From .Net DataTable to Java which object?

[Timothy Sam]

I don't know C#/.Net but the C# code I want to communicate with returns a DataTable. I'm thinking ResultSet but I'm not sure... Does anybody here have a clue as to which reference type I should set the call to? Thanks!

[Peer Reynders]

Originally posted by Timothy Sam:
Does anybody here have a clue as to which reference type I should set the call to?

There isn't one. Non-.NET platforms have no clue what a DataTable is. Visual Studio generates a new XML schema for each DataTable type exposed through a Web Service. Which basically means that a non-.NET client has to pull the relevant information out of that incomprehensible mess. You can try to run a WSDL2Java tool on the published WSDL to see if you can make any sense of it.

Ideally the web service should translate the objects to an XML representation that its consistent with its business domain and not let any of the object implementation model leak through.

Web services exchange XML messages (which are hierarchal), not objects (which are object-oriented). Have a look at Tech Talk: Ted Neward on Web Services and Security

Start from your code, just sprinkle some web service magic pixie dust on it and lo and behold you have a web service, bad things, bad, bad, bad, bad. I need to beat the vendors over the head to stop doing that, to instead make tools, build tools that want to look at and see and recognize that (A) this is a message and (B) it�s in XML because wanting to take your code and seamlessly turning it into objects and back again, we�ve already talked about that. That�s just not going to work. It�s not going to happen. Once we beat the vendors into line, then it�s going out to the development community and saying, �Okay, here we have tools that support the idea of looking at this from a message oriented perspective, don�t fight that, don�t try to build RPC scenarios out of this messaging oriented approach�.

[Timothy Sam]

Hmmm... I think that got me a little more confused there... Does this mean I have to parse manually?

[Peer Reynders]

Not necessarily. The first step is to design the Web services interface - i.e. WSDL (which you can create manually or with some sort of tool(like XMLSpy)). Then on the .NET side you can use Visual Studio to create the server stub from the WSDL. Then you write the glue code to move the data between your .NET object implementation model and the server stub. On the Java side you can use a WSDL2Java tool to create a client stub - then you write the glue code to move the data between the stub and the Java object implementation model.

Now in some more complicated cases some additional help is useful. There is Web Services Contract First on the .NET side. On the Java side JAXB is handy to transform your Java objects to and from XML - there is a lot of flexibility in the transformation process which is controlled through configuration.

[Timothy Sam]

Hi! Thanks for your effort to answer. I've generated some Java code using the WSDL2Java tool. However, an Exception is appearing now...

java.io.FileNotFoundException: C:\Program Files\netbeans-5.5\enterprise3\apache-tomcat-5.5.17\bin\org.tempuri.TimServiceSoapStub@fe0ce1 (The system cannot find the file specified)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:106)
at java.io.FileInputStream.<init>(FileInputStream.java:66)
at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:70)
at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:161)
at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
at org.apache.xerces.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.DOMParser.parse(Unknown Source)
at org.apache.xerces.jaxp.DocumentBuilderImpl.parse(Unknown Source)
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:180)
at com.wp.wpinventory.controller.FixedItemController.getEmployeeIds(FixedItemController.java:303)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.faces.el.PropertyResolverImpl.getValue(PropertyResolverImpl.java:79)
at com.sun.faces.el.impl.ArraySuffix.evaluate(ArraySuffix.java:167)
at com.sun.faces.el.impl.ComplexValue.evaluate(ComplexValue.java:151)
at com.sun.faces.el.impl.ExpressionEvaluatorImpl.evaluate(ExpressionEvaluatorImpl.java:243)
at com.sun.faces.el.ValueBindingImpl.getValue(ValueBindingImpl.java:173)
at com.sun.faces.el.ValueBindingImpl.getValue(ValueBindingImpl.java:154)
at javax.faces.component.UISelectItems.getValue(UISelectItems.java:110)
at com.sun.faces.util.Util.getSelectItems(Util.java:600)
at com.sun.faces.renderkit.html_basic.MenuRenderer.getOptionNumber(MenuRenderer.java:488)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderSelect(MenuRenderer.java:465)
at com.sun.faces.renderkit.html_basic.MenuRenderer.encodeEnd(MenuRenderer.java:430)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:720)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:443)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:233)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:701)
at javax.faces.webapp.UIComponentTag.encodeChildren(UIComponentTag.java:607)
at javax.faces.webapp.UIComponentTag.doEndTag(UIComponentTag.java:544)
at com.sun.faces.taglib.html_basic.PanelGridTag.doEndTag(PanelGridTag.java:460)
at org.apache.jsp.fixedItem.New_jsp._jspx_meth_h_panelGrid_0(New_jsp.java:369)
at org.apache.jsp.fixedItem.New_jsp._jspx_meth_h_form_0(New_jsp.java:195)
at org.apache.jsp.fixedItem.New_jsp._jspx_meth_f_view_0(New_jsp.java:143)
at org.apache.jsp.fixedItem.New_jsp._jspService(New_jsp.java:103)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
at com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:322)
at com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:130)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:87)
at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:619)

