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We are currently using MICO to establish the communication between a server and a client, where the client is a simulator written in C++ and the server is a java program displaying an animation of what happens in the simulation. It seems that the developemt of MICO has slowed down to an almost halt and bugs that only allow us to hack around them (as we don't have the time to first figure out which parts of MICO are responsible for codegeneration and so on) keep us from making real progress.
So, does any one of you know of a good drop-in replacement? We would like to have the following:
The compiler can generate both C++ and Java-Code from the idl.
The project should still show considerable support.
The implementation should be open-sourced (GPL or BSD, or something alike), as we use our programs to teach students as well.
The migration from MICO should be as easy as possible. (This is not a hard requirement, but would be a good thing)
I found some other CORBA implementations, e.g. TAO, but I didn't find any of which I could
say that they are still supported. Correct me if I am wrong here.
The Free CORBA® Downloads page might be of interest to you.
Just naming:
orbit2 1, also pyorbit etc.
omniORB
TAO (has already been mentioned)
1 On my Ubuntu box, apt-rdepends -r liborbit2 returns 5530 lines...
I don't know where CORBA or MICO in particular has gone in the last 5 years, but back then a drop in replacement was not really possible, since differences between vendors where still there.
Not necessarily API differences (POA, etc.) but
in implementation behavior,
in custom extensions which were required to make it work in a real-world environment (threading, load balancing, security, etc.),
in how the development tools worked
and also about the whole deployment or runtime story.
We had Orbix ASP/2000/Whatever and ORBacus which were interchangeable having a small compatibility layer, some Makefile framework to hide differences in tools (e.g. the IDL compiler) and some scripts for wrapping ORB specific processes.
Unfortunately, ORBacus has long been bought by (then) IONA, which already make Orbix. IONA itself has been bought by someone else (I forgot). The original authors of ORBacus, plus some devs from IONA Orbix, changed their ways somewhat and produced Ice, which is not CORBA but somewhat alike - of course without the glitches ;-)
Concerning TOA, I think it would be the "best" choice concerning still being developed as it is driven by research on the Washington University. But last time I looked, they didn't have Java implementation but people seemed to use JacORB.
Maybe all this helps you little, unless it brings even more confusion :-)
TAO as C++ ORB is still actively supported and developed (see http://www.cs.wustl.edu/~schmidt/commercial-support.html). For Java I would propose JacORB.
On http://www.orbzone.org there is an overview of available corba implementations.
A friend of mine uses in his company an ERP software written in PowerBuilder. Unfortunately the (one and only) developer is going into retirement soon. My friend really likes the software and wants to keep using it for at least ten more years, so my friend decided to buy the source code.
He wants to start a business to maintain the software and develop new features. At the moment there are probably about 50 installations of that software out in the wild and he already knows of a bunch of potential buyers.
Now he's searching for a developer and asked me... I did a little C/C++ programming, a bit of VB and a bunch of other languages but in the last years I earned my money by writing Java web applications.
From what I read, PowerBuilder looks quite antiquated to me, there are hardly any tutorials out there, no open source frameworks, awkward version control, didn't even read about any test frameworks. People here on StackOverflow say they hope, the language/IDE is dead. Additionally the code I'd maintain is completely undocumented and untested.
Do you think it's possible, for someone who never even heard of PowerBuilder before, to maintain such a software?
EDIT: okay, thanks for your answers. We decided to kick the old application completely and re-write it in an up-to-date-language.
Yes, it's possible. Powerbuilder is not a hard language to pick up, particularly if you have used VB already.
The Powerbuilder community is far smaller than what you may be used to with e.g. Java, but it does exist. The best place (other than SO!) to ask questions are the sybase.public.powerbuilder.* newsgroups.
For unit testing, try PowerUnit, and for source control, you can use Subversion via PBSCCProxy, TamTam SVN SCC, or PushOK SVN SCC proxy.
It's been a niche language for a long time now. In my opinion this is due the upfront cost of the tools required, which is essentially blocking anyone new from considering it.
The future is reasonably bright though: Sybase is flourishing, committed to PowerBuilder, and regularly announcing progress towards version 12, which will be a full .NET language like C# and VB.NET, and will ship with an IDE based on VisualStudio. You will be able to directly migrate your code to version 12, no rewrites required.
I started my career as a PowerBuilder developer, but quickly changed to java and python, as soon as I realized PB was almost a dead language.
Also, even if there are tools that can be used to apply programming "good practices", they are not widely known and somewhat expensive, so I've had to work even without version control (!!), left aside automated testing or continuous integration.
It is a language in which almost anyone can start to build usable apps in a short period of time and with little training, and the apps are built really fast, in contrast with java, that demands a period of learning until a developer can be productive, and even then, a webapp takes time to be developed.
