DwarfFaq

Chair for Computer Aided Medical Procedures & Augmented Reality
Lehrstuhl für Informatikanwendungen in der Medizin & Augmented Reality

The DWARF FAQ

The following two-step algorithm probably solves your problem:

  1. Search the Dwarf Mailing List Archives
  2. If you still can't solve your problem, send an E-Mail to the Dwarf Mailing List


Understanding DWARF

I have no clue what this CORBA stuff is all about...

Go read the DwarfCorbaTutorial.

I think that CORBA is not fast enough for AugmentedReality.

In the COVRA project, Kim et al. showed that CORBA is viable for virtual reality applications, which pose the same stringent performance requirements as augmented reality. In addition, we use other protocols, such as shared memory for local high-bandwidth communication, and CORBA method invocations for tightly coupled reliable communication.


Installing DWARF

What do i need to do to checkout the DWARF source from the CVS?

The DWARF CVS tree can be checked out using:

  • cvs -d :ext:$USER@cvsnavab.informatik.tu-muenchen.de:/cvs/dwarf co dwarf -P .

For this, you need an account on cvsbruegge in the group dwarf, which can be obtained via the Lehrstuhl. Dont forget that you need to set CVS_RSH=ssh for this to work, since rlogin (which is the default) is not allowed on the server.

If you only need read-only access, you may require a password (contact us via ) and use the command:

  • cvs -d :pserver:dwarf@cvsnavab.in.tum.de:/cvs/dwarf login
  • cvs -d :pserver:dwarf@cvsnavab.in.tum.de:/cvs/dwarf co -d dwarf -P .

Which platforms are supported for DWARF?

  • Most flavors of Linux should work, however, full support is given only for SuSE Linux 8.1 and SuSE Linux 9.0 other flavours of Linux on which succesful installations have been reported:
  • it also runs on iPAQs using Linux
  • DanielPustka reported a successful build of DWARF using FreeBSD
  • MacOS X is supported (full support only for 10.3) see MacOSXFinkPackages for install instructions(for now without python)
  • Windows (at least XP)

I have only Windows. Can i use DWARF?

Yes. You may check the directory win32 in the DWARF source tree for build instructions. They are somewhat weird and require both cygwin CMake and Visual C++. The service manager currently will compile with Windows, but also single services (e.g. Java) are easily compiled and may connect to a service manager running on a supported platform. see the DwarfWindowsTutorial and the DwarfJavaTutorial

I want to install DWARF and already got the source code out of the CVS repository. Now I am searching for the configure script. I can't find it. Why?

You should read the README and QUICKSTART files in the cvs root. There you can find all the information you need for bootstrapping the system.

After running the configure script, it is automatically run a second time when I run make. How can I stop this waste of time?

The GNU autotools automatically create Makefile rules that rebuild all generated files when input files like Makefile.am and configure.ac change. The detection of these changes is based on timestamps. A common mistake is to use cvs checkout instead of cvs update to refresh the working copy of files. A checkout updates all timestamps, leading to the autotools input files being newer as the generated files.

I use Mac OS X and when i try to run the bootstrap script, automake crashes. What's wrong?

automake crashes with
./bootstrap: line 12:  2313 Segmentation fault      automake --add-missing
For some reason, this version of automake does not work with DWARF on Mac OS X. Go read the QUICKSTART file from the CVS root on how to install the working versions.

I just installed DWARF, compilation and installation went allright. However, my OS complains that some libraries are missing when I want to execute some binaries. What's wrong?

GNU libtool handles the compilation of all binaries. The DWARF specific GNU autoconf macros in the config directory handle correct settings of linker flags such as libraries needed and these libraries' paths. Therefore, compilation should always work. Things change when the binaries get executed, the OS run time environment must then find the libraries itself. On Linux, you may help the system by including the missing library paths in LD_LIBRARY_PATH. Alternatively, you may change the relevant autoconf macro to include the following options in the LDFLAGS it outputs:

-Xlinker --rpath -Xlinker ${your_lib_path_here}
config/dwarf_have_mkl.m4 contains an example.

I try to compile DWARF remotely on janus.informatik.tu-muenchen.de, but it does not work

Janus is our server, and only server. You cannot compile DWARF on janus. See AugmentedRealityLabor for machines to use remotely.

Compilation of DWARF is just ...slow. What can I do to speed it up?

Tune your configure options! The following options should double the compilation speed:
configure --disable-static CFLAGS="-g -O0" CXXFLAGS="-g -O0" GCJFLAGS="-g -O0"
It is advisable to store this complicate commandline as an alias.

TamerFahmy gave another hint: do a

make -j2
this should speed up compilation around factor 2! The argument to -j should be (CPU ammount)*2.