This is the code that generates the exception:

        public javax.faces.model.SelectItem[] getEmployeeIds()
        {
            SelectItem[] select = null;
            
            System.out.println("Accessing service...");
            
            try
            {
                TimService locator = new TimServiceLocator();
                TimServiceSoap soapResponse = locator.getTimServiceSoap();
                
                DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                DocumentBuilder docBuilder = dbf.newDocumentBuilder();
                Document document1 = docBuilder.newDocument();
                
                ListEmployeesResponseListEmployeesResult listEmployeeResult = soapResponse.listEmployees();
                
                Document document2 = docBuilder.parse( soapResponse.toString() );
                
                NodeList empNodeList = document2.getElementsByTagName("Employees");
                
                List<Employee> employeeList = new ArrayList<Employee>();
                
                Node node = null;
                NodeList childNodes = null;
                Employee employee = null;
              
                System.out.println("Printing nodes...");                
                
                
                for(int i =0; i < empNodeList.getLength() - 1; i++)
                {
                    node = empNodeList.item(i);
                    childNodes = node.getChildNodes();
                    
                    employee = new Employee();
                    employee.setEmployeeId(i);
                    employee.setEmployeeName(i + "name");
                    
                    employeeList.add(employee);
                    
                    employee = null;
                    
                    System.out.println("Item: " + childNodes.item(1) );
                }
                    
                select = new SelectItem[employeeList.size()];
                
                int i = 0;
                for (Employee e : employeeList)
                {
                    select[i] = new SelectItem(e);
                    select[i].setValue( e.getEmployeeId() );
                    select[i].setLabel( e.getEmployeeName() );
                    
                    i++;
                }
                
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
         
            return select;
        }

What does this error mean? Thanks!

[michael warren]

From the stack trace I'm guessing the exception is from the line

    Document document2 = docBuilder.parse( soapResponse.toString() );

The parse method that takes a String takes a URI (e.g. path to a file), I guess soapResponse.toString() isn't a valid URI.
Although I don't know what the TimServiceSoap class toString method does I'd make a guess that it returns the XML in the SOAP message ? in which case I think creating a StringBufferInputStream from it and passing that to the parse method that takes an InputStream would work.

[Timothy Sam]

Hmmmm... Problem. I think the TimServiceSoap.toString() doesn't return the XML SOAP message as I thought it would... I tried printing in the console and gave me

org.tempuri.TimServiceSoapStub@1881bb1


this is the content of TimServiceSoap

package org.tempuri;
 
public interface TimServiceSoap extends java.rmi.Remote {
    public org.tempuri.ListEmployeesResponseListEmployeesResult listEmployees() throws java.rmi.RemoteException;
    public org.tempuri.ListDepartmentsResponseListDepartmentsResult listDepartments() throws java.rmi.RemoteException;
}
 

and TimService

/**
 * TimService.java
 *
 * This file was auto-generated from WSDL
 * by the Apache Axis 1.4 Apr 22, 2006 (06:55:48 PDT) WSDL2Java emitter.
 */
 
package org.tempuri;
 
public interface TimService extends javax.xml.rpc.Service {
    public java.lang.String getTimServiceSoapAddress();
 
    public org.tempuri.TimServiceSoap getTimServiceSoap() throws javax.xml.rpc.ServiceException;
 
    public org.tempuri.TimServiceSoap getTimServiceSoap(java.net.URL portAddress) throws javax.xml.rpc.ServiceException;
    public java.lang.String getTimServiceSoap12Address();
 
    public org.tempuri.TimServiceSoap getTimServiceSoap12() throws javax.xml.rpc.ServiceException;
 
    public org.tempuri.TimServiceSoap getTimServiceSoap12(java.net.URL portAddress) throws javax.xml.rpc.ServiceException;
}

it would seem to me that I first need to get the XML from the SOAP message. How do I do that? Thanks for the clue!

[Peer Reynders]

org.tempuri.TimServiceSoapStub@1881bb1

That is the standard Java toString implementation:

packagename.classname@instanceID

it would seem to me that I first need to get the XML from the SOAP message. How do I do that?

Why would you want to? You should obtain an object implementing the service interface (TimService) from the stub. Your service interface has methods that return an object that implements the TimServiceSoap interface. The TimServiceSoap interface has two methods:

listEmployees() returning ListEmployeesResponseListEmployeesResult

listDepartments() returning ListDepartmentsResponseListDepartmentsResult

Use those instead. WSDL-to-Java hides all the SOAP-stuff in the generated code.
See Creating Web Services with Apache Axis 3. WSDL2Java: Generate the Server-side Wrapper Code and Stubs For Easy Client Access for a simple example.

You will want to change the default namespace of tempuri.org (temporary URI) that tools like visual studio put into XML documents like the WSDL - otherwise you could run into some bizarre errors due to naming collisions.
[ May 16, 2007: Message edited by: Peer Reynders ]

[Timothy Sam]

Hi! Thanks! I already seem to be able to get the Nodes. However, the nodes doesn't their correct values. I can retrieve the right number of nodes from the service(by comparing it to the XML output in the .Net service) and the number is the same. The only difference is the the Node values are null... The XML output from the XML would be something like this...

