A while ago, I wrote an article on RSS and the Java Informa API for O’Reilly’s java.net site. This morning, my Google blog search called up an odd search result – it seems as though a certain Dr. Charlie Peng had copied the article wholesale for his BlogSpot blog, ‘IT Architect’. It looks like a blatant attempt to create a high-ranked blog in order to achieve something (probably commercial gain – I don’t think it’ll help him get girls). If achieving high-ranking is his goal, I’m sure he could of picked some better articles to steal, with some better buzzword density – RSS is so 2003.
I’ve flagged the site, left a comment and informed O’Reilly. Knowing how responsive Google are at removing dodgy blogspot blogs, I don’t expect much to happen anytime soon – unless O’Reilly decide to throw so weight around that is. In the meantime, you can view the stolen article at “architectit dot blogspot dot com /2006/07/rss-in-JSP-using-RSS-in-JSP-pages-by.html” (no link referrals for him) – although I’d prefer it if you simply read the original article over at Java.net.
June 29th, 2006
11:10 pm
Java
I’ve been struggling with configuring a password protected Resin-deployed JMX application on windows recently. This is being blogged in the hope that Google will pick this up and make the process much simpler for someone later on.
These instructions assume you are using Resin, but should work for any container.
Enabling Password Protection
Starting Resin secured using a password is pretty simple. Firstly, start Resin with the following properties:
com.sun.management.jmxremote.port=<portnumber>
com.sun.management.jmxremote.authenticate=true
com.sun.management.jmxremote.ssl=false
com.sun.management.jmxremote.password.file=<absolute or relative path to jmx.passwd>
com.sun.management.jmxremote.access.file=<absolute or relative path jmx.access>
Next, you’ll need to create jmx.access file, like so:
joeblogs readwrite
And a jmx.passwd:
joeblogs password1
jmx.passwd needs to be secured such that only the user running the Resin process can access the file. On Linux or Unix, this is simply a case of running chmod 400 jmx.passwd. However on Windows this is more involved – the five step process required to secure the file is rather baroque, and worst of all makes running JMX applications secured in this manner rather hard for development teams, as this has to be done each time the file is checked out. I suspect a Calcs or SetAcl script could be folded into the build, but it really shouldn’t be that hard. I suspect Sun want us all to use SSL instead.
Programatically working with password protected JMX
This sample from sun shows how to work with your newly password-protected JMX app:
public class Client {
public static void main(String[] args) {
try {
HashMap env = new HashMap();
String[] credentials = new String[] { "username" , "password" };
env.put("jmx.remote.credentials", credentials);
JMXServiceURL URL = new JMXServiceURL(
"service:jmx:rmi:///jndi/rmi://localhost:9999/server");
JMXConnector jmxc = JMXConnectorFactory.connect(URL, env);
MBeanServerConnection mbsc = jmxc.getMBeanServerConnection();
String domains[] = mbsc.getDomains();
for (int i = 0; i < domains.length; i++) {
System.out.println("Domain[" + i + "] = " + domains[i]);
}
ObjectName mbeanName =
new ObjectName("MBeans:type=SimpleStandard");
mbsc.createMBean("SimpleStandard", mbeanName, null, null);
// Perform MBean operations
[...]
mbsc.unregisterMBean(mbeanName);
jmxc.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
When connecting to a database from Java, it’s very handy to tag your connections. When tracking down performance issues and monitoring at a database levels, being able to seperate out your program’s connections (which could come from a variety of machines). Most database drivers allow you to specify a program name when creating your connection.
With SqlServer, you can specify a program name on the query string of your JDBC connection. However with Oracle it’s not quite as simple. I spent ages trying to track down how to do this with Oracle, but it seems that where Oracle is concerned useful documentation lies behind expensive consultants or registration screens. Eventually resident database guru (thanks Jason) sent me a snippet of code which does exactly that, and I’m blogging it here for prosperity (and for consumption by the Google spider).
This code opens a connection with the name Test. By querying the database’s v$session dictionary view we can see each connection from our application (by the way, good luck searching
Google using a $ in a search term). v$session exposes a variety of information – including the program name. The final lines of the code prints out the program name of every session currently connected to the database, helping confirm that the snippets code has worked.
class SetProgram
{
public static void main (String args [])
throws SQLException
{
// Load the Oracle JDBC driver
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
java.util.Properties props = new java.util.Properties();
props.put("v$session.program", "Test");
// Connect to the database
Connection conn =
DriverManager.getConnection ("jdbc:oracle:thin:user/tiger@localhost:1521:xe",
props);
// Create a Statement
Statement stmt = conn.createStatement ();
// Select the PROGRAM field from the V$SESSION table
ResultSet rset = stmt.executeQuery ("select program from v$session");
// Iterate through the result
while (rset.next ())
System.out.println (rset.getString (1));
}
}
Specifying program name with C3P0
When configuring this value using the C3P0 connection pool, if you want to specify properties like v$session.program, you cannot configure login and password using the normal setPasword or setUser methods as it gets its knickers in a twist. Instead you’ll have to place those in the properties object which you pass to the connection pool using the setProperties method on ComboPooledDataSource.
