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RE: [soapbuilders] Schema question

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  • Wes Moulder
    Well, as far as Java goes, if you have two classes, Address and USAddress, Like this: public class Address { String city; String zip; String country; } public
    Message 1 of 23 , Apr 3, 2002
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      Well, as far as Java goes, if you have two classes, Address and USAddress, Like this:

       

      public class Address

        {

        String city;

        String zip;

        String country;

        }

       

      public class USAddress extends Address

        {

        int zip;

        }

       

      Both zips are around.  However, anything that uses Address, and accesses zip will get a null value.  Preserving that semantic would be a bad idea to me, as it breaks the principal of least surprises.  SOAP is more about Data from an OO standpoint, and less about Objects.  When you pass an object back and forth across platforms, there is no guarantee that the other side will have the same methods available.

       

      IE:

       

      public static void main( String[] args )

        {

        USAddress address = new USAddress();

        address.zip = 1;

        printOutZip( address );

        }

       

      public void printOutZip( Address address )

        {

        System.out.println( address.zip );

        }

       

      Hope that helps you understand my POV.

      --Wes

       

      -----Original Message-----
      From: Robert van Engelen [mailto:engelen@...]
      Sent
      : Wednesday, April 03, 2002 1:07 PM
      To: soapbuilders@yahoogroups.com
      Subject: Re: [soapbuilders] Schema question

       


      Hi Wes,

      I see. But don't you find it strange that the O in SOAP refers to Objects
      while XML schemas don't seem to be able to preserve basic OO semantics?

      A restriction won't work as you pointed out because the zip field of the base
      is overwritten with a new definition for zip. Extension seems to be more
      natural. After all, we add new fields to a base class to get a derived class.

      Again, if this cannot be resolved in schemas/WSDL then SOAP will not be
      suitable for object exchange. The .NET guys must have a tremendous problem
      at their hands when they say that C# is competative to Java while Java
      preserves simple OO semantics while C# cannot? I would like to hear some
      more, especially from the .NET people :-)

      Wes Moulder wrote:
      >
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      >
      > Robert,
      > I believe it would have to be a restriction, not an extension, since
      > you're changing the behaviour of zip, and even then, I don't think
      > you're allowed to completely alter the type of data, just restrict its
      > possibilities.

      > This is all from a vague understanding of xmlschema-1/ section 3.9.6,
      > though.
      > The multiple zip problem is still in effect, though; thus you wouldn't
      > have two zip entries.

      > For better understanding of where I'm coming from, take it as if zip
      > were defined as ur-type, and string.
      > Now, send in two normalized strings.  Which zip maps to which field?
      > <sequence> would say it's order dependant, right? 
      > Where do parent elements go in terms of extension?

      > You might also look in xmlschema-1 section 2.2.1, where it talks about
      > DataTypes.

      > As far as OO goes, I don't think you can take an object that contains a
      > String, and replace it with an int, and have any assumptions still hold
      > up.
      > Take this for an example:

      > Address{
      >   String zip;
      >   String city;
      >   String country;
      > }

      > and
      > USAddress :: Address {
      >   Int zip;
      > }

      > if I set the int on USAddress, and pass it into a function that looks
      > for an Address, the String would be empty/null, which isn't what you're
      > after.

      > --Wes


      > -----Original Message-----
      > From: Robert van Engelen [mailto:engelen@...]
      > Sent: Wednesday, April 03, 2002 12:27 PM
      > To: soapbuilders@yahoogroups.com
      > Subject: Re: [soapbuilders] Schema question

