Wednesday, March 3, 2010

Calling an ASP.NET web service from a Java application

First, the Java application must contain a class that will encapsulate the functionality to invoke a XML web service via SOAP calls. The code is below:

import java.net.*;
import java.io.*;
import org.w3c.dom.Document;
import org.w3c.dom.*;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

public class WebServiceInvoker {
private String HTTPContinue = "^.*HTTP/[0-9].[0-9] 1[0-9][0-9].*$";
private String HTTPOk = "^.*HTTP/[0-9].[0-9] 200.*$";
private String HTTPSuccess = "^.*HTTP/[0-9].[0-9] 2[0-9][0-9].*$";
private String HTTPRedirect = "^.*HTTP/[0-9].[0-9] 3[0-9][0-9].*$";
private String HTTPClientError = "^.*HTTP/[0-9].[0-9] 4[0-9][0-9].*$";
private String HTTPServerError = "^.*HTTP/[0-9].[0-9] 5[0-9][0-9].*$";

private String _namespace;
private String _host;
private String _path;
private int _port;

private int _timeout;

/**
* @param host The server hosting the web service
* @param port The port on the server which will accept the call (default 80)
* @param wsPath The relative path of the web service on the server
* @param namespace The namespace defined in the webservice ("http://tempuri.org")
*/
public WebServiceInvoker(String host, int port, String wsPath,
String namespace) {
_host = host;
_port = port;
_path = wsPath;
_namespace = namespace;
_timeout = 60000;
}

public void setTimeout(int timeout) {
_timeout = timeout;
}

public int getTimeout() {
return _timeout;
}

public String invokeRPC(String remoteProcedure, ParameterCollection params)
throws Exception {
String result = "";

try {
String xmlData = ""
+ ""
+ "" + "<" + remoteProcedure + " xmlns=\""
+ _namespace + "\">";
for (int i = 0; i < params.size(); ++i) {
String[] sParam = params.Get(i);
if (sParam.length == 2) {
String paramName = sParam[0];
String paramValue = GeneralUtil.FixSpecialChar_forXML(sParam[1]);

xmlData += "<" + paramName + ">";
xmlData += paramValue;
xmlData += "";
} else {
System.out.println(xmlData);
throw new Exception("Poorly formatted parameter returned from Parameter Collection. WsTester.testWs");
}
}

xmlData += "" + "
"
+ "
";
InetAddress addr = InetAddress.getByName(_host);
Socket sock = new Socket(addr, _port);
sock.setSoTimeout(_timeout);

// Send header
BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(sock.getOutputStream(), "UTF-8"));
wr.write("POST " + _path + " HTTP/1.1\r\n");
wr.write("Host: " + _host + "\r\n");
//wr.write("Content-Type: application/soap+xml; charset=\"utf-8\"; action=\"http://[URL to ASP.NET web service]\" \r\n");
wr.write("Content-Type: application/soap+xml; charset=\"utf-8\"; action=\"\" \r\n");
wr.write("Content-Length: " + xmlData.length() + "\r\n");
wr.write("\r\n");

// Send data
System.out.println("Soap Message:\n" + xmlData);
wr.write(xmlData);
wr.flush();

// Response
BufferedReader rd = new BufferedReader(new InputStreamReader(sock.getInputStream()));
String line = "";
String header = "";
boolean bContinue = true;
int byteCount = 0;
// Read Header
while (bContinue) {
do {
line = rd.readLine();
header += line + " ";
} while (!line.matches(""));

