I have written a two part article for this months .net magazine detailing how easy it is to write a Google Talk bot with the evented power of Node.js.

“Programming a chat bot was once the domain of the hardcore hacker, tapping packets as they passed over the wire from proprietary client applications to closed source servers, but not any more!”

In issue 225 (out now) you will learn how to build a Google Talk bot that is able to set its own status messages and accept new contact requests. I then follow this up in part two of the tutorial (issue 226, on sale 28 February) by adding message bounce back and Twitter searching functionality.

Additionally, I give a little bit of history from both Node.js and XMPP/Jabber along with some background on projects and companies that are using Node.js and hiring experts. As an aside there is a micro-tutorial on creating webpages with Node.js using the express framework like the bots demo website.

There is also a demo bot and documentation over at njsbot.simonholywell.com, which is hosted on cloudno.de (Thanks Hans). The source code for the demo site and bot can be found on github.

When installing a UDF recently I got an annoying error message, which didn’t seem to want to go away. Deleting the function before attempting to remove it did not work so I used the following set of escalating commands to attempt to get it to install.

But back to the error for a moment:

bash > mysql -u user -p < installdb.sql
Enter password:
ERROR 1125 (HY000) at line 7: Function 'lib_mysqludf_ssdeep_info' already exists

This can be solved really simply with the following options:

1. Attempt to delete the function and then reinstall it
2. Delete the function row from the mysql.func table and then reinstall it
3. Stop the MySQL server (after trying option 2), start it again and then reinstall it

When I began using Cloudno.de recently to have a go at Node.js and CouchDB I stored my username and password in plain text in a configuration file. If you are also looking to get CouchDB going with CloudNo.de then my earlier Getting started with Node.js and CouchDB post may be of interest.

The configuration file was fine for testing as nobody who came across the database login details could do any real damage, but as the project got more interesting I wanted to send it live and these details would need to be kept private.

Thankfully the Nodester platform, which CloudNo.de is using, has environment variables built in and you can use them to store sensitive data such as passwords. It is also good to know that the variables will persist even after the host machine is cycled.

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Node.js and CouchDB feel like they were made for each other right from the very first time I used them. With the cradle node package the integration becomes even easier.

Whilst both Node.js and CouchDB are open source with packages for most operating systems it maybe easier for you to start out using a hosted solution such as CloudNo.de (has CouchDB now) or Nodester for example. As far as the CouchDB portion goes there is only one place to go and that is IrisCouch.

With the exception of IrisCouch they are all in private beta so there might be a small wait before you get access.

I wrote the following example code before CloudNo.de supported CouchDB so it references IrisCouch, but the setup is similar.

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necora-markus:

Released a new version of the Agavi framework support plugin for the shiny new NetBeans 7.0. Still depends on implementation versions of the PHP-plugin, so if something doesn’t work, please let me know.

Prebuilt NBM available here, source code here.

UPDATE: Even newer version available here. Should fix a null pointer exception.

Quite often when you are working with legacy code you will come across a mess of globals. Every single method will make use of the same global instance of the database class for example. So where do you begin to work with this massive impediment?

Logging is a great way to see what methods and classes are being used by you application and where. To achieve this you would normally need to add a logging call to each and every method in the code base. Clearly this would be incredibly tedious and time consuming.

This is where a proxy object can be implemented to save time and centralise the logging functions. The basic idea of a proxy object is that it will be instantiated in place of the actual class and the proxy will delegate any calls through to the original class. For the purposes of this example the original class will be called Database and the proxy object will be called LazyLoadingProxy.

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I needed to add a new port forward to a router, but I did not have access to the web interface through a graphical browser. Attempts to get in using Lynx stalled as it seems the router will not serve up the frames in the interface independently of each other and it kept issuing 404 errors.

Either way I had to use the telnet interface using the following command (replace 192.168.1.1 23 with the IP address of your router):

telnet 192.168.1.1 23

This is fine except that Draytek have absolutely no documentation available for the commands. So to discover the correct command I had to go through all the available options (and sub options and sub sub options) as it was not immediately clear to me which option port forwarding was hiding under. To give you an idea here is a list of the top level options (run the `?` command to get this view):

> ?
% Valid commands are:
adsl         bpa          csm          webf         ddns         ddos
urlf         kw           exit         fe           internet     ip
ipf          log          mngt         port         portmaptime  prn
quit         show         srv          sys          tsmail       upnp
vigbrg       vlan         vpn          wan          wol          qos

The option we are interested in is `srv` which has a number of sub options but we are only interested in `nat`. Now we have yet more options but lets just stick with `portmap`.

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