      >
      > Thanks!
      >
      > It is easy to overlook this kind of information in these long specs.
      >
      > One more question though: is the following legal?
      >
      > <complexType name="baseAddress">
      >   <sequence>
      >     <element name="city" type="xsd:string"/>
      >     <element name="zip" type="xsd:string"/>
      >     <element name="country" type="xsd:string"/>
      >   </sequence>
      > </complexType>
      >
      > <complexType name="address">
      >   <complexContent>
      >     <extension base="tns:baseAddress">
      >       <sequence>
      >         <element name="zip" type="xsd:integer"/>
      >       </sequence>
      >     </extension>
      >   </complexContent>
      > </complexType>
      >
      > If this is legal, is the resulting XML allowed to carry two zip elements
      > or
      > only one?
      >
      > I am asking this because:
      >
      > 1. gSOAP supports single inheritance. When communicating derived class
      > instances over SOAP also the base class members need to be present in
      > the
      > SOAP message (just like any OO implementation keeps base class
      > information
      > in the derived class instances).
      >
      > 2. The problem is that if schemas/WSDL disallows the above then SOAP is
      > not
      > suitable for OO! (or maybe it need to be accomplished with some tricks).
      >
      > - Robert
      >
      >
      >
      >
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      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>Robert,<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>I believe it would have to be a
      > restriction, not an extension, since you&#8217;re changing the behaviour of zip,
      > and even then, I don&#8217;t think you&#8217;re allowed to completely alter the
      > type of data, just restrict its possibilities.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>This is all from a vague understanding of
      > xmlschema-1/ section 3.9.6, though.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>The multiple zip problem is still in
      > effect, though; thus you wouldn&#8217;t have two zip entries.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>For better understanding of where I&#8217;m
      > coming from, take it as if zip were defined as ur-type, and string.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>Now, send in two normalized strings.<span
      > style='mso-spacerun:yes'>&nbsp; </span>Which zip maps to which field?
      > &lt;sequence&gt; would say it&#8217;s order dependant, right?<span
      > style='mso-spacerun:yes'>&nbsp; </span><o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>Where do parent elements go in terms of
      > extension?<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>You might also look in xmlschema-1 section
      > 2.2.1, where it talks about DataTypes.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>As far as OO goes, I don&#8217;t think you
      > can take an object that contains a String, and replace it with an int, and have
      > any assumptions still hold up.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>Take this for an example:<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>Address{<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><span style='mso-spacerun:yes'>&nbsp;
      > </span>String zip;<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><span style='mso-spacerun:yes'>&nbsp;
      > </span>String city;<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><span style='mso-spacerun:yes'>&nbsp;
      > </span>String country;<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>}<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>and <o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>USAddress :: Address {<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><span style='mso-spacerun:yes'>&nbsp;
      > </span>Int zip;<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>}<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>if I set the int on USAddress, and pass it
      > into a function that looks for an Address, the String would be empty/null,
      > which isn&#8217;t what you&#8217;re after.<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'>--Wes<o:p></o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
      > 10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal style='margin-left:.5in'><font size=2 face=Tahoma><span
      > style='font-size:10.0pt;font-family:Tahoma'>-----Original Message-----<br>
      > <b><span style='font-weight:bold'>From:</span></b> Robert van Engelen
      > [mailto:engelen@...] <br>
      > <b><span style='font-weight:bold'>Sent:</span></b> </span></font><st1:date
      > Month="4" Day="3" Year="2002"><font size=2 face=Tahoma><span style='font-size:
      >  10.0pt;font-family:Tahoma'>Wednesday, April 03, 2002</span></font></st1:date><font
      > size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> </span></font><st1:time
      > Hour="12" Minute="27"><font size=2 face=Tahoma><span style='font-size:10.0pt;
      >  font-family:Tahoma'>12:27 PM</span></font></st1:time><font size=2 face=Tahoma><span
      > style='font-size:10.0pt;font-family:Tahoma'><br>
      > <b><span style='font-weight:bold'>To:</span></b> soapbuilders@yahoogroups.com<br>
      > <b><span style='font-weight:bold'>Subject:</span></b> Re: [soapbuilders] Schema
      > question</span></font></p>
      >
      > <p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times New Roman"><span
      > style='font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>
      >
      > <p class=MsoNormal style='margin-left:.5in'><font size=2 face="Courier New"><span
      > style='font-size:10.0pt;font-family:"Courier New"'><br>
      > <tt><font face="Courier New">Thanks!</font></tt><br>
      > <br>
      > <tt><font face="Courier New">It is easy to overlook this kind of information in
      > these long specs.</font></tt><br>
      > <br>
      > <tt><font face="Courier New">One more question though: is the following legal?</font></tt><br>
      > <br>
      > <tt><font face="Courier New">&lt;complexType name=&quot;baseAddress&quot;&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp; &lt;sequence&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp; &lt;element
      > name=&quot;city&quot; type=&quot;xsd:string&quot;/&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp; &lt;element
      > name=&quot;zip&quot; type=&quot;xsd:string&quot;/&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp; &lt;element
      > name=&quot;country&quot; type=&quot;xsd:string&quot;/&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp; &lt;/sequence&gt;</font></tt><br>
      > <tt><font face="Courier New">&lt;/complexType&gt;</font></tt><br>
      > <br>
      > <tt><font face="Courier New">&lt;complexType name=&quot;address&quot;&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp; &lt;complexContent&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp; &lt;extension
      > base=&quot;tns:baseAddress&quot;&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &lt;sequence&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      > &lt;element name=&quot;zip&quot; type=&quot;xsd:integer&quot;/&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &lt;/sequence&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp;&nbsp;&nbsp; &lt;/extension&gt;</font></tt><br>
      > <tt><font face="Courier New">&nbsp; &lt;/complexContent&gt;</font></tt><br>
      > <tt><font face="Courier New">&lt;/complexType&gt;</font></tt><br>
      > <br>
      > <tt><font face="Courier New">If this is legal, is the resulting XML allowed to
      > carry two zip elements or</font></tt><br>
      > <tt><font face="Courier New">only one?</font></tt><br>
      > <br>
      > <tt><font face="Courier New">I am asking this because:</font></tt><br>
      > <br>
      > <tt><font face="Courier New">1. gSOAP supports single inheritance. When
      > communicating derived class</font></tt><br>
      > <tt><font face="Courier New">instances over SOAP also the base class members
      > need to be present in the</font></tt><br>
      > <tt><font face="Courier New">SOAP message (just like any OO implementation
      > keeps base class information</font></tt><br>
      > <tt><font face="Courier New">in the derived class instances).</font></tt><br>
      > <br>
      > <tt><font face="Courier New">2. The problem is that if schemas/WSDL disallows
      > the above then SOAP is not</font></tt><br>
      > <tt><font face="Courier New">suitable for OO! (or maybe it need to be
      > accomplished with some tricks).</font></tt><br>
      > <br>
      > <tt><font face="Courier New">- Robert</font></tt><br>
      > </span></font><br style='mso-special-character:line-break'>
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      --
          Robert van Engelen: Assistant Professor, Computer Science Department
         Florida State University, 206 J. Love Bldg., Tallahassee, FL32306-4530
           Offices: 162LOV/471DSL, (850)644-9661/645-0309, Fax: (850)644-0058
             Email: engelen@..., URL: http://www.cs.fsu.edu/~engelen




      (Message over 64 KB, truncated)
    • Bob Cunnings
      Hello, How do C# or Java come into the picture? I though you were discussing the limitations of XML Schema... not C# RC
      Message 2 of 23 , Apr 3, 2002
      • 0 Attachment
        Hello,

        How do C# or Java come into the picture? I though you were
        discussing the limitations of XML Schema... not C#

        RC

        >
        > Hi Wes,
        >
        > I see. But don't you find it strange that the O in SOAP refers to Objects
        > while XML schemas don't seem to be able to preserve basic OO semantics?
        >
        > A restriction won't work as you pointed out because the zip field of the base
        > is overwritten with a new definition for zip. Extension seems to be more
        > natural. After all, we add new fields to a base class to get a derived class.
        >
        > Again, if this cannot be resolved in schemas/WSDL then SOAP will not be
        > suitable for object exchange. The .NET guys must have a tremendous problem
        > at their hands when they say that C# is competative to Java while Java
        > preserves simple OO semantics while C# cannot? I would like to hear some
        > more, especially from the .NET people :-)
        >
        > Wes Moulder wrote:
        > >
        > > ------=_NextPart_000_007B_01C1DB0D.2C1B77E0
        > > Content-Type: text/plain;
        > > charset="US-ASCII"
        > > Content-Transfer-Encoding: 7bit
        > >
        > > Robert,
        > > I believe it would have to be a restriction, not an extension, since
        > > you're changing the behaviour of zip, and even then, I don't think
        > > you're allowed to completely alter the type of data, just restrict its
        > > possibilities.
        > >
        > > This is all from a vague understanding of xmlschema-1/ section 3.9.6,
        > > though.
        > > The multiple zip problem is still in effect, though; thus you wouldn't
        > > have two zip entries.
        > >
        > > For better understanding of where I'm coming from, take it as if zip
        > > were defined as ur-type, and string.
        > > Now, send in two normalized strings. Which zip maps to which field?
        > > <sequence> would say it's order dependant, right?
        > > Where do parent elements go in terms of extension?
        > >
        > > You might also look in xmlschema-1 section 2.2.1, where it talks about
        > > DataTypes.
        > >
        > > As far as OO goes, I don't think you can take an object that contains a
        > > String, and replace it with an int, and have any assumptions still hold
        > > up.
        > > Take this for an example:
        > >
        > > Address{
        > > String zip;
        > > String city;
        > > String country;
        > > }
        > >
        > > and
        > > USAddress :: Address {
        > > Int zip;
        > > }
        > >
        > > if I set the int on USAddress, and pass it into a function that looks
        > > for an Address, the String would be empty/null, which isn't what you're
        > > after.
        > >
        > > --Wes
        > >
        > >
      • Robert van Engelen
        Hi, ... Sorry, I am primarely looking for OO representations in SOAP and I think there are some problems that need to be addressed at the protocol level. Again
        Message 3 of 23 , Apr 3, 2002
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          Hi,

          > How do C# or Java come into the picture? I though you were
          > discussing the limitations of XML Schema... not C#

          Sorry, I am primarely looking for OO representations in SOAP and I think
          there are some problems that need to be addressed at the protocol level.