if (header.matches(HTTPContinue)) {
// Connection's established. Wait for the next header
header = "";
bContinue = true;
} else if (header.matches(HTTPOk)) {
// HTTP Ok. Retreive the data
byteCount = parseContentLength(header);
header = "";
bContinue = false;
} else if (header.matches(HTTPSuccess)) {
// Some other non-error success code
// Try again to see what happens, or wait until the socket
// times out
header = "";
bContinue = true;
} else if (header.matches(HTTPRedirect)) {
// Shouldn't encounter this one, but if we do I have no idea
// how to handle it
bContinue = false;
throw new Exception("HTTP Redirect encountered:\r\n"
+ header);
} else if (header.matches(HTTPClientError)) {
// Client error, most likely a Server not Found (404) or
// Forbidden (403, bad credentials).
//header = "";
bContinue = false;
throw new Exception("HTTP Client Error encountered:\r\n"
+ header);
} else if (header.matches(HTTPServerError)) {
// Server errors. Internal Service Error (500) type errors
byteCount = parseContentLength(header);
char c[] = new char[byteCount];
rd.read(c, 0, byteCount);

//header = "";
bContinue = false;

throw new Exception("HTTP Server Error encountered:\r\n" + header + "\r\n" + String.valueOf(c));
} else {
throw new Exception("Unknown HTTP header:\r\n" + header);
}
}

if (byteCount != 0) {
// Read Data
char c[] = new char[byteCount];
rd.read(c, 0, byteCount);

DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();

StringReader reader = new StringReader(String.valueOf(c)+ "\r\n");
InputSource source = new InputSource(reader);

Document doc = docBuilder.parse(source);
doc.getDocumentElement().normalize();

NodeList list = doc.getElementsByTagName(remoteProcedure + "Result");
if (list.getLength() > 0) {
result = list.item(0).getFirstChild().getNodeValue();
}
}
}

catch (Exception ex) {
System.out.println(ex.toString());
}

return result;
}

private int parseContentLength(String header) {
try {
int start = header.indexOf("Content-Length: ");
int end = header.indexOf(" ", start + 16);
String contentLine = header.substring(start, end);
contentLine = contentLine.replaceAll("^Content-Length: ", "");
contentLine = contentLine.trim();

return Integer.valueOf(contentLine).intValue();
} catch (Exception ex) {
return 0;
}
}
}

Also create a class called ParameterCollection which will hold the parameters to the web method invoked by the Java invoker:

public class ParameterCollection {
private String[][] _params;
int _index;
int _size = 10;

public ParameterCollection()
{
_params = new String[_size][2];
_index = 0;
}

public void Add(String param_name, String param_value)
{
if (_index >= _size)
{
IncreaseSize();
}

_params[_index][0] = param_name;
_params[_index][1] = param_value;

++ _index;
}

public String[] Get(int index) throws Exception
{
String[] retVal = new String[2];

if (index >= _index)
{
// Out of bounds
throw new Exception("Parameter Collection index is out of bounds: ParameterCollection.Get(" + index + ")");
}

retVal[0] = _params[index][0];
retVal[1] = _params[index][1];

return retVal;
}

public int size()
{
return _index;
}

private void IncreaseSize()
{
String[][] sOld = _params;
_size *= 2;

_params = new String[_size][2];

for (int i = 0; i < _size/2; ++i)
{
_params[i][0] = sOld[i][0];
_params[i][1] = sOld[i][1];
}
}
}


Next, after using the Visual Studio ASP.NET web service project wizard to create a web service project, add the following attribute to the class declaration of the class representing the web service:

[SoapDocumentService(RoutingStyle=SoapServiceRoutingStyle.RequestElement)]

The class declaration should look something like:
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ToolboxItem(false)]
[SoapDocumentService(RoutingStyle=SoapServiceRoutingStyle.RequestElement)]
public class Service1 : System.Web.Services.WebService


In the java class that will invoke the web service, create an instance of the WebServiceInvoker class:

WebServiceInvoker proxy = new WebServiceInvoker(webserviceservername, port, webserviceurl);

Create a list of parameters and populate appropriately:
ParameterCollection() oColl = new ParameterCollection();
oCall.Add(“parameter1”, “value1”);

Then use this as a parameter to the invokeRPC method of the web service proxy class:

Proxy.invokeRPC(“Name of web method to call”, oCall);

In IIS, make sure the ASP.NET web service accepts anonymous connections, and set which user the anonymous connections will use to access resources.

1 comment:

Charles said...

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