Configuration

Each WebVM installation can be customized to fit best with the underlying operating system, Java VM and browser using a generic interface which needs to be implemented for different platforms and storage mechanisms.

Requirements

The configuration of WebVM needs to implement the following requirements:

• General path/storage information representing the home directory/namespace of the local WebVM installation
• Path/storage to store temporary files/data in
• Path/storage to store persistent files/data in (e.g. persistent APIs)
• Path/storage to store security policy files/data in
• Path to dynamic/shared library which provides the VM being run (only JNI)
• Major and minor Java class file version numbers to reflect the VM in use
• Java CLASSPATH to locate the stub and core class files resp. archives
• Additional VM invocation options (e.g. for the JNI-based WebVM)

Interface

The interface of the Configuration looks like the following abstract class definition:

class Setup {

public:

    // Returns the value of the option key, NULL if option is not
    // set/unknown.
    const char *getOption(const char *key) = 0;

    // Sets the option value with the specific key. If the value is
    // NULL, the option is unset. If key is NULL the call has no
    // effect.
    void setOption(const char *key, const char *value) = 0;

    // Discards the existing options and reads the new options from
    // the specified input stream.
    bool readOptions(istream *in) = 0;

    // Writes the existing options to the specified output stream.
    bool writeOptions(ostream *out) = 0;

};

Configuration storage format

The option storage format is implementation-dependent. However the default storage format of the file-based implementation uses the following syntax:

# comment
key: value

Each line might contain a single key value pair, which are separated by the first occurrence of the colon character. Leading and trailing whitespace characters are dropped from the key and value. Values containing a sequence of $NAME will be evaluated to the value of environment variables, if present.

Default option keys

To implement the above requirements using a file-based configuration approach, the following default keys are specified:

# Home directory/namespace of WebVM
home: /usr/lib/webvm 
# Temporary directory/storage
store.temp: /tmp
# Persistent storage
store.persistent: $HOME/.webvm/modules
# Security policy storage
store.security: $HOME/.webvm/security
# The VM provider
java.vm: /usr/lib/java/jre/lib/i386/client/libjvm.so
# The number of additional VM options
java.vm.nOptions: 2
# Additional VM options
java.vm.option.0: -Djava.library.path=/usr/lib/webvm/jni/lib
java.vm.option.1: -Dverbose=class
# Java class file major.minor version
java.classfile.version: 49.0
# The default Java classpath to execute WebVM modules
java.class.path: /usr/lib/webvm/java/lib/J2SE.jar:/usr/lib/webvm/java/lib/midlet.jar

Unix

The system-wide webvm configuration file should be stored in

/etc/webvm.conf

If WebVM is deployed only by a single user, the user’s WebVM configuration should be stored in

$HOME/.webvm.conf

Windows

The system-wide webvm configuration file should be the value of the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Aplix Corporation\WebVM\ConfigFile

If WebVM is deployed only by a single user, the user’s WebVM configuration file should be the value of the following registry key:

HKEY_CURRENT_USER\SOFTWARE\Aplix Corporation\WebVM\ConfigFile