          Again sorry, I want to demonstrate this with Java (no preference).

          Let's define a Test program:

          import java.io.*;
          public class Test
          { public static void doit(Base b) throws IOException
          { b.print();
          }
          public static void main(String argv[]) throws IOException
          { Derived d = new Derived();
          doit(d);
          }
          }

          With Base and Derived classes:

          import java.io.*;
          public class Base
          { String zip;
          public Base()
          { zip = new String("hello");
          }
          public void print() throws IOException
          { System.out.print(zip);
          }
          public void show() throws IOException
          { System.out.print(zip);
          }
          }

          import java.io.*;
          public class Derived extends Base
          { int zip;
          public Derived()
          { zip = 3;
          }
          public void show() throws IOException
          { System.out.print(zip);
          }
          }

          When running the Test program, it will print "hello" which is the zip of Base.

          Now suppose that we implement 'doit' as a remote method. You see that it
          expects a Base class instance but we hand it a Derived class instance.

          The implementation will either:
          1. pre-convert the Derived class instance to a Base class at the sending side
          2. post-convert the Derived class instance to a Base class instance at the
          recieving side.

          #1 has the advantage that it will limit the data but the disadvantage is that
          an upgrade to the receiving server-side (to allow derived class instances)
          requires recompilation of the client.

          #2 has the advantage that the client does not have to be recompiled when the
          service is upgraded to accept derived instances.

          I recall (if correct) that SOAP 1.1 allowed for a scenario such as #2 which
          explains the fact that accessors can be ignored (unless MU=1).

          Even when you use #1, it may get you into trouble. Consider echoing a derived
          class instance:

          import java.io.*;
          public class Test
          { public static Base echo(Base b) throws IOException
          { return b;
          }
          public static void main(String argv[]) throws IOException
          { Derived d = new Derived();
          Base b;
          b = echo(d);
          b.show()
          }
          }

          This should print '3' instead of 'hello'.

          All I am saying is that SOAP and schema's don't seem to support these simple
          OO semantics for RMI.

          gSOAP does support it (using scenario #2) and I have an echo method example
          that works just like the above example. I am afraid that this is not
          interoperable and cannot be supported by SOAP/WSDL because of schema problems.

          Are there any other SOAP implementation out there that supports the above
          echo example?

          - Robert
        • Yann Christensen
          ... while XML schemas don t seem to be able to preserve basic OO semantics? From what I understand, in SOAP 1.2 the S, O, A, and P don t stand for anything.
          Message 4 of 23 , Apr 3, 2002
          • 0 Attachment
            > But don't you find it strange that the O in SOAP refers to Objects
            while XML schemas don't seem to be able to preserve basic OO semantics?

            From what I understand, in SOAP 1.2 the S, O, A, and P don't stand for
            anything.

            -----Original Message-----
            From: Robert van Engelen [mailto:engelen@...]
            Sent: Wednesday, April 03, 2002 11:07 AM
            To: soapbuilders@yahoogroups.com
            Subject: Re: [soapbuilders] Schema question


            Hi Wes,

            I see. But don't you find it strange that the O in SOAP refers to
            Objects
            while XML schemas don't seem to be able to preserve basic OO semantics?

            A restriction won't work as you pointed out because the zip field of the
            base
            is overwritten with a new definition for zip. Extension seems to be more
            natural. After all, we add new fields to a base class to get a derived
            class.

            Again, if this cannot be resolved in schemas/WSDL then SOAP will not be
            suitable for object exchange. The .NET guys must have a tremendous
            problem
            at their hands when they say that C# is competative to Java while Java
            preserves simple OO semantics while C# cannot? I would like to hear some
            more, especially from the .NET people :-)

