Fixing the default settings for a webMethods Integration Server

 

Having installed a webMethods Integration Server, there are a few defaults, that you would like to change. (If you know them.) The you, in that case, would be a person like me, a webMethods developer. In most cases, that's the first thing I do, after the server's first lauch. Let's discuss them.

Extended Settings

In general, it's worth to know all the extended settings. Unfortunately, there are too many of them to know even the majority. However, I found the following to be particularly relevant for me:

•  watt.server.compile, and watt.server.compile.unicode: These manage, how to launch the Java compiler, if you are editing Java services. In general, the defaults (Something like javac -classpath {0} -d {1} {2}.) are fine. However, note that the {0} is being replaced by the IS classpath. And, that can become extremely long. Too long for a Windows command line.
  My definite recommendation would be, to clear these settings (empty string as the value). That will cause IS to use the Java Compiler API, instead of the command line. In that case, the length of the classpath doesn't matter.
• watt.server.httplog: By setting this to "common", you will get an additional log file <INSTANCE_DIR>/logs/http.log, which is basically like the Apache server's access log. This is important information, if you want to know, whether a client actually reaches  IS, or not.
• watt.server.ns.hideWmRoot: If you ever walked through your integration servers packages directory, you might have noticed an unknown package, named WmRoot. If so, you might also have noticed, that this package is not in the list of packages, that the IS Administration UI, and Designer display to you. Well, here's why: By setting this variable to "false", that package becomes visible
  Knowing that package is certainly not necessary. However, sooner or later in your career as a webMethods developer, you'll find yourself wondering "How does one do X?", where X is something, that you would usually do in the IS Administration UI.
  Well, the answer to your question would most likely be something "The UI does this by invoking the service wm.server.whatever:DoX in the WmRoot package.
  Warning: While it is common practice to use services in WmRoot, at least for tasks like "Is Y a valid package, or service name?", you should be aware, that they are not part of the public IS API. In other words: As soon as you start using such services, you are starting to pile up a migration risk for your next upgrade. You are warned!
• watt.server.ns.lockingMode: Set that to none. It's your development server, so no harm done. If you need to align with coworkers, use a proper version control system, aka Git.

The mess, that is business.

 Typo of the day: "Busimess requirements". Should teach that to my f...ing auto correction. :-)

Installing native Docker on AlmaLinux

 

Today, I had to reinstall a Docker host, which was previously running on my beloved CentOS 8. As that is quickly approaching it's end, I decided to give AlmaLinux a try. To use it as a Docker host, I had to install native Docker. (I prefer to use native Docker over the one, that is part of the distribution.) So, according to https://get.docker.com/, this is supposed to work as follows:

    curl -fsSL https://get.docker.com -o get-docker.sh

    sudo sh get-docker.sh

In the past, I did that on CentOS, quite a lot, so I expected it to work out of the box. Unfortunately, that didn't quite work, and failed with the error message below:

    sudo sh get-docker.sh

# Executing docker install script, commit: 7cae5f8b0decc17d6571f9f52eb840fbc13b2737 ERROR: Unsupported distribution 'almalinux'

In other words, the Docker installer isn't quite uptodate. Fortunately, fixing a shell script isn't that big of a problem, and I got it running by applying the following patch:

[jwi@gitjndhost ~]$ diff -ub get-docker-orig.sh get-docker.sh --- get-docker-orig.sh 2021-04-28 12:10:12.477498011 +0200 +++ get-docker.sh 2021-04-28 12:03:23.300011495 +0200 @@ -342,7 +342,7 @@ esac ;; - centos|rhel) + centos|rhel|almalinux) if [ -z "$dist_version" ] && [ -r /etc/os-release ]; then dist_version="$(. /etc/os-release && echo "$VERSION_ID")" fi @@ -427,8 +427,8 @@ echo_docker_as_nonroot exit 0 ;; - centos|fedora|rhel) - yum_repo="$DOWNLOAD_URL/linux/$lsb_dist/$REPO_FILE" + centos|fedora|rhel|almalinux) + yum_repo="$DOWNLOAD_URL/linux/centos/$REPO_FILE" if ! curl -Ifs "$yum_repo" > /dev/null; then echo "Error: Unable to curl repository file $yum_repo, is it valid?" exit 1

Note: In order to overcome minor dependency conflicts with podman, buildah, and the like, I also had to issue the command

    sudo dnf -y remove runc

        

Incompatibility of Process.waitFor() between Linux, and Windows.

 

Today, after maybe two years, I figured out, why one particular piece of code works excellent on Windows, but has been causing a lot of trouble on Linux. That piece of code is the class Executor in my Java application framework library afw.

The reason turned out to be, that the method Process.waitFor() behaves differently on Windows, and Linux, with regard to the launched processes output.

• On Windows, the waitFor() method waits, until
1. the launched process has terminated, and
2. the processes standard output, and error output has been consumed (in other words: The input streams, as returned by Process.getInputStream(), and Process.getErrorStream() have been read.

This behaviour can have the unexpected result, that the waitFor() method never returns, which can easily be dealt with by simply launching two separate threads, that read those input streams.

 

• On Linux, however
1. The method waits, again, until the launched process has terminated, but
2. It doesn't wait for the consumption of the processes output.

 

In other words: If you are interested in the processes output, then it is not sufficient, to invoke Process.waitFor(), because the expected output may arrive later on. Instead, you need to launch the same two threads, and then wait, until

1. both threads have received EOF from their respective input streams, and
2. the invocation of Process.waitFor() has returned.

That's a bit tricky, indeed.

 

In summary: Java is a highly portable platform. That being said, there might still be issues. Glad, that I could clarify this one.

 

Announce: JSGen (Java Source Generation Framework)

It is with some pride, that I can announce JSGen today, as a new, and very minor, open source project, under the Apache Software License, 2.0

JSGen is short for Java Source Generation framework. As the name (hopefully) suggests, it is a tool for generating Java source code. It is the result of close to 20 years working on, and with Java source generation. That includes, in particular, the XML data binding framework JaxMe, its predecessor Apache JaxMe, and a lot of application programming in my professional work.

