Tuesday, 4 August 2009

Groovy Tutorial for MongoDB

Java Tutorial (http://www.mongodb.org/display/DOCS/Java+Tutorial)

Since Groovy is based on Java, you can make use of the Java driver for MongoDB as well as go through the tutorial shown above. The code can be used as-is or modified to look more groovy.

Create a groovy file (mongo.groovy) and place the Java driver in the same directory. Edit it so the code looks like:

this.class.classLoader.rootLoader.addURL(new File("mongo-0.6.jar").toURL())

import com.mongodb.*

DBAddress address = new DBAddress("localhost", "mydb")
Mongo db = new Mongo(address)
db.authenticate('testUser', 'testPassword')

DBCollection coll = db.getCollection("testCollection")

BasicDBObject doc = new BasicDBObject()
doc.put("name", "MongoDB")
doc.put("type", "database")
doc.put("count", 1)

BasicDBObject info = new BasicDBObject()
info.put("x", 203)
info.put("y", 102)
doc.put("info", info)


for(i in 1..100) {
coll.insert(new BasicDBObject().append("i", i))

println coll.getCount()

DBCursor cursor = coll.find()
while(cursor.hasNext()) {
println cursor.next()

You can see it's just a rehash of part of the Java tutorial, the output will be a count of the number of inserted objects followed by the objects themselves.

The first line of code loads the jar file, this is useful if you're not looking to put the jar in a classpath or one of groovy's configured library paths like '~/.groovy/lib'.

Running the script is accomplished by 'groovy mongo.groovy' in the terminal. You can also type in 'groovyConsole' to load the console then opening the script and running inside it.

Installing MongoDB on Ubuntu 9.04 Jaunty Jackalope

For the installation, I decided to build MongoDB (http://www.mongodb.org/) from source. The documentation regarding this is thorough and getting it running was a cinch. A Javascript engine called Spider Monkey is used and you need to build it with UTF8 support.

The documents referred to:

The all-in-one command line version:
sudo apt-get install curl tcsh git-core scons g++
sudo apt-get install libpcre++-dev libboost-dev libmozjs-dev

Spider Monkey installation:
curl -O ftp://ftp.mozilla.org/pub/mozilla.org/js/js-1.7.0.tar.gz
tar zxvf js-1.7.0.tar.gz
cd js/src
make -f Makefile.ref
sudo JS_DIST=/usr make -f Makefile.ref export

MongoDB installation:
git clone git://github.com/mongodb/mongo.git
scons all
sudo scons --prefix=/opt/mongo install

Finishing up:
add /opt/mongo/bin to your path
create a /data/db directory structure and chown it to your user or add read-write permission.
System -> Preferences -> Startup Applications -> Startup Programs
click add, click browse and select /opt/mongo/bin/mongod
add run to the end of the line so that it reads '/opt/mongo/bin/mongod run'
enter name and comment then save

And you're done. mongodb will start up with no authentication as default at localhost:27017, the web information interface is at localhost:28017. You can use mongo to enter the interactive shell, similar to mysql's shell client.

Some links to get you started:

Tuesday, 17 March 2009

Delegation for iphone-google-maps-component

The iphone-google-maps-component is a way for you to use Google Maps on the iPhone through the use of an extended UIWebView and an html file on a server somewhere that does the map loading.

The present code overrides the default delegate UIWebViewDelegate with its own, MapWebViewDelegate. You cannot use the setCenterWithLatLng to establish the starting location until the view has finished loading. With the override, the webViewDidFinishLoad delegate method is unavailable.

Going by this post, the following code changes will allow the use of both delegates.

1) Change protocol definition.
@protocol MapWebViewDelegate < UIWebViewDelegate >

2) Remove the synthesize line.
//@synthesize delegate;

3) Replace with own methods, to hook into super.delegate.

- (id ) delegate {
return (id )super.delegate;

- (void) setDelegate :(id ) delegate {
super.delegate = delegate;

webViewDidFinishLoad should be accessible, as well as the other methods in the UIWebViewDelegate.

Another way of setting the starting location is through the loadMap method in MapWebView.h. The URL string can accept two more variables, latitude and longitude.

Change this:
NSString *urlStr = [NSString stringWithFormat:
width, height, DEFAULT_ZOOM_LEVEL];

To this:

NSString *urlStr = [NSString stringWithFormat:
width, height, location.coordinate.latitude, location.coordinate.longitude, DEFAULT_ZOOM_LEVEL];

Here, location is a CLLocation, part of the CoreLocation framework. The loadMap method is publicly defined in the interface and it accepts location as its variable. The call in didMoveToSuperview should be properly handled.

The latitude and longitude are doubles and can be hardcoded instead.

Monday, 9 February 2009

XML and the Copyright symbol, ©

For anyone parsing an XMl file and wondering what in the world is an org.xml.sax.SAXParseException: Invalid byte 1 of 1-byte UTF-8 sequence error message, check to see whether the XML file has any special characters like the copyright symbol, ©. The default encoding of UTF-8 will choke on these.

Solved my woes by changing the encoding to <?xml version="1.0" encoding="iso-8859-1"?> to get the character to display correctly. You can also filter it out or replace the symbol with its character reference.

Monday, 5 January 2009

Google Friend Connect & Facebook Connect

Google Friend Connect

A Google, Yahoo, AIM or OpenID account can be used for authentication.

You start it off with logging into your Google account and going to http://www.google.com/friendconnect/.
  • From there, click on 'Set up a new site' and enter your site name and url.
  • You'll be given two files, canvas.html and rpc_relay.html, to copy onto your web site.
  • The last step is testing for those two files.
After that, it's a matter of choosing the gadgets you wish to add, customizing it and then copying the code generated into one of your site pages. The code is normal html and javascript.

From the current gadgets available, you can add on to your site to make it more 'sociable', like knowing the site members, adding in a chat box and reviewing/rating stuff.

You can create your own custom gadgets from these sites:

Facebook Connect

Only a Facebook account can be used for authentication.

Login into your Facebook account and follow the instructions located here:

The main page for developers for Facebook Connect is http://developers.facebook.com/connect.php.

Facebook uses it's own Facebook Markup Language (FBML), in contrast to normal HTML, to facilitate creation of all Facebook applications. Facebook Connect is therefore embedded into user pages using FBML.

Facebook Connect is more of an expansion of Facebook onto other sites, depending on the application, it allows for data on a user site to be displayed back in Facebook.

HOW TO: Add Facebook Connect to Your Blog in 8 Minutes