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the global <CODE>ArrayList</CODE> of Registration records returned
by the <CODE>RegistrationServer</CODE> object and 
notifies the <CODE>SellerBean/auditAccounts</CODE> method that it can return 
that <CODE>ArrayList</CODE> of Registration records to the <CODE>AuctionServlet</CODE>.

<PRE>
  public void updateResults(Registration[] ar) 
	throws registration.FinderException {
    if(ar == null) {
          throw new registration.FinderException();
    }
    try{
      for(int i=0; i&lt; ar.length; i++) {
        returned.add(ar[i]);
      }
    }catch (Exception e) {
     System.out.println("updateResults="+e);
     throw new registration.FinderException();
    }
     synchronized(ready) {
     ready.notifyAll();
    }
  }
</PRE>

<A NAME="any"></A>
<H3>Using the Any type</H3>

The <CODE>RegistrationServer.customSearch</CODE> method uses the IDL 
<CODE>Any</CODE> type to pass in and return results.
The <CODE>customSearch</CODE> is called by the <CODE>AuctionServlet</CODE>
as follows:

<PRE>
  http://localhost.eng.sun.com:7001/
     AuctionServlet?action=customSearch&amp;searchfield=2
</PRE>

The <CODE>searchfield</CODE> parameter can be set to a number or a string.
The <CODE>AuctionServlet.customFind</CODE> method passes the search field 
directly to the <CODE>SellerBean.customFind</CODE> method and
retrieves a <CODE>String</CODE> that is then displayed to the user.

<PRE>
  private void customSearch(ServletOutputStream out,
               HttpServletRequest request) 
               throws IOException{

    String text = "Custom Search";
    String searchField=request.getParameter(
                                 "searchfield");

    setTitle(out, "Custom Search");
    if(searchField == null ) {
      addLine("Error: SearchField was empty", out);
      out.flush();
      return;
    }
    try{
      addLine("&lt;BR&gt;"+text, out);
      SellerHome home = (SellerHome) 
                           ctx.lookup("seller");
      Seller si= home.create();
      if(si != null) {
        String displayMessage=si.customFind(
                                   searchField);
        if(displayMessage != null ) {
          addLine(displayMessage+"&lt;BR&gt;", out);
        }
      }
    }catch (Exception e) {
     addLine("AuctionServlet customFind error",out);
     System.out.println("AuctionServlet " + 
                        "&lt;customFind&gt;:"+e);
    }
    out.flush();
  }
</PRE>

The <CODE>SellerBean.customFind</CODE> method calls the <CODE>RegistrationHome</CODE>
object implemented in the <CODE>RegistrationServer.java</CODE> class, and depending
on whether the <CODE>searchField</CODE> can be converted into a double or a string,
inserts this value into an object of type <CODE>Any</CODE>. The <CODE>Any</CODE>
object is created by a call to the ORB, <CODE>orb.create_any();</CODE>

<P>
The <CODE>customFind</CODE> method also uses an <CODE>out</CODE> parameter, 
<CODE>count</CODE>, of type <CODE>int</CODE> that returns the number of records 
found.  The value of <CODE>count</CODE> is retrieved using <CODE>count.value</CODE>
when the call returns.

<PRE>
//SellerBean.java
  public String customFind(String searchField) 
	   throws javax.ejb.FinderException, 
	   RemoteException{

  int total=-1;
  IntHolder count= new IntHolder();

  try{
      NameComponent[] fullname = new NameComponent[2];
      fullname[0] = new NameComponent("auction", "");
      fullname[1] = new NameComponent(
                          "RegistrationBean", "");

      RegistrationHome regRef = 
        RegistrationHomeHelper.narrow(
                            nctx.resolve(fullname));
      if(regRef == null ) {
        System.out.println(
                     "cannot contact RegistrationHome");
        throw new javax.ejb.FinderException();
      }
      Any sfield=orb.create_any();
      Double balance;
      try{
        balance=Double.valueOf(searchField);
        try {
            sfield.insert_double(balance.doubleValue());
        }catch (Exception e) {
         return("Problem with search value"+balance);
        }
       sfield=regRef.customSearch(sfield,count);
       if(sfield != null ) {
         total=sfield.extract_long();
       }
       return(total+" 
	accounts are below optimal level from" +
	count.value+" records");
     }catch (NumberFormatException e) {
      sfield.insert_string(searchField);
      Registration reg;
      if((reg=RegistrationHelper.extract(
	  	regRef.customSearch(
	  	         sfield,count))) 
	  	         != null ) {
        return("Found user "+reg.getUser() +" 
		who has email address "+
		reg.getEmailAddress());
      }else {
       return("No users found who have email address " +
		searchField);
      }
     }
    }catch(Exception e){
        System.out.println("customFind problem="+e);
        throw new javax.ejb.FinderException();
    }
  }
</PRE>

The return value from the call to <CODE>customFind</CODE> is extracted
into an object of type <CODE>Any</CODE> and a <CODE>String</CODE> is constructed 
with the output displayed to the user. For simple types, the 
<CODE>extract_&lt;type&gt;</CODE> method of the <CODE>Any</CODE> object can be used. 
However, for the <CODE>Registration</CODE> type, the <CODE>RegistrationHelper</CODE> 
class is used.