It is my opinion, that

1. Java source generators have a tendency to grow into CLOB's over time, becoming less maintainable, and understandable.
2. Java source generators do typically contain a real lot of boilerplate code, organizing things like import lists, and syntactical details, rather than their actual purpose.

In contrast, JSGen provides an object model, that aims to make source generation just yet another developers task, on which modern software engineering principles can be applied. JSGen will support you by

• Creating import lists semiautomatically (with the exception of static imports)
• Supporting multiple formatting code styles (An Eclipse-like format, the default, and an Apache-Maven-like alternative format.) Switching between code styles is as easy as replacing one configuration object with another.
• Enabling a more structured approach to source code generation. (Example: Implement the case of handling a single instance, and use that to handle the case of a collection.)

Let's have a look at an example, which is quoted from the JUnit tests. We intend to create a simple HelloWorld.java. Here's, how we would do that with JSGen.

    JSGFactory factory = JSGFactory.create();
    Source jsb =
        factory.newSource("com.foo.myapp.Main").makePublic();
    Method mainMethod =
        jsb.newMethod("main").makePublic().makeStatic();
    mainMethod.parameter(JQName.STRING_ARRAY, "pArgs");
    mainMethod.body().line(System.class,
                           ".out.println(",
                           q("Hello, world!"), ");");
    File targetJavaDir = new File("target/generated-sources/mysrc");
    FileJavaSourceWriter fjsw = new
       FileJavaSourceWriter(targetJavaDir);
    // You might prefer MAVEN_FORMATTER in the next line.
    fjsw.setFormatter(DEFAULT_FORMATTER);
    fjsw.write(factory);

Some things I'd finally like to note:

1. JSGen is a complete rewrite of two mature, and reliable predecessors, namely JaxMeJS, and Apache JaxMe JS. As such, it is based on a mature API, and a real lot of applied experience. It may be new, but it should be quite reliable, nevertheless.
2. It provides all the features, of the predecessors, but adds
1. Support for Generics
2. Support for Annotations
3. Switchable Code formatters
4. Builders heavily used in the API

This announcement has intentionally been deferred until the point, where JSGen has succesfully been used for a professional project in my professional work. 

Finally, a few links:

• Web site
• Github Project
• License (ASL 2.0)
• Bug Reports, Feedback, and other Issues

  

Don't use Copy+Paste on Windows, if you've got a lot of data

Windows never ceases to disappoint me. I've got an external hard drive, on which resides a 60 GB VM, which I need to copy now and then to emulate a snapshot. So far, I used the standard Windows file copy stuff to do that. (Copy, and paste the VM directory.) Ran with about 8-20 MB per second. Or in other words: Took up to two hours. And, worst of all, the procedure isn't reentrant. Interrupting the copying means to restart.

So, tried something different: CygWin's rsync, the swiss army knife for backups, and related stuff. In other words, I am using the command

  rsync -a -r --progress
Runs with 30MB per second (50% faster than native Windows copying). And is reentrant...

VMWare Shared Folders oin Fedora 23

Hi,

if you haven't noticed: Fedora 23 is out, and its time to get your hands wet on it. Being forced to use a Windows Laptop, I am typically doing this by installing a VMware guest. Once the virtual machine is up, the first thing i want to do is accessing my Windows home directory. The easiest way to do this is by creating a so-called "Shared Folder" in the VMware settings for my machine. On the guest, you need to install the "VMware Tools" and do something like

mkdir /home/username/sharedfolder
sudo mount -t vmhgfs -o uid=1000,gid=1000 .host:sharename /home/username/sharedfolder

(The options uid=1000,gid=1000 ensure, that the mounted directory is readable, and writable for the user with uid=1000, and gid=1000, which is me.)

The problem with that procedure is, that it depends on a kernel module called "hgfs", which must be installed as part of the "VMware Tools". And, needless to say: Installation of the VMware Tools (version 9.2.0-799703, as of this writing) fails, because the Kernel isn't compatible to the sources distributed by VMware.

So far, the only reasonable solution was to wait for an updated tools version by VMware. (I generally ignored the possibility to patch those distributed sources as overly complicated, and insecure. However, there's a new, and better solution available:

Fedora 23 automatically installs an RPM named open-vm-tools. And this includes two programs, that allow use of shared folders without the kernel module:

  # Display a list of all shared folders:

  # Note, that it includes a share called "sharedfolder".
  $ vmware-hgfsclient sharedfolder

  # Create a directory named /home/username/foo, and mount the shared folder there.
  $ vmhgfs-fuse .host:foo /home/username/sharedfolder
  $ cd /home/username/sharedfolder
  $ touch testfile
  $ rm testfile

Note, that neither "sudo" nor the specification of any options was required.

So, in other words: As of Fedora 23, the VMware Tools are no longer required. Mouse integration, Cut and Paste, and using shared folders: Everything works out of the box. (I can live without the thin print drivers.)

Honouring Terry Pratchett: Java Web Application

This Blogs name is Grumpy Apache. These days, there are excellent reasons, for being grumpy: After all, my favourite author Terry Pratchett has died, way too early. But, as Terry wrote in Going Postal about John Dearheart:

His name, however, continues to be sent in the so-called Overhead of the clacks. The full message is "GNU John Dearheart", where the G means, that the message should be passed on, the N means "Not Logged" and the U that it should be turned around at the end of the line. So as the name "John Dearheart" keeps going up and down the line, this tradition applies a kind of immortality as "a man is not dead while his name is still spoken".

This means, we'll be celebrating "Being childish day" today, by adding the HTTP Header

      X-Clacks-Overhead: GNU Terry Pratchett

to our web sites. And, here's how to do that with any Java Web Application.

Its simple. First of all, you'll be adding this class to your web application. It is a so-called servlet filter. I'll quote the relevant method here:

public void doFilter(ServletRequest pReq, ServletResponse pRes,
                                         FilterChain pChain) throws IOException,
ServletException {
if (pRes instanceof HttpServletResponse) {
final HttpServletResponse res = (HttpServletResponse) pRes;
res.addHeader("X-Clacks-Overhead", "GNU-Terry-Pratchett");
}
pChain.doFilter(pReq, pRes);
}

Besides, add the following snippets to your web.xml:

 
    ClacksOverheadFilter
    com.github.jochenw.clacksov.ClacksOverheadFilter
 
 
    ClacksOverheadFilter
    *
 

And, that's it! No modification of servlets, or the like, just a simple addition, that you can make to any web application.