Look for distcc and ccache, both decrease the compile time massively.

Compilation of DWARF fails with the error: "jar: -u mode unimplemented".

You are using GNU jar, which comes with gcj, the GNU compiler for java. That version of jar is incomplete. Throw it out and use your Java SDK's jar instead. you'll have to touch all idl files in src/idl

Compilation of DWARF fails on compilation of Service.idl

see error "jar: -u mode unimplemented".

Compilation of DWARF fails in some Java-related parts.

If that happens with some "cannot resolve symbol symbol : ..." error message of javac, try to issue the make command another time (and repeat this several times...). Ususally, this is a workaround for this long standing problem in our build process. If you have knowledge on ant and automake, and some idea how to marry these two tools, you are happily invited to implement a new build process for the Java parts of DWARF.


The Service Manager

How Do i Start the Service Manager?

Use the ./run-servicemgr script. Do not try to start the Service Manager directly, this will not work. The script checks for some preconditions and sets up the Service Manager correctly. With the first command-line argument of the script, you can specify an example application to run (for example labsheep). If you do not specify an application to run, the Service Manager will parse all service descriptions located in the share directory but it will not start any service. You would need to do this manually in this case.

I have a Service without any Abilities, and it never gets connected. Why?

You should set the parameters startOnDemand and stopOnNoUse to false in the service description. Setting these to true makes the Service start only when one of its Abilities is requested, and your Service doesn't have any...

This happens with Services that are started directly by the user, i.e. Views and debugging services like the TestStringReceiver.

How can I specify a predicate for a Need? The string format is strange...

Check out the SLP attribute specification under http://www.openslp.org/doc/rfc/rfc2608.txt . It's LDAP format.

When I start a service that has an XML description, it crashes, and the service manager says, "invalid service name". What's happening?

You should start the service manager with run-servicemgr.sh rather than servicemgr. This tells the service manager which directory the XML service descriptions are in.

The service manager won't start; I get "perhaps notification service is not running" as an error message.

Make sure your network configuration is ok. Try ping `hostname` - if that doesn't work; neither will CORBA (or anything else...)

I keep getting "SLP error 20" messages; my services won't communicate.

Make sure your SLP configuration is ok. Probably the SLP daemon is not running.
On a Mac this helps: mv /usr/sbin/slpd /usr/sbin/slpd.krupuk
Also sometimes (especially when using our openslp-rpms) it is necessary to do:
(Linux:) ln -s /usr/local/etc/slp.conf /etc/slp.conf
(Mac:) ln -s /sw/etc/slp.conf /etc/slp.conf

To test your SLP configuration, try

slptool findsrvs service:service-agent

...that should show all SLP daemons in the network, including your local host. If that doesn't work, neither will DWARF.

I keep getting "SLP error -23" messages

Your SLP installation is corrupted, probably you need to modify your routing table. See http://www.openslp.org/doc/html/faq.html and http://www.openslp.org/doc/html/UsersGuide/Installation.html for details.

I am disconnected from the Network and DWARF isn't working anymore.

Maybe your SLP Daemon tries to communicate on the wrong network interface, you can force him with the following line in the /etc/slp.conf

net.slp.interfaces = 127.0.0.1

if you want to use the loopback interface, you have to add to following route:

route add -net 239.0.0.0/8 gw 127.0.0.1 dev lo

The services are slow in connecting!

You should patch your SLP configuration file, usually /etc/slp.conf, to include the fillowing lines:

net.slp.multicastMaximumWait = 500
net.slp.multicastTimeouts  = 50,75,100,150,200,300
net.slp.unicastMaximumWait = 500
net.slp.unicastTimeouts  = 50,75,100,150,200,300

My services won't start up correctly, they get CORBA execptions. The service manager says "invalid service name".

The service manager probably is not parsing the XML service descriptions, meaning that most services cannot register themselves with the service manager. If the service descriptions are parsed correctly, you will see messages like newServiceDescription(Sheep). If not,

  • Either you forgot to run make install for the services; this copies the XML descriptions to the right directory,
  • Or your Xerces-C library is not found correctly. Check that config.h includes the line #define USE_XERCESC 1. If it doesn't, re-run configure with the right --with-xercesc argument.

The services don't connect!

There are several reasons why this might happen...

  • You mis-spelled an ability, need or a connector type.
  • None of the services is started beacuse they all have the startOnDemand flag set.
  • You used a malformed LDAP predicate for the need.
  • You used a non-alphanumeric character in an attribute name or value, such as an undersocre. (This is an OpenSLP bug).
  • You did not specify a strong enough predicate for your need, so your need is being connected to some other services that are not started yet, but for which you have XML descriptions. You did not get the ability that you wanted, since your maxInstances have been used up. Debug this by turning on "Show unregistered services" in DIVE; fix it by adding a sensible predicate to your need. Removing unneeded XML files also generally improves performance and stability.

