JGDMS Project 3.0-SNAPSHOT API Documentation

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Package org.apache.river.example.browser

A visualization tool for exploring Jini Network Technology communities (djinns) with support for ServiceUI.

See: Description

Package org.apache.river.example.browser Description

A visualization tool for exploring Jini Network Technology communities (djinns) with support for ServiceUI. The Service Browser lets you discover lookup services and inspect the various services registered within those lookup services. This tool is provided as an example program within the JGDMS release but many who use it think of it more as a utility than an example.

Note this example is obsolete as it was written before JSR 133, it is presented here for historical purposes, it doesn't export services safely. Do not copy this example. For a modern example see Dennis Reedy's apache-river-example on GitHub

This document provides the following information about the Service Browser:

Running the Service Browser

The Service Browser is started with the following command line structure: 
% java java_options
       -jar install_dir/lib/browser.jar
       config_options
where java_options includes such things as the security policy file and the RMI codebase annotation, install_dir is the directory where the JGDMS release is installed, and config_options includes any Configuration provider options. The Service Browser can be run with no config_options. For the RMI codebase annotation, the system property java.rmi.server.codebase should be set to two URLs that provide HTTP-based access to the Service Browser's download JAR files, install_dir/lib-dl/browser-dl.jar and install_dir/lib-dl/jsk-dl.jar, in that order.

The Service Browser also can be run as a nonactivatable entity under the Service Starter, using org.apache.river.example.browser.Browser for the implementation class, install_dir/lib/browser.jar for the implementation class path, and a codebase containing URLs for install_dir/lib-dl/browser-dl.jar and install_dir/lib-dl/jsk-dl.jar (in that order).

Discovering and Selecting a Lookup Service

The lookup services that will be discovered are initially controlled by configuration entries, with the default being to perform multicast discovery for all lookup services. If you specify one or more groups or addresses in a configuration file (as described in Configuring the Service Browser), the browser only discovers lookup services that are members of those groups or that are at those addresses.

The Service Browser presents a single window when it is started. The window has the menu items File, Registrar, Options, Services, and Attributes. The upper text area changes to show which groups and/or addresses are being used for discovery and how many lookup services have been discovered. The picture below shows a typical Service Browser main window, in which nine lookup services have been discovered, but none have yet been selected.

Picture of the lookup browser as it looks when it first starts.

As lookup services are discovered, they appear under the Registrar menu, listed by unicast address. A specific lookup service can then be selected from this menu for browsing. When a lookup service is selected, the upper text area will be revised to show the number of services registered in that lookup service, and the lower folder area will show the registered services. Administrable services are shown with a blue icon, and non-administrable services are shown with a gray icon. As new services register or existing services unregister, the contents of the window will change automatically to reflect them.

After initial start up, different lookup services can be discovered using several items available from the File menu:

For example, the picture below shows the dialog box presented when the Find By Group... menu item is selected.

Picture of the lookup browser with File menu pulled down.

In this next picture, the group name examples.jini.sun.com will be entered.

Picture of the lookup browser with group dialog box visible.

After the group examples.jini.sun.com has been entered, a list of discovered lookup services will appear in the Registrar menu. In this example, only the host kahlua has a lookup service running that is a member of examples.jini.sun.com, so kahlua is the only address in the drop-down list from the Registrar menu.

Picture of the lookup browser with drop-down registrar list visible.

When kahlua is selected from the Registrar menu, the window contents change as shown in the next picture. In this example, six services are registered:

Picture of the lookup browser with six services visible.

Inspecting Services

Double clicking on a service listed in the lower area of the main window will open a new window, which can be used to inspect and optionally edit attributes of the selected service. The window is titled ServiceItem Editor if the service's administrative proxy implements any of the administrative interfaces supported by the Service Browser, otherwise it is titled ServiceItem Browser. In our running example, double clicking on the net.jini.core.lookup.ServiceRegistrar item opens this window:

Picture of the ServiceItem editor when first opened.

The window shows all of the attribute sets that can be inspected and, in some cases, altered. Attribute sets and attributes with blue icons can be edited, those with gray icons cannot. An attribute set can be edited if it is not ServiceControlled and the service's administrative proxy implements the JoinAdmin interface. Within an editable attribute set, an attribute can be edited if it is of type String or one of the primitive wrapper classes. The two attribute sets shown in the example above are ServiceInfo and BasicServiceType. Each of these entries can be expanded by double-clicking on them as illustrated in the next two pictures.

