndElement() ' arg

        '    </cmd>
        writer.WriteEndElement() ' cmd

        '    <cmd name="7" action="9">
        writer.WriteStartElement("cmd")
        writer.WriteAttributeString("name", "7")
        writer.WriteAttributeString("action", "9")

        '        <arg name="9" value = "0"/>
        writer.WriteStartElement("arg")
        writer.WriteAttributeString("name", "9")
        writer.WriteAttributeString("value", "0")
        writer.WriteEndElement() ' arg

        '    </cmd>
        writer.WriteEndElement() ' cmd

        ' </CommandXML>
        writer.WriteEndElement() ' CommandXML

        writer.WriteEndDocument()
        writer.Close()

Hope this helps
Jay

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Hello Scott,

Well, may be I'm simplistic, but if you just want to send a string to a
server, then build the string:

StringBuilder xml=new StringBuilder();
xml.Append("<CommandXML>\n");
xml.Append("     <cmd name=\"1\" action=\"2\">\n");
xml.Append("         <arg name=\"3\" value=\"4\"/>\n");
xml.Append("         <arg name=\"5\" value=\"6\"/>\n");
xml.Append("     </cmd>\n");
xml.Append("     <cmd name=\"7\" action=\"9\">\n");
xml.Append("         <arg name=\"9\" value=\"0\"/>\n");
xml.Append("     </cmd>\n");
xml.Append("</CommandXML>");

Then, when you want to access the string you do a
xml.ToString();

And, if you want to check the Xml you do a:
try {
    XmlDocument doc=new XmlDocument();
    doc.LoadXml(xml.ToString());
} catch (XmlException e) {
   throw new Exception("Error "+e.Message+" in line "+e.LineNumber+"
at\n"+xml.ToString());
}

Hope this helps,
  jmgonet

jmgonet wrote:

Bad idea. Then you must take care of XML syntax issues - well-formdness,
escaping special characters, encoding issues etc etc etc. It's always
much better to let XML API to deal with XML.

That's a code from 1998. In 2005 you can have a luxury to use XmlTextWriter.

jmgonet,
As Oleg suggests using a StringBuilder is a "bad" idea. In addition to the
reasons Oleg states. Item #29 "Always Use a Parser" from Elliotte Rusty
Harold's book "Effective XML - 50 Specific Ways to Improve Your XML" from
Addison Wesley lists a number of other reasons to use a parser. Although
Item #29 is largely reading, I find the topic apropos to writing also.

Hope this helps
Jay


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