Keep in mind:

As long as we are shifting his name on the Internet, Terry isn't dead.

Installing CentOS 7 Prerelease on VMWare

Hi,

if you haven't heard the news: A prerelease of CentOS 7 is out. This is important, because:

1. CentOS 7 is a major release and will be the base of the Linux Distro that people like me will be using in the next years on servers. (Yes, I do know about Ubuntu 14.04 LTS, OpenSUSE Whatever, Debian Something, etc. However, that is most likely not what I will be using. Logically, so won't do people like me. End of discussion.)
2. Quite a few things have changed since CentOS 6. In particular, much has been adopted from recent Fedora versions: 
1.  The new Anaconda Installer. (I am personally not overly happy with it. The old one worked quite well for me, but I had my share of trouble with the new one. In particular, I am less than enthusiastic about how Disk Partitioning works nowadays. OTOH, this version of Anaconda (the one distributed with the CentOS 7 Prerelease) is a step forward in that aspect. Perhaps, more people like me had similar trouble.)
2.  GNOME 3: Well, this one will definitely be the cause of a major uproar on the Red Hat Continent. I readily admit that I was one of the people who initially went with MATE as a GNOME 2 replacement, so as to avoid GNOME 3. However, in the meantime, I've learned to live with it and can even appreciate some features like the enhanced keyboard control. The one thing I am still missing is the pictures screenblanker, though. I learned to live with xscreensaver, although this still smells like a very ugly hack.) Like it, or not, people like me (c) will have to face it.
3.  This prerelease was published not even one weak after the release of RHEL 7. Compare that to the months we had with some minor versions of CentOS 6. So, we benefit from Red Hat adopting CentOS. Good news!

So, what is this posting about?

•  I won't cover generic aspects of installing CentOS, or Fedora. I'll assume that you have installed either of which before and have a rough idea of what I am talking about. In particular, I assume that you know what a network installation is, because right now this is the only installation method available through an ISO image. (Forget "Live DVD", or whatever else you have hoped for.)
• I will, hovever, concentrate on installing this very special prerelease version, because it is not quite like installing an official version. (Neither is it overly complex, though.) Hopefully, I'll also cover what has changed since version 6.

 If that is interesting for you: Read on. If not: I am sorry! Google (Planet Apache, or whatever else brought you here, did wrong and is to blame).

So, what's to do?
Download the ISO Image from http://buildlogs.centos.org/centos/7/os/x86_64-20140614/images/boot.iso and save it, for example as "centos7-netinstall.iso".

1. Create a new VM (My Parameters were "I will install the operating system later.", "Guest operating system=Linux", Version="CentOS 64-bit", Maximum disk size=30GB, Memory=3072GB. Everything else was as suggested by VMWare Player 6.0.2 build-1744117.
2. Select Virtual Machine Settings, CD/DVD (IDE). Enable "Connect at power on" and "Use ISO Image file". Select the file you downloaded in step 1.
3. Start up the created VM. From the boot menu, select "Install CentOS 7". (You may as well test the media, but you did check the MD5 Sum anyways, did you? :-) At least, you know the difference... (Remember that "won't cover generic aspects" above?)
4. Hopefully, the Anaconda graphical installer will come up. (At least, it does so on a VMWare machine. I'd never hope so on a machine with an NVIDIA or AMD graphics card. Don't expect me to help you with that crap.  I'm all with Linus on that. :-)
5. Select your language (Safe choice is, of course,"English-US").
6. Anaconda will notify that  this is prerelease, unstable software. You knew that anyways, so click on "I want to proceed."
7. The Anaconda "Installation Summary" screen will come up. This will be an unknown thing (Remember: New Anaconda) for a lot of people, so here's a screenshot:
   
   
   
   
   The important thing to keep in mind is the order of the following steps.
8.  Start with the Keyboard. (You're likely to use that in the following steps.) Click on "Keyboard" (Not the small keyboard icon, but the big icon, or the word.) Click on the "+" sign, and select your favourite keyboard layout. (In my case "German, Germany, Eliminate dead keys".) Remove any unwanted layout by clicking on it, and clicking on the "-" sign. Finish by clicking on "Done" in the upper left corner. (Who the heck came up with that? Anyways, remember the location.)
9. The next thing you're gonna need is the network. (Most likely, you are currently "Not Connected".) Click on "Network & Hostname". Click on "Off" in the upper right corner to enable networking. Enter a meaningful host name. (I choose "c7wm96.mcjwi01.eur.ad.sag". Avoid "localhost.localdomain".) Click on "Done". (Upper left corner, remember?)
10. Now we can edit "Date & Time", aka time zone. I choose "Europe/Berlin".
11. If you need that (You don't, really...), click on "Language Support" and select additional languages.
12. The most obvious trap is the "Installation Source" (Hopefully, it won't be in the official releases, which will select an URL automatically): Click on that, enable "On the network", and enter the URL buildlogs.centos.org/centos/7/os/x86_64-20140614/. If you need to use an HTTP Proxy, click on "Proxy setup". Enter your proxy host name and port (in my case "httpprox.hq.sag:8080") Click on "Add". Click on "Done". Wait a few seconds until you see "Downloading package metadata", or the like. If you do see something like "Error setting up Base Repository", changes are that the URL is wrong. Fix it, and retry. Wait a few seconds more until downloading the package data and checking for dependencies has finished.
13. Next, go to "Software Selection". The default is "Minimal Install". This is fine, if you are happy with a server that has no X11 enabled. I choose "Server with GUI" instead, to make my colleagues happy. On the right hand side, you can choose to have KDE installed addizionally. (AFAIK, no support for MATE, Cinnamon, LXDE, whatever. No idea, whether that will come.) You might wish to deselect LibreOffice, if you manage to do that. Click on "Done". Wait a few seconds until the message "Checking for software dependencies" disappears.
14. Another, somewhat difficult step is the "Installation Destination". Click on that. If you need "Custom Partitioning", enable "I will configure partitioning." below. (The default is "Automatically configure partitioning.", The presence of this option is what has changed since Fedora 20, and I consider this to be a major improvement.) Click on "Done", even if you're actually not. If the window for "Manual Partitioning" appears, select your desired partition type ("Standard Partition", "BTRFS", "LVM") and add a few partitions by clicking on the "+" button. I create the following partitions (in that order):
1. /boot with a Capacity of 500MB.
2. Swap with a Capacity of 6GB. (I need that much, because the Oracle Installer wants 8GB of physical memory, but accepts Swap as a replecement.)
3. / with a Capacity of 8 GB.
4. /home with a Capacity of 16.21GB
Click on "Done". Click on "Accept Changes". If no error messages can be seen on the "Installation Summary" screen, then you have mastered the major hurdles.

