On the road to Grails 1.0: An incredible amount of Grails stuff going on

Apologies to frequent readers of this blog that I've been a bit quite, but we're plowing away trying get get Grails 1.0 out in time for Christmas. In the meantime an incredible amount of activity has gone on around the Grails community.

Firstly, congrats to Martin and Geertjan from Sun for their work on the NetBeans Groovy/Grails integration, it looks very promising and it is nice to see the progress made by the open source IDEs given the great support we have in IntelliJ iDEA.

Next thing I wanted to mention was the incredible amount of code that is being written by the community to make Grails even better. The guys at Catalina Consulting have created no fewer than 3 new plug-ins that provide integration with Amazon S3, the Red5 Flash Server and Streaming Video support to Grails.

However, there is more! To further increase Grails' integrations with Java based Ajax stacks two new plug-ins have been created by our users. The ZK Grails Plugin provides integration with ZK, a rich event-driven, component oriented Ajax stack. Whilst, the Echo2 Grails Plugin does the same for Echo2, another component oriented Ajax stack that lets you create Ajax apps in a similar way to Swing.

What is interesting for me about these two plug-ins is:

1. It demonstrates how Grails can be integrated with existing Java frameworks to further enhance its capabilities. This is all down to Groovy's seamless integration with Java and Grails' extensible Plug-in system.
2. We now have Plug-ins that provide varying levels of integration for many of the significant Java based Ajax stacks such as GWT, Echo2, DWR, ZK, Open Laszlo and Dojo. All driven by our user community.

Other things of significance include the launch of 4 new public Grails based sites in the past month, including:

• WorkBoard - A FaceBook application that provides classified ads
  
• Food Tube - A London restaurant guide and booking service
• FilmSuggestions.com - Catalogue your favourite films, commenting and tagging as you go
• Job Insiders - A German Job rating community

Congrats to the guys behind those sites. So overall exciting times for Groovy and Grails and with 1.0 out soon, hopefully 2008 will be another big year.

Grails Development with IntelliJ IDEA

The JetBrains folks have contributed a great write-up on the wiki summarising the powerful capability offered by JetGroovy, their Groovy/Grails plug-in for IntelliJ IDEA.

Grails eXchange - The aftermath

I have been meaning to do a write-up on the Grails eXchange 2007, a great conference hosted by my former employers Skills Matter.

Overall the conference was great, it had the feel of some of the No Fluff events I've been to and it was awesome to have so many people passionate about Groovy & Grails in the same place.

Some of the highlights for me were seeing the amazing JetGroovy plug-in in action demo'ed by JetBrains, Meeting the awwwesome (pronounced with a proper ozzy accent of course) Glen Smith (the man behind Groovy blogs) and his presentation entitled "The Whole Nine Yards" and the general networking and social aspect.

Now its back to focusing on getting Grails 1.0 out. My current focus is not on code, but on improving our documentation. Stay tuned.

Groovy Quote of the Day from Geertjan at Sun

"The main message I'm going home with is the rather obvious realisation that Groovy is in a completely different category to any other scripting language, because of its relationship with Java. Hence, lots of stuff (such as the Java debugger, as indicated above) can simply be reused when working with Groovy. That insight should also inform the tooling provided for Groovy." - Geertjan at the Grails eXchange

This is a great quote from Geertjan from Sun and highlights what we've been saying about Groovy for years: Java integration is more than being able to invoke a method on a Java class, it is object model integration, tools integration, debugger integration, profiling integration etc. etc. etc.

Grails 1.0 RC1, IntelliJ 7.0 & Grails eXchange Day 1

You can probably tell by the title that I am trying to cram too much into one blog post, but anyway there you go..

First off, we released Grails 1.0 RC1 there first of a few release candidates that will go out before 1.0 final. Check out the release notes for all the good stuff in this release.

Second, JetBrains have released IntelliJ IDEA 7.0. What was simply the best Java IDE on the planet is now also simply the best Groovy/Grails IDE on the planet. Congrats to the JetBrains guys and check it out.

Finally, today was day 1 of the Skills Matter's Grails eXchange conference which went well. It has the feel of some of the No Fluff conferences I've been to and it is great to have so many people excited about Groovy & Grails in one place. Big thanks to Skills Matter for organising it all.

