When WLDJ wanted someone to take a First Look at Visual MainWin for J2EE, we turned to interoperability expert Laurence Moroney - coauthor of a forthcoming book on Web services security and a senior architect in a major financial services house in New York City. In the course of assessing the product, Laurence in fact became more and more involved - in the end, on a staff basis - with the company behind it, Mainsoft. So this First Look should be read with that basic journalistic disclosure in mind.

When WebLogic workshop was first conceived and presented to the public, it was done so as an alternative to the hugely popular Visual Studio.NET development environment - one that was just as easy to use, and equally if not more powerful, because it would allow you to build J2EE applications, including EJBs, in as easy a manner as a VB programmer could put together a Windows-based object.

However, many shops that have existing assets in .NET and build in C# would have to port all that code into Java using Workshop, and effectively throw away their existing investments should they want to run on the WebLogic J2EE platform. This became, and still is, a huge hurdle in migrating between the platforms. In addition to this, a real strength of WebLogic Workshop 8.1 is in its ability to easily construct EJBs and to easily construct workflow applications and expose them as services. On the front end, it has the very useful pageflow technology that can be used to construct UIs that consume these, but many would argue that there is no better productivity alternative for front-end Web applications than ASP.NET with Visual Studio.NET. It would be nice if you and your team could use WebLogic for what it does best - middleware EJBs and Workflows, and ASP.NET for what it does best - front ends.

Now there is a way: Visual MainWin for J2EE is a product from Mainsoft (dev.mainsoft.com) that offers a unique and innovative solution to this. In a nutshell, this product, nicknamed Grasshopper, takes the Microsoft Intermediate Language (MSIL) generated by .NET and converts it into Java Byte Code, supported by a Java port of the Mono libraries. This way your C# code can be compiled and run on a J2EE application server such as WebLogic on Windows, Linux, or anywhere else it is supported. It's a wonderful way of capitalizing on the usability of Visual Studio.NET with the run-time reliability and characteristics of WebLogic.

In this article you will take a look at what it takes to deploy your existing ASP.NET front ends to WebLogic 8.1, and to interop with assets such as EJBs that are already running on that platform.

How It Works
The concept behind this product is very simple - but very effective. Mainsoft is a major contributor to the Mono project, and they have used their tool to port the Mono source code to Java. This provides the namespace support so that the ASP.NET namespaces can be called from Java. It then takes your C# or VB.NET code and cross-compiles the MSIL generated by the .NET framework compilers into Java Byte code. This is then a pure Java solution that will run on your J2EE application server. They also add support to consume Java References and EJBs.

When developing an application you simply create an ASP.NET application and use their wizard to convert it to J2EE, or you can create a C#/VB.NET for J2EE application using the new project types in Visual Studio.NET after installing.

The rest - developing, debugging, code completion, intellisense, etc. - all work cleanly within Visual Studio.NET. It's very compelling, and if you or any member of your team is comfortable in this development environment, you'll be amazed at how cleanly it integrates. There's something very cool about writing C# and running and debugging it on WebLogic as cleanly as you would on IIS.

Getting Started - A Very Simple Example
This first example takes a standard C# Web form, adds an EJB reference to it to allow it to consume an EJB off a WebLogic 8.1 server, and then compiles the Web form to run on WebLogic.

To get started, use WebLogic Workshop to create a simple EJB that implements the following method:

/**
* @ejbgen:remote-method
*/
public String echoHelloWorld(String strIn)
{
return "Hello World, " + strIn;
}

It is very simple and just returns "Hello World" and the caller's name.

You'll need to install the enterprise edition of Visual MainWin for J2EE to continue, because only the enterprise edition supports BEA WebLogic. You can find this at dev.mainsoft.com. They also have a free edition of the tool that supports Tomcat. Once you have downloaded and installed the tool, you can launch Visual Studio.NET and create a simple Web form like the one shown in Figure 1.

Adding a reference to an EJB is very straightforward - and will look very familiar if you are used to consuming Web services in Visual Studio.NET. If you right click on the "References" node in the solution explorer, you will notice two new entries - "Add Java Reference" and "Add EJB Reference." The former allows you to consume JAR files and use them from within ASP.NET, and the latter does the same but for EJBs. If your EJB (from above) is deployed to WebLogic and the Application Server is running you can use the Add EJB reference, and you'll get the dialog that is shown in Figure 2.

You can add the EJB reference using either a path to the JAR file that contains it, or by using JNDI.

Once the EJB reference is made, Visual Studio.NET and Visual MainWin for J2EE create a proxy class that allows you to talk to it. This then allows you to code to the J2EE using all of the productivity features of Visual Studio.NET, such as autocomplete.

On the simple ASP.NET UI that you created earlier, you can now add the following code (the textbox should be called "txtName" and the label should be called "lblResp" for this code to work):

localhost.ejbhwRemote myEjb = new localhost.ejbhwRemote();
string strTest = myEjb.echoHelloWorld(txtName.Text);
lblResp.Text = strTest;

Using a WebLogic Workflow
One of the massive strengths of the WebLogic Workshop 8.1 is the impressive workflow engine. This allows you to graphically design workflows and processes, and to interface them with external components such as Web services or EJBs. In many ways it is the foundation of an enterprise service bus. In this section you will look at how you can tie your ASP.NET user interfaces to these workflows using Web References, and deploy both the workflow and the UI to WebLogic.