• Click on "Begin Installation".
• Regardless of the ongoing installation, click on "Root Password". Enter a meaningful, and secure, root password. Repeat it. Click on "Done". (You never even considered to enter a weak password, did you? Well, if you did: Click on "Done" twice. :-)
• The installation is still ongoing. Click on "User Creation". Enter a real name and a login name, enable "Make this user administrator" (The option will actually add the created user to the "wheel" group, which has permissions to use "sudo"). Enter a password and repeat it. Click on "Done" twice. (Oops, your passsword is secure: Then once is sufficient.)
• Keep in mind that this is a "network installation": Anaconda will download each and every single RPM to install (In my case about 1200.), so the process will take time. OTOH, with a fast network (DSL, or something like that) it won't take much longer than installation from a DVD.
• Once the actual installation is finished, you'll be asked for a reboot. Confirm that, and the new system comes up. Almost done. One minor step to perform: Accept the GPL license, and accept another reboot. (No, this isn't Windows, but still....)

If you got this far, then you've got a system running CentOS 7 Prerelease. Congratulations. Unfortunately, one thing is still left. Your system doesn't have a valid Yum configuration. (Convince yourself by running

  sudo yum repolist all

Oops, you need a terminal window to do that. That's no problem if you are running KDE or any other desktop that you are used to. If it's GNOME 3, and you are not, here's what to do: Press, and release, the "Windows" key. (No, this is still not Windows, but anyways. If it helps, call it the "Linux" key.) Press, and release, the following keys, in that order: "t", "e", "r", "m", and Enter. At that point, a GNOME Terminal window should appear. (Or, in theory, any other desktop application containing the word "term". However, you had no chance to install "xterm" do far. :-) Using the command

  sudo yum vi /etc/yum.repos.d/centos7-prerelease.repo

create a new file with the following contents:

  [centos7-prerelease]
  name=CentOS 7 Prerelease
  url=http://buildlogs.centos.org/centos/7/os/x86_64-20140614/
  enabled=1
  priority=1
  gpgcheck=0

And now (I am not avoiding any flame wars today :-) you can do

  sudo yum install emacs emacs-nox gcc make binutils kernel-headers

A final note on the VMware tools: Anaconda did automatically install "open-vm-tools-desktop". So, mouse integration, copy and paste, etc. worked immediately for me. No need for a seprate installation.

Build System Performance on Windows

Over the last three months I had the pleasure to run Fedora 20 Linux on the Laptop I am using for work. Last week, I was forced to downgrade to Windows 7. (Mainly, because my employers system administrators don't support everything else. I am quite ready to have the occasional fight for my freedom against the admins, but I won't accept the constant struggle. To name just the most important problem: Accessing an MS Exchange Server without IMAP enabled is, at best, exhausting.) Why the word "downgrade"? Because my machine is so much slower now. I am a developer. My Eclipse is open for 10 hours a day and I can't count the number of invocations of Ant, Maven, Make, and other build systems. (Ant, and Maven, being my personal favourites.) Of course, the machine isn't actually slower. It is the same hardware, after all. Same amount of RAM, still without an SSD. However, and that's a fact: Running one and the same build system against the same project on Windows 7 takes more time than doing just that on Linux. If you don't believe me, try the following: Install a Linux VM on your Windows PC. Then run the following command, first on the VM, then on the Windows host:

git checkout https://github.com/torvalds/linux.git

What are the odds, that this command will run faster on the Linux VM than on the Windows hosts. I'd bet. And I'd win. (It's true: Linux Git on the emulated hardware wins against Windows Git on the raw iron.) Btw, for an even more convincing example, try "git svn checkout".) This week, I decided to waste some time to think about the issue: How do I get my build system on Windows as fast as on Linux. First, let's identify the guilty party: It's none other than... (drum roll) NTFS! I'm not making this up: Others are quite aware of the problem. See, for example, this page. A Google search for "ntfs performance many small files" returns about 168000 hits. So, let's state this as a fact: NTFS behaves extremely poor when dealing with lots of small files. But that's exactly, what a build system is all about. Let's take a typical example:

1. The first typical step is to remove a build directory (like "target", or "bin", or whatever you name it.)
2. The compiler reads a lot of small source files (named *.java, *.c, or whatever) from the "src" directory.
3. For any such file, the compiler creates a corresponding, translated file (named *.class, or *.o, or whatever) in the build directory.
4. A packager, or linker, like "jar", or "ln" combines all these files we have just created into a single target file.

Notice something? This is the same for all build systems. It really doesn't matter, whether your build script uses XML, a DSL, JSON, or a binary format. (No, this is holy war won't have my participation.) What matters is this: All current build systems are based on the mantra of an output directory, where lots of small files are created. But, that's not a necessity. So, here's the challenge: Let's modify our build systems in a manner that replaces the output directory with a "virtual file system". If we do it right, we can be much, much faster. As a poof of concept, I wrote a small Java program, that extracts the Linux Kernel sources (aka the file "linux-3.14.2.tar.gz") and writes them into implemantations of the following interface:

public interface IVFS {

	OutputStream createFile(String pPath) throws IOException;

	void close() throws IOException;
}

For any source file (45941 files) the method createFile is invoked, the file is copied intoo the OutputStream, and the stream is closed. Finally, the method IVFS.close() is invoked. Here's my programs output:

   Linux Kernel Extraction, NullVFS: 4159
   Linux Kernel Extraction, SimpleVFS: 1740044
   Linux Kernel Extraction, MapVFS: 78134

The three implementations are:

1. The NullVFS inherits the idea of /dev/null: It is basically a write-only target. Of course, this isn't really useful. On the other hand, it shows how fast we could be, in theory, if our target were arbitrarily fast: In this case 4159 milliseconds. (This is, mainly, the time for reading the Linux Kernel sources.)
2. The SimpleVFS is basically, what we have now. Files are actually created. As expected, this is really slow, and it takes more than 1740 seconds.
3. Finally, the MapVFS is basically an In-Memory store. However, it might be really useful, because its close method is creating a big file with the actual contents on disk. With 78 seconds, this implementation is still close to the NullVFS. It demonstrates what might be really possible.