G2One: The Groovy/Grails Company is born

As announced to the Groovy & Grails mailing lists today we communicated the formation of G2One Inc, the source for Groovy/Grails expertise and today is my first "official" day as CTO at G2One Inc.

Almost overnight we now have like 4 fulltime people working on Groovy/Grails and what a difference it makes.

Exciting times. The ball is now rolling !

PS A special thank you to the guys at Skills Matter who I have, up until recently, been working for, for the past year. They're organising a great little Groovy/Grails get together and have been superb in their support for Groovy/Grails over the last year.

SAP Using Groovy & Grails, Release Grails-based Product

SAP, one of the largest providers of enterprise software and services in the world today, have been using Groovy/Grails internally for a while now. I first met the nice chaps from SAP at JavaOne in May where they attended my half-day Groovy/Grails workshop.

However, the big news is the announcement that they have released a new community driven product called Composition on Rails (Side note - not sure DHH and co will be happy with the name, oh well...) that allows you to use their SAP NetWeaver Composition Environment to quickly prototype applications using Groovy/Grails. Exciting stuff!

LinkedIn Looking for Groovy/Grails Developers

The guys over at popular networking site LinkedIn are looking for software engineers with experience building web 2.0 apps preferably with Groovy/Grails. Check it out.

Refactr Interview Grails Dev Marc Palmer

Software consultancy Refactr have posted a great interview with Marc Palmer, one of the committers for Grails, about his experiences developing Grails apps.

Grails at JAOO 07

Just finished my talk on Grails at JAOO. It went very well, the room was packed out with people having to stand at the back. Grails was extremely well received and the audience enthusiastic.

The conference seems interesting, there aren't many low level technical talks. Most talks seem to be design or patterns or enterprise architecture talks. There are also many .NET talks, so its quite a diverse conference. An interesting concept.

JAOO uses a system of rating talks with red, yellow and green papers depending if the talk was rubbish, average or good. I managed 15 yellows, 98 greens and no reds. Not bad :-)

The new meta-programming APIs in Groovy 1.1 beta 3

As announced by Guillaume, Groovy 1.1 beta 3 is out and the final release is just round the corner. There is lots of good stuff in there, but I want to talk here primarily about the new meta-programming API improvements that have been introduced in this release.

Groovy has always had the underlying Meta Object Protocol (MOP) that allowed the same behaviour as languages such as Ruby and Small Talk, however the API onto these has, up until now, not been as elegant as it could have been. With Groovy 1.1 beta 3 there is a lot more at your finger tips including...

Runtime evaluation with respondsTo & hasProperty
It is now a lot easier to inspect the runtime thanks to the addition of hasProperty and respondsTo for meta classes so you can do:

class Foo {
    String name = "Wilma"
    def sayHello() { println "hello $name" }
    def sayHello(String message) { println "hello $message" }
}
def f = new Foo()

if(f.metaClass.respondsTo(f,'sayHello') {
    f.sayHello()
}

Since Groovy supports method overloading and typed arguments to support good Java interoperability you can also specify a type:

if(f.metaClass.respondsTo(f,'sayHello', String) {
    f.sayHello("Fred")
}

Groovy also differentiates method and property access so you can do this:

if(f.metaClass.hasProperty(f,'name') {
     println f.name
}

See the docs here for more info on hasProperty and respondsTo

Missing method/property interception with methodMissing & propertyMissing

As of beta 3, Groovy now supports the concept of "method missing". It has always been possible to intercept method dispatch using invokeMethod. However, this has the overhead of intercepting every method call instead of just the "missing" ones. As of Groovy 1.1 beta 3, Groovy now supports "method missing" and "property missing", which are only called when method dispatch fails (ie just before a MissingMethodException would be thrown anyway.)

