I would like to wrap a java application as a Windows Service using C#. I can do it easily using the Process class and calling Process.Start("java.exe", "args"), but doing this way I have 2 process, my service wrapper and the java process. I'm looking to fully wrap the java application, including the java process.
Does anybody here has done it or knows the best way to do this in C#?
The two basic approaches are to either run the Java application as a separate process, or to host the JVM directly, and use it to launch your application. There isn't a direct way to do this in C#, as the JNI interfaces for hosting are C++ interfaces only.
However, there are commerical products that allow you to do this directly from Java.
Related
is it possible to invoke function which is written in Java using WCF or any class application written in C# .net
Can it be possible by using webOrb..
i can't find enough information about Java to .Net remoting..
If you want to communicate between C# and Java you have a couple of options.
The cleanest: Build a service.
This assumes you have access to the source code of both your C# component and your Java component. In the case that you want to call a method within Java, you can build a service that allows a connection from your C# client, to your Java service, and the service then executes the desired functionality, and returns a value back to the C# client. Some easy ways to do this is by building a RESTful service or using Thrift. I recommend you choose a solution similar to this one.
The most complex: Corba
Corba is a standard defined to communicate amongst different computer languages. Most mature languages have support for it, but it is a bit unusual, and the use of it has declined in favor of building service. This also assumes access to both source codes.
You'd have to independently look for the information regarding how to use Corba on both Java and C#. I would really advice against this.
The dirtiest but quickest: Execute as process and parse output
I really do NOT recommend you to do it this way unless you really have no choice. This would entail executing a Java program from within C#. This is only a good choice when you have no other option, because all you have is an executable. If that were the case, you can use the Process class to execute the external program, sending it parameters, and then reading the output. See the example mentioned here:
How do I start a process from C#?
This has many downsides though, as you'll have to think of every exceptional cause, determine the output for those cases, and then determine how to parse that output. If the program has any level of complexity, before you know it, you'll end up with hard to maintain code.
Conclusion: Build a Service
That's probably your best bet. Build a service that exposes an API that the C# client can call on.
We are using JCOBridge package: it is able to create a bidirectional invocation of Java API from C# (.NET Core/6/Framework).
The templates available on Templates was our good starting point for the needs we had. We reach the goal in few lines of code.
UPDATE 2022: the JNet project on GitHub can be used as a starting point. Another project is KNet, hosted on GitHub and based on JNet, that is a gateway for Apache Kafka Java API.
Is there a way rather than using server/client approach or file save/load approach that I can use to transfer objects between two separate C++ and C# applications?
Actually what I am trying to do is that I create the GUI part of a project in C# and create some parts of the project in C++ and by communicating between these two applications I proceed and go on.
For some reasons I only want to use C++ console application (I don't know how to create a DLL in C++ and aside form that I want to know the current possibilities without using DLLs)
You can use IPC if they really must be separate items.
Otherwise, look into managed C++. You can create a wrapper around your C++ code and call it directly from C#. Here's one tutorial...
Of course a gooooood way to go would be using dlls. Also, you could create command line programs in c++ and calling them in c#. If you want to return complex data you have to implement a communication protocol.
Another way would be using a console application leaving its input opened while it processes data in another thread, this way you can handle communication streaming data (as if you open a console). Of course you need to parse the output.
There are several ways to achieve communication between two tasks (although they've been developed in different programming languages ;-) ).
One simple way is to implement a Client/Server-Class in each application. That way you can send complex data in both directions between your tasks and let them communicate.
Can Delphi 4 and\or 5 application functionality (.exe) be integrated into a C# application?
I've been tasked with rewriting a new application which will be based off of existing Delphi 4/5 written application, which are currently held together with a Batch Processing Script that no one at my company understands.
As an interum solution, I've been asked to investigate whether a C# GUI\wrapper can be placed on top so it's easier to maintain and run.
I know that Delphi 6 applications can be called within a C# application using reflection but I'm not entirely sure how.
So back to my original question can a Delphi 4/5 application functionality be called within a C# application?
Thanks in advance.
The underlying premise of the question appears to be that a C# wrapper around a Delphi core is easier to maintain and run, and if that is not true, then the idea of creating the wrapper becomes not-very-useful. I believe it is a wrongly-conceived notion.
Imagine that I made an application that can talk to a telescope. It does it perfectly. In that case, I might be able to extract just the telescope-communication part and put it in a DLL and then write a user interface in C# that uses the Delphi DLL just to do the communicate-with-telescope task. However, unless your Delphi application was already structured in a nice way, and unless a task like this telescope-communications library already exists, you won't find it very easy to extract any part of a Delphi application, and use it from C#. If that situation existed, I would use native Delphi DLL function exports and invoke them from C#. This is not using the existing delphi executable, and requires many hours of work to refactor part of a Delphi application into something that could be used from C#.
Another answer mentions COM Servers, and while that is possible, it is not going to make things easier; Like the old joke about regular expressions; When you have a problem and try to solve it by using regular expressions, now you have two problems. The same becomes true when you try to use COM Servers to hide your existing application and write a whole new UI on top of it using C#. It would actually take more technical skill to improve, debug, and continue to develop it that way, than to keep developing it either purely in delphi or purely in C#. It's a negative savings of effort.
You have given no information about what the Delphi application does, but let's assume that it's a line-of-business or vertical market application that reads some file format, or does some communication protocol, or even connects to some old database, that you don't want to rewrite.
If by making the C# UI you mean, to never show the Delphi application user interface and replace it with a C# one, it is nearly certain that your idea is not going to make anything any better, and can only ever make things worse. Your deadlock either comes from not having skilled delphi developers, or else it comes from not having clever developers who can figure out what an existing application does.
