GODIET

GODIET is a Java-based tool for automatic DIET deployment that manages configuration file creation, staging of files, launch of elements, monitoring and reporting on launch success, and process cleanup when the DIET deployment is no longer needed [5]. The user of GODIET describes the desired deployment in an XML file including all needed external services (e.g., omniNames and LogService); the desired hierarchical organization of agents and servers is expressed directly using the hierarchical organization of XML. The user also defines all machines available for the deployment, disk scratch space available at each site for storage of configuration files, and which machines share the same disk to avoid unecessary copies. GODIET is extremely useful for large deployments (e.g., more than 5 elements) and for experiments where one needs to deploy and shut-down multiple deployments to test different configurations. Note that debugging deployment problems when using GODIET can be difficult, especially if you don't fully understand the role of each element you are launching. If you have trouble identifying the problem, read the rest of this chapter in full and try launching key elements of your deployment by hand. GODIET is available for download on the web^11.2.

An example input XML file is shown in Figure 11.1; see [5] for a full explanation of all entries in the XML. You can also have a look at the fully commented XML example file provided in the GODIET distribution under examples/commented.xml, each option is explained. To launch GODIET for the simple example XML file provided in the GODIET distribution under examples/example1.xml, run:

~ > java -jar GoDIET-x.x.x.jar example1.xml
XmlScanner constructor
Parsing xml file: example1.xml
GoDIET>

GODIET reads the XML file and then enters an interactive console mode. In this mode you have a number of options:

GoDIET> help
The following commands are available:
   launch:       launch entire DIET platform
   launch_check: launch entire DIET platform then check its status
   relaunch:     kill the current platform and launch entire DIET platform once again
   stop:         kill entire DIET platform using kill pid
   status:       print run status of each DIET component
   history:      print history of commands executed
   help:         print this message
   check:        check the platform status
   stop_check:   stop the platform status then check its status before exit
   exit:         exit GoDIET, do not change running platform.

We will now launch this example; note that this example is intentionally very simple with all components running locally to provide initial familiarity with the GODIET run procedure. Deployment with GODIET is especially useful when launching components on multiple remote machines.

GoDIET> launch
* Launching DIET platform at Wed Jul 13 09:57:03 CEST 2005

Local scratch directory ready:
        /home/hdail/tmp/scratch_godiet

** Launching element OmniNames on localHost
Writing config file omniORB4.cfg
Staging file omniORB4.cfg to localDisk
Executing element OmniNames on resource localHost
Waiting for 3 seconds after service launch

** Launching element MA_0 on localHost
Writing config file MA_0.cfg
Staging file MA_0.cfg to localDisk
Executing element MA_0 on resource localHost
Waiting for 2 seconds after launch without log service feedback

** Launching element LA_0 on localHost
Writing config file LA_0.cfg
Staging file LA_0.cfg to localDisk
Executing element LA_0 on resource localHost
Waiting for 2 seconds after launch without log service feedback

** Launching element SeD_0 on localHost
Writing config file SeD_0.cfg
Staging file SeD_0.cfg to localDisk
Executing element SeD_0 on resource localHost
Waiting for 2 seconds after launch without log service feedback
* DIET launch done at Wed Jul 13 09:57:14 CEST 2005 [time= 11.0 sec]

The status command will print out the run-time status of all launched components. The LaunchState reports whether GODIET observed any errors during the launch itself. When the user requests the launch of LogService in the input XML file, GODIET can connect to the LogService after launching it to obtain the state of launched components; when available, this state is reported in the LogState column.

GoDIET> status
Status   Element   LaunchState   LogState   Resource     PID
         OmniNames running       none       localHost    1232
         MA_0      running       none       localHost    1262
         LA_0      running       none       localHost    1296
         SeD_0     running       none       localHost    1329

Finally, when you are done with your DIET deployment you should always run stop. To clean-up each element, GODIET runs a kill operation on the appropriate host using the stored PID of that element.

GoDIET> stop

* Stopping DIET platform at Wed Jul 13 10:05:42 CEST 2005
Trying to stop element SeD_0
Trying to stop element LA_0
Trying to stop element MA_0
Trying to stop element OmniNames

* DIET platform stopped at Wed Jul 13 10:05:43 CEST 2005[time= 0.0 sec]
* Exiting GoDIET. Bye.

Figure 11.1: Example XML input file for GODIET.

One of the main problem when writing a GODIET XML input file is to be compliant with the dtd. A good tool to validate a GODIET file before using GODIET is xmllint. This tool exist on most platforms and with the following command:

$ xmllint your_xml_file --dtdvalid path_to_GoDIET.dtd -noout

you will see the different lines where there is problem and a clear description of why your XML file is not compliant.