Conclusion: When creating one file with our actual contents, we need 78 seconds, as opposed to 1740 seconds. Of course, the IVFS interface is an oversimplification. The implementations certainly aren't thread safe. We have omitted the possibility to modify files that have previousöy been created. But the numbers are so impressive that I am personally convinced: If we a) modify our build system to use a virtual file system as the output and b) provide fast implementations, then we have much to gain, fellow developers! In practice, this won't be so easy. The biggest hurdle I am anticipating, is the Java Compiler. Even the Java Compiler API (aka the interface javax.tools.JavaCompiler) is based on real files: We won't be able to use the Java Compiler, as it is now. Instead, we have to manipulate them to use the VFS. ECJ, the Eclipse Java Compiler might be our best option for that. Who'll take the first step? Well, Gradlers, Buildrs, SConsers, of the world: Here's something where your users could have a real difference!

The sins of our fathers

"Fathers shall not be put to death for their sons, nor shall sons be put to death for their fathers; everyone shall be put to death for his own sin." (Deuteronomy 24:16) But, of course, we are paying for our fathers sins. Not so much our biological fathers or ancestors, but our predecessors. In my case, this is what's happened today: I wrote a very small Java program that extracts the Linux Kernel sources (More on the reasons and background, hopefully, in my next posting. Suffice it for now, that I'm not rewriting "tar xzf". I'm not that stupid! I had a good reasons. Now, the Kernel Sources are containing in particular, a small file named "aux.c". And my own program threw a FileNotFoundException when creating that file. Reproducible! The error message was, of course, meaningless, so I began to start thining about all kinds of reasons:

1. Permissions, either those of the file itself, or the containing directory. Mo, the permissions were just fine!
2. Length of the path name. Actually, the full path name contained quite some characters, but still far away from the 256 that I am aware of.
3. Too many open files. No, I have had my share of beginners faults and was properly closing.

Any other ideas. I guess you don't get this one: Some JDK programmer was actually implementing a check for aux.*, nul.*, prt.* etc when creating a file, because these file names where in fact a problem with Windows in the past. Of course, the sensible solution would have been:

1. Wait for the error message from Windows.
2. Check the file name.
3. Throw a meaningful error message that explains the problem.

That way, veything would have worked fine, if the unthinkable happened: Windows eliminates that stsupid restriction. Because that was exactly what happened. There is now problem with creating that file. Convince yourself:

  $ touch aux.c

  jwi@MCJWI01 /c/Users/jwi/workspace/afw-vfs
  $ ls -al aux.c
  -rw-r--r--+ 1 jwi Domain Users 0 May  1 16:02 aux.c

  jwi@MCJWI01 /c/Users/jwi/workspace/afw-vfs

So, our JDK programmer has managed to move the problem with the "aux.c" file name from Windows to the JDK. Thanks, a lot!

Installing Obsolete Java JDK versions on Fedora Linux

As a Java developer, one is frequently forced to use obsolete, or even deprecated, Java versions. So I came to the necessity to install Java 6 on Fedota 19. The problem: In the Fedora 19 repositories, there's only Java 7 and 8. Convince yourself:

$ sudo yum list | grep openjdk
java-1.6.0-openjdk.x86_64              1:1.6.0.0-59.1.10.3.fc16         installed
java-1.6.0-openjdk-devel.x86_64        1:1.6.0.0-59.1.10.3.fc16         installed
java-1.6.0-openjdk-javadoc.x86_64      1:1.6.0.0-59.1.10.3.fc16         installed
java-1.7.0-openjdk.x86_64              1:1.7.0.60-2.4.2.0.fc19          @updates
java-1.7.0-openjdk-demo.x86_64         1:1.7.0.60-2.4.2.0.fc19          @updates
java-1.7.0-openjdk-devel.x86_64        1:1.7.0.60-2.4.2.0.fc19          @updates
java-1.7.0-openjdk-javadoc.noarch      1:1.7.0.60-2.4.2.0.fc19          @updates
java-1.7.0-openjdk-src.x86_64          1:1.7.0.60-2.4.2.0.fc19          @updates
java-1.7.0-openjdk-accessibility.x86_64
java-1.8.0-openjdk.i686                1:1.8.0.0-0.9.b89.fc19           updates 
java-1.8.0-openjdk.x86_64              1:1.8.0.0-0.9.b89.fc19           updates 
java-1.8.0-openjdk-demo.x86_64         1:1.8.0.0-0.9.b89.fc19           updates 
java-1.8.0-openjdk-devel.i686          1:1.8.0.0-0.9.b89.fc19           updates 
java-1.8.0-openjdk-devel.x86_64        1:1.8.0.0-0.9.b89.fc19           updates 
java-1.8.0-openjdk-javadoc.noarch      1:1.8.0.0-0.9.b89.fc19           updates 
java-1.8.0-openjdk-src.x86_64          1:1.8.0.0-0.9.b89.fc19           updates 

The same goes for Fedora 18 and 17, btw. (I'll skip the output here. Note, that processing these commands will take some time, as yum will download the complete repository metadata for the respective version.

$ sudo yum --releasever=17 list | grep openjdk
$ sudo yum --releasever=18 list | grep openjdk

However, Java 6 is available for Fedora 16!