But the payback is with maintenance, that quickly becomes a nightmare. Even a minor change in the database like a type change in a database column can destroy every datawindow (the PB ubiquitous data-access component) that refers to it.
It's pretty much similar to VB, in that as almost anyone can develop applications in it, with very little programming knowledge, the average quality of applications is very low, with unmanageable database coupling and plagued of bad coding practices.
My advice is not to build a Developer career in such kind of language unless the money justifies it, and in that case, continue training yourself in alternative technologies as a "plan b" to not become obsolete along with the language.
And always work to keep your coding and problem solving skills "in good shape" as this kind of language does not help in that.
Yes, any competent programmer, and even some not-so-competent ones can use PowerBuilder. However, I'd disagree somewhat with one of the earlier answers. It is different from pre-.Net VB in one sense: it supports true OO principles (encapsulation, inheritance, and inclusional polymorphism [but not operational polymorphism via Interfaces as in C# and Java]). Classic VB didn't have inheritance.
Other answers from Paul Lefebvre and Colin Pickard are correct: PB is still alive though more of a niche language than it used to be, and Sybase is indeed moving it in the direction of .Net. As for source control, PB supports some interfaces (we use it with VSS) but I'm thankful for Colin's nice set of links, which may come in handy in the future.
Frameworks: the most common one is the PowerBuilder Foundation Class, which Sybase open sourced years ago.
My caveat to you is this: I said above that people didn't have to be particularly strong programmers to write PB. PB is easy to learn but takes time to master. It had its biggest days in the late 90's, when anyone that could double-click on a Windows icon to launch an app thought they were a programmer. Despite truly supporting OO, most PB apps are not well designed and well written apps. They're usually total hack jobs (a criticism of the lack of experienced developers and immaturity of software development at the time, not of PB itself, which is still a very powerful tool). If you are inheriting a code base that is truly easy to maintain and manage, you are in the minority. PB code can nearly always be classified as legacy code. The good news is that there is plenty of challenge. You will have many quick-win refactoring opportunities and plenty of production support.
With the risk of sounding biased I think PB is one of the better RAD tools out there and the new version PB12 scheduled next year will make it once again interesting since it uses the VSShell from Visual studio as its new IDE (Intellisense etc). I am currently busy working in the compiler team adding all the .NET goodies to PowerScript that one is used to from C# like delegates, interfaces, attributes etc but still keeping the language simple to use. PB is also one of the few development platforms that provide migration from older to newer versions and the new PB12 is no exception. The applications generated by PB12 will be modern looking using WPF and later Silverlight for post PB12 so I am quite excited. I am not a PB developer per se (C++) but I still think for producing C/S apps fast its hard to beat.
It depends on the technical quality of the original application whether migrate to another language is feasible at all.
BEFORE YOU READ MY "PB IS GOOOD": I'm a PowerBuilder developer since '93. PowerBuilder is very much alive and kicking. Yes a lot of people left the language shortly after the millenium but quite a few have returned later. No I don't earn money selling PB!
The biggest differentiator between PowerBuilder applications and any other tool is the DataWindow technology. It is such a strong tool in the hands of an knowledgeable developer. Examples: Dynamic creation of optimal SQL for INSERT/UPDATE/DELETE. Close to every property of everything can be an expression using data in the DW buffers. DropDown DWs are so cool. DW and the rest of PB is truly DBMS independent!
How important is code completion when many of my DataWindows only need 4 function calls anyway?
Define DB connection >> dwData.SetTransObject(SQLCA)
Read all data from DB >> dwData.Retrieve()
Write data to DB >> dwData.Update(true, false)
Reset when committed >> dwData.ResetUpdate( )
My bet: If the original developers knew how to really exploit DataWindows - any estimates you make on migration to Java or C# will not even come close to what will actually happen. If they didn't: The application is just another application that does data binding differently than your new tool.
What you loose when using PowerBuilder? You need to accept that the 4GL and its VM are designed as they are - no access to the source code of the VM so you can't make your own VM customizations. No turning off the NULL support to increase speed. No changing the event order by rewriting the VM's event manager. 4GL means less lines of code. DataWindow means a lot less LOC. 4GL means less geaky bit tweaking.
/MicKr-
BTW: PocketBuilder is PB for Windows Mobile - cool idea!
Yes, you would certainly be able to learn PowerBuilder. Whether you want to is a question only you can answer, though.
I used PowerBuilder for many, many years (versions 4 through 9). There were parts I truly liked. It's a great way to build business applications. It's object-oriented and the DataWindow is a wonderful technology.