<?xml version="1.0" encoding="utf-8" ?>
- <DataTable xmlns="http://tempuri.org/">
- <xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
- <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:MainDataTable="Employees" msdata:UseCurrentLocale="true">
- <xs:complexType>
- <xs:choice minOccurs="0" maxOccurs="unbounded">
- <xs:element name="Employees">
- <xs:complexType>
- <xs:sequence>
<xs:element name="empid" type="xs:int" minOccurs="0" />
<xs:element name="firstname" type="xs:string" minOccurs="0" />
<xs:element name="middlename" type="xs:string" minOccurs="0" />
<xs:element name="lastname" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
</xs:element>
</xs:schema>
- <diffgr iffgram xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" xmlns iffgr="urn:schemas-microsoft-com:xml-diffgram-v1">
- <DocumentElement xmlns="">
- <Employees diffgr:id="Employees1" msdata:rowOrder="0">
<empid>2</empid>
<firstname>Timothy</firstname>
<middlename>Whatever</middlename>
<lastname>Sam</lastname>
</Employees>
- <Employees diffgr:id="Employees2" msdata:rowOrder="0">
<empid>3</empid>
<firstname>Some</firstname>
<middlename>Other</middlename>
<lastname>Person</lastname>
</Employees>

</DocumentElement>
</diffgr iffgram>
</DataTable>

and now with my method...

        public void getEmployeeIds()
        {
            SelectItem[] select = null;
            
            System.out.println("Accessing service...");
            
            try
            {
                TimService locator = new TimServiceLocator();
                TimServiceSoap soapResponse = locator.getTimServiceSoap();
                
                DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                DocumentBuilder docBuilder = dbf.newDocumentBuilder();
                
                ListEmployeesResponseListEmployeesResult listEmployeeResult = soapResponse.listEmployees();                
                
                
                MessageElement[] listEmployeeElement = listEmployeeResult.get_any();
                
                for (MessageElement m : listEmployeeElement)
                {                   
                   Document document = m.getAsDocument(); 
                   
                   NodeList nList = document.getElementsByTagName("Employees");
                   
                   for(int i =0; i < nList.getLength(); i++)
                   {
                       Node n = nList.item(i);
 
                       System.out.println("NodeName: " + n.getNodeName() );
                       System.out.println("NodeValue[" + i + "]: " + n);
                       
                       NodeList childs = n.getChildNodes();
                       
                       
                       for(int p =0; p < childs.getLength(); p++)
                       {
                           System.out.println("ChildName:" + childs.item(p).getNodeName() );                           
                           System.out.println("ChildValue:" + childs.item(p).getNodeValue() );
                       }
                       
                   }
                   
                }
                
                
                
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
         
            return select;
        }

the getNodeValue() just return NULL. The getNodeName() however does return the correct node name... Sample output would be like this:

Node: Employees
Node[0]: [Employees: null]
Child:empid
Child:null
Child:firstname
Child:null
Child:middlename
Child:null
Child:lastname
Child:null
Node: Employees
Node[1]: [Employees: null]
Child:empid
Child:null
Child:firstname
Child:null
Child:middlename
Child:null
Child:lastname
Child:null

I'm using the following libraries for Document and XML parsing stuff...

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;

and ofcourse the MessageElement class

import org.apache.axis.message.MessageElement;


Hmmm... What could be wrong? Thanks!
[ May 17, 2007: Message edited by: Timothy Sam ]

[Timothy Sam]

Solved it! I just used the getTextContent() method instead. Weeeee! Thank you guys for all your help! I'll be posting the solution on my Blog so keep posted.

[Peer Reynders]

Originally posted by Timothy Sam:
Hmmm... What could be wrong? Thanks!

Any non-XML text between the start tag and end tag of an ELEMENT_NODE goes into separate TEXT_NODEs which are children of the ELEMENT_NODE. (Remember XML can also be document-oriented. Web Services deal with data-oriented XML so some of the conventions may seem a bit odd). So you need to dig deeper.

import org.w3c.dom.*;
import org.w3c.dom.traversal.*;
 

public class TextExtractor {
 
  public static String getText(Node node) {
    
    if (node == null) return "";
    
    // Set up the iterator
    Document doc = node.getOwnerDocument();
    DocumentTraversal traversable = (DocumentTraversal) doc;
    int whatToShow 
     = NodeFilter.SHOW_TEXT | NodeFilter.SHOW_CDATA_SECTION;
    NodeIterator iterator = traversable.createNodeIterator(node, 
     whatToShow, null, true);
     
    // Extract the text
    StringBuffer result = new StringBuffer();
    Node current;
    while ((current = iterator.nextNode()) != null) {
      result.append(current.getNodeValue());
    }
    return result.toString();
    
  }
 
}

From: Chapter 12. The DOM Traversal Module
The DOM 3 getTextContent() won�t work on Document objects (not that you care here).
Processing XML with Java
DOM
[ May 17, 2007: Message edited by: Peer Reynders ]