A trivial example can be seen below, we use this feature in Grails to implement dynamic finders such as findByTitleAndAuthor("Groovy in Action", "Dierk Koenig"):

Foo.metaClass.methodMissing = { String name, args ->
    Foo.metaClass."$name" = { Object[] varArgs -> 
        "$name : ${varArgs.inspect()}" 
    }
    delegate."$name"(args)
}

def f = new Foo()
f.sayHello('Fred')
assert f.notARealMethod("boo") 
            == 'notARealMethod : [["boo"]]'
assert f.notARealMethod("boo", "hoo") 
            == 'notARealMethod : [["boo", "hoo"]]'

Notice how in the example above we can dynamically register a new method on the fly and then call that method. This also has the implicationthat the next dispatch to the same method is faster. See the docs here for more info and there are a whole load of docs on doing dynamic Groovy and meta-programming to be found here.

Gavin King saying nice stuff about Groovy/Grails

Gavin King has been featured in a podcast where he has some nice things to say about Grails. Transcript here. Thanks Gavin! For what its worth Seam makes JSF palatable ;-)

In related news Gavin also has a blog post about the downside of ActiveRecord storing model info in the DB. The funny thing is this is nothing new, we realised that having your model in the DB was a crap idea from day one when we created Grails. That is why GORM has not such deficiencies.

David HH Living in Cloud Cookoo-land

This latest little outburst from David HH of Rails fame is hilarious. Even Charles Nutter must be on the floor laughing. David honestly believes that JRuby is a bridge for people to move to the C Ruby runtime because its a superior environment without the "junk"? I had to do a double take when I read that.

So let's see, enterprises are going to give up on a platform that provides monitoring, profiling, JIT, a deployment architecture that isn't a joke, threading, a compiled byte-code format, clustering, distributed caching, transactions that don't suck, maturity and performance all to build Rails apps?

Ignore the enterprise, it is ok. Grails is settling in quite nicely in the enterprise, and everything else will flow from there ;-)

Grails 0.6 Released with Rich Conversation Support (AKA Spring Web Flow)

We've just released Grails 0.6 which takes Grails even further away from its Rails-like beginnings. Thanks to integration with the Spring Web Flow project and support for Spring scopes Grails now supports rich conversations a la Seam.

The essence of it is that we have created a Groovy builder for construction Web Flows. This is both a good thing for Grails and for the Web Flow project as the current mechanism for flow definition in Web Flow is via XML which has limited expressiveness and too many angles for my liking.

An example of a Grails Flow can be seen below:

 showCart {
    on("checkout").to "enterPersonalDetails"
    on("continueShopping").to "showCatalogue"
 }                                         
 enterPersonalDetails {
  on("submit") {
   def p = new Person(params)
   flow.person = p 
   def e = yes()
   if(p.hasErrors() || !p.validate())return error()    
  }.to "enterShipping"   
  on("return").to "showCart"
  on(Exception).to "handleError"
 }              
 enterShipping  {
  on("back").to "enterPersonalDetails"
  on("submit") {
   def a = new Address(params)                           
   flow.address = a
   if(a.hasErrors() || !a.validate()) return error()    
  }.to "enterPayment"
 }

Web Flow will completely manage the state transitions and Grails integrates Hibernate into the picture to make sure you get atomic conversations.

You can also encapsulate business logic inside service classes and define services as living in a particular scope:

class BookService {
   static scope = "flow"
   ...
}

Thus allowing conversations with a particular service scoped to individual clients. It is all rather exciting stuff and extends Grails' capabilities allowing much more complex workflows.

This is not the only exciting feature in Grails 0.6. The headliners are:

* Joint Groovy/Java Compilation
* Spring Web Flow Integration
* Support for Spring scopes to allow scoped services
* Improved support for REST with automatic XML/JSON marshalling and RESTful URL mappings
* New Config DSL for configuration not possible by convention
* Refreshed scaffolding interface and branding
* Support for Sitemesh inline decorators
* Controllers can now call tag libraries as methods
* New GSP tags
* Massive improvements to speed of start-up time, unit tests and generation tools

Checkout the full release notes for details and download here

Setting up an Apple Airport Exreme Router with Virgin Media set-top box

A while ago I set-up my Airport Extreme router with my Virgin Media cable connection and it was painful, but I got it working. Anyway, a friend had similar trouble so I helped him set up his and given that this might be a relatively frequent occurance and Virgin's support for Apple products equates to zero I thought I would post the info here for others to benefit.