This is worth noting, as where setUser and setPassword will be JDBC driver agnostic, the properties bundle passed in isn’t – or more correctly, the properites themselves aren’t.
April 24th, 2006
8:46 pm
Java
[java]
Table person = new Table(“person”);
return select(person.star())
.from(person)
.where(person.column(“startDate”).greaterThan(“2005-01-01”)
.and(person.column(“numberOfFriends”).greaterThan(100))
.and(person.column(“age”).greaterThan(21)));
[/java]
[java]
Table person = new Table(“person”);
Column startDate = person.column(“startDate”);
Column numberOfFriends = person.column(“numberOfFriends”);
return select(person.star())
.from(person)
.where(startDate.greaterThan(“2005-01-01”)
.and(numberOfFriends.greaterThan(100)
.or(numberOfFriends.lessThan(50))));
[/java]
[java]
Table person = new Table(“person”);
return select(star())
.from(person)
.where(person.column(“psnId”).notIn(new String[] { “1”, “2” }));
[/java]
From the Squiggle acceptance tests…
April 2nd, 2006
9:09 pm
Java
[java]
Table person = new Table(“person”);
return select(person.star()).
from(person).
orderBy(person.column(“name”));
[/java]
[java]
Table person = new Table(“person”);
Column age = person.column(“age”);
return select(person.star()).
from(person).
where(age.lessThan(25))
[/java]
[java]
Table person = new Table(“person”);
Column wage = person.column(“wage”);
return select(count(person.star())).
from(person).
where(wage.greaterThan(52000))
[/java]
Yes, I know what you’re thinking – “So soon after the announcement of the March meeting? Has Sam started getting organised?”. Well, kind of – actually I heard from Harry Pot Simon W that one of the Django devs, Adrian Holovaty, was going to be in town.
Given that it’s so far in advance, I’m sure many of you won’t know if you can make it, but once again it’ll be the same cross-language cross-technology meetup, broadly aligned along Web 2.0 lines – all are welcome, whether or not you think Web 2.0 is great, or just a crock of poo.
Read the rest of this entry »
Just a quick note after a long absence (no doubt a flood of posts will now follow, preceding another too long gap). Anyway, London 2.0rc2 is on for this Tuesday. Once again it’ll be combining the Python meetup, and will be open to all Ruby, Django, Rails, Python, RSS, Catalyst, web.py, TurboGears, Java, RDF and Struts enthusiasts, and interested observers. After missing the last two (which is bad form as an organiser) I’ll be making a concerted effort to put in a prolonged apperance.
If you’re coming, you could either signup on Upcoming.org, or leave a comment here. As normal, it’s from 6pm til late at the Old Bank of England.
*We need a snappier name…
As the calendar gets a little crowded in December, myself, Simon and Jez have decided to combine the Java, Django/Rails and Python nights together in one big bash at the Old Bank Of England, on the 12th of December, from 7pm onwards. As normal there is no particular agenda, although people wanting to do demos are more than welcome (just let me know first so we can publicise it).
Oh, and as Jez has had to stick a deposit down for the reserved space, please leave a comment to let us know you’re coming!
September 18th, 2005
12:46 pm
Java
A recent post by Cedric in response to an article by Michael Feathers (danger, community navel gazing alert! Obviously this blog is above such things) casts doubt on the necessity of unit tests.
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August 1st, 2005
11:04 pm
Java
It’s been a while since I’ve had to unleash the angry kitten, but it seems that the OpenAdaptor developers have rather inadvisably irked me, to the extent that I’ve withheld the kitten’s food for two days now, to make the ensuing carnage all the more…well, carnagy.
To start with, I like the concept and some of the architecure behind Open Adaptor. It’s a fine arhictecture – it’s no suprise that plenty of other APIs out there have come up with similar solutions to the same problems. The JBI spec obviously owes a lot to OpenAdaptor. That said its implementation frequently makes me want to have a few minutes with the developers, a pair of pliers and a blowtorch.
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