Soften interface for and friends

Dave Brosius dbrosius at
Fri Feb 24 00:17:13 UTC 2017

Greetings. the method

public static ObjectName getInstance(String domain,
Hashtable<String,String> table)
         throws MalformedObjectNameException {
         return new ObjectName(domain, table);

in allows for a provided Hashtable to 
specify properties for the objectname.

The semantics of an ObjectName don't consider the order of these 
properties, however certain tools like jconsole (when used as a name for 
a jmx property) does consider the order.

If you wish to create a folder structure to report metrics in jmx, you 
need to use this properties map to specify the folder names. JConsole, 
then, uses order of iteration to determine the order of the folder 

Suppose you want a folder hierarchy similar to a package name, you may 
specify properties like

table.put("a0", "com");
table.put("a1", "acme");
table.put("name", "MyMetric");

in hopes of producing a metric in JConsole in the folder structure, 

The problem is of course, that the argument is a Hashtable, not a Map, 
and so the items are not ordered at all, yet JConsole uses iteration 
order to build the path, so you may get

acme/ao/MyMetric or MyMetric/acme/ao or .....

This means if you really want to have ordered packages, you have to 
derive from Hashtable, and override the entrySet() method, including 
that set's iterator() to return the values in the order you wish to have 
them shown.

That is really janky.

I'm proposing that the interface for getInstance be softened to

public static ObjectName getInstance(String domain,
                                          Map<String,String> table)

as well as

public ObjectName(String domain, Map<String, String> table)


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