<PRE>
  Registration reg =
    RegistrationHelper.extract(
                 regRef.customSearch(sfield,count))
</PRE>

The <CODE>RegistrationServer.customSearch</CODE> method determines the
type of Object being passed in the <CODE>searchField</CODE> parameter
by checking the <CODE>.type().kind().value()</CODE> of the <CODE>Any</CODE>
object.

<PRE>
 if(searchField.type().kind().value() == 
                         TCKind._tk_double)
</PRE>

Finally, because the <CODE>customSearch</CODE> method returns an object of
type <CODE>Any</CODE>, a call to <CODE>orb.create_any()</CODE> is required. 
For simple types like <CODE>double</CODE>, the <CODE>insert_&lt;type&gt;</CODE> method 
is used. For a Registration record, the <CODE>RegistrationHelper</CODE> class is 
used: <CODE>RegistrationHelper.insert(returnResults, regarray[0])</CODE>.

<PRE>
//RegistrationServer.java
  public Any customSearch(Any searchField, 
                          IntHolder count){
    Any returnResults= orb.create_any();

    int tmpcount=count.value;
    if(searchField.type().kind().value() == 
                          TCKind._tk_double){
// return number of balances greater 
// than supplied amount
      double findBalance=searchField.extract_double();
      Connection con = null;
      ResultSet rs = null;
      PreparedStatement ps = null;
      try{
        con=getConnection();
        ps=con.prepareStatement("select count(*) from 
                      registration where balance &lt; ?");
        ps.setDouble(1, findBalance);
        ps.executeQuery();
        rs = ps.getResultSet();
        if(rs.next()) {
          tmpcount = rs.getInt(1);
        }
        count.value=tmpcount;
        rs.close();
       }catch (Exception e) {
                 System.out.println("custom search: "+e);
                 returnResults.insert_long(-1);
                 return(returnResults);
       }
       finally {
         try{
           if(rs != null) { rs.close(); }
           if(ps != null) { ps.close(); }
           if(con != null) { con.close(); }
         } catch (Exception ignore) {}
       }
         returnResults.insert_long(tmpcount);
         return(returnResults);
     }else if(searchField.type().kind().value() == 
		TCKind._tk_string) {
      // return email addresses that match supplied address
      String findEmail=searchField.extract_string();
      Connection con = null;
      ResultSet rs = null;
      PreparedStatement ps = null;
      ArrayList ar = new ArrayList();
      RegistrationImpl reg=null;
      try{
        con=getConnection();
        ps=con.prepareStatement("select theuser, 
           emailaddress from registration 
	   where emailaddress like ?");
        ps.setString(1, findEmail);
        ps.executeQuery();
        rs = ps.getResultSet();
        while (rs.next()) {
          reg= new RegistrationImpl();
          reg.theuser = rs.getString(1);
          reg.emailaddress = rs.getString(2);
          ar.add(reg);
        }
        rs.close();

        RegistrationImpl[] regarray = 
             (RegistrationImpl [])ar.toArray(
	     new RegistrationImpl[0]);
          RegistrationHelper.insert(
                               returnResults, 
                               regarray[0]);
          return(returnResults);
       }catch (Exception e) {
        System.out.println("custom search: "+e);
        return(returnResults);
       }
       finally {
        try{
          if(rs != null) { rs.close(); }
          if(ps != null) { ps.close(); }
          if(con != null) { con.close(); }
        } catch (Exception ignore) {}
      }
    }
    return(returnResults);
  }
</PRE>

<A NAME="conclude"></A>
<H3>Conclusion</H3>

As you can see, converting the application to use RMI or CORBA requires
very little change to core programs. The main difference has been the
initialization and naming service. By abstracting these two areas in your
application away from the business logic you ease migration between different
distributed object architectures.

<P>
_______<BR>
<A NAME="TJVM"><SUP>1</SUP></A> As used on this web site, 
the terms &quot;Java virtual 
machine&quot; or &quot;JVM&quot; mean a virtual machine 
for the Java platform.

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