Step 1) Plug in the relevant cables

I'm not going to go into detail here, but basically plug the ethernet cable into the "Ethernet" slot of the set-top box then the other end into the router in the slot with the circle of dots around it. Make sure the set-top box is powered on and the router is too.

Step 2) Install Airport Extreme Software Update

Chuck in the Apple provided CD and run the installer, then reboot.

Step 3) Enable Wireless and Connect to the Base Station

Enable your wireless connection and then connect to the Wireless network. It is probably called "Apple Base Station" or some generic default name.


Step 4) Run "Airport Utility"

Run the "Airport Utility" program in "/Applications/Utilities/Airport Utility". Then it should automatically discover your base station. Click on the base station and then click the "Continue" button in the bottom right. When prompted choose "Assist me".

Note: Do not confuse it with "Airport Admin Utility" this is the older software.

Step 5) Network/Base Station Name

Select an appropriate network and base station name. Anything you like really.

Step 6) Country/Radio Mode

Choose your country (ie United Kingdom for Virgin Media) then set the Radio Mode. If you have any already Macs or PCs you may need to be 802.11a compatible.

Step 7) Security

Set-up security, don't choose WEP as it is known to be insecure. Select WPA2 Personal and enter an appropriate password of your choice (make sure to check the "Remember password in Keychain option")

Step 8) How do you connect to the Internet?

Select "I use a DSL or cable model with a static IP address or DHCP" then continue

Step 9) Internet Setup

Now the fun begins. If it weren't that Virgin Media's customer service people were so incompetent this bit might not be such a pain, but in my experience they gave wildly different numbers for the primary and secondary DNS depending on who you spoke to. Anyway, enter the information as per the below:

DNS Server: 62.253.162.237
Domain Name: ntlworld
DHCP Client ID: (Your Virgin Media PID - phone them if you don't know what this is)

Some Virgin Media reps stated you could leave the DHCP Client ID blank, but in my experience this didn't work when setting up both mine and my friends. Once you're done click "Continue"

Step 10) Enter a base station password

Make sure you enter a "base station" password and then once you're done click the "Update" button.

At this point your Apple router will reboot, but it is likely it will flash an Orange light and give several error messages relating to different things. So go back to "Airport Utility" and click on the router again and the "Continue". Now instead of "Assist Me" select "Manual Setup".

Step 11) Share a public IP address

The router is probably set-up in bridge mode. This is problematic as it means you have to do the whole "NTL provisioning" thing for each machine in the house, a pain. So instead in the "Manual Setup" screen of "Airport Utility" select the "Internet" tab.

Now at the "Connection Sharing" bit under the "Internet Connection" tab change the "Off (Bridge Mode)" setting to "Share a public IP address".

You may also want to click on the "DHCP" tab at the top and change the lease time to a bit longer if you want to have the same IP for longer.

Also in DNS Server(s) it only has a primary DNS server, enter "194.168.8.100" as the secondary DNS (in the second DNS Server field).

Once you're done click the "Update" button again and wait for the router to reboot.

Step 12) Diagnosing problems

If the router is still flashing orange go back into the "Manual Setup" bit and in the "Summary" screen click on the Orange icon next to the "Base Station Status" field.

If you get the "Double NAT" problem ignore this for the moment as it is only because the router has been assigned the temporary provisioning IP address from Virgin.

If however you have a "Internet Connection" problem, then unplug both the set-top box and the router then restart the set-top box wait for the lights on it to stop flashing then turn on the router. Once they've both rebooted you will probably still have a flashing orange light, but it should be related only to the "Double NAT" problem mentioned earlier

If you go back into "Manual Setup" of your router and look at the "IP Address" field in of the "Summary" page your router should have an IP Address that starts 10.* etc. This is the private network of the Virgin provisioning system.

Step 13) Provisioning

If the router is only saying it has a "Double NAT" problem and it has successfuly obtained an IP address starting 10.* and not 168.* then you are ready to start the provisioning step.

Open up a browser and go to some common site like google. You will get redirected to a "NTL Provisioning" site that has a big "Start" button on it. Go through the steps. You will need your Virgin PID and password handy. If is not getting as far as the NTL Provisioning screen then try to quit the browser and start it up again then try again.

