4.4 CloudTran Configuration
This section describes CloudTran configuration.
This covers both
- the some product properties, separate from the Coherence cache and POF configuration described in the previous section.
- application-specific properties you can set in your application, which can be overridden when the application is started.
This section lists the various ways you can affect configuration parameters. These are separated from the CloudTran cache and POF configuration.
4.4.1 Configuration Timing and Priority|
The list here is in time order - starting with items that are baked into the CloudTran executables,
and ending up with system properties you can enter as you start each executable.
The 'CloudTran executables' we refer to are the clients using CloudTran, the Manager nodes and the Isolator.
The order below is also the priority order: a configuration item earlier in the list is overriden by
redefining the property later in the list. For example, the default properties baked into CloudTran
can be overridden by setting values in the model, which in turn can be overridden by JVM system properties.
- A number of configuration properties affecting the CloudTran product
are built into the executable. These properties, and the default values,
engine define most of the standard configuration in the model.
The default properties are documented here.
- Next, you can set Java system properties on starting a node.
You do this by setting properties using -D (along with -X and other options) into the Java start line.
In Eclipse, you have to go into each run configuration in turn and change the 'VM arguments':
- Finally, you can change many properties on the fly - after CloudTran is running.
This is mostly used for tuning, but could also be used to tune the capacity of the system at runtime.
As described above, configuration properties can be collected into one or more "config.properties" files.
This is optional.
4.4.2 The configuration file 'config.properties'|
To be used, the config.properties files must be available in the top level of the classpath.
In Eclipse, put config.properties in a
The config.properties file is useful for specifying default runtime properties for the application
or a given deployment. It gives an intermediate priority for specifying configuration properties -
it has less priority than properties specified on the command line, but higher priority than
defaults built into a program. Put another way, if there is a setting the same property name
in config.properties and on the command line, the command line value is used.
Using a config.properties file, you can create basic configuations - "small development", or "performance" -
for use in standard situations, and leave the command-line properties for small variations.
The types of properties you can put in the config.properties are:
- values for built-in properties.
For all built-in properties, there are defaults built into CloudTran.
These are documented in the next section,
based on a file in Java properties format, copied here.
- application-specific configuration properties - for example, the number of iterations on a test.
Although CloudTran has a default config.properties file for CloudTran-specific properties,
you can put any properties into the config.properties file that you would otherwise put on a command line.
It is up to you what to name your own properties, but you need to avoid predefined names.
CloudTran currently uses names beginning with "config.", "ct." and "trace.".
The convention is to use the application name followed by '.', such as 'myApp.nCustomers', for live
and a "test." prefix (e.g. 'test.soaktest.iterations') for test programs.