Exchange of object data types in Web Service development

Author: Weng Yan

Time: 2003-7-24

Welcome everyone to contact me, enhydra_boy @ Tom.com

Welcome to reprint, please reserve the declaration information.

The last time I talked about how Tomcat quickly developed the web service application and gave an example. However, the passing parameters are common data types. If you want to pass complex data types, such as object types, how should you do it? This article is to discuss this problem.

My solution is to implement, the Web Service server side and the client's complex data type exchange. Of course, this String is an XML format string that implements the storage of complex data types.

So, this process is roughly like this:

1 Client sending a SOAP call request

2 The server accepts data from the database, and processed into an XML string as required.

3 The client accepts the XML string and parses the information in it.

vice versa. Speaking here, it should be said that such implementation is not difficult. Then, the problem we have to solve is a quick development plan. In Java development, use objects to store complex data types, and there is also a concept in VB, then the program written by different development tools communicates with data, What technology should be adopted to ensure the development speed and quality of the software? This is the purpose of the author.

The author believes that using XML professional design tools to design data structure, using third-party development tools to automatically generate source code for the development platform. This is a relatively fast and reliable development method.

Java and VB have corresponding automatic generation tools. Java is Sun Web Service Developer Pack, VB has Microsoft Soap Toolkit. Briefly illustrate as follows:

1 Design a Schema file with XML SPY (XML Design Tool).

2 Sun Web Service Developer Pack can automatically generate Java code according to Schema, compile into a Class file. The Java program can be implemented to directly PARSE into an XML string, and the XML string is loaded, and the object information is initialized.

3 XML Spy converts Schema into XDR files (XML Data Abstract Files), SOAP MESSAGE Object Generator in SOAP Toolkit automatically generates VB class code. Function is the same.

Let's start practice.

First step, XML Schema design

Start XML SPY (if not installed, downloaded and installed), create new schema files, all design is visualized.

Save and get an EMPLOYEEROT.XSD file.

In the second step, the Java source program is automatically generated.

First download the Sun Web Service Developer Pack 1.1, install and follow the documentation.

In the Command window, run% jaxb_home% / bin / xjc.bat employeeroot.xsd -p com.sam.util.emp. After the command is successful, the Java source file will be automatically generated.

The third step is compiled and generated and generates a CLASS code.

In the Command window, run% java_home% / bin / javac COM / SAM / UTIL / EMP / *. Java COM / SAM / UTIL / EMP / IMPL / *. JAVA.

You can run the JAR command to pack. You can also generate a technical document for your class for your class.

The fourth is established to establish a web service for testing.

In this example, the platform used by the author is Tomcat Axis. You can see http://www.9cbs.net/develop/read_article.asp?id=19782 to learn about the specific configuration. Note, please copy the JAXB and JAXP libraries to $ Tomcat_Home / Axis / Web-INF / LIBS. Main there are: jaxb-api.jar, jaxb-libs.jar, jaxb-ri.jar, jaxb-xjc.jar, jaxp-api.jar. And copy the class library package you get in the third step. In the AXIS directory, create an EmpService.jws file, the code is as follows: import java.io.fileinputstream;

Import java.io.fileoutputstream;

Import java.io.ioException;

Import java.math.bigdecimal;

Import javax.xml.bind.jaxbcontext;

Import javax.xml.bind.jaxbexception;

Import javax.xml.bind.marshaller;

Import javax.xml.bind.unmarshaller;

Import javax.xml.transform.stream. *;

Import Java.io.stringReader;

Import java.io.stringwriter;

Import com.sam.util.emp. *;

Public class empservice {

Public string geteMPloyees ()

{

StringWriter Sout = New StringWriter ();

Try {

// Create a jaxbcontext capable of handling classes generated INTO

JAXBCONText JC = jaxbcontext.newinstance ("com.sam.util.emp"); unmarshaller u = jc.createunmarshaller ();

