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How to Consume an ASP.NET webservice from Java via SOAP

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4.37 (24 votes)
18 Oct 2018
Demonstrates how to call ASP.NET webservices from the client within other languages and platforms

Sample Image - WSfromJava.jpg

Introduction

This article will be useful if you need to consume ASP.NET webservices from languages or platforms without .NET support. In this example, I am consuming a webservice from a Java applet, but it would take very little work to adapt my code to run as a Java application. Although I have only tested this on Windows XP, the code should run on other platforms, providing cross-platform client-side consumption of ASP.NET webservices.

I developed this solution because I needed to add complex client-side processing to my ASP.NET application. I did not want to have to cope with all of the slightly different JavaScript implementations used by the main browsers, and this led me to consider a Java applet.

This article shows you how to use a Java applet in your webpage and get it to communicate back to ASP.NET by consuming an XML webservice on the client.

Background

There are, no doubt, many reasons why somebody might want cross-platform consumption of ASP.NET webservices, but this is my story:

I have an ASP.NET application where I needed to add client side image manipulation facilities. I looked into writing the client-side code in JavaScript which seemed like the obvious choice, but was frustrated by different implementations in the browsers, especially when trying to use image manipulation features. For example, if you want to alpha blend your image, you would have to use img.style.MozOpacity in Netscape, img.filters.alpha.opacity in Internet Explorer and there is no way to do this at all in Opera. I really didn't want to have to write special code for each browser or downgrade the functionality to the lowest common denominator.

Therefore, I decided to try writing my client-side code in Java 1.1. Note that I'm using the Java 1.1 SDK, as Internet Explorer currently does not support code developed with Java SDKs after 1.1.4 (although it seems to me that Java SDK 1.1.7 code seems to work OK in IE). A Java applet can do all of the image manipulation I needed and is supported by many browsers. Finally, I don't have to write separate code for each browser.

The next problem was, how do I get the result of the data processing done in the Java applet back into my ASP.NET application? The answer that I came up with was to create an ASP.NET webservice and consume it in the Java applet.

A Simple Example

Take a look at the following very basic webservice:

[WebMethod]
public string ConcatWithSpace(string one, string two)
{
    return one+" "+two;
}

It could be consumed very simply by making the Java applet perform a request to: webservice.asmx/ConcatWithSpace?one=FirstValue&two=SecondValue... But what if we wanted to send larger amounts of data to the webservice? How would we go about implementing a SOAP request and response in a Java applet...? There are probably many options if you are using a more recent Java SDK, but because I want to support many browsers including Internet Explorer, I'm stuck with the Java 1.1 SDK. However, this gives us a better opportunity to understand how to talk to ASP.NET web services on other languages and platforms. Therefore, I have written my own SoapRequestBuilder class in Java that makes it quite easy to consume a service and return a single string response. Take a look at this example, which consumes the webservice above:

SoapRequestBuilder s = new SoapRequestBuilder();
s.Server = "127.0.0.1"; // server ip address or name
s.MethodName = "ConcatWithSpace";
s.XmlNamespace = "http://tempuri.org/";
s.WebServicePath = "/SimpleService/Service1.asmx";
s.SoapAction = s.XmlNamespace+s.MethodName;
s.AddParameter("one", "David");
s.AddParameter("two", "Hobbs");
String response = s.sendRequest();

In this example, the response string is filled with the result from the webservice after we sent it two parameters. The full source code of the SoapRequestBuilder class is included in the source files.

That's it! It's only a very simple example and at the moment, I'm only interested in returning a single value back from the webservice, but I have used something similar with a webservice that talks to my back-end database and this allows my Java applet to store data which can then be accessed by the ASP.NET pages.

To run the example code, set up the webservice first, then copy the Java applet files to any folder on the same machine and double-click the HTML file. All of the parameters are configured inside the HTML file, so you can change the values passed to the webservice by editing the HTML; you should not have to re-compile the Java source. I have tested the example in IE 6.0, Netscape 7.1 and Opera 7.23 on Windows XP.

Notes

Some Java Virtual Machines (like the Microsoft one) only allow you to make a socket connection to the same machine that hosts the Java class files. Therefore, if you're using an applet like me, you will need to host the Java class files on the same machine where the webservice resides.