            Wes Moulder wrote:
            >
            > ------=_NextPart_000_007B_01C1DB0D.2C1B77E0
            > Content-Type: text/plain;
            > charset="US-ASCII"
            > Content-Transfer-Encoding: 7bit
            >
            > Robert,
            > I believe it would have to be a restriction, not an extension, since
            > you're changing the behaviour of zip, and even then, I don't think
            > you're allowed to completely alter the type of data, just restrict its
            > possibilities.
            >
            > This is all from a vague understanding of xmlschema-1/ section 3.9.6,
            > though.
            > The multiple zip problem is still in effect, though; thus you wouldn't
            > have two zip entries.
            >
            > For better understanding of where I'm coming from, take it as if zip
            > were defined as ur-type, and string.
            > Now, send in two normalized strings. Which zip maps to which field?
            > <sequence> would say it's order dependant, right?
            > Where do parent elements go in terms of extension?
            >
            > You might also look in xmlschema-1 section 2.2.1, where it talks about
            > DataTypes.
            >
            > As far as OO goes, I don't think you can take an object that contains
            a
            > String, and replace it with an int, and have any assumptions still
            hold
            > up.
            > Take this for an example:
            >
            > Address{
            > String zip;
            > String city;
            > String country;
            > }
            >
            > and
            > USAddress :: Address {
            > Int zip;
            > }
            >
            > if I set the int on USAddress, and pass it into a function that looks
            > for an Address, the String would be empty/null, which isn't what
            you're
            > after.
            >
            > --Wes
            >
            >
            > -----Original Message-----
            > From: Robert van Engelen [mailto:engelen@...]
            > Sent: Wednesday, April 03, 2002 12:27 PM
            > To: soapbuilders@yahoogroups.com
            > Subject: Re: [soapbuilders] Schema question
            >
            >
            > Thanks!
            >
            > It is easy to overlook this kind of information in these long specs.
            >
            > One more question though: is the following legal?
            >
            > <complexType name="baseAddress">
            > <sequence>
            > <element name="city" type="xsd:string"/>
            > <element name="zip" type="xsd:string"/>
            > <element name="country" type="xsd:string"/>
            > </sequence>
            > </complexType>
            >
            > <complexType name="address">
            > <complexContent>
            > <extension base="tns:baseAddress">
            > <sequence>
            > <element name="zip" type="xsd:integer"/>
            > </sequence>
            > </extension>
            > </complexContent>
            > </complexType>
            >
            > If this is legal, is the resulting XML allowed to carry two zip
            elements
            > or
            > only one?
            >
            > I am asking this because:
            >
            > 1. gSOAP supports single inheritance. When communicating derived class
            > instances over SOAP also the base class members need to be present in
            > the
            > SOAP message (just like any OO implementation keeps base class
            > information
            > in the derived class instances).
            >
            > 2. The problem is that if schemas/WSDL disallows the above then SOAP
            is
            > not
            > suitable for OO! (or maybe it need to be accomplished with some
            tricks).
            >
            > - Robert
            >
            >
            >
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            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
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            10.0pt;font-family:Arial;color:navy'>Robert,<o:p></o:p></span></font></p
            >
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>I believe it would have to be a
            > restriction, not an extension, since you’re changing the
            behaviour of zip,
            > and even then, I don’t think you’re allowed to completely
            alter the
            > type of data, just restrict its
            possibilities.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>This is all from a vague
            understanding of
            > xmlschema-1/ section 3.9.6, though.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>The multiple zip problem is still
            in
            > effect, though; thus you wouldn’t have two zip
            entries.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>For better understanding of where
            I’m
            > coming from, take it as if zip were defined as ur-type, and
            string.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>Now, send in two normalized
            strings.<span
            > style='mso-spacerun:yes'>  </span>Which zip maps to which field?
            > <sequence> would say it’s order dependant, right?<span
            > style='mso-spacerun:yes'>  </span><o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>Where do parent elements go in
            terms of
            > extension?<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>You might also look in
            xmlschema-1 section
            > 2.2.1, where it talks about DataTypes.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>As far as OO goes, I don’t
            think you
            > can take an object that contains a String, and replace it with an int,
            and have
            > any assumptions still hold up.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>Take this for an
            example:<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'>Address{<o:p></o:p></span></font></
            p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'><span
            style='mso-spacerun:yes'> 
            > </span>String zip;<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'><span
            style='mso-spacerun:yes'> 
            > </span>String city;<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'><span
            style='mso-spacerun:yes'> 
            > </span>String country;<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>}<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>and <o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>USAddress :: Address
            {<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'><span
            style='mso-spacerun:yes'> 
            > </span>Int zip;<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>}<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            > 10.0pt;font-family:Arial;color:navy'>if I set the int on USAddress,
            and pass it
            > into a function that looks for an Address, the String would be
            empty/null,
            > which isn’t what you’re
            after.<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'>--Wes<o:p></o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal><font size=2 color=navy face=Arial><span
            style='font-size:
            >
            10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal style='margin-left:.5in'><font size=2
            face=Tahoma><span
            > style='font-size:10.0pt;font-family:Tahoma'>-----Original
            Message-----<br>
            > <b><span style='font-weight:bold'>From:</span></b> Robert van Engelen
            > [mailto:engelen@...] <br>
            > <b><span style='font-weight:bold'>Sent:</span></b>
            </span></font><st1:date
            > Month="4" Day="3" Year="2002"><font size=2 face=Tahoma><span
            style='font-size:
            > 10.0pt;font-family:Tahoma'>Wednesday, April 03,
            2002</span></font></st1:date><font
            > size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
            </span></font><st1:time
            > Hour="12" Minute="27"><font size=2 face=Tahoma><span
            style='font-size:10.0pt;
            > font-family:Tahoma'>12:27 PM</span></font></st1:time><font size=2
            face=Tahoma><span
            > style='font-size:10.0pt;font-family:Tahoma'><br>
            > <b><span style='font-weight:bold'>To:</span></b>
            soapbuilders@yahoogroups.com<br>
            > <b><span style='font-weight:bold'>Subject:</span></b> Re:
            [soapbuilders] Schema
            > question</span></font></p>
            >
            > <p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times
            New Roman"><span
            > style='font-size:12.0pt'><o:p> </o:p></span></font></p>
            >
            > <p class=MsoNormal style='margin-left:.5in'><font size=2 face="Courier
            New"><span
            > style='font-size:10.0pt;font-family:"Courier New"'><br>
            > <tt><font face="Courier New">Thanks!</font></tt><br>
            > <br>
            > <tt><font face="Courier New">It is easy to overlook this kind of
            information in
            > these long specs.</font></tt><br>
            > <br>
            > <tt><font face="Courier New">One more question though: is the
            following legal?</font></tt><br>
            > <br>
            > <tt><font face="Courier New"><complexType
            name="baseAddress"></font></tt><br>
            > <tt><font face="Courier New">  <sequence></font></tt><br>
            > <tt><font face="Courier New">    <element
            > name="city" type="xsd:string"/></font></tt><br>
            > <tt><font face="Courier New">    <element
            > name="zip" type="xsd:string"/></font></tt><br>
            > <tt><font face="Courier New">    <element
            > name="country"
            type="xsd:string"/></font></tt><br>
            > <tt><font face="Courier New">  </sequence></font></tt><br>
            > <tt><font face="Courier New"></complexType></font></tt><br>
            > <br>
            > <tt><font face="Courier New"><complexType
            name="address"></font></tt><br>
            > <tt><font face="Courier New"> 
            <complexContent></font></tt><br>
            > <tt><font face="Courier New">    <extension
            > base="tns:baseAddress"></font></tt><br>
            > <tt><font face="Courier New">     
            <sequence></font></tt><br>
            > <tt><font face="Courier
            New">       
            > <element name="zip"
            type="xsd:integer"/></font></tt><br>
            > <tt><font face="Courier New">     
            </sequence></font></tt><br>
            > <tt><font face="Courier New">   
            </extension></font></tt><br>
            > <tt><font face="Courier New"> 
            </complexContent></font></tt><br>
            > <tt><font face="Courier New"></complexType></font></tt><br>
            > <br>
            > <tt><font face="Courier New">If this is legal, is the resulting XML
            allowed to
            > carry two zip elements or</font></tt><br>
            > <tt><font face="Courier New">only one?</font></tt><br>
            > <br>
            > <tt><font face="Courier New">I am asking this because:</font></tt><br>
            > <br>
            > <tt><font face="Courier New">1. gSOAP supports single inheritance.
            When
            > communicating derived class</font></tt><br>
            > <tt><font face="Courier New">instances over SOAP also the base class
            members
            > need to be present in the</font></tt><br>
            > <tt><font face="Courier New">SOAP message (just like any OO
            implementation
            > keeps base class information</font></tt><br>
            > <tt><font face="Courier New">in the derived class
            instances).</font></tt><br>
            > <br>
            > <tt><font face="Courier New">2. The problem is that if schemas/WSDL
            disallows
            > the above then SOAP is not</font></tt><br>
            > <tt><font face="Courier New">suitable for OO! (or maybe it need to be
            > accomplished with some tricks).</font></tt><br>
            > <br>
            > <tt><font face="Courier New">- Robert</font></tt><br>
            > </span></font><br style='mso-special-character:line-break'>
            > <![if !supportLineBreakNewLine]><br
            style='mso-special-character:line-break'>
            > <![endif]><o:p></o:p></p>
            >
            > </span></font><tt><font size=2
            > face="Courier New"><span
            style='font-size:10.0pt'>-----------------------------------------------
            ------------------</span></font></tt><font
            > size=2 face="Courier New"><span
            style='font-size:10.0pt;font-family:"Courier New"'><br>
            > <tt><font face="Courier New">This group is a forum for builders of
            SOAP
            > implementations to discuss implementation and interoperability
            issues. 
            > Please stay on-topic.</font></tt><br>
            > <br>
            > <tt><font face="Courier New">To unsubscribe from this group, send an
            email to:</font></tt><br>
            > <tt><font face="Courier
            New">soapbuilders-unsubscribe@yahoogroups.com</font></tt><br>
            > <br>
            > </span></font><br>
            > <br>
            > <tt><font size=2 face="Courier New"><span
            style='font-size:10.0pt'>Your use of
            > Yahoo! Groups is subject to the <a
            href="http://docs.yahoo.com/info/terms/">Yahoo!
            > Terms of Service</a>.</span></font></tt> <o:p></o:p></p>
            >
            > </br></div>
            >
            >
            > <br>
            >
            > <!-- |**|begin egp html banner|**| -->
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            > -----------------------------------------------------------------<BR>
            > This group is a forum for builders of SOAP implementations to discuss
            implementation and interoperability issues.  Please stay
            on-topic.<BR>
            > <BR>
            > To unsubscribe from this group, send an email to:<BR>
            > soapbuilders-unsubscribe@yahoogroups.com<BR>
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            > <tt>Your use of Yahoo! Groups is subject to the <a
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            >
            > </body>
            >
            > </html>
            >
            > ------=_NextPart_000_007B_01C1DB0D.2C1B77E0--
            >