But it has its bad points as well. The IDE is archaic. The code editor is simplistic (no code completion, for example). Integration with source control is annoying and the community is pretty small. And it's Windows-only.
There is a magazine (PowerBuilder Developer's Journal - SYSCON), but it's pretty thin these days. Sybase does appear to have some neat things up their sleeves for future versions of PowerBuilder, however.
Personally, I liked it enough that I would go back to it if an opportunity arose.
I worked on powerbuilder quite sometime back, version 6.5
Its quite easy to use and one can compare it to VB.
I feel it would be quite easy to maintain an application and do small fixes and enhance the system.
There are quite a few companies that still use powerbuilder and maintain old application.
Powerbuilder is very easy, and you will find datawindows objects very helpfull to make reports, interfaces, forms, etc..
If you know visual basic, it will be easier
i learned powerbuilder in 2 months.
A disadvantage of powerbuilder is the cost per license.
Since both the java implementation (OpenJDK) and Android's virtual machine DalvikVM are opensource it must be possible to implement Sun's JavaVM on top Google's DalvikVM. This would make it possible to run JVM based apps and languages (Clojure, Jython) out-of-the-box on the android.
Is there an ongoing effort to produce such an implementation of the Sun JVM?
The OpenJDK makes use of native code so it would be a non-trivial port... there is at least one VM (JikesRVM) that is written in Java, unfortunately it is not a completely working implementation of Java.
Since DalvikVM runs classes that were converted from .class files it should be possible to convert the classes over. Then the "only" issue is when languages generate bytecode on the fly - for that it would require the extra step of converting the generated bytecode over to the DalvikVM format while the program is running on the DalvikVM.
Hmmm.... sort of a JITT (Just In Time Translator) that covertes class files to a DalvikVM files at runtime on the phone. I wonder how slow that would be.
Porting OpenJDK to Android platform is possible. There are effort like : Shark, Zero and caciocavallo that vastly ease the port process (= no ASM, simple AWT peer). Plus Android is nothing but a linux kernel behind. The only question is when will it be done by anybody ?
By the way, both iphones and android phones got Jazelle compatible processor, somebody with very strong processor hacking skills would be very welcome to add Jazelle support to OpenJDK.
Doing so, we could choose between : very light resource acceleration (Jazelle) and JIT ;-)
About iPhone, it is the same thing : a port is possible. Only Apple has put a section in the the iPhone license that clearly forbid VM usage. As per European law, to me, this license section is unlegal. Two reasons : You can not force/link buy of two of your product. Here I tune and Iphones are linked. You can not refuse to sell something that you can sell. Here as soon as a VM would be build for iPhone, if it is refused to be put on the iTune store, then this point will apply. Is there anybody that want to chalenge Apple licence legality on earth ? I don't think so, unhappy people will be flying to Android or any other platform.
In the meantime I have found a possible solution (only JavaME):
"MicroEmulator is a pure Java implementation of Java ME in Java SE."
Running Java ME applications on Android
technically it should be possible to interpret hotspot byte-code on dalvik vm or dalvik's byte-code on hotspot, but it will never be efficient (not mentioning elegant) design for a long run. the cost of doing that might become very high especially with respect to maintenance in the future evolution of such a split ecosystem.
i think, from the very beginning, dalvik vm is a matter of power/market control rather than innovative effort to improve java virtual machine ecosystem. dalvik vm and hotspot vm are lake two highway bridges across the same river build in parallel five meters from each other. it divides and brings confusion to java technological ecosystem.
google is, in my opinion, definitely the technological leader with innovative contributions over last decade that dwarf far more conservative oracle, but in this very subject they have shaken the java ecosystem in nearly destructive way. we (programmers) should strive for a single uniform solution to this problem. that is the main idea behind the concept of "virtual machine" anyway - it should not belong to neither google nor oracle.
try GNURoot app (proot ptrace container) with debian Wheezy;
apt-get update
apt-get install openjdk-7-jre
/usr/lib/jvm/java-7-openjdk-armel/jre/bin/java ...
(including long path)
I don't think the problem is technical. In theory you can migrate OpenJDK to the iPhone for example, but there are legal restriction in place.
See http://davy.preuveneers.be/phoneme/ for MIDP, Foundation and Personal Profile jvms for Android ARM apks. (Thank you Davy!!!)
I have repackaged the Foundation jvm for command line use and host it at vkfox.com/android/bin/foundation-jvm.bin for your pleasure. One could use the eclipse compiler in the JavaIDEdroid free app, or the old kopi or kopisusu compilers with this jvm, togeather with the stubbed cdc + foundation jar file from a J2ME jdk for an onboard development system. Using the features of TerminalIDE -- console and sun compiler -- with indicated ref jars would also get you there. This is essentially equivalent to a headless jdk1.4 with the possibility of MIDP or awt graphics.
