JNI, C++, Idea, and Netbeans looks good

I’ve been trying to get comfortable with C++. I’m finding quite a few native libraries that I need to talk to… programmatically. So I tried GEdit. Then I moved on to Windows and Eclipse. Everytime I want to install an Eclipse plugin I somehow find it easier to just grab an Eclipse bundle. (Plugin conflicts can burn so much clock.) Grabbing the Eclipse CDT, I found myself accidentally expanding and overwriting my Blackberry Eclipse install. (I always expand to C:\eclipse, it’s just a habit.) Frustrated, I decided to boot back into Linux and try Idea. I tried out the C++ plugin under Idea and had some minor trouble because there’s no documentation on it. I then tried KDevelop. Then something came over me. I decided to try out Netbeans. Netbeans…

Once upon a time there was an IDE I kinda liked. It was Forte (based on Netbeans). That was my first Netbeansy experience. Back then I was satisfied but then I found Eclipse and later got hooked on Idea. Netbeans was something I always toyed with here and there. I liked it but it lacked the refactoring support in Idea. Still it was kinda cool.

Fast forward a couple of years and now I’m all about Eclipse and Idea. I use Eclipse only because others force it on me. RIM tools are built for it, most people in my company swear by it. Every time I need to do something slightly different there seems to be an Eclipse bundle for that. It’s pretty full featured only falling behind Idea in a couple of spots. It’s just a pain to configure/setup. Idea has always been my tool of choice. If I could write ObjC in Idea I’d pitch XCode in a minute.

Today I tried Netbeans for the first time since it turned 5. I almost fell out my chair when I instinctively hit Alt+Enter to fix a syntax error. It worked! Just like Idea! Then I started looking at the right click and refactoring menus. I got really happy! Netbeans is now starting to feel like Idea felt back in the day. To be honest, Idea has been giving me lots of trouble these days with plugin “Blame this plugin” error pop-ups and the AWT_TOOLKIT thing that causes the text area to become uneditable. Overall Netbeans is looking much improved! I am totally impressed… I want to write more about both, my experience with Netbeans and my use of the C++ plugin under Idea.

Don’t forget to flush!

It’s been a rough day. I spent the majority of it chasing down random misbehavior on a staging server. My development machine is 32 bit. (Technically my development machine is 64 bit but I’m running a 32bit Kernel in my OS.) The staging server is 64bit. I write Java. Java sez, “you write once and run anywhere!” In reality, when I move compiled source code from my development machine to my staging machine things act radically different.

The big picture is that I’m trying to make the staging machine talk to me. I mean literally talk, using english words and all. It’s the extra 32 bits in this staging machine that have been getting in the way. They force me to scour the web and find native libraries that contain the same amount of extra chromosomes… err… bits. Then on top of that, Tomcat likes to do different things when you throw war files in it.

Today’s lesson begins from Tomcat. Pretend you’ve written a servlet. (Ok, you don’t have to pretend. Go on and write a servlet if it makes you feel better, I’ll wait here patiently.) In your servlet make like you have a lot of binary stuff that you want to share with connecting web people. These people might be sitting under a MacbookPro, or scrolling a Blackberry wheel, or flicking an iPhone or something. Whatever the case, they came to your servlet to get these wonderful binary thingies. These binary thingies are larger than your typical web page, spanning a few kilobytes. So now you have to use one of those stream classes. If you’re really smart, like I think I am, then you’ll do something clever [stupid] and try pipelining, or reading from an input stream and writing to an output stream. You’ll do this because you’re afraid of materializing too much binary goodness in your precious RAM sticks. You’ll say “1024 bytes is plenty enough! Let’s take these one thousand twenty four bytes and put them on the output stream for the people can get those!” Then if you’re really really smart, you’ll do this in a loop until you reach the bottom of your input stream.