$ export http_proxy=MY_PROXY_URL, for example http://my.proxy.server:8080
$ wget wget http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/16/Fedora/x86_64/os/Packages/java-1.6.0-openjdk-1.6.0.0-59.1.10.3.fc16.x86_64.rpm
$ wget http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/16/Fedora/x86_64/os/Packages/java-1.6.0-openjdk-devel-1.6.0.0-59.1.10.3.fc16.x86_64.rpm
$ wget http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/16/Fedora/x86_64/os/Packages/java-1.6.0-openjdk-javadoc-1.6.0.0-59.1.10.3.fc16.x86_64.rpm

Now, my first (and preferred) attempt to install these would be

$ sudo yum localinstall --obsoletes java-1.6.0-openjdk*

which fails, due to the following error message:

  error: Failed dependencies:
  java-1.6.0-openjdk is obsoleted by (installed) java-1.7.0-openjdk-1:1.7.0.60-2.4.2.0.fc19.x86_64
  java-1.6.0-openjdk-devel is obsoleted by (installed) java-1.7.0-openjdk-1:1.7.0.60-2.4.2.0.fc19.x86_64
  java-1.6.0-openjdk-javadoc is obsoleted by (installed) java-1.7.0-openjdk-1:1.7.0.60-2.4.2.0.fc19.x86_64

(Please contact me, if you have an idea on how to get rid of these!) Fortunately, there's another possibility, which does the job quite neatly:

$ sudo rpm --nodeps -i java-1.6.0-openjdk*

If you're an Eclipse user, the JDK can now be found in /usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/

Slow Startup of Cygwin Bash

When on Windows, I never use another terminal/shell than MinTTY/CygWin Bash. So I was heavily harmed by a problem that started quite some time ago: Suddenly, when I opened MinTTY, it took 10 seconds or so, before the bash prompt became visible. Today, I finally discovered the culprit by reading another post. As you posssibly know, there is a directory /etc/profile.d containing scripts that are executed when a login shell is starting. Now, one of these scripts, called bash_completion.sh is extremely slow. You can try for yourself:

$ time . /etc/profile.d/bash_completion.sh

real    0m8.908s
user    0m1.402s
sys     0m7.310s

In other words, solving the issue for me was as simple as renaming this script:

$ mv /etc/profile.d/bash_completion.sh /etc/profile.d/bash_completion.sh.disabled

Voila! My MinTTY opens immediately again. Update: The above time command is only slow when the script is being executed for the first time. In other words, if your bash was starting slow due to executing it, then you might see a result like this:

$ time . /etc/profile.d/bash_completion.sh

real    0m0.000s
user    0m0.000s
sys     0m0.000s

RfC: Improving Mavens Performance

I am typically working in projects that are relatively complex, like one parent projects and 20 modules, or so. To handle the complexity, I have learned to use and appreciate Maven. OTOH, after 8 years or so with Maven, I am still missing some aspects of Ant builds, in particular the speed. Maven does a good job when it comes to understand Build scripts (biggest problem of Ant), but it can be painfully slow. Why is that? I could name several reason, but the most obvious seems to be that Maven is always building the whole project, whereas Ant allows to implement logic like

   if (module.isUpToDate()) {
     // Build it
   } else {
     // Ignore it

Of course, Ant's syntax is completely different, but that's not the point, unless you are a fanatic XML hater and really believe that a Groovy or JSON syntax is faster by definition (If so, stop reading, you picked up the wrong posting!)
The absence of such an uptodate check isn't necessarily a problem. Most Maven plugins are nowadays implementing an uptodate check for themselves. OTOH, if every plugin does an uptodate check and the module is possibly made up of other modules itself, then it sums up.
Apart from that, uptodate checks can be unnecessarily slow. Suggest the following situation, which I have quite frequently:
A module contains an XML schema. JAXB is used to create Java classes from the schema If the schema is complex, then the module might easily have severeal thousand Java source files.
This means, that the Compiler plugin needs to check the timestamps of several thousand Java and .class files, before it can detect that it is uptodate. Likewise, the Jar Plugin will check the same thousands of .class files and compare it against the jar file, before building it.
That's sad, because we could have a very easy and quick uptodate check by comparing the time stamps of the XML schema, and the pom file (it does affect the build, does it) with that of the jar file. If we notice that the jar file is uptodate with regard to the other two, then we might ignore the module at all: Ignore it would mean to completely remove it from the reactor and not invoke the Compiler or Jar plugins at all. Okay, that would help, but how do we achieve that without breaking the complete logic of Maven? Well, here's my proposal:

1. Introduce a new lifecycle phase into Maven, which comes before everything else. (Let's call it "init". In other words, a typical Maven lifecycle would be "init, validate, compile, test, package, integration-test, verify, install, deploy" (see this document, if you need to learn about these phases.
2. Create a new project property called "uptodate" with a default value of false (upwards compatibility).
3. Create a new Maven plugin called "maven-init-plugin" with a configuration like

      groupid: org.apache.maven.plugins
           artifactId: artifactid>="maven-init-plugin"
           configuration:
              sourceResources:
                sourceResource:
                  directory: src/main/schema
                  includes:
                    include: **/*.xsd
                sourceResource:
                  directory: .
                  includes:
                    include: pom.xml
              targetResources: ${project.build.directory}
                  includes:
                    include: *.jar
       (Excuse the crude syntax, I have no idea how to dixplay XML on blogspot.com!
        I hope, you do get the idea, though.)
       The plugins purpose would be to perform an uptodate check by comparing source-
       and target resources and set th "uptodate" flag accordingly.
     

Modify the Maven core as follows: After the "init" phase, search for modules with isUptodate() == true and remove those modules from the reactor. Then run the other lifecycle phases.

That's it. Perfectly upwards compatible. Moderate changes. Much faster builds. How about that?