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Closed 11 years ago.
Why would you choose java over others? Why did you choose java to program your application?
Please include what you are using java for (desktop application/ web application/ mobile).
Excellent tooling: IDE, CI, etc.
Vast array of 3rd party libraries.
Huge amount of documentation available.
Large pool of developers available.
Platform ubiquitous.
Excellent performance.
Excellent specification.
Sturdy garbage collection.
Managed memory.
Native threads.
Choice - implemented by multiple vendors.
I have used Java to build various middle-ware products: Inventory mgmt; CMS; chemical registration; etc.
One of the nice things about Java is that everyone knows it. Of course, now that I've said that, I'll get 80 comments from people claiming to have never learned the language. Be that as it may...
Like it or not, Java is the closest thing to a lingua franca (the idiom means "common language") we have in the industry today. Just about every has either used Java at some point, or (more commonly) is actively using it now. That sort of ubiquity can be extremely attractive to some companies, particularly those reliant on consultants. If you start a project in Java, you're pretty much guaranteed to be able to find talent to maintain the code base for years down the road.
On a different tack, Java is an excellent language for developing cross-platform desktop applications...it's just that nobody knows it. Most of Java's dominance is on the server side coupled with a little bit of love from the J2ME crowd. However, if you objectively consider Swing in Java 6uN, it's hard to find a better tool for the job. Don't get me wrong, I see that it has its flaws, but many of those have been fixed in recent releases. Most of the issue now is mindshare: everybody knows that Java is slow and ugly (neither of which is strictly true anymore). The other problem is that Swing is very much a cross-platform UI toolkit. This means that it is inherently much harder to create professional UIs in Swing than in Cocoa or even WinForms.
Finally, a really great reason to pick Java (as opposed to .NET or Objective-C) is the ecosystem. Other answers have mentioned libraries, which really deserve a significant spotlight; but I'm thinking specifically of the rising language diversity. If you write an application in Java today, you can seamlessly transition to Scala at any time. You also have the option to do scripting in Groovy or JRuby, not to mention taking advantage of the powerful concurrency abstractions in Clojure. Because of its portability and high-level nature, the JVM is increasingly the preferred target for language compilers and interpreters (even more than the CLR). Java is really at the center of that nexus, not really benefiting directly from the vast cloud of languages which swarm around it, but certainly deriving value from all of the interoperability, present and future.
My reasons for prefering Java over other programming languages at this time are:
price - it's free
performance - really fast these days thanks to the HotSpot JIT compiler
effectiveness - lots of power with rigorous features like type-safe, sand-boxed, etc.
OOP capability
very good, well-thought out exception handliing; C++ exceptions are the opposite!
portability - it runs on almost everything
tool availability - awesome IDEs like Eclipse & NetBeans are free, as are web servers like Tomcat and application servers (JBoss, Glassfish, Geronimo, etc.)
flexibility - does graphics, desktop GUIs, web user interfaces - all kinds of things in all kinds of runtime environments
aptness - many enterprise apps today have to support HTML, SQL, and XML - Java has good support for all of them built in and you can get third-party libraries for free that make this even easier/better
well-supported - Sun keeps adding improvements and fixing thing going one or two versions back
forward compatibility - unlike something like VB which undergoes wrenching change in its syntax every couple versions or so, Java's syntax and semantics seem about 99.9% upward compatible from version to version
I have been writing programs in Java for over a decade and I am pretty satisfied with it. I have used other languages for almost two decades before that. So I am not biased by describing the one thing I know - it is one of many languages I know intimately.
When upgrades to the JDK/JRE come out, I look the documentation over to see what is changed. Sun is good about telling/explaining this. I have never had an extremely rough time porting from one JDK to the next.
When I have switched from one OS to another as my main OS at home or at work, it has not caused a problem for the Java applications I write - or the tools I use, generally. The one exception is Borland JBuilder, which some Borland marketing or technical genius decided to frequently stop supporting. Eclipse and Netbeans run terrifically on the Mac and probably always will. I have used Java on:
MS-Windows 95, 98, NT4, 2000, XP
Sun Solaris/SunOS Unix
IBM AIX
Mac OS X
Linux
Motorola cell phones (MIDP, CLDC)
Palm Pilot PDA
Java VMs (virtual machines) are everywhere! They are in:
web browsers
cell phones
PDAs
desktop computers
web servers
application servers
I have written programs on all of these. All you have to do is get an IDE with the right plugins, get the API documentation for the target environment you want, and start programming.
The GUI programs I write actually do look & work correctly on different platforms! I cannot tell you how long other vendors promised to do and how often/long they have failed. Just look around, some still exist.