Are you all done with your computer program? I think I’m done with mine! Goody! Lets mash the run button and see what happens? Is yourz doing like mine isn’t doing? Minez is supposed to be shuttling all of the binary stuff across teh internets, but its not because its borked. I only get part of what I thought I was gonna git. Now go scratch your head like the guys in the head and shoulders commercials and pour another cup of coffee. when you get back we’ll figure out wha happend…

Are you back yet? Cool! Lets look into your really really smart looping program. Do you see it? Right there in the middle of your loop. You keep writin’ stuff but only part of it is showing on the other end. Any idea why? My Mommy told me a long time ago, “never forget to flush! It’s just bad manners…” She was also famous for saying stuff like, “poop or get off the pot!” In the loop thing we never flush our output stream! Maybe that’s why we only see a part of the stuff on the other end. So then there’s a happy ending to the story after all isn’t there?

Linux Can’t load library:libmawt.so

Your a Java developer and you’ve installed Linux. Maybe this is your first time converting from Windows. Maybe you’re a Linux veteran trying Java for the first time. Maybe you’re new to both Java and Linux and you’re running some crappy program some other Java guy wrote. Whatever your background is, you now find yourself staring at an unstatisfied link error. You don’t know what angered the link and you have no idea how to satisfy it. Hi, I’m Cliff and you’re here because you suck at satisfying links. But we already knew that, didn’t we? Does the error below look familiar?

java.lang.UnsatisfiedLinkError: Can’t load library: /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/motif21/libmawt.so
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1666)
at java.lang.Runtime.load0(Runtime.java:787)
at java.lang.System.load(System.java:1022)
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1767)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1684)
at java.lang.Runtime.loadLibrary0(Runtime.java:840)
at java.lang.System.loadLibrary(System.java:1047)
at sun.security.action.LoadLibraryAction.run(LoadLibraryAction.java:67)
at sun.security.action.LoadLibraryAction.run(LoadLibraryAction.java:47)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Toolkit.loadLibraries(Toolkit.java:1610)
at java.awt.Toolkit.(Toolkit.java:1632)

The long answer begins, “four score and seventeen (…seven? …several?) years ago…” and continues with babbling about openjdk and motif libs with a bunch of other nonsense you probably don’t particularly care about. The short story (which is also why you’re here listening to the most long-winded developer this side of the east coast that loves to insert rambling between parenthesis as if that makes any of his blog posts easier on the eyes…) is that you probably need to unset or set an environment variable. “export AWT_TOOLKIT=MToolkit” will cause the error while “export AWT_TOOLKIT=XToolkit” should make it go away. The environment variable controls which one of Linux’s windowing toolkits are used to draw the program on your screen. The MToolkit causes the Java program to look for the “libmawt.so” file which is a Motif Abstract Windowing Toolkit Shared Object, hence the “m-a-w-t.s-o” in the file name. Shared objects are the Linux way of sharing code. Other operating systems use other files. Windows uses “.dll” files, while Mac OSX uses “dylib” files. The Abstract Windowing Toolkit is the Java way of drawing programs on your screen which is abstract so that it can change the way the program looks and feels. Motif is one of the many looks of a java program, while others include “Native”, “Metal”, “Aqua” and others. Not all of these looks are available in each distribution of Java so chances are that you copied a program from a system (or developed a program for a system) that included the Motif look and feel and now you’re trying to run it on your fresh Linux install.

The good news is the problem is easy to fix once you know the how and why. The bad news is you’ll probably do something clever like putting “AWT_TOOLKIT=XToolkit” in your “~/.bash_profile” and forget this hack is in place which will likely cause other issues several months down the line when you want to toy with Compiz-Fusion but your IntelliJ editor is acting funny, locking up or going completely dark or something. That’s your good-news/bad-news for the day. Happy coding and clever hacking to you all.