The solution is usually a human solution when you are in this situation; either to hire a skilled delphi developer and bring the application forward into the modern Delphi era (Delphi XE2) or to hire a skilled non-delphi developer and port the application to some other language. Anybody who would suggest writing a "wrapper" over top of the delphi application who thinks that will make it "easier" obviously feels incapable of rewriting the existing application.
I don't know enough about what your delphi application does, to be sure, but it sure sounds to me like "fear driven" decisions. Wrapping old code is almost never a good idea, and is most often, just the creation of more problems.
A Delphi .exe can be run from C#. But I guess this is not your point.
You can either use a COM server, which is standard but needs the COM object to be registered on the computer (by running regsrv32.exe). Not so easy to deploy.
Or you can define the Delphi code as a library, then load and execute the .dll from the C# code.
If you prefer to access C# objects from Delphi 4 or 5 (that is access C# RTTI), you'll have to use some low-level unit like Managed extensions for VCL - .Net interop for Delphi Win32. Which is quite complete, and works with old versions of Delphi (whereas something more high-level than Hydra will not support Delphi 4 or 5, sadly).
Edit
Another possible easy communication is GDI messages. You can send GDI commands from your C# code to control the Delphi application, but using PostMessage() API calls.
Sure. C# can call any .exe. Just use Process.Start:
http://www.dotnetperls.com/process-start
http://msdn.microsoft.com/en-us/library/system.diagnostics.process.aspx
Delphi 5 supports implementing COM server functionality (don't know about earlier versions, D2 definitely did not).
If you have the sources available,
add a type library and a COM implementation of the interfaces defined in the type library,
register the executable (typically done automatically on startup thanks to Delphi magic)
follow the steps on MSDN: Exposing COM Components to the .NET Framework
We've written a Java program which we are looking to use and interact with from C#. What are our options? Optimally it would be possible to compile the Java application as a library (.DLL) that we could reference from C# perhaps using P/Invoke. This, however, doesn't appear to be an option according to the first few searches online.
We opt to be able to use ASP.NET to built a search engine powered by the Java code, so if this opens up for any other options please let us know.
Sorry, you cannot call java code / classes Directly from C# code.
One way of doing this is to wrap up your java classes in a java Web Service and call classes indirectly through that web service interface in your C# code.
Another way is using
javareg.exe which exposes java classes as COM. You can find it at following location:
C:\Program Files\Microsoft VisualStudio\VIntDev98\bin\javareg.exe
Following posts might help as well
Calling Java Classes Directly from
.NET (uses runtime bridge)
Calling Java from Microsoft.NET
The simplest approach would probably be to publish the functionality of your java library as web services and add a web-reference from your asp.net application.
Java isn't meant to be embedded in another program, so you need a bridge. The most simple solution is to use a socket: Create a Java process which listens for commands on a socket. In the C#, send the commands to the socket and read the answers.
The main problem here is serialization but if you use XML, it's not such a big pain anymore. Try the built-in XML serialization (see this article) or custom frameworks like XStream or Simple.
It is certainly possible to wrap Java in a .dll, and has been a part of the core Java platform for over 10 years. JNI (Java Native Interface) has an interface for embedding a JVM in your code, meaning you can run Java classes using C-style linking. Note that this will require that you write a simple C wrapper, there are samples within:
http://java.sun.com/docs/books/jni/html/invoke.html#11202
As some of these other posts suggest, sometimes it's desirable to be less tightly coupled, so you may want to consider using another design. One option would be a simple database, where the Java application regularly polls for requests from the C# code. If you want tighter coupling, for things like call-backs, you can look at distributed interfaces.
I'm a programming student, and I've now had two classes in C#, this semester I'm taking my first C++ class.
Out of curiosity, is it possible to call a C# application from a C++ application?
If so, is it also possible to check if the computer running the program has the .NET framework?
I'm just curious, and I think if its possible, it would be a great little program to write and have as a tool for the future.
Just for your information, here's what I'd like to do:
Check to see if .NET framework is installed on the computer
If it's not, ask the user if they would like to install it, and if they would, proceed to download and install the framework
Call my program written in C# and then kill the C++ program
There are many ways to call .Net code from C#.
You can expose a class using COM Interop, or you can make a "bridge" using C++/CLI.
You can do it in "raw" C++ (without COM) by exporting methods from the C# DLL.
However, in your case, you might as well simply launch the C# EXE file using CreateProcess.
Out of curiosity, is it possible to call a C# application from a C++ application?
Yes. There are a few options here. If you use C++/CLI, you can use types defined in C# directly from within C++. Otherwise, a typical approach is to use COM, esposing your C# types as COM objects.
If so, is it also possible to check if the computer running the program has the .NET framework?
Yes. Here, typically, you'd just install the framework along with your application. Here's a page that shows a few options for checking which version of .NET (if any) is installed.
A C# (actually .NET) application is really a unmanaged stub exe that loads the .NET environment and then jumps into the C# code.
In other words, a C# app is always contained within an unmanaged process. So if you are willing to restrict yourself to using C# DLLs rather than C# applications you can host them in
your own C++ process.
Check to see if .NET framework is installed on the computer
If it's not, ask the user if they would like to install it, and if they would, proceed to download and install the framework
Initialize the .NET runtime, load my C# library into it and jump into the C# code.
profit
Note the difference here is that you never shut down the C++ process, it becomes the host for your C# code - this is basically what Windows does anyway when you run a C# application.