DB2 Weirdness

In the year 2012, what serious database might require code like this:

private ResultSet getColumns(DatabaseMetaData pMetaData,
                             String pCat,
                             String pSchema,
                             String pTableName)
    throws SQLException {
 if (pMetaData.getDatabaseProductName().startsWith("DB2")) {
   final String q = "SELECT null, TABSCHEMA, TABNAME, COLNAME," 
  + " CASE TYPENAME"
  + " WHEN 'BIGINT' THEN -5"
  + " WHEN 'BLOB' THEN 2004"
  + " WHEN 'CHARACTER' THEN 1"
  + " WHEN 'DATE' THEN 91"
  + " WHEN 'INTEGER' THEN 5"
  + " WHEN 'SMALLINT' THEN 4"
  + " WHEN 'TIMESTAMP' THEN 93"
  + " WHEN 'VARCHAR' THEN 12"
  + " WHEN 'XML' THEN -1"
  + " ELSE NULL"
  + " END, TYPENAME, LENGTH FROM SYSCAT.COLUMNS"
  + " WHERE TABSCHEMA=? AND TABNAME=?";
   final PreparedStatement stmt =
     pMetaData.getConnection().prepareStatement(q);
   stmt.setString(1, pSchema);
   stmt.setString(2, pTableName);
   return stmt.executeQuery();
 } else {
   return pMetaData.getColumns(pCat, pSchema, pTableName, null);
 }
}

or this:

  private ResultSet getExportedKeys(DatabaseMetaData pMetaData)
     throws SQLException {
    if (pMetaData.getDatabaseProductName().startsWith("DB2")) {
      final String q = "SELECT null, TABSCHEMA, TABNAME,"
      +  " PK_COLNAMES, null, REFTABSCHEMA, REFTABNAME,"
      +  " FK_COLNAMES, COLCOUNT FROM SYSCAT.REFERENCES"
      +  " WHERE TABSCHEMA=? OR REFTABSCHEMA=?";
      final PreparedStatement stmt =
        pMetaData.getConnection().prepareStatement(q);
      stmt.setString(1, "EKFADM");
      stmt.setString(2, "EKFADM");
      return stmt.executeQuery();   
    } else {
      return pMetaData.getExportedKeys(null, "EKFADM", null);
    }
}

BPM Process Migration

BPM Process Migration

Having worked in several BPM projects for quite some time, I usually enjoy the help of the BPM server. In particular, BPMN etc. are excellent for conversations with the customers. Of course, you still need to translate the customers desires into your own technical picture (which might differ considerably), but in the end you'll likely to get something that gives the customer a "I know this" feeling, which is worth a lot. Of course, there are still gaps, problems, and all that stuff. However, what really sucks, are upgrades of the project version.

Disclaimer: I am no BPM expert, much less skilled in the theory, just an experienced user. This is just the result of my thinkings. In particular, don't mismatch this post with a statement of my employer, Software AG, or Fujitsu. It reflects my impression of how to work with the webMethods BPM Server, or the Fujitsu Interstage Server. I have no idea how these ideas can be transferred to other BPM tools like, for example, Apache ServiceMix, or whatever.

Terminology

A BPM Process Model in the sense of this posting is a set of Process Nodes and a set of transitions between these nodes. In what follows, let PM be a process model, PN be the set of PM's nodes and TPN the set of transitions. PN consists two special subsets, the start nodes (SPN), and the end nodes (EPN). A process model typically reflects some kind of workflow can be graphically visualized (see, for example, this picture:





The possibility of graphical visualization is what's so attractive about BPM for non-technical folk.)
A BPM Process State is an element from a universe U, typically an unstructured set of named objects. In the case of Interstage BPM, these named objects are strings, in the case of webMethods BPM these objects can be complex (maps, arrays, etc.: the webMethods Pipeline):

A BPM Process Instance is an element of the set PN x U: A combination of a process node and a process state. This definition is too geeneral, of course. For example, the node PN must be reachable from a start node via a series of transitions out of TPN. However, for now we can ignore this.
A BPM Process Model can have multiple versions. These versions are usually related, for example, the sets of process nodes and transitions are frequently subsets. In general, however, they can be completely unrelated.
A BPM Process Migration involves

1. the creation of one or more new process models, or model versions.
2. Possibly the removal of existing process models and process instances.
3. Possibly a migration of process instances from one, or more process models to a new process model, typically a new version of their current model.

This last part is the one that sucks, because it is completely unsupported. The developers are completely left alone. (All you can do is to ensure some kind of compatibilty, which usually implies leaving old software versions, or at least parts thereof, in place and hoping, that old and new versions are working fine together.)

But, how could such tools look like? This is what my post is about:

• It should be possible to replace process models with new versions by migrating the process instances.
• This means that a developer ought  to be able to specify a mapping from the set PN1 x U to PN2 x U. (The mapping would usually be a Java class implementing a special interface.)

Example: A process state usually contains entries like these:
ID (Database or any other internal ID, for example an incoming order; the process specific details are stored elsewhere and not as part of the pipeline, which would otherwise grow too big. However, the details are easily accessible.)
State (A human readably process state, like "unconfirmed", "available", or "acknowledge".)
Names (for example, name of the orderer, etc. These are frequently not really required, but redundant and just copied from the details for the sake of convenience.)

A new process version might introduce a new ID (for example, from another external system, which is now connected to the processs), a new state, or something like that. In order to get the existing process instances working with the new model, we can either
- modify the process so that it does support null values, even if they are mandatory from a business perspective
- enhance the process state by adding these new values as part of the migration.
Guess, which I'd prefer? And, guess which we are left with now?

Maven and property files

After so many years (since 2004, indeed when the first version of Maven 2 was still in development), I am still learning new stuff every day. For example, so far I was always specifying properties in my POM file. But you can use external property files! There is a Maven Properties Plugin over at Mojo with a goal "properties:read-project-properties".

Maven is groovy!