Sun promised this in Java 1.0 and they sort of delivered it with AWT. However, the abstract windowing toolkit used native GUI components and the differences between these components (which followed no unifying standard at all) were too great to get same/nice look/behavior on all platforms.
Sun delivered very well upon this portable GUI promise when the Swing GUI API was delivered a decade ago, back in December 1998.
1) Very good and free documentation
2) Very good developer commercial and free tools
3) good certification and training resources
4) good runtime and free tools
5) good profiling and monitoring tools
6) very good support options from various companies
7) very good open source community with huge amount of libraries
Things not yet mentioned:
Cross-platform Desktop Application, even with sophisticated GUI
bunch of tools
static typing (see GWT)
error messages at compile time
very clear error messages
Java provides a very rich API right out of the box and hands-down produces the most portable applications since there is a Java VM for almost every platform.
BTW: I haven't used Java since I left college since I work for a Microsoft shop, but I can't think of a single thing I can do in C# that I can't do in Java, whether it be enterprise applications, web applications, or desktop applications.
Portability is the key to java. I know that a program that i am coding will run on any system, there is no need to create different releases for different OS's.
Java also offers built in security, making the coding of the safe programs easier.
Java is fast, with clean code java is benchmarking in the same range as C++.
C# is the language that gets compared to java the most often. C# isn't as portable as java, and has very few features that java doesn't. This makes java much more attractive unless the program will ONLY be run on a single OS, in that case i might code it in C++.
I switched from years of C++ to Java because I was working on higher level stuff and needed the benefits of memory management, reflection, and sandboxed execution that I get with Java.
I have tried COM in the late nineties and could not touch it.
.NET looks promising and in many ways is now much better than Java. Unfortunately, being window-centric is a complete dealbreaker for me.
Another benefit is the awesome static analysis tools available e.g. FindBugs. These perform a lot of checking on your code above and beyond those performed by the compiler, and can help identify bugs and/or code smells before testing begins.
Lots of great reasons have already been mentioned. I'd like to add the political part. I trust Suns language a lot more than Microsoft alternatives. It's not because I hate Microsoft, it's just that Sun is going a direction with Java that I really like, and Microsoft is going a direction with .net etc. that I really don't like.
This is very subjective, I know. But to me it seems like Sun really want to create a great language, and try to make money somehow. While Microsoft seems more interested in making money by vendor lock-in and systems that looks great and feels great, but may not be as good as it looks in the long run.
So the way Microsoft is handling it right now, I don't even care about how good or bad it is, technically. I don't care, I'm not going to use it.
Java has everything I want from this kind of programming language, including all the boring political stuff most people just skip. I don't know about any other current language that has all that.
The main reason I use Java for most of my desktop app projects is for cross-platform compatibility. It's quite easy to make your app run on OS X, Windows, and Linux and look native on all platforms.
I use Java for our BPM platform and used Java in the past for enterprise web apps.
It depends on what you want to do. Considering language features, libraries available and IDE experience, I personally would choose C# over Java. C# 3.0 has many useful features that Java lacks, such as LINQ, Lambda expressions, etc. Some people prefer the huge library choice that is available for Java, but I think there are just too many ways of doing things. Java IDEs like Eclipse and NetBeans are getting better, but I think Visual Studio is still much easier to work with.
Of course,if you are not using Windows, you don't have much of a choice but to choose Java. Ruby and Python can be good options for things like utility apps and GUIs, including Web apps, but for enterprise apps that don't use Windows, Java is pretty much the only option.
Please don't follow blindly all java-entousiasts. Java has its own flaws. Java is great for rapid development, enterprise oriented stuff, and "high productivity" project (with the tons of projects, community,...).
And if one guy show me a benchmark highlighting how java code can be as optimal as C stuff doesn't mean the complete java solution is fast and lightweight.
Java will never find its way on some performance critical applications, like games, codecs, web browser. No major game software is developed in java, and not because the developper are not capable of writing one piece of Java code that has the same speed as C or C++, this is because the very limitations of the language involves that performance and memory consuption will never reach a good C/C++ code. Takes VisualStudio and Eclipse. Java is great for one stuff (productivity stuff, enterprise middleware), but if you want to write codecs, games, performance critical libraries, you'd better try knowing C.
But, one the other hand, you'll write the java code faster and safer, with C and C++ you're taking more risk (pointers!) and this takes usually more time.
And don't forget the joke "Write once, Debug everywhere", this is actually true. You have to deal with different JVM implementation nightmare with Java.
Other programming language have their interest, bash/python scripts for local scripts (repetitive action, fast and quick UI,...). Php or ruby for webapplication are very well deployed and documented on the web.
Using it for desktop applications.