StringBuffer Xmlstr = new stringbuffer (" "); Employees Emps = (EMPLOYEES) u.unmarshal

New streamsource (New StringReader)

Xmlstr.tostring ()))))) ;;

Emps.geTemPloyee (). clear ();

Employee EMP = New com.sam.util.emp.impl.employeeImpl ();

Emp.SetFirstName ("john");

Emp.SETMIDDLENAME ("");

Emp.SetlastName ("Bob");

Emp.Setssn ("555-111");

Emps.geTemPloyee (). Add (emp);

EMP = new com.sam.util.emp.impl.employeeImpl ();

Emp.SetFirstName ("Tom");

Emp.SETMIDDLENAME ("");

Emp.SetlastName ("bill");

Emp.Setssn ("567-281");

Emps.geTemPloyee (). Add (emp);

Marshaller M = jc.createmarshaller ();

M.SETPROPERTY (Marshaller.jaxb_formatted_output, boolean.true);

StreamResult Result = New StreamResult (Sout);

M.Marshal (EMPS, RESULT);

//System.out.println (sout.tostring ());

} catch (jaxbexception je) {

Je.printStackTrace ();

""; "

}

Return Sout.toString ();

}

}

Run http: // localhost: 8080 / axis / Empservice.jws? WSDL, you can see the WSDL interface corresponding to the service file.

Step 5, use the Convert DTD / Schema in XML SPY to convert Employeeroot.xsd to the XML Data file (EMPLOYEEROOT.XDR).

The converted file is as follows:

Sixth step, start Visual Basic Engineering, if you have SOAP Toolkit3 installed, you can see that there is an Add-in program in Visual Basic, called Microsoft Soap Messaging Object Generator, using This tool can automatically get the corresponding VB class code. Use this tool to generate a VB class code, and compile into an ActiveX DLL. About the specific content, in the future, I will explain it in the use of the SOAP Toolkit tool. Seventh step, Write a client test program. Place a text box text1 and List blocks on the screen. Place a button cmdread. Writing code is as follows:

Private subduDread_click ()

ON Error ResMe next

Dim SoapClient As Object

DIM SRESULT AS STRING

Set soapclient = creteObject ("mssoap.soapclient30")

Call SoapClient.msoapinit2 (Text1.Text, "," "" "" "" "" "" "", ""

IF Err.Number <> 0 THEN

Msgbox soapclient.faultstring, vbexclamation

EXIT SUB

END IF

'Now the client can call an operation listed in the porttype element

'specified when caling mssoapinit ().

SResult = soapclient.geTemPloyees ()

IF Err.Number <> 0 THEN

Msgbox soapclient.faultstring, vbexclamation

EXIT SUB

END IF

Dim OSoAP as mssmo.ioapMessagePart

Dim Odom as msxml2.domdocument30

DIM Oemps as EmployeesRoot.employees

DIM OEMP as EmployeesRoot.employee

'Now We Parse the XML Data Into Our Class

Set = new msxml2.domdocument30if om.loadXML (SRESULT) THEN

Set Oemps = New EmployeesRoot.employees

Set OSoAP = OEMPS

For Each Oxmlnode in in odom.childnodes

IF oxmlnode.nodetype = node_element then

IF _

Oxmlnode.basename = osoap.elementname and _

Oxmlnode.namespaceuri = osoap.namespaceuri _

THEN

Set osoap.element = oxmlnode

EXIT for

END IF

END IF

NEXT

List1.clear

For Each Oemp in Oemps.Employee

List1.additem Oemp.ssn & Vbtab & Oemp.Firstname & "," & Oemp.middlename & "" & Oemp.Firstname

NEXT

END IF

End Sub

Run, the test results are as follows: Summary, through this example, the author believes that it has brought us a new concept and ideas. Using XML to design the design of the data structure, the code is automatically obtained based on the design mode. This development method makes it possible to concentrate concentrate on data models and business logic, and the maintenance cost of code is also greatly reduced.