Expanding the BasicServiceType entry:

Picture of the ServiceItem editor with BasicServiceType expanded.

Expanding the ServiceInfo entry:

Picture of the ServiceItem editor with all items expanded.

Double clicking again on an entry collapses the view. In an expanded entry, double clicking on an editable attribute brings up a dialog box that allows you to input a new value for the attribute. You can also use the Edit menu in the ServiceItem Editor window to add and remove attribute sets, if the service's administrative proxy implements the JoinAdmin interface. Select Add attribute... from the Edit menu to add an attribute set. (Note that for this to work, you will have to run the Service Browser in such a way that the desired attribute set classes are in both its class path and its codebase.) Click on an attribute set and then select Remove attribute from the Edit menu to delete an attribute set.

Filtering Services

Back in the main window, the Services menu shows various types that the registered services are instances of. You can select one or more of these types to add them your current template to refine the set of services displayed in the lower area of the window. When you select a type, it appears in the upper text area to show you what your new template contains, the revised number of matching services is shown, and only the services that are instances of all of the selected types are displayed in the lower area.

Similarly, the Attributes menu shows attribute set classes (with package prefixes removed) that can be added to your current template to refine the set of services. When you select a class, it appears in the upper text area to show you what your new template contains, the revised number of matching services is shown, and only the services with such an attribute set are displayed in the lower area. In addition, the selected menu item changes to a pull-aside menu. You can go back to the Attributes menu to select additional attribute set classes, or traverse a pull-aside menu to see the names of attributes, each of which is itself a pull-aside menu. You can traverse these to see the possible values for the attributes, and select one to further refine your search. You can deselect existing attribute choices, and you can deselect the (match) menu item to deselect an entire class.

By default, the Services menu only shows service interface types. You can select Service classes from the Options menu to see service implementation classes instead. By default, only the most-derived interfaces or classes are shown, but you can select Service supertypes from the Options menu to see supertypes as well. Similarly, by default only the most-derived attribute set classes are shown in the Attributes menu, but you can select Attribute supertypes from the Options menu to see superclasses as well.

Select Reset from the File menu of the main window to reset the template to the initial (empty) state.

Other Operations

In the lower area of the main window, you can right click on a service to obtain a popup menu. Select Show Info from this menu to see details about service ID and service types. If the service's administrative proxy implements any of the administrative interfaces supported by the Service Browser, selecting Admin Service from this menu brings up the ServiceItem Editor window. Selecting Browse Service from this menu brings up the ServiceItem Browser window. If the service is a JavaSpaces service and either its proxy implements the JavaSpace05 interface or its administrative proxy implements the JavaSpaceAdmin interface, selecting Browse Entries from this menu brings up a window that displays all of the current entries.

In a ServiceItem Editor window, the Admin menu allows various administrative operations to be performed on the service. If the service's administrative proxy implements the JoinAdmin interface, you can use the Joining groups... and Joining locators... menu items to control which lookup groups and lookup locators the service uses for lookup discovery and join. If the service is itself a lookup service and its administrative proxy implements the DiscoveryAdmin interface, you can use the Member groups... menu item to control which groups the lookup service is a member of, and you can use the Unicast port... menu item to control which unicast port the lookup service uses for its lookup locator. If the service's administrative proxy implements the DestroyAdmin interface, you can use the Destroy menu item to destroy the service. This last menu selection is illustrated in the picture below.

Picture of the ServiceItem editor with Destroy selected from the Admin menu.

Configuring the Service Browser

The Service Browser obtains its configuration by calling ConfigurationProvider.getInstance with the config_options specified on the command line and the class loader for the main implementation class.

