tnameserv(1) tnameserv(1)
NAME
tnameserv - Java IDL name server starter script
SYNOPSIS
tnameserv -ORBInitialPort port_number
DESCRIPTION
The CORBA COS (Common Object Services) Naming Service pro-
vides a tree-like directory for object references much
like a filesystem provides a directory structure for
files. The Naming Service provided with Java IDL is a
simple implementation of the COS Naming Service specifica-
tion.
Object references are stored in the namespace by name and
each object reference-name pair is called a name binding.
Name bindings may be organized under naming contexts.
Naming contexts are themselves name bindings and serve the
same organizational function as a file system subdirec-
tory. All bindings are stored under the initial naming
context. The initial naming context is the only persis-
tent binding in the namespace; the rest of the namespace
is lost if the Java IDL name server process halts and
restarts.
For an applet or application to use COS naming, its ORB
must know the name and port of a host running a naming
service or have access to a stringified initial naming
context for that name server. The naming service can
either be the Java IDL name server or another COS-compli-
ant name service.
USAGE
Starting the Java IDL Name Server
You must start the Java IDL name server before an applica-
tion or applet that uses its naming service. Installation
of the Java IDL product creates a script named tnameserv
that starts the Java IDL name server. Start the name
server so it runs in the background.
If you do not specify otherwise, the Java IDL name server
listens on port 900 for the bootstrap protocol used to
implement the ORB resolve_initial_references() and
list_initial_references() methods. Specify a different
port, for example, 1050, as follows:
example% tnameserv -ORBInitialPort 1050
Clients of the name server must be made aware of the new
port number. Do this by setting the org.omg.CORBA.ORBIni-
tialPort property to the new port number when creating the
ORB object.
Stopping the Java IDL Name Server
To stop the Java IDL name server, use the relevant operat-
ing system command, such as kill(1). Note that names reg-
istered with the Java IDL name service disappear when the
server is terminated.
Sample Client: Adding Objects
The following sample program illustrates how to add names
to the namespace. It is a self-contained Name Server
client that creates the following simple tree.
Initial
Naming Context
\
\
plans personal
\
\
calendar schedule
In this example, "plans" is an object reference and "per-
sonal" is a naming context that contains two object refer-
ences: "calendar" and "schedule".
import java.util.Properties;
import org.omg.CORBA.*;
import org.omg.CosNaming.*;
public class NameClient
{
public static void main(String args[])
{
try {
In the above section, Starting the Java IDL Name Server,
the nameserver was started on port 1050. The following
code ensures that the client program is aware of this port
number.
Properties props = new Properties();
props.put("org.omg.CORBA.ORBInitialPort", "1050");
ORB orb = ORB.init(args, props);
The following code obtains the initial naming context and
assigns it to ctx. The second line copies ctx into a
dummy object reference, objref, that we will attach to
various names and add into the namespace.
NamingContext ctx = NamingContextHelper.narrow
(orb.resolve_initial_references("NameService"));
NamingContext objref = ctx;
The following code creates a name "plans" of type "text"
and binds it to our dummy object reference. "plans" is
then added under the initial naming context using rebind.
The rebind method allows us to run this program over and
over again without getting the exceptions we would get
from using bind.
NameComponent nc1 = new NameComponent("plans", "text");
NameComponent[] name1 = {nc1};
ctx.rebind(name1, objref);
System.out.println("plans rebind sucessful!");
The following code creates a naming context called "Per-
sonal" of type "directory". The resulting object refer-
ence, ctx2, is bound to the name and added under the ini-
tial naming context.
NameComponent nc2 = new NameComponent("Personal", "directory");
NameComponent[] name2 = {nc2};
NamingContext ctx2 = ctx.bind_new_context(name2);
System.out.println("new naming context added..");
The remainder of the code binds the dummy object reference
using the names "schedule" and "calendar" under the "Per-
sonal" naming context (ctx2).
NameComponent nc3 = new NameComponent("schedule", "text");
NameComponent[] name3 = {nc3};
ctx2.rebind(name3, objref);
System.out.println("schedule rebind sucessful!");
NameComponent nc4 = new NameComponent("calender", "text");
NameComponent[] name4 = {nc4};
ctx2.rebind(name4, objref);
System.out.println("calender rebind sucessful!");
} catch (Exception e) {
e.printStackTrace(System.err);
}
}
}
Sample Client: Browsing the Namespace
The following sample program illustrates how to browse the
namespace.
import java.util.Properties;
import org.omg.CORBA.*;
import org.omg.CosNaming.*;
public class NameClientList
{
public static void main(String args[])
{
try {
In the above section, Starting the Java IDL Name Server,
the nameserver was started on port 1050. The following
code ensures that the client program is aware of this port
number.
Properties props = new Properties();
props.put("org.omg.CORBA.ORBInitialPort", "1050");
ORB orb = ORB.init(args, props);
The following code obtains the initial naming context.
NamingContext nc = NamingContextHelper.narrow
(orb.resolve_initial_references("NameService"));
The list method lists the bindings in the naming context.
In this case, up to 1000 bindings from the initial naming
context will be returned in the BindingListHolder; any
remaining bindings are returned in the BindingItera-
torHolder.
BindingListHolder bl = new BindingListHolder();
BindingIteratorHolder blIt= new BindingIteratorHolder();
nc.list(1000, bl, blIt);
The following code gets the array of bindings out of the
returned BindingListHolder. If there are no bindings, the
program ends.
Binding bindings[] = bl.value;
if (bindings.length == 0) return;
The remainder of the code loops through the bindings and
prints the names out.
for (int i=0; i < bindings.length; i++) {
// get the object reference for each binding
org.omg.CORBA.Object obj = nc.resolve
(bindings[i].binding_name);
String objStr = orb.object_to_string(obj);
int lastIx = bindings[i].binding_name.length-1;
// check to see if this is a naming context
if (bindings[i].binding_type == BindingType.ncontext) {
System.out.println
("Context: " + bindings[i].binding_name[lastIx].id);
} else {
System.out.println
("Object: " + bindings[i].binding_name[lastIx].id);
}
}
} catch (Exception e) {
e.printStackTrace(System.err);
}
}
}
SEE ALSO
kill(1)
14 July 2000 tnameserv(1)