            --
            Robert van Engelen: Assistant Professor, Computer Science Department
            Florida State University, 206 J. Love Bldg., Tallahassee,
            FL32306-4530
            Offices: 162LOV/471DSL, (850)644-9661/645-0309, Fax: (850)644-0058
            Email: engelen@..., URL: http://www.cs.fsu.edu/~engelen


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          • Rich Salz
            The SOAP RPC encoding can send data (e.g., aliased pointers via href/id) that cannot be expressed in XML Schema. There is no requirement that WSDL use XML
            Message 5 of 23 , Apr 3, 2002
            • 0 Attachment
              The SOAP RPC encoding can send data (e.g., aliased pointers via href/id)
              that cannot be expressed in XML Schema. There is no requirement that
              WSDL use XML Schema, although it is the "preferred" (er, sorry,
              "canonical") data description.

              You could, e.g., define your own "types" extgension element that
              contained a URL to a Java interface, a Corba IDL file, etc.

              It would seem that since you want to use SOAP for things that cannot be
              expressed in XML Schema, then you shouldn't use XML Schema, and you
              needn't. :)
              /R$
            • Martin Gudgin
              No, for the same reason. The effective type definition for address is;
              Message 6 of 23 , Apr 3, 2002
              • 0 Attachment
                No, for the same reason. The effective type definition for address is;

                <complexType name="address">
                <sequence>
                <element name="city" type="xsd:string"/>
                <element name="zip" type="xsd:string"/>
                <element name="country" type="xsd:string"/>
                <element name="zip" type="xsd:integer"/>
                </sequence>
                </complexType>

                Martin


                ----- Original Message -----
                From: "Robert van Engelen" <engelen@...>
                To: <soapbuilders@yahoogroups.com>
                Sent: Wednesday, April 03, 2002 7:27 PM
                Subject: Re: [soapbuilders] Schema question


                >
                > Thanks!
                >
                > It is easy to overlook this kind of information in these long specs.
                >
                > One more question though: is the following legal?
                >
                > <complexType name="baseAddress">
                > <sequence>
                > <element name="city" type="xsd:string"/>
                > <element name="zip" type="xsd:string"/>
                > <element name="country" type="xsd:string"/>
                > </sequence>
                > </complexType>
                >
                > <complexType name="address">
                > <complexContent>
                > <extension base="tns:baseAddress">
                > <sequence>
                > <element name="zip" type="xsd:integer"/>
                > </sequence>
                > </extension>
                > </complexContent>
                > </complexType>
                >
                > If this is legal, is the resulting XML allowed to carry two zip elements
                or
                > only one?
                >
                > I am asking this because:
                >
                > 1. gSOAP supports single inheritance. When communicating derived class
                > instances over SOAP also the base class members need to be present in the
                > SOAP message (just like any OO implementation keeps base class information
                > in the derived class instances).
                >
                > 2. The problem is that if schemas/WSDL disallows the above then SOAP is
                not
                > suitable for OO! (or maybe it need to be accomplished with some tricks).
                >
                > - Robert
                >
                >
                > -----------------------------------------------------------------
                > This group is a forum for builders of SOAP implementations to discuss
                implementation and interoperability issues. Please stay on-topic.
                >
                > To unsubscribe from this group, send an email to:
                > soapbuilders-unsubscribe@yahoogroups.com
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >
              • Rosimildo daSIlva
                ... I agree. The programming languages are what they are. C#, Java, C++ and others have the constructs to build Classes, Inheritance, Polymorphism, etc.These
                Message 7 of 23 , Apr 3, 2002
                • 0 Attachment
                  >
                  > How do C# or Java come into the picture? I though
                  > you were
                  > discussing the limitations of XML Schema... not C#
                  >

                  I agree. The programming languages are what they are.
                  C#, Java, C++
                  and others have the constructs to build Classes,
                  Inheritance, Polymorphism, etc.These mechanisms are
                  very powerful.

                  At the same time, I understand where Robert is
                  coming from.

                  As has been debated before, XML-Schema and in some
                  extent SOAP/WSDL, are
                  very limited regarding modeling of systems using
                  techniques sich as Object
                  Orientation. The Schema limits you on how you define
                  "Messages" to be delivered
                  back and forth, and WSDL is very weak regarding
                  composition of end-points.

                  Assuming that one "portType", defines one interface.
                  It would be nice
                  to compose more complex interfaces ( portTypes ) using
                  inheritance:

                  interface SuperTV extends PublicTV, CableTV, DishTV
                  {


                  };

                  where: PublicTV --- described by public_tv.wsdl,
                  CableTV --- described by cable_tv.wsdl,
                  DiskTV --- described by dish_tv.wsdl

                  Now this service, super_tv.wsdl is higher level
                  service that using composition
                  provide a more sophisticated service that wants
                  simplicity for a fee. <g>

                  This is very basic, and still missing in WSDL/SOAP.
                  Imagine things
                  like Security, Session Managment, QoS, etc.