Eclipse: Multiple Problems Have Occurred

So I’m working on some Blackberry development and I’m using the MTJ plugin stuff for Eclipse, right? I’m running things in the debugger using the WTK simulator. Now I wanna add a watch point. I add a watch on a local variable with no problem. Then I right click an instance variable and select “watch”. Eclipse has multiple problems:

Eclipse Has Multiple Problems
Eclipse Has Multiple Problems

Why can’t Eclipse process its asynch thread queue? Why should I care? I’ve posted tough problems like this before and sometimes one or two of you chime in with helpful advice. I don’t normally use Eclipse but I’m trying it for size during this project. Can somebody weigh in here? Have you seen this before? Am I not supposed to watch variables in the debugger while running JME apps under WTK?

`Which Java`?

I’m a little frustrated because I’ve been hitting some memorable distro-issues throughout the week and revisiting some of my old topics to help me through. Today I wanted to install Charles proxy so I can sniff HTTP traffic and rememberize all of the neat-o stuff I used to know about HTTP. Here’s one thing that used to bug me alot, Java explodes on linux. No matter what distro I tried and would inevitably hit a situation where Java would just blow up in my face. I’ll be running my IDE and it will just vanish. Or I’ll be running some app I just wrote and it craps out with VM error stack trace.That prompted me to see which Java I had installed in Mepis. A naive person would type “java -version” on the command line but after years of experience I learned that not only is that misleading it’s downright dangerous! If Java is officially installed (a process that varies from machine to machine and OS to OS and distro to distro) you have to understand that the system can pick a different version of Java than what you get on the command line. The command line is influenced by the $PATH while there are a number of different ways to invoke Java on your system. Consider hitting a page with an Applet? Java runs out of your Browser. Depending on which browser you run you’ll get a different JVM. Consider what happens when you click a Web Start link. You can have Firefox configured to associate it with one version of Java while your file manager (Windows Explorer, KWin, whatever) can associate it with another. Then there’s the executable jar thing. Once again window manager file associations can point someplace you never intended. Lastly there’s batch files and shell scripts. On Linux your $PATH can be overridden in your .bash_profile and/or your .bashrc while the $PATH assumed by your Window Manager is completely different.

So which Java do you get? On Linux you can literally type `which java` and it will tell you the path to the executable but that doesn’t help much. Try adding “ls -la” in front.

ls -la `which java`

Then you’ll see that this is a symbolic link to the actual (sometimes other sym link to the actual) executable. Keep following sym links until you get tired and you’ll find the true path to Java. This used to be controlled by and update-alternatives -config java command but I just tried that on Mepis and it doesn’t exist. I tried looking for update-alternatives under apt-get install update and got nowhere. I’m spilling all these details here because now I really don’t know `which java`???

How to use rapc from RIM… dirty details!

What’s really going on in rapc, Blackberry’s crazed compile tool? Let me begin by telling you that everything you’ve read until this point is not entirely accurate. There are those that will tell you that you have to run preverify.exe prior to running rapc. Then there are those who will tell you that the bb-ant-tools are sufficient. There are people that complain that the RIM compiler has bugs in it. (This may be true but I’ve so far been able to fix broken builds by using all of the advice I’m including here.) I’ve also found a blog that claims you can build from non-Windows operating systems. I’ve read in some places that either WTK or the JDE must be in the PATH so that rapc can find a preverifier. While some of these tips, tools, tutorials work they all have limits. Eventually you’ll find your application either throws random NPE’s, verification errors, or infinitely reboots the device! Now pay attention!

Now let me explain my project. I have a little bit of dependency injection going on via source generation. Then I also have some external jar dependencies. All of this creates a bit of a challenge for basic rapc invocation. In order to generate my midlet cod file I need to:

  • Run a source generator
  • Include the generated source in my list of things to compile
  • somehow include my external jar dependencies in the compile.
  • Include resources in my compiled output
  • Pick up my suit from the cleaners
  • Get the entire thing to run on my Mac?