Excellent IDEs available, wonderful API, "C-style" syntax makes it easy to pickup. Once the JVM starts, the performance is great.
Why would I choose Java - is it the most popular language out there right now? If not, it's gotta be damn close, so if I'm building a product I might choose this because it would be the easiest to hire developers for.
Why did I choose Java - because it's what I know best.
Why would I choose Java? If I happened to have a team of replaceable code monkeys developers that knew Java better than anything else, that is probably what I'd go with.
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Closed 10 years ago.
How much less libraries are there for Mono than for Java?
I lack the overview over both alternatives but I have pretty much freedom of choice for my next project. I'm looking for hard technical facts in the areas of
performance (for example, I'm told Java is good for threading, and I hear the runtime code optimization has become very good recently for .NET)
real world portability (it's both meant to be portable, what's Catch-22 for each?)
tool availability (CI, build automation, debugging, IDE)
I am especially looking for what you actually experienced in your own work rather than the things I could google. My application would be a back-end service processing large amounts of data from time series.
My main target platform would be Linux.
Edit:
To phrase my question more adequately, I am interested in the whole package (3rd party libraries etc.), not just the language. For libraries, that probably boils down to the question "how much less libraries are there for Mono than for Java"?
FYI, I have since chosen Java for this project, because it seemed just more battle-worn on the portability side and it's been around for a while on older systems, too. I'm a tiny little bit sad about it, because I'm very curious about C# and I'd love to have done some large project in it, but maybe next time. Thanks for all the advice.
Mono does a better job at targeting the platforms I want to support. Other than that, it is all subjective.
I share C# code across the following platforms:
- iOS (iPhone/iPad)
- Android
- The Web (HTML5)
- Mac (OS X)
- Linux
- Windows
I could share it even more places:
- Windows Phone 7
- Wii
- XBox
- PS3
- etc.
The biggie is iOS since MonoTouch works fantastically. I do not know of any good way to target iOS with Java. You cannot target Windows Phone 7 with Java, so I would say that the days of Java being better for mobile are behind us.
The biggest factor for me though is personal productivity (and happiness). C# as a language is years ahead of Java IMHO and the .NET framework is a joy to use. Most of what is being added in Java 7 and Java 8 has been in C# for years. JVM languages like Scala and Clojure (both available on the CLR) are pretty nice though.
I see Mono as a platform in it's own right (a great one) and treat .NET as the Microsoft implementation of Mono on Windows. This means that I develop and test on Mono first. This works wonderfully.
If both Java and .NET (Mono let's say) were Open Source projects without any corporate backing, I would choose Mono over Java every time. I believe it is just a better platform.
Both .NET/Mono and the JVM are great choices, although I would personally use some other language than Java on the JVM.
My take on some of the other comments:
Issue: Performance.
**Answer: Both the JVM and the CLR perform better than detractors say they do. I would say that the JVM performs better. Mono is generally slower than .NET (though not always).
I personally would take ASP.NET MVC over J2EE any day both as a developer and an end-user. Support for Google Native Client is pretty cool too. Also, I know that poor GUI performance for desktop Java apps is supposed to be a thing of the past but I keep finding slow ones. Then again, I could say the same for WPF. GTK# is plenty fast though so there is no reason they have to be slow.
Issue: Java has a larger ecosystem of libraries available.
Answer: Probably true, but it is a non-issue in practice.
Practically every Java library (including the JDK) runs just dandy on .NET/Mono thanks to IKVM.NET. This piece of technology is a true marvel. The integration is amazing; you can use a Java library just like it was native. I have only had to use Java libraries in one .NET app though. The .NET/Mono ecosystem generally offers more than I need.
Issue: Java has better (broader) tools support
Answer: Not on Windows. Otherwise I agree. MonoDevelop is nice though.
I want to give a shout-out to MonoDevelop; it is a jewel. MonoDevelop integrates most of the tools I want use including code completion (intellisense), Git/Subversion integration, support for unit tests, SQL integration, debugging, easy refactoring, and assembly browsing with on-the-fly decompilation. It is wonderful to use the same environment for everything from server-side web to mobile apps.
Issue: Compatibility across platforms.
Answer: Mono is a single code-base across all platforms, including Windows.
Develop for Mono first and deploy to .NET on Windows if you like. If you compare .NET from MS to Java though then Java has the edge in terms of consistency across platforms. See next answer...
Issue: Mono lags .NET.
Answer: No it does not. IMHO, this is an often stated but incorrect statement.
The Mono distribution from Xamarin ships with C#, VB.NET, F#, IronPython, IronRuby, and I think maybe Boo out of the box. The Mono C# compiler is completely up to date with MS. The Mono VB.NET compiler does lag the MS version. The other compilers are the same on both platforms (as are other .NET languages like Nemerle, Boo, and Phalanger (PHP) ).