                  Rosimildo.



                  __________________________________________________
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                  Yahoo! Tax Center - online filing with TurboTax
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                • david_cleary
                  ... Since I haven t seen a reply that tells you how to code this, here it goes. Use a union type. Here is the syntax using an anonyomous type decl and requires
                  Message 8 of 23 , Apr 4, 2002
                  • 0 Attachment
                    --- In soapbuilders@y..., Robert van Engelen <engelen@a...> wrote:
                    >
                    > Hi,
                    >
                    > I have a question with regard to the validity of the following
                    schema:
                    >
                    > <complexType name="address">
                    > <sequence>
                    > <element name="city" type="xsd:string"/>
                    > <element name="zip" type="xsd:string"/>
                    > <element name="zip" type="xsd:integer"/>
                    > <element name="country" type="xsd:string"/>
                    > </sequence>
                    > </complexType>

                    Since I haven't seen a reply that tells you how to code this, here it
                    goes. Use a union type. Here is the syntax using an anonyomous type
                    decl and requires both to be present.

                    <xs:element name="zip" minOccurs="2" maxOccurs="2">
                    <xs:simpleType>
                    <xs:union memberTypes="xs:int xs:string"/>
                    </xs:simpleType>
                    </xs:element>

                    You need to use xsi:type in the instance if the datatype can't be
                    determined by the data.

                    David Cleary
                    Progress Software
                  • Noah Mendelsohn/Cambridge/IBM
                    ... No, but the reason is either subtle (or pretty) as you prefer. Gudge has already pointed out that [1]: When two or more particles contained directly or
                    Message 9 of 23 , Apr 4, 2002
                    • 0 Attachment
                      Rob van Engelen asks:

                      >> One more question though: is the following legal?

                      >> <complexType name="baseAddress">
                      >> <sequence>
                      >> <element name="city" type="xsd:string"/>
                      >> <element name="zip" type="xsd:string"/>
                      >> <element name="country" type="xsd:string"/>
                      >> </sequence>
                      >> </complexType>
                      >>
                      >> <complexType name="address">
                      >> <complexContent>
                      >> <extension base="tns:baseAddress">
                      >> <sequence>
                      >> <element name="zip" type="xsd:integer"/>
                      >> </sequence>
                      >> </extension>
                      >> </complexContent>
                      >> </complexType>

                      No, but the reason is either subtle (or pretty) as you prefer. Gudge has
                      already pointed out that [1]:

                      'When two or more particles contained directly or indirectly in the
                      {particles} of a model group have identically named element declarations
                      as
                      their {term}, the type definitions of those declarations must be the
                      same.'

                      If you read [2] you will find out that when <extension> is used in a
                      schema document, the derived type has a {term} (essentially a particle)
                      which is the net content model. In your case, a sequence of city,zip,
                      country, zip (actually, I think it's
                      sequence(sequence(city,zip,country),zip)). This model group violates the
                      rule cited by Gudge. Hence, invalid.

                      Actually, if you are a real schema guru, you will note that this only
                      covers the common case in which you used the <schema> syntax to declare
                      your schema. The general case is covered at [3], combined with [1]. It
                      states:

                      "[Definition:] For a particle (call it E, for extension) to be a valid
                      extension of another particle (call it B, for base) one of the following
                      must be true:
                      1 They are the same particle.
                      2 E's {min occurs}={max occurs}=1 and its {term} is a sequence group whose
                      {particles}' first member is a particle all of whose properties,
                      recursively, are identical to those of B, with the exception of
                      {annotation} properties. "

                      In other words, the constructs from the base type appear in the same
                      particle of as the derived, and hence are subject to the rule cited by
                      Gudge.

                      In short, this example is clearly invalid, IMO at least.

                      [1] http://www.w3.org/TR/xmlschema-1/#Model_Group_details
                      [2] http://www.w3.org/TR/xmlschema-1/#declare-type
                      [3] http://www.w3.org/TR/xmlschema-1/#cos-particle-extend

                      ------------------------------------------------------------------
                      Noah Mendelsohn Voice: 1-617-693-4036
                      IBM Corporation Fax: 1-617-693-8676
                      One Rogers Street
                      Cambridge, MA 02142
                      ------------------------------------------------------------------







                      Robert van Engelen <engelen@...>
                      04/03/02 01:27 PM
                      Please respond to soapbuilders


                      To: soapbuilders@yahoogroups.com
                      cc: (bcc: Noah Mendelsohn/Cambridge/IBM)
                      Subject: Re: [soapbuilders] Schema question


                      Thanks!

                      It is easy to overlook this kind of information in these long specs.

                      One more question though: is the following legal?

                      <complexType name="baseAddress">
                      <sequence>
                      <element name="city" type="xsd:string"/>
                      <element name="zip" type="xsd:string"/>
                      <element name="country" type="xsd:string"/>
                      </sequence>
                      </complexType>

                      <complexType name="address">
                      <complexContent>
                      <extension base="tns:baseAddress">
                      <sequence>
                      <element name="zip" type="xsd:integer"/>
                      </sequence>
                      </extension>
                      </complexContent>
                      </complexType>

                      If this is legal, is the resulting XML allowed to carry two zip elements
                      or
                      only one?

                      I am asking this because:

                      1. gSOAP supports single inheritance. When communicating derived class
                      instances over SOAP also the base class members need to be present in the
                      SOAP message (just like any OO implementation keeps base class information
                      in the derived class instances).

                      2. The problem is that if schemas/WSDL disallows the above then SOAP is
                      not
                      suitable for OO! (or maybe it need to be accomplished with some tricks).

                      - Robert


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                      implementation and interoperability issues. Please stay on-topic.

                      To unsubscribe from this group, send an email to:
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                    • Rosimildo daSIlva
                      ... I am glad that there are people around here with that qualifications. Everytime I get close to the XML Schema spec, I feel sorry for myself, and I feel
                      Message 10 of 23 , Apr 4, 2002
                      • 0 Attachment
                        <noah_mendelsohn@...> wrote:
                        > Rob van Engelen asks:
                        >
                        > Actually, if you are a real schema guru, you will
                        > note that this only
                        > covers the common case in which you used the
                        > <schema> syntax to declare
                        > your schema. The general case is covered at [3],
                        > combined with [1]. It
                        > states:
                        >

                        I am glad that there are people around here with that
                        qualifications. <g>

                        Everytime I get close to the XML Schema spec, I feel
                        sorry for myself, and I feel so "small" thinking to
                        myself that I need the next 10 years to really
                        understand it.

                        Rosimildo.