If this STILL doesn't work then phone up Virgin by dialing 150 on your phone and ask them what the IP address of the NTL Provisioning site is (when we did it started with 173.* but this might change) and then enter the IP into your address bar.

Once you have successfully registered the router with the "NTL Provisioning" system restart the router (turn it off at the wall and on again)

General Advice

When phoning Virgin Media don't mention the words "Apple", "Mac" or "Wireless". They will use any excuse to say they don't support it. Just saying you're setting up a generic router, and need help and they're more open. If they ask the make of the router, fabricate something like a "Belkin router". As I said they're just keen to get you off their backs than anything. Good luck!

Grails Employment Oppurtunities

Couple of requests for Grails developers (yeh that means Java developers ;-) have appeared on the mailing list over the last couple of days:

• Grails/Groovy Jobs in Halifax, NS, CANADA
• Grails Developer Needed

Grails more Productive than Rails? Surely not you say?

Software consultancy ALTERthought posted an analysis of their discovery that Grails is more productive (for them) than Rails. Queue outcry from the Rails crowd including the usual "You stupid Java guys, what the hell do you know" kind of commentry. All rather entertaining.

Of course, having done my bit of Rails dev I don't actually believe that Grails or Rails are more productive than each other if you're using purely Groovy (in the case of Grails) or purely Ruby (in the case of Rails). In fact Rails might still have the edge here due to its greater maturity, nevertheless if you're mixing Java into the picture their is really only one winner. This is what the ALTERthought guys have discovered on their Fortune 200 Grails project.

It is of course a growing trend. More and more and more consultancies are discovering that Grails is easier to integrate with existing Java and legacy systems. With Grails you can do things like:

1. Use an existing Hibernate domain model written in Java and still get the benefit of dynamic finders, persistence methods etc.
2. Re-use existing Spring services as Grails built entirely on Spring with all its enterprise application integration goodness
3. Leverage an array of enterprise proven technologies such as Sitemesh, Quartz, Lucene, Compass ... (this list could go on)
4. And in the upcoming 0.6 release, thanks to contributions from JetBrains, you can jointly compile Java & Groovy and have circular references between the Groovy and Java code (a Groovy class is just a Java class after all)

People of course automatically raise the JRuby on Rails argument, but as of this writing you can't do 1) or 4) of the above list whilst 2) requires some trickery.

The other revelation that Java people are discovering is that they no longer need to abandon their existing Java knowledge to get RAD development. The Java platform now has its answer to Rails, why go else where?

Method missing in Groovy - Part 2

In my previous post I showed how to use invokeMethod to provide "method missing" behaviour in Groovy. Well, if you're prepared to live on the cutting edge and install the latest Groovy 1.1 beta 3 code from SVN then you can try out Groovy's new "method missing" feature that will be more familiar to Ruby programmers.

This came about after I had a productive discussion with Charles Nutter of JRuby, and in the spirit of cross pollination here is the example from my previous post using the new "method missing" feature of the upcoming Groovy 1.1 release:



1 def dynamicMethods = [...]
2 Book.metaClass.'static'.methodMissing = { String methodName, args ->
3   StaticMethodInvocation method =
4           dynamicMethods.find { it.isMethodMatch(methodName) }
5   if(method) {
6        Book.metaClass.'static'."$methodName" = { Object[] varArgs ->
7            method.invoke(Book.class, methodName, varArgs)
8        }
9        result = method.invoke(Book.class, methodName, args)                                                                                                   
10   }
11   else {
12       throw new MissingMethodException(methodName, Book.class, args)
13   }
14   result
15 }

So what is the difference between this and invokeMethod? Well invokeMethod will deal with every method call and hence has a certain amount of overhead. The behaviour of invokeMethod is more useful for AOP type use cases where you need to intercept a method call and wrap behaviour around the invocation.

The "method missing" approach will only take effect when a method is not found to invoke using the normal runtime and hence has no additional overhead plus the code is a bit more concise. Thanks for the help Charles! ;-)

Dealing with method missing with Groovy's MetaClass system

One of the new features coming up in Groovy 1.1 to be released later this year is ExpandoMetaClass. Its an elegant API to programatically extend a class' functionality with Groovy's Meta Object Protocol (MOP).