The Service Manager uses 100% of the CPU-Performance

The Service Manager creates a thread for every XML description. It could be that there are too much XML descriptions. Try to move some unused descriptions from the /share folder of your DWARF Installation to a new folder.

The SLP daemon keeps dying.

You probably specified an ability or service attribute with an empty string as a value. This kills the OpenSLP daemon for some reason.


Writing your own DWARF service

I have two needs for events, and both are handled by the same object. Why do I loose events from time to time?

Loosing events is usually inidicating bad object design. If two event channels get connected to the same object, two threads try to access this object simultaneously. Thus, access has to be synchronized. It may now happen that one of the threads gets too few computation time, the events delivered queue up and eventually get dropped if the maximum queue length is reached.

Consequence: Use a single object for every need you have. This makes the design of your service much more elegant and extensible, prevents you from querying event type strings when receiving events and prevents loss of events in case of high system load.


DWARF Interactive Visualization Environment

My nodes in the graph keep running off the bottom-right hand side of the window such that they disappear out of range after about 30 seconds or so...

You need to install Graphviz, a graph visualization software package from AT&T: http://www.research.att.com/sw/tools/graphviz/download.html . The layouter, dot, should be within the search path; DIVE calls it to do the graph layout.

The service keeps crashing. What can i do?

Try this command to get an unlimited version: while true; do ./DIVE; done;

Does this have anything to do with DIVE?

No... the Distributed Interactive Virtual Environment (DIVE) at http://www.sics.se/dive/ is a different project.


Running on a Mac

More information can be found here: MacOSXFinkPackages

When I run a program on Mac OS X, it crashes with a "bus error".

You should set the environment variable DYLD_BIND_AT_LAUNCH to 1. That improves the behavior of many libraries.

The SLP daemon is not started correctly.

Restart it manually with sudo /usr/local/bin/slpd . You will have to repeat this when your network connection changes. On 10.3. with fink install (as we recommend you to do it): sudo /sw/sbin/slpd


Running on Windows

More information can be found in the DwarfWindowsTutorial and in the DwarfInstallTutorial.

When I run a Python service I get unexpected crashes together with omniORBpy.

This can be caused by the compilation of Python has been compiled with another compiler than omniORB has. (ref. http://mail.python.org/pipermail/python-dev/2003-May/035444.html)


Java

When I run a java service I always get the exception org.omg.CORBA.CODESET_INCOMPATIBLE

This problem arises from incompatible codesets between openorb 1.3.0/1.4.0 and omniORB 4.0.3. Try to set the LANG environment variable in the shell you run the java service to en_US. E.g. 'export LANG=en_US' or 'setenv LANG en_US'.

When I run a java service I always get the exception org.omg.CORBA.XXXX

Check if you wrote return XXXXXX._this(orb) at the end of your create[Ability|Need]Object method. When you wrote return XXXXXX._this() it will not work.

Compile error :_class DynamicCompiler is public..._

Error:
graham-kirby-compiler.jar(compiler/DynamicCompiler.java):87: class DynamicCompiler is public, should be declared in a file named DynamicCompiler.java
(source unavailable)

We often has this problem and don't know why, so plaese let us know (MarcusToennis). What we did against it is to remove the sourcecode:

  • > jar xvf graham-kirby-compilier.jar
  • > rm compiler/*.java
  • > jar cvfm graham-kirby-compilier.jar META-INF/MANIFEST.MF compiler


Python

Which version of Python is needed?

In order to get python services up and running you will a python interpreter and omniORBpy installed. The latest version of python is 2.3 and much-optimized over the 2.2 version. However, there are currently some problems in getting it to work with DWARF, so do not install any version higher than 2.2.3. The latest version of omniORBpy (2.2) is fine and it also works well with the (beta) cvs version of omniNotify and the latest version of omniORB (4.0.2).

What can i do to make Python services running from inside my Source directory?

If you want to avoid installing your python service every time you make changes (which somehow contradicts the use of a scripting language), then you need to adjust your pythonpath such that common sources can be found from your source directory. Simply add export PYTHONPATH=$PYTHONPATH:$HOME/dwarf/bin to your .bashrc file (assuming that you have used $HOME/dwarf as the prefix when running configure).



Edit | Attach | Refresh | Diffs | More | Revision r1.75 - 22 Sep 2006 - 23:25 - MarcusToennis

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