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                      • Robert van Engelen
                        Noah, Thanks. Your comments are highly appreciated. Based on this I can conclude that the extension mechanism is not suitable to implement the usual OO base
                        Message 11 of 23 , Apr 4, 2002
                        • 0 Attachment
                          Noah,

                          Thanks. Your comments are highly appreciated.

                          Based on this I can conclude that the extension mechanism is not suitable
                          to implement the usual OO base class overriding semantics. Which means that
                          a derived class (in the OO sense) must be represented with a schema
                          that is separate from the base class schema. E.g. to represent the base
                          class zip with the derived class zip I have to use a <union>. The unfortunate
                          consequence is that the base class <-> derived class information is completely
                          lost in the process and can't be retained in a WSDL document. One can argue
                          that the OO hierarchies have nothing in common with XML schemas. However,
                          since SOAP utilizes WSDL for declaring the necessary data types for RPC,
                          the OO hierarchy may be exploited by SOAP-enabled applications that have to
                          deal with object exchange. It appears that the two cannot be mixed, which is
                          unfortunate for SOAP. For example, when I declare a remote procedure in WSDL
                          with a parameter of a base type, then the procedure can never accept a derived
                          type (with additional elements) because of validation violations. A solution
                          is to write overloaded procedure definitions, one for each class. Is that a
                          recommended solution?

                          Question: Can <union> be used to refer to any schema type or only to primitive
                          schema types?

                          - Robert
                        • graham glass
                          hi robert, there is another way to look at this which i think is more useful. you *can* pass a derived schema type to a method which accepts a base schema type
                          Message 12 of 23 , Apr 4, 2002
                          • 0 Attachment
                            hi robert,
                             
                            there is another way to look at this which i think is more useful.
                             
                            you *can* pass a derived schema type to a method which accepts
                            a base schema type as long as the derived type doesn't contain
                            a field name which is a duplicate of the base name.
                             
                            i bet that 99% of the derived classes don't contain field names
                            that override those of their base classes, so this approach (with
                            a noted restriction) seems pragmatic.
                             
                            this is the kind of functionality that GLUE and many other SOAP
                            platforms support.
                             
                            cheers,
                            graham
                            -----Original Message-----
                            From: Robert van Engelen [mailto:engelen@...]
                            Sent: Thursday, April 04, 2002 4:31 PM
                            To: soapbuilders@yahoogroups.com
                            Subject: Re: [soapbuilders] Schema question


                            Noah,

                            Thanks. Your comments are highly appreciated.

                            Based on this I can conclude that the extension mechanism is not suitable
                            to implement the usual OO base class overriding semantics. Which means that
                            a derived class (in the OO sense) must be represented with a schema
                            that is separate from the base class schema. E.g. to represent the base
                            class zip with the derived class zip I have to use a <union>. The unfortunate
                            consequence is that the base class <-> derived class information is completely
                            lost in the process and can't be retained in a WSDL document. One can argue
                            that the OO hierarchies have nothing in common with XML schemas. However,
                            since SOAP utilizes WSDL for declaring the necessary data types for RPC,
                            the OO hierarchy may be exploited by SOAP-enabled applications that have to
                            deal with object exchange. It appears that the two cannot be mixed, which is
                            unfortunate for SOAP. For example, when I declare a remote procedure in WSDL
                            with a parameter of a base type, then the procedure can never accept a derived
                            type (with additional elements) because of validation violations. A solution
                            is to write overloaded procedure definitions, one for each class. Is that a
                            recommended solution?

                            Question: Can <union> be used to refer to any schema type or only to primitive
                            schema types?

                            - Robert


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                          • Noah Mendelsohn/Cambridge/IBM
                            Exactly the answer I would have given. Schema s type system is at best an 80/20 as a basis for representing this or that existing object system. First of all,
                            Message 13 of 23 , Apr 5, 2002
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                              Exactly the answer I would have given. Schema's type system is at best an
                              80/20 as a basis for representing this or that existing object system.
                              First of all, most programming languages emphasize inheritance of methods
                              rather than data (though there is no-doubt data inheritance going on as
                              well, but in many uses of OO only the methods are made public or protected
                              and are thus part of the overt interface contract.) Anyway, another
                              glaring hole is that schema makes no attempt at multiple inheritance (a
                              conscious keep it simple compromise.) Covering redefinition of a
                              like-named member property is probably below multiple-inheritance in terms
                              of the number of users who have screamed that they can't effectively
                              mapped to our system.

                              ------------------------------------------------------------------
                              Noah Mendelsohn Voice: 1-617-693-4036
                              IBM Corporation Fax: 1-617-693-8676
                              One Rogers Street
                              Cambridge, MA 02142
                              ------------------------------------------------------------------







                              "graham glass" <graham@...>
                              04/05/02 02:33 AM
                              Please respond to soapbuilders


                              To: <soapbuilders@yahoogroups.com>
                              cc: (bcc: Noah Mendelsohn/Cambridge/IBM)
                              Subject: RE: [soapbuilders] Schema question

                              hi robert,

                              there is another way to look at this which i think is more useful.

                              you *can* pass a derived schema type to a method which accepts
                              a base schema type as long as the derived type doesn't contain
                              a field name which is a duplicate of the base name.

                              i bet that 99% of the derived classes don't contain field names
                              that override those of their base classes, so this approach (with
                              a noted restriction) seems pragmatic.

                              this is the kind of functionality that GLUE and many other SOAP
                              platforms support.

                              cheers,
                              graham
                              -----Original Message-----
                              From: Robert van Engelen [mailto:engelen@...]
                              Sent: Thursday, April 04, 2002 4:31 PM
                              To: soapbuilders@yahoogroups.com
                              Subject: Re: [soapbuilders] Schema question


                              Noah,

                              Thanks. Your comments are highly appreciated.

                              Based on this I can conclude that the extension mechanism is not suitable
                              to implement the usual OO base class overriding semantics. Which means
                              that
                              a derived class (in the OO sense) must be represented with a schema
                              that is separate from the base class schema. E.g. to represent the base
                              class zip with the derived class zip I have to use a <union>. The
                              unfortunate
                              consequence is that the base class <-> derived class information is
                              completely
                              lost in the process and can't be retained in a WSDL document. One can
                              argue
                              that the OO hierarchies have nothing in common with XML schemas. However,
                              since SOAP utilizes WSDL for declaring the necessary data types for RPC,
                              the OO hierarchy may be exploited by SOAP-enabled applications that have
                              to
                              deal with object exchange. It appears that the two cannot be mixed, which
                              is
                              unfortunate for SOAP. For example, when I declare a remote procedure in
                              WSDL
                              with a parameter of a base type, then the procedure can never accept a
                              derived
                              type (with additional elements) because of validation violations. A
                              solution
                              is to write overloaded procedure definitions, one for each class. Is that
                              a
                              recommended solution?