Mono ships with a lot of the actual Microsoft written code including the Dynamic Language Runtime (DLR), Managed Extensibility Framework (MEF), F#, and ASP.NET MVC. Because Razor is not Open Source, Mono currently ships with MVC2 but MVC3 works on Mono just fine.
The core Mono platform has kept pace with .NET or many years and the compatibility is impressive. You can use the full C# 4.0 language and even some C# 5.0 features today. In fact, Mono often leads .NET in many ways.
Mono implements parts of the CLR spec that even Microsoft does not support (like 64 bit arrays). One of the most exciting new pieces of technology in the .NET world is Rosylyn. Mono has offered the C# compiler as a service for many years. Some of what Rosylyn offers is available via NRefractory as well. An example of were Mono is still ahead would be the SIMD instructions to accelerate gaming performance.
Microsoft does offer a number of products on top of .NET that are not available in Mono which is were the misconception about Mono lagging comes from. Windows Presentation Foundation (WPF), Entity Framework (EF), WCF (Windows Communication Foundation) are examples of products which do not work, or are poorly supported, on Mono. The obvious solution is to use cross-platform alternatives like GTK#, NHibernate, and ServiceStack instead.
Issue: Microsoft is evil.
Answer: True. So what.
Many people offer the following reasons to avoid using Mono:
1) You should not use Mono because Microsoft tech should be avoided
2) Mono sucks because it does not let you use every technology that Microsoft offers
To me, it is clear that these statements are incompatible. I reject the first statement but will skip that argument here. The second statement is true of all .NET alternatives.
The JVM is a great platform and the explosion of JVM languages is awesome. Use what makes you happy. For now, that is often .NET/Mono for me.
Well....Java is actually more portable. Mono isn't implemented everywhere, and it lags behind the Microsoft implementation significantly. The Java SDK seems to stay in better sync across platforms (and it works on more platforms).
I'd also say Java has more tool availability across all those platforms, although there are plenty of tools available for .NET on Windows platforms.
Update for 2014
I still hold this opinion in 2014. However, I'll qualify this by saying I'm just now starting to pay some attention to Mono after a long while of not really caring, so there may be improvements in the Mono runtime (or ecosystem) that I haven't been made aware of. AFAIK, there is still no support for WPF, WCF, WF, of WIF. Mono can run on iOS, but to my knowledge, the Java runtime still runs on far more platforms than Mono. Also, Mono is starting to see some much improved tooling (Xamarin), and Microsoft seems to have a much more cross-platform kind of attitude and willingness to work with partners to make them complimentary, rather than competitive (for example, Mono will be a pretty important part of the upcoming OWIN/Helios ASP.NET landscape). I suspect that in the coming years the differences in portability will lessen rapidly, especially after .NET being open-sourced.
Update for 2018
My view on this is starting to go the other way. I think .NET, broadly, particularly with .NET Core, has started to achieve "portability parity" with Java. There are efforts underway to bring WPF to .NET Core for some platforms, and .NET Core itself runs on a great many platforms now. Mono (owned by Xamarin, which is now owned by Microsoft) is a more mature and polished product than ever, and writing applications that work on multiple platforms is no longer the domain of deep gnosis of .NET hackery, but is a relatively straightforward endeavor. There are, of course, libraries and services and applications that are Windows-only or can only target specific platforms - but the same can be said of Java (broadly).
If I were in the OP's shoes at this point, I can think of no reason inherent in the languages or tech stacks themselves that would prevent me from choosing .NET for any application going forward from this point.
I actually develop in .NET, run all my tests first on Mono, and then on Windows. That way I know my applications are cross platform. I have done this very successfully on both ASP.NET and Winforms applications.
I am not really sure where some people get the impression Mono is so horrible from, but it certainly has done it's job in my cases and opinions.It is true you will have a bit of lag for the latest and greatest inventions in the .NET world, but so far, .NET 2.0 on Windows and Linux is very solid for me.
Keep in mind there are obviously many quirks to this, but most of them come from making sure you are writing portable code. While the frameworks do a great job of abstracting away what OS you are running on, little things like Linux's case sensitivity in paths and file names takes a bit of getting used to, as do things like permissions.
.NET is definitely very cross platform due to Mono based on my experiences so far.
Java actually is as cross-platform as everyone says it is. There's a JVM implementation for just about any mainstream OS out there (even Mac OS X, finally), and they all work really well. And there's tons of open source tools out there that are just as cross platform.
The only catch is that there are certain native operations you can't do in Java without writing some DLLs or SOs. It's very rare that these come up in practice. In all those cases, though, I've been able to get around it by spawning native processes and screen-scraping the results.