Recently, I had another one of those cases where Maven almost does the right thing, but not quite. Let me explain the use case:
I've got a software component that can initialize the database from an SQL script. Such an SQL script (in what follows: The DDL, or data definition language script) is ideally generated by the Hibernate Schema Exporter, aka "hbm2ddl", which in turn is available in Maven by running the Hibernate3 Maven Plugin. But, if just creating the database is not sufficient and you need to run a second SQL script (in what follows: The data script) to populate the DB with some initial entries? Well, I came up with the following solution:

1. At build time, have Maven create the DDL script (below target/classes, so that it is available at run time)
2. At development time, manually create the data script (in src/main/db)
3. At build time, have Maven concatenate these scripts into a third SQL script (in what follows: The concatenated script, also below target/classes, as it must also be available at runtime)

Question: How do we do that last step? The most obvious solution was the Maven Antrun Plugin, Ant even's got a "concat" task, which should do exactly what I want (Including uptodate checks). However, I wasn't really happy with that solution, because Ant, or the "concat" task behaved too unpredictable (For example, no error was produced, if either of the source files didn't exist. An, error checking is, where Ant scripts become really nasty.) In the end, I had to admit: It didn't work.
So I came up with another idea: Why not have a small Groovy Script in the Maven POM. And, as is usually the case, someone else already had that idea and there is a Maven Plugin, which already provides just that:
I can embed a Groovy snippet into my Maven POM and have it executed at a suitable point of my build script. Here's the snippet I came up with:

<plugin>
<groupId>org.codehaus.gmaven</groupId>
<artifactId>gmaven-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<phase>prepare-package</phase>
<goals>
<goal>execute</goal>
</goals>
<configuration>
<source><![CDATA[
def concat(s1, s2, t) {
def java.io.File f1 = new java.io.File(s1)
def java.io.File f2 = new java.io.File(s2)
def java.io.File ft = new java.io.File(t)
def long l1 = f1.lastModified()
def long l2 = f2.lastModified()
def long lt = ft.lastModified()
if (l1 == 0) {
throw new IllegalStateException("Source file must exist:" + f1);
} else if (l2 == 0) {
throw new IllegalStateException("Source file must exist:" + f2);
} else if (lt == 0 || l1 > lt || l2 > lt) {
java.io.File pd = ft.getParentFile()
if (pd != null && !pd.isDirectory() && !pd.mkdirs()) {
throw new IOException("Unable to create parent directory: " + pd)
}
println("Creating target file: " + ft)
println("Source1 = " + f1)
println("Source2 = " + f2)
java.io.FileInputStream fi1 = new java.io.FileInputStream(f1)
java.io.FileInputStream fi2 = new java.io.FileInputStream(f2)
ft.append(fi1)
ft.append(fi2)
fi1.close()
fi2.close()
} else {
println("Target file is uptodate: " + ft)
println("Source1 = " + f1)
println("Source2 = " + f2)
}
}
concat("target/classes/com/softwareag/de/s/framework/demo/db/derby/initZero.sql",
"src/main/db/init0.sql",
"target/classes/com/softwareag/de/s/framework/demo/db/hsqldb/init0.sql")
concat("target/classes/com/softwareag/de/s/framework/demo/db/derby/initZero.sql",
"src/main/db/init0.sql",
"target/classes/com/softwareag/de/s/framework/demo/db/hsqldb/init0.sql")
]]></source>
</configuration>
</execution>
</executions>
</plugin>

perhaps in combination with a byte array, for performance reasons, but in Groovy a file has got a method append(InputStream), which does exactly that. And, although I am declaring the variable ft above as an instance of java.io.File, it is nevertheless a Groovy file, with all the added sugar of Groovy! Which is, why embedding Groovy into the POM is much nicer than embedding Java!

In the future. I will most likely never ever write Maven plugins and use Groovy scripts instead.

 Second: We are inside a Maven POM, or, to put it different: Inside an XML file. As a consequence, I've got to be careful with characters like '&', or '!'. Which is why I am using the strings ">" and "&" instead. I might as well use a CDATA section, or, even better: An external script (in src/main/groovy) However, I believed to make this postings point better with an internal (albeit somewhat lengthy) snippet. Hope, you agree, so let's be groovy!

ICU

Last weekend, I had the unexpected opportunity to participate in the nightly snoring contest held at the intensive care unit (ICU) of the neurological clinic, university of Tübingen. Such a chance comes once in a lifetime, so I could not miss it. Here's how it went:

My wife certainly considered me to be the odds-on favorite. But, alas, even wifes can overestimate their husband: Bed 1 (the contents of which have been yours truly) lost by far. At aboUT 21:00, bed 3 opened with a sonorous snore of about 80 decibel (about enough to be heard in a disco) and immediately took the lead. But even such an awesome competitor had to give in: During the night, bed 2 never ceased to impress with staccati of four to five 70-decibel-snores in a row, taking the first price with him.

Every morning there a friendly female woke me, one of the doctors, who asked to take my blood and apologized in so many words for waking me. When that was done, she continued to do the same at the other beds, effectively waking all of us.

On the last morning there (sunday) I prepared a little speech for her, which I could never hold, because I was moved from the ICU to a normal bed in the night. So, I am trying to do it here and now:

I don't know whether any of my readers has ever spent a night in an ICU bed. It's deeply depressing. The only thing to look at are the bubbles in the bottles over you, which are pooring liquids in your veins, or the monitor, which is showing your blood pressure, heart beat, and stuff like that. With three apoplectic strokes in a row behind you (I promise to stop counting in public now. My inner self is a different matter.) there isn't much to expect or even hope for. Forget about sleep: There is a continuous background noise. Light is never completely lit and every five minutes some machine is beeping alarm, ideally on another bed, but from time to time it's at your own. (Usually, because you turned yourself to the other side.) Think of a Jura coffee machine that requests service to imagine the sound. In my worst moment, the nurse saw fit to blow oxygene in my nose because I seemed to be loosing. (Usually an indication of a heart that no longer works properly, fortunately not in this case.)

After such a night, waking up is a gift! I'm still alive! I can kiss my wife today. With a bit of luck, I can hod our daughter. I can enjoy the smell of coffee. (Something, I couldn't do in the last months even if
I had coffee. But, it works again!) So, don't apologize, Dr., you're more than welcome. I can't tell, whether the other gentlemen share my feelings, but I'll be glad to give a few centiliters of blood, if I can have this day in exchange!

Still there, world!

This is not the end. But, let's face it: This (or any future post) might very well be my last. (In fact, last saturday I'd have been surprised about the additional week that I had since then. So, it seems to be ino order to prepare. So, how can a coder like me leave the world in grace? Like this:

#include <stdio.h>

main()
{
printf("Good Bye, World \n");
}

Sadly, I'm no wizard. For Dennis Ritchie, this would have been

#include <stdio.h>

main()
{
printf("GOOD BYE, WORLD!\n");
}

(One of deaths silly jokes. That'd be style!)

But, for now and me, the only proper thing seems to be:

#include <stdio.h>

main()
{
printf("Still there, World \n");
}