While the last bullet is entirely optional and irrelevant, I include it because its the only way to get completely familiar with rapc. That is, if I can meet/greet/beat the challenge of cross platform compilation of Blackberry then I’ll really understand the intracacies of compiling with rapc. Now onto the juice.

How Rapc works… I think…
There are various approaches to compiling Blackberry applications that I know of.

  • Compile your app against the MIDP and CLDC APIs (include either WTK or MPowerplayer or someother party’s midp and CLDC jars on your bootstrap classpath for javac… making sure you use javac1.3 or below), preverify with JDE preverify.exe (found in %JDE_HOME%/bin), jar and finally compile with rapc.
  • Compile your application source files entirely with Rapc.

The first option has problems because there’s the possibility that javac will generate class files that will cause verification errors or (as my team discovered recently) the white screen of death when loaded onto the device. The second option has problems because it’s very tricky and prone to the same errors unless you are very dillegent. It took a lot of head banging and trial/error to come up with these details so read closely.

How do we use rapc? This is the question that still plagues me. There’s little documentation around the nuances you’ll encounter when invoking the rapc compiler from the command line. The rapc compiler is an executable (.exe) file in the JDE install directory living under the bin subfolder. First thing to note is the rapc.exe just delegates everything to rapc.jar. That means the same exact command line parameters you would use with rapc.exe will work with rapc.jar. (Call the jar with the “java -jar” command.) The most important thing to understand is that you cannot mix and match. That is you cannot use the output of javac/WTK preverify to fuel rapc. Furthermore you need to pay strict attention to the version of the JDE you use because it must be the same (or earlier) version of your target platform. For eg., if you intend to target Blackberry devices running a 4.2.2 OS you should use the compiler tools from the JDE version 4.2.2 or earlier. If you don’t pay attention to this step your product will work just fine until it’s time to ship… at which time you’ll experience weird, impossible to track/reproduce on a developer workstation, errors. There are other important tools in the JDE that you’ll need as well. The preverify tool is required (unless you’re using JDE 4.3.0 and targeting OS 4.3+) as well as the SignatureTool.jsr. Finally there is the net_rim_api.jar which lives under the lib folder in the JDE install directory. The next big thing to understand is the command line options.

Use the import= to specify the location of the net_rim_api.jar. This flag takes the relative or absolute path of not only the rim APIs but any other jar or cod dependencies your application has. (I haven’t tried cod dependencies but the docs say you can list cod files.) Be careful because this is only for resolving dependencies. Anything you list here will not be included in the final output cod. What this means is any jar files listed here must either be compiled as separate cod libraries or their source files somehow inlined in the final compiled. Dependencies listed here are scope as provided. In other words it is assumed they will be made available at runtime by either the RIM platform or by some pre-installed package.

(codname for 4.3.0+)
This parameter threw me for a minute when I attempted to roll back to an earlier version of the RIM compile toolchain. I believe (and I need to double check and update this fact later) that rapc version 4.3.0 and higher expect a codname flag while versions prior to 4.3.0 expect a codename flag. The value you specify here will be the value used in the output codfile name. Paths can be relative to the working directory (the folder rapc is called from) or possibly absolute paths. For instance if you give build/MyApp as the value then rapc will spit all of its output into the build folder relative to the working directory giving you a final MyApp.cod file there. (you’ll also have MyApp.jar, MyApp.csi, MyApp.debug and other files in this folder.)

This is the application type. Use this flag if you plan to develop a J2ME spec compliant midlet. Blackberry support another application type, cldc, which provides RIM specific features (more on that in possibly another post) and is specified by the mutually exclusive -cldc flag. A You have to -midlet or -cldc to specify which kind of application you are building.

Use this flag if your are building a CLDC application that adheres to RIM’s proprietary launching interfaces. CLDC apps offer abilities to run in the background and be started at device boot time. There are other hidden gems here that I’d have to get into with another post.