An example of how we take advantage of this is Grails' dynamic finders in GORM. Dynamic finders allow you to do things like Book.findByTitleAndAuthor("It", "Stephen King"). So how are these implemented in Grails?

First we defined an interface that allows the matching of a method signature to a given method pattern. That interface goes something like this:

interface StaticMethodInvocation {
   boolean isMethodMatch(String methodName)
   Object invoke(Class theClass, String methodName, Object[] args)
}

The implementation of this interface just uses regular expressions to match the method signature. Simple enough. So how do we use this from the MetaClass itself? Well, this is where the magic of ExpandoMetaClass comes in as it allows us to override a static "invokeMethod" in Groovy:

1 def dynamicMethods = [...]
2 Book.metaClass.'static'.invokeMethod = { String methodName, args ->
3    def metaMethod = Book.metaClass.getStaticMetaMethod(methodName, args)
4    def result
5    if(metaMethod) {
6         result = metaMethod.invoke(dc.clazz, args)
7    }
8    else {
9         StaticMethodInvocation method =
10                dynamicMethods.find { it.isMethodMatch(methodName) }
11        if(method) {
12            Book.metaClass.'static'."$methodName" = { Object[] varArgs ->
13               method.invoke(Book.class, methodName, varArgs)
14            }
15            result = method.invoke(Book.class, methodName, args)                                                                                                    
16         }
17         else {
18             throw new MissingMethodException(methodName, Book.class, args)
19         }
20    }
21    result
22 }

So what is actually happening here? First we look to see if the method already exists
on the line:

3    def metaMethod = Book.metaClass.getStaticMetaMethod(methodName, args)

If it does we simply invoke the method:

6    result = metaMethod.invoke(dc.clazz, args)

Otherwise we attempt to find a method that matches the method signature using a previously defined list of StaticMethodInvocation instances:

9    StaticMethodInvocation method =
10          dynamicMethods.find { it.isMethodMatch(methodName) }

If the method exists we dynamically register a new method on the MetaClass so that the next time the method is invoked it doesn't have to go through the matching process and will simply dispatch like normal:

12    Book.metaClass.'static'."$methodName" = { Object[] varArgs ->
13         method.invoke(dc.clazz, methodName, varArgs)
14    }

Finally, we invoke the method itself, or if the method isn't matched we throw a MethodMissingException:

15    result = method.invoke(dc.clazz, methodName, args) 

Job done. As simple as that ;-)

I'm doing a talk at the Grails eXchange about the Grails plug-in system and how we dynamically extend the behaviour of classes. See you there!

Groovy 1.1 beta 2 out. Configuration made easy with ConfigSlurper

So we've put out the 1.1 beta 2 release of Groovy, which is a really significant milestone for the project. Guillaume has the lowdown of all the new features in his blog.

One of the things I worked on for this release was a new utility class called ConfigSlurper. It allows you to write configuration files as Groovy scripts in a Java properties file like format. What advantage does this give you?

1) You get to take advantage of native Java types and not do type conversion from properties
2) You can use "global variables" and write more DRY configurations
3) You can take advantage of Groovy's advanced syntax for lists and maps to make config easier

Here is an example of configuring log4j with a ConfigSlurper script:

log4j.appender.stdout = "org.apache.log4j.ConsoleAppender"
log4j.appender."stdout.layout"="org.apache.log4j.PatternLayout"
log4j.rootLogger="error,stdout"
log4j.logger.org.springframework="info,stdout"
log4j.additivity.org.springframework=false

Not that disimilar from standard Java properties files and you can convert to and from Java properties files, merge configurations and serialize them back to disk. To use this this script you can use the ConfigSlurper class to parse it:

def config = new ConfigSlurper().parse(new File('myconfig.groovy').toURL())

assert "info,stdout" == config.log4j.logger.org.springframework
assert false == config.log4j.additivity.org.springframework

We're using this as our primary means to deal with necessary configuration (not possible by convention in Grails. Checkout some more examples of its usage here.