The Service Browser supports the following configuration entries, with component org.apache.river.example.browser:

• adminPreparer
  Type: ProxyPreparer
  Default: new BasicProxyPreparer()
  Description: Prepares administrative proxies obtained by calling the Administrable.getAdmin method on service proxies. The value should not be null. The Service Browser only calls methods on an administrative proxy if administrative operations are performed using menu items. Methods of the JoinAdmin, DiscoveryAdmin, DestroyAdmin, and JavaSpaceAdmin interfaces can be invoked.
• discoveryManager
  Type: DiscoveryManagement
  Default: 
new LookupDiscoveryManager(
    DiscoveryGroupManagement.NO_GROUPS,
    null,  // locators
    null,  // listener
    this)  // config
  Description: Supplies the object used to discover lookup services. The value should not be null. The object returned must also implement DiscoveryGroupManagement and DiscoveryLocatorManagement, and should be configured initially to discover no groups and no specific lookup services.
• exitActionListener
  Type: ActionListener
  Default: see the Browser constructors for details
  Description: The action listener for the Exit item of the File menu.
• folderView
  Type: boolean
  Default: true
  Description: Controls the format of the main window. If true, the main window is split into two areas as described in the rest of this documentation. If false, the main window a single text area, and many of the browsing and administrative operations are not available; the Show Matches item of the File menu must be used to display services registered in the selected lookup service.
• initialLookupGroups
  Type: String[]
  Default: null
  Description: The names of the lookup groups that the Service Browser should initially discover. An empty array specifies that no groups should be discovered. A null value specifies that all lookup services should be discovered. Otherwise, the value specifies the names of the groups to discover. The array must not contain null elements. This entry used when the Service Browser is first started; after initial startup, lookup service discovery is controlled through the File menu.
• initialLookupLocators
  Type: LookupLocator[]
  Default: null
  Description: The locators for specific lookup services that the Service Browser should initially discover. An empty array or null specifies that no specific lookup services should be discovered. The array must not contain null elements. This entry is used when the Service Browser is first started; after initial startup, lookup service discovery is controlled through the File menu.

Note that the constraints specified in the locatorConstraints configuration entry will not be used for these initial locators; any desired constraints should be attached directly to the initial locators.

• leaseManager
  Type: LeaseRenewalManager
  Default: new LeaseRenewalManager(this /* config */)
  Description: Supplies the lease renewal manager used to renew leases for remote event registrations and when obtaining the entries of a JavaSpaces service. The value should not be null.
• leasePreparer
  Type: ProxyPreparer
  Default: new BasicProxyPreparer()
  Description: Prepares leases obtained from registering for event notifications with lookup services and from requesting the entries of a JavaSpaces service. The value should not be null.

The Service Browser calls the renew and cancel methods on leases, and the renewAll method on lease maps created (via the LeaseRenewalManager) from leases.

• listenerExporter
  Type: Exporter
  Default: 
new BasicJeriExporter(
    TcpServerEndpoint.getInstance(0),
    new BasicILFactory(), false, false)
  Description: The object to use for exporting all RemoteEventListener instances used by the Service Browser when registering for event notifications from lookup services. The value should not be null.
• locatorConstraints
  Type: MethodConstraints
  Default: null
  Description: Constraints to attach to any LookupLocator instances constructed from the addresses entered using the Find By Address... menu item.

These constraints are not attached to the locators obtained from the initialLookupLocators configuration entry.

• loginContext
  Type: LoginContext
  Default: null
  Description: Specifies the JAAS login context to use for performing a JAAS login and supplying the Subject to use when running the Service Browser. If null, no JAAS login is performed and no subject is used.
• servicePreparer
  Type: ProxyPreparer
  Default: new BasicProxyPreparer()
  Description: Prepares service proxies obtained from lookup servics. The value should not be null. The Service Browser calls the Administrable.getAdmin method on a service proxy for most administrative operations, and calls the JavaSpace05.contents method on a JavaSpaces service proxy to browse entries.
• uninterestingInterfaces
  Type: String[]
  Default: 
new String[]{
    "java.io.Serializable",
    "java.rmi.Remote",
    "net.jini.admin.Administrable",
    "net.jini.core.constraint.RemoteMethodControl",
    "net.jini.id.ReferentUuid"
    "net.jini.security.proxytrust.TrustEquivalence"}
  Description: Supplies the set of interface names that are not interesting to choose when displaying service instances the lower area of the main window. If the service proxy implements exactly one interface that is not in this list, the name of that interface is used to name the service, otherwise the concrete class of the service proxy is used appended with all the names of the 'interesting' interfaces implemented by that proxy. The value should not be null.
• autoConfirm
  Type: boolean
  Default: false
  Description: Controls whether a confirmation window must popup that requires a confirmation for the update or removal of the service editor window. In case set to true closing of the service editor window will occur automatically in case a service is removed, in case of modifications to the lookup attributes of a service the service editor window will be updated.