                              Question: Can <union> be used to refer to any schema type or only to
                              primitive
                              schema types?

                              - Robert


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                              implementation and interoperability issues. Please stay on-topic.

                              To unsubscribe from this group, send an email to:
                              soapbuilders-unsubscribe@yahoogroups.com



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                            • Robert van Engelen
                              Noah and Graham, Thanks! Please allow me to elaborate on this a little further for sake of clarity and usefulness to the SOAP interop community after which (I
                              Message 14 of 23 , Apr 5, 2002
                              • 0 Attachment
                                Noah and Graham,

                                Thanks!

                                Please allow me to elaborate on this a little further for sake of clarity
                                and usefulness to the SOAP interop community after which (I hope) this
                                issue can be closed.

                                gSOAP does support single inheritance and allows a derived class to be passed
                                to a method that accepts a base class.

                                However, to generate valid WSDL schemas for the 1% of code that does in fact
                                override base class fields needs some tweaking by renaming derived class fields
                                (in the language domain) to unique element names (in the schema domain).
                                I was just concerned that this renaming might break interoperability
                                between OO-based SOAP implementations (whatever that means) and I am very
                                interested to hear how other SOAP implementations handle this. [Note that gSOAP
                                has a fully automatic mapping from C/C++ data types to SOAP data types.]

                                As a general solution, a field 'F' of a derived class 'D' can be renamed to an
                                element '<D.F>' in case 'F' is a field in a base class. Any WSDL importer will
                                just use this (unique) element and doesn't need to be concerned about
                                overriding issues.

                                When gSOAP would import such as schema though, gSOAP could in fact declare a
                                derived class with field 'F' to recreate the (language-specific) OO hierarchy
                                with member overriding.

                                Interestingly enough, this approach allows for both OO implementations and
                                non-OO implementations to cope with schemas derived by extension. Maybe
                                I am reinventing the wheel here?

                                - Cheers, Robert
                              • Noah Mendelsohn/Cambridge/IBM
                                Thanks. I would have thought there were other potential member name issues. For example, if your programming language allows variable names to have
                                Message 15 of 23 , Apr 5, 2002
                                • 0 Attachment
                                  Thanks. I would have thought there were other potential member name
                                  issues. For example, if your programming language allows variable names
                                  to have characters that are not XML Name characters. In general, I would
                                  expect that for real interop of some particular inheritance model, someone
                                  would have to write a specification saying: "here's how we map member
                                  names that aren't legal XML names, here is how we rename members in the
                                  1% of cases where a derived class does an incompatible override of a base,
                                  etc."

                                  ------------------------------------------------------------------
                                  Noah Mendelsohn Voice: 1-617-693-4036
                                  IBM Corporation Fax: 1-617-693-8676
                                  One Rogers Street
                                  Cambridge, MA 02142
                                  ------------------------------------------------------------------







                                  Robert van Engelen <engelen@...>
                                  04/05/02 11:40 AM
                                  Please respond to soapbuilders


                                  To: soapbuilders@yahoogroups.com
                                  cc: (bcc: Noah Mendelsohn/Cambridge/IBM)
                                  Subject: Re: [soapbuilders] Schema question


                                  Noah and Graham,

                                  Thanks!

                                  Please allow me to elaborate on this a little further for sake of clarity
                                  and usefulness to the SOAP interop community after which (I hope) this
                                  issue can be closed.

                                  gSOAP does support single inheritance and allows a derived class to be
                                  passed
                                  to a method that accepts a base class.

                                  However, to generate valid WSDL schemas for the 1% of code that does in
                                  fact
                                  override base class fields needs some tweaking by renaming derived class
                                  fields
                                  (in the language domain) to unique element names (in the schema domain).
                                  I was just concerned that this renaming might break interoperability
                                  between OO-based SOAP implementations (whatever that means) and I am very
                                  interested to hear how other SOAP implementations handle this. [Note that
                                  gSOAP
                                  has a fully automatic mapping from C/C++ data types to SOAP data types.]

                                  As a general solution, a field 'F' of a derived class 'D' can be renamed
                                  to an
                                  element '<D.F>' in case 'F' is a field in a base class. Any WSDL importer
                                  will
                                  just use this (unique) element and doesn't need to be concerned about
                                  overriding issues.

                                  When gSOAP would import such as schema though, gSOAP could in fact declare
                                  a
                                  derived class with field 'F' to recreate the (language-specific) OO
                                  hierarchy
                                  with member overriding.

                                  Interestingly enough, this approach allows for both OO implementations and
                                  non-OO implementations to cope with schemas derived by extension. Maybe
                                  I am reinventing the wheel here?

                                  - Cheers, Robert


                                  -----------------------------------------------------------------
                                  This group is a forum for builders of SOAP implementations to discuss
                                  implementation and interoperability issues. Please stay on-topic.

                                  To unsubscribe from this group, send an email to:
                                  soapbuilders-unsubscribe@yahoogroups.com



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                                • Robert van Engelen
                                  ... That s an accurate observation. I came up with conventions for special characters. For example, element maps to ns2__x_DOT_y_z, assuming that
                                  Message 16 of 23 , Apr 8, 2002
                                  • 0 Attachment
                                    > Thanks. I would have thought there were other potential member name
                                    > issues. For example, if your programming language allows variable names
                                    > to have characters that are not XML Name characters. In general, I would

                                    That's an accurate observation. I came up with conventions for special
                                    characters. For example, element <ns1:x.y-z> maps to ns2__x_DOT_y_z,
                                    assuming that ns1 refers to the same namespace URI as ns2 (light validation).

                                    This way, I can map

                                    class ns__X
                                    { int n;
                                    };
                                    class ns__Y:ns__X
                                    { int n;
                                    int m;
                                    };

                                    to

                                    <?xml version="1.0" encoding="UTF-8"?>
                                    <schema
                                    xmlns="http://www.w3.org/2001/XMLSchema"
                                    xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
                                    xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
                                    targetNamespace="XXXXX"
                                    xmlns:ns="XXXXX">
                                    <complexType name="X">
                                    <sequence>
                                    <element name="n" type="xsd:int" minOccurs="0" maxOccurs="1"/>
                                    </sequence>
                                    </complexType>
                                    <complexType name="Y">
                                    <complexContent>
                                    <extension base="ns:X">
                                    <sequence>
                                    <element name="ns:Y.n" type="xsd:int" minOccurs="0" maxOccurs="1"/>
                                    <element name="m" type="xsd:int" minOccurs="0" maxOccurs="1"/>
                                    </sequence>
                                    </extension>
                                    </complexContent>
                                    </complexType>
                                    </schema>

                                    and vice-versa. I made a change to my schema generator to accomodate
                                    overriding. Is the use of the element name="ns:Y.n" valid in this case?

                                    - Robert
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