Use this parameter if you have a JAD file that includes your application’s meta data. This parameter is optional as you may substitue a .rapc file to include the meta data. Application meta data includes things like the icon to display on the desktop, the midlets contained in your aplication bundle, runtime properties, etc. Referr to the J2ME midlet spec for more detail.

rapc file
This would be the path to a “.rapc” file that includes meta data about your application. I’ll probably follow up with another post to explain the details behind this proprietary RIM spec. While a JAD file also includes meta data there are certain properties that can be included in this file that cannot be included in the JAD file and vice-versa.

class or java files
The last parameter should specify either a jar file containing the compiled classes or be a list of the .java files you intend to compile. Here’s where rapc gets really interesting. If you precompile your “.java” files you had better be certain you run the RIM preverify tool against these class files prior to invoking the compiler. Also I will repeat that you must use the same (or earlier) version preverify as your target platform. For eg., if you intend to target Blackberry devices running a 4.2.2 OS you should use both RIM’s rapc and preverify tools from the JDE version 4.2.2 or earlier. If you don’t pay attention to this step your product will work just fine until it’s time to ship… at which time you’ll experience weird, impossible to track/reproduce on a developer workstation, errors. (I said this before didn’t I?) Rapc is very picky here and the behavior varies between versions. It first calls out to javac assuming that the Java compiler is in the PATH. It then passes the output from javac to preverify. Note that in JDE 4.3.0 both “.java” source compiling and preverification is done from within the rapc.jar while earlier versions of rapc call out to the command line using the command “preverify” (not “preverify.exe”… this is an important distinction) and passing standard preverify parameters. Finally it creates the final “.cod” that will run on the device. What is included in the cod file depends on what is passed on the command line and what’s available from the working directory. For instance, your application icon (and I found this through trial and error) must be locatable from the working directory unless you specify an absolute path in the jad file. If you compile a jar file (not recommended for rapc prior to 4.3.0) then everything in that jar file (images, multimedia files, application resources, etc.) will be included in the final cod file. If you compile “.java” files directly from rapc then no application resources will make it into the final output cod file, only the compiled .class files will be there (along with the application icon specified in the jad if it can be found from the working directory). It took a lot of banging my head to figure this out. Finally instead of a jar file or space delimited list of “.java” files, you can specify a text file that lists (new line delimited style) all of the “.java” files you wish to pass to the compiler. This is a potential work-around to command line size restrictions that may be present on some versions of Windows. This file should be given with an @ prefix. For eg. if your have a MyApp.txt file then the last parameter for rapc will be @MyApp.txt. This is the preferred method of giving files to rapc because as your application grows so will the list of files.

One last got’cha I found was with trying to use rapc.jar directly instead of rapc.exe. If you are running a JDE earlier than 4.3.0 then you’ll get into trouble here because there is a secret parameter passed from rapc.exe that RIM won’t tell me about. Because the command line syntax for the jar is identical to the command line syntax for the “.exe” you can almost get away with it but because of a secret exchange happening between the Jar and exe you’ll get undefined behavior and weird errors in certain circumstances. This last gotcha is what makes it impossible to compile on an OS other than Windows while targeting a RIM OS earlier than 4.3.0.

In the end I’ve determined that it is not possible to accurately build a blackberry application on an operating system other than Windows. Also while there may be some truth to the myth of bugs in rapc I believe it all boils down to a bunch of nasty assumptions the RIM developers made during the design. (they assumed everyone would be so thrilled with their Swing based IDE that they would throw away Eclipse/Idea/Netbeans and burn their Macintosh laptops in celbration of the obviously superior RIM tool chain.) I do believe that if you pay close attention to the details outlined above you can diagnose most preverification and random erros you may be suffering from. I plan to revist this topic in the future as I’ve taken a break from mobile and begun work on some other things. However I do not plan to let rapc defeat me entirely. Keep an eye out because I’ll likely be updating this very same post with more details.