Note that additional entries can also be specified to configure the LeaseRenewalManager, LookupDiscovery, and LookupLocatorDiscovery components. For example, the Service Browser assumes you have configured the discovery manager (obtained from the discoveryManager configuration entry) to enforce any desired constraints for multicast discovery and to perform any desired proxy preparation for all discovered lookup services.

The most commonly used configuration entries are likely to be:

Secure deployments typically will provide values for most of the following configuration entries:

plus the following configuration entries for LookupDiscovery (if groups are used for discovery): and the following configuration entry for LookupLocatorDiscovery (if locators are used for discovery):

Loggers and Logging Levels

The Service Browser uses the Logger named org.apache.river.example.browser to log information at the following logging levels:

org.apache.river.example.browser
Level Description
SEVERE Problems that prevent Service Browser startup
INFO Potentially interesting exceptions that occur when performing operations
HANDLED Less interesting exceptions that occur when performing operations

See the LogManager class for one way to use the HANDLED logging level in standard logging configuration files.

Examples for Running the Service Browser

An example command line for starting the Service Browser is: 
% java -Djava.security.policy=browser.policy
       -Djava.rmi.server.codebase="http://your_host:http_port/browser-dl.jar http://your_host:http_port/jsk-dl.jar"
       -Djava.protocol.handler.pkgs=net.jini.url
       -jar install_dir/lib/browser.jar
In this example, the local host is assumed to have the name your_host, running an HTTP server on port http_port, serving files in the lib subdirectory of install_dir, the directory where the JGDMS release is installed. When the Service Browser is run this way, without a configuration file, it will perform multicast discovery to find all available lookup services, and will use Jini extensible remote invocation (Jini ERI) over TCP/IP for its remote event listeners.

An example command line for starting the Service Browser with a configuration file is: 

% java -Djava.security.policy=browser.policy
       -Djava.rmi.server.codebase="http://your_host:http_port/browser-dl.jar http://your_host:http_port/jsk-dl.jar"
       -Djava.protocol.handler.pkgs=net.jini.url
       -jar install_dir/lib/browser.jar
       public.config
The example configuration file public.config only discovers lookup services in the public group: 
org.apache.river.example.browser {
    initialLookupGroups = new String[]{""};
}

The following example configuration file initially discovers no lookup services and uses JRMP for its remote event listeners: 

org.apache.river.example.browser {
    initialLookupGroups = new String[]{};
    listenerExporter = new net.jini.jrmp.JrmpExporter();
}

In all the above command lines, the policy file browser.policy was specified for the java.security.policy system property. An example policy file is: 

grant codebase "file:install_dir/lib/browser.jar" {
    permission java.security.AllPermission;
};

grant codebase "file:install_dir/lib/jsk-platform.jar" {
    permission java.security.AllPermission;
};

grant codebase "file:install_dir/lib/jsk-lib.jar" {
    permission java.security.AllPermission;
};

grant {
    permission java.net.SocketPermission "*:1024-", "connect";
};

Note: Of course, a more restrictive policy file could be used; the one shown here is for illustrative purposes only.

An example of running under the Service Starter is: 

% java -Djava.security.policy=start.policy
       -Djava.protocol.handler.pkgs=net.jini.url
       -jar install_dir/lib/start.jar
       start.config

where start.config is the following configuration file: 

import org.apache.river.start.NonActivatableServiceDescriptor;
import org.apache.river.start.ServiceDescriptor;

org.apache.river.start {

  serviceDescriptors = new ServiceDescriptor[]{
    new NonActivatableServiceDescriptor(
      "http://your_host:http_port/browser-dl.jar http://your_host:http_port/jsk-dl.jar",
      "browser.policy",
      "install_dir/lib/browser.jar",
      "org.apache.river.example.browser.Browser",
      new String[]{"public.config"})
    };
}
An example policy file for start.policy is: 
grant codebase "file:install_dir/lib/start.jar" {
    permission java.security.AllPermission;
};

grant codebase "file:install_dir/lib/jsk-platform.jar" {
    permission java.security.AllPermission;
};
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