I think the question is phrased incorrectly. C# vs. Java is much less interesting in terms of cross-platform usage than is (a) which platforms you need to support, and (b) considering the core libraries and available third party libraries. The language is almost the least important part of the decision-making process.
Java is a better choice for Cross-Platform development.
Performance. Java and .Net have similar performance level due to the virtual machine, but JVM normally has better performance because of years and years optimization.
Library. Although this depends on your task, Java has much more open source or third party libraries available there. For server App, J2EE, Spring, Struts, etc. For GUI, although .Net provides Win32 layer API but this causes compatibility issues. Java has Swing, SWT, AWT, etc. It works in most cases.
Compatibility. This is the key issues that need to be considered when develop the cross-platform program. Two issue: first, platform compatibility. Java still wins since JDK is well maintained by single and original company Sun. Mono is not maintained by MS, so you have no guarantee yet for update compatibility. 2. Backward compatibility. Sun maintains a good reputation on their backward compatibility, although sometimes this seems too rigid and slows the pace.
Tools. Java has good cross-platform IDEs. Netbeans, Eclipse, etc. Most of them are free. VS Studio is good but only on Windows, and not cost a bit. Both of them provides good unit tests, debugs, profiles, etc.
Hence I'd suggest that Java is a better choice. As a show case, there are some famous desktop cross-platforms apps developed by Java: Vuze, Limewire, BlogBridge, CrossFTP, not to mention those IDEs. As to .Net, I have limited knowledge on such success apps.
I've been asking the same question off-late and IMHO, .NET/Mono seems to be a better option simply because Mono has a great track record for cross-platform desktop applications (as opposed to Java) and of course, Mono is improving by leaps and bounds these days.
I'm going to say Java as well. If you look at it in terms of maturity, a lot more time and effort has been expended by Sun (and others) in getting the JVM to work on non-Windows platforms.
In contrast, Mono is definitely a second class citizen in the .NET ecosystem.
Depending on who your target customers are, you may also find there is real pushback against using Mono - does Novell offer the same kind of vendor support for Mono that you would get for Java or .NET on Windows?
If you were primarily targeting hosting your service on Windows, it would make sense to be considering this choice, but since you're targeting Linux primarily, it seems like kind of a no-brainer to me.
Java was designed to be cross-platform; C#/.Net wasn't. When in doubt, use the tool that was designed for your purpose.
EDIT: in fairness, .NET was designed to work on embedded/PC/Server environments, so that's SORT of cross-platform. But it wasn't designed for Linux.
I think the answer is "it depends." Java runs on just about anything, but .NET/Mono are (IMHO) a better framework for the desktop. So I guess the answer really depends on what platforms you plan on targeting.
To add a bit more to the conversation, Java is more portable if you remain about one version behind - Java 5 still has many excellent features so you can wait for Java 6 and still have a lot of range in terms of language and libraries to develop with. The Mac is the primary platform that can take some time to catch up to the latest Java version.
Java also has an excellent standards body that intelligently grows the platform based on input from many different companies. This is an oft overlooked feature but it keeps even new features working well across multiple platforms and provides a lot of range in library support for some esoteric things (as optional extensions).
I would vote for Java being more portable than C#. Java definitely also has a very rich set of standard libraries. There is also a broad set of open source 3rd party libraries out there such as those provided by the Jakarta project (http://jakarta.apache.org/).
All the usual suspects exist for CI, Unit testing, etc too. Cross platform IDE support is also very good with the likes of Eclipse, Netbeans, IntelliJ IDEA etc.
There are other language choices too. I've become quite fond of Python, which works well on Windows, Linux, and Mac, and has a rich set of libraries.
While Mono has its share of problems I think it has a better cross-platform compatibility story especially IF you have reliance on native platform invocation.
There are not enough words on Stack Overflow to stress how much smoother it is to get something native called and executed in .NET/Mono on (at least in my experience 3...) multiple platforms vs. the equivalent Java effort.
Gatorhall do you have some data to back that up?
Performance. Java and .Net have similar performance level due to the virtual machine, but JVM normally has better performance because of years and years optimization.
Background: I'm a Windows guy since Windows 3.1 and currently a Linux user (still running Windows 7, great OS, on a VM for Visual Studio 2010 and other tools).
The point: me and a lot of users (windows, linux, etc) I know, may disagree from you. Java tends to perform slower even on a linux desktop application, ASP.NET perform's faster that java server pages many of the times. Some may agree that even non-compiled PHP performs better i several scenarios.
Java is more cross-platform? I have no doubts about this (the history back this on), but faster (not saying .NET is) not so certain and I would like to see some real benchmarks.