License

This article has no explicit license attached to it, but may contain usage terms in the article text or the download files themselves. If in doubt, please contact the author via the discussion board below.

A list of licenses authors might use can be found here.

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Comments and Discussions

 
GeneralClass for consuming asp .net webservices Pin
chrho99415-Jul-05 3:40
Memberchrho99415-Jul-05 3:40 
GeneralRe: Class for consuming asp .net webservices Pin
Guhanath18-Jul-05 23:12
MemberGuhanath18-Jul-05 23:12 
GeneralRe: Class for consuming asp .net webservices Pin
circuit_breaker229-Aug-05 8:02
susscircuit_breaker229-Aug-05 8:02 
GeneralInstead of Java Applet want to use Java Class only Pin
sumbhavana19-May-05 14:30
Membersumbhavana19-May-05 14:30 
GeneralQuestion for David S Hobbs (or anybody else) Pin
circuitbreaker2-May-05 9:12
Membercircuitbreaker2-May-05 9:12 
GeneralRe: Question for David S Hobbs (or anybody else) Pin
User 2573282-May-05 20:59
MemberUser 2573282-May-05 20:59 
GeneralRe: Question for David S Hobbs (or anybody else) Pin
circuitbreaker3-May-05 5:20
Membercircuitbreaker3-May-05 5:20 
GeneralRe: Question for David S Hobbs (or anybody else) Pin
User 2573284-May-05 21:57
MemberUser 2573284-May-05 21:57 
GeneralRe: Question for David S Hobbs (or anybody else) Pin
Guhanath23-Jun-05 4:51
MemberGuhanath23-Jun-05 4:51 
GeneralRe: Question for David S Hobbs (or anybody else) Pin
Guhanath23-Jun-05 6:01
MemberGuhanath23-Jun-05 6:01 
GeneralRe: Question for David S Hobbs (or anybody else) Pin
epideme127-Nov-07 23:24
Memberepideme127-Nov-07 23:24 
GeneralIt now works regardless of the parameters!!! Pin
circuit_breaker27-Apr-05 9:00
susscircuit_breaker27-Apr-05 9:00 
GeneralRe: It now works regardless of the parameters!!! Pin
circuitbreaker28-Apr-05 1:11
Membercircuitbreaker28-Apr-05 1:11 
GeneralRe: It now works regardless of the parameters!!! Pin
yktan4-Mar-07 16:23
Memberyktan4-Mar-07 16:23 
GeneralWorks with 2 parameters only Pin
circuit_breaker226-Apr-05 9:10
susscircuit_breaker226-Apr-05 9:10 
GeneralRe: Works with 2 parameters only Pin
User 25732826-Apr-05 11:04
MemberUser 25732826-Apr-05 11:04 
GeneralRe: Works with 2 parameters only Pin
Circuit_breaker27-Apr-05 6:11
sussCircuit_breaker27-Apr-05 6:11 
GeneralRe: Works with 2 parameters only Pin
Myedvyed9-Nov-05 0:38
MemberMyedvyed9-Nov-05 0:38 
GeneralRe: Works with 2 parameters only Pin
shomprabu24-Feb-07 0:26
Membershomprabu24-Feb-07 0:26 
GeneralWorks like a charm Pin
circuitbreaker18-Apr-05 8:01
Membercircuitbreaker18-Apr-05 8:01 
GeneralCommunicating with Database. Pin
ganeshvijay17-Apr-05 22:23
Memberganeshvijay17-Apr-05 22:23 
Generalgetting TimeOut by connecting to Server Pin
Andreas_Manthey11-Jan-05 6:37
MemberAndreas_Manthey11-Jan-05 6:37 
Questionthe other way around? Pin
ansonchtouk19-Oct-04 3:54
Memberansonchtouk19-Oct-04 3:54 
GeneralbserviceNot working for me Pin
hpb_732-Jun-04 23:39
Memberhpb_732-Jun-04 23:39 
GeneralRe: bserviceNot working for me Pin
User 2573283-Jun-04 0:11
MemberUser 2573283-Jun-04 0:11 

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Article
Posted 15 Jan 2004

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