Groovy, Programming

Low Expectations for the Build

I attended the talk on Gradle by Hans Doktor tonight and while I found myself agreeing that Maven is wholly unsatisfactory I did end up thinking that actually our expectations of build tools in the Java space are really low. What kind of things does Gradle offer us? Proper event interception, genuine integration with the build lifecycle, build targets dynamically defined at runtime, a directed cyclic dependency graph.

Looking at the list some of things you can’t believe are not part of our standard build package. We should be able to know when a build starts and stops and be able to attach code to those events. We should have decent target resolution that avoids duplication of tasks.

Gradle is head and shoulders about the morass that is Maven and is clearly superior to the ageing but faithful Ant but that it manages to be so on so little functionality is a shame.

Java, Programming, Work

The Java Developer’s Dilemmia

I believe that Java developers are under a tremendous amount of pressure at the moment. However you may not feel it if you believe that Java is going to be around for a long time and you are happy to be the one maintaining the legacy apps in their twilight. Elliotte Rusty Harold has it right in the comments when someone says that there are a lot of Java jobs still being posted. If you enjoy feasting off the corpse then feel free to ignore the rest of this post because it is going to say nothing to you.

Java is in a tricky situation due to competition on all fronts. C# has managed to rally a lot of support. Some people talk nonsense about C# being what Java will look like in the future. C# is what Java would like if you could break backwards compatibility and indeed even runtime and development compatibility in some cases (with Service Packs). C# is getting mind share by leapfrogging ahead technology-wise at the expense of its early adoptors. Microsoft also does a far better job of selling to IDE dependent developers and risk-adverse managers.

Ruby and Python have also eaten Java’s lunch in the web space. When I am working on web project for fun I work with things like Sinatra, Django and Google App Engine. That’s because they are actually fun to work with and highly productive. You focus on your problem a lot sooner than you do in Java.

The scripting languages have also done a far better job of providing solutions to the small constant problems you face in programming. Automating tasks, building and deployment, prototyping. All these things are far easier to do in your favourite scripting language than they are in Java which will have to wait for JDK7 for a decent Filesystem abstraction for example.

Where does this leave Java? Well in the Enterprise server-side niche, where I first started to use it. Even there though issues of concurrency and performance are making people look to things like Erlang and JVM alternatives like Scala and Clojure.

While, like COBOL and Fortran there will always be a market for Java skills and development. The truth is that for Java developers who want to create new applications that lead in their field; a choice about what to do next is fast approaching. For myself I find my Java projects starting to contain more and more Groovy and I am very frustrated about the lack of support for mixed Java/Groovy projects in IDEs (although I know SpringSource is putting a lot of funding into the Eclipse effort to solve the problem).

If a client asks for an application using the now treadworn combination of Spring MVC and Hibernate I think there needs to be a good answer as to why they don’t want to use Grails which I think would increase productivity a lot without sacrificing the good things about the Java stack. Companies doing heavy lifting in Java ought to be investigating languages like Scala, particularly if they are arguing for the inclusion of properties and closures in the Java language spec.

Oracle’s purchase of Sun makes this an opportune moment to assess where Java might be going and whether you are going to be on the ride with it. It is hard to predict what Oracle will do, except that they will act in their perceived economic interest. The painful thing is that whatever you decide to do there is no clear answer at the moment and no bandwagon seems to be gaining discernible momentum. It is a tough time to be a Java developer.


Let’s hear it for the Groovlets

I am a big fan of Groovlets, the Groovy wrapper around servlets. Although it is theoretically possible to do this with any scripting language Groovlets are definitely the easiest to get working and the most powerful to use quickly, in my experience, as unlike Jython and Jruby you don’t have to deal with the original languages packaging system to get access to templating and data access.

I’ve created a little wiki (and it is quite small currently) to record my experiences of using Groovlets and to provide a few examples that I felt were lacking in the official pages. If you haven’t already seen it you may also want to have a look at my Gant wiki too.

Groovy, Java, Programming, Scripting, Software

Working with Groovy Tests

For my new project Xapper I decided to try and write my tests in Groovy. Previously I had used Groovy scripts to generate data for Java tests but I was curious as to whether it would be easier to write the entire test in Groovy instead of Java.

Overall the experience was a qualified “yes”. When I was initially working with the tests it was possible to invoke them within Eclipse via the GUnit Runner. Trying again with the more recent 1.5.7 plugin, the runner now seems to be the JUnit4 one and it says that it sees no tests, to paraphrase a famous admiral. Without being able to use the runner I ended up running the entire suite via Gant, which was less than ideal, because there is a certain amount of spin-up time compared to using something like RSpec’s spec runner.

I would really like all the major IDEs to get smarter about mixing different languages in the same project. At the moment I think Eclipse is the closest to getting this to work. NetBeans and Intellij have good stories around this but it seems to me to be a real pain to get it working in practice. I want to be able to use Groovy and Java in the same project without having Groovy classes be one of the “final products”. NetBeans use of pre-canned Ant files to build projects is a real pain here.

Despite the pain of running them though I think writing the tests in Groovy is a fantastic idea. It really brought it home to me, how much ceremony there is in conventional Java unit test writing. I felt like my tests improved when I could forget about the type of a result and just assert things about the result.

Since I tend to do TDD it was great to have the test run without having to satisfy the compiler’s demand that methods and classes be there. Instead I was able to work in a Ruby style of backfilling code to satisfy the runtime errors. Now some may regard this a ridiculous technique but it really does allow you to provide a minimum of code to meet the requirement and it does give you the sense that you are making progress as one error after another is squashed.

So why use Groovy rather than JRuby and RSpec (the world’s most enjoyable specification framework)? Well the answer lies in the fact that Groovy is really meant to work with Java. Ruby is a great language and JRuby is a great implementation but Groovy does a better job of dealing with things like annotations and making the most of your existing test libraries.

You also don’t have the same issue of context-switching between different languages. Both Groovy and Scala are similar enough to Java that you can work with them and Java without losing your flow. In Ruby, even simple things like puts versus println can throw you off. Groovy was created to do exactly this kind of job.

If the IDE integration can be sorted out then I don’t see any reason why we should write tests in Java anymore.


Playing around with Neo4J and Groovy

After hearing about Neo4J at Ruby Manor I decided to have a play around with the graph database but for me playing doesn’t mean creating a whole Java project anymore. Since using Python/Ruby/Scala I want to be doing it in an interactive session.

I had quite a few issues getting Neo4J to run but the summary is that for convenience you want all three jars from the distribution in your classpath and you pass a String representing a directory path to the EmbeddedNeo constructor. Once you do have it running make sure to shutdown the database on an exception otherwise you will have to shutdown the JVM (i.e. close the whole Groovy Console session) to unlock the underlying file resources.

Okay so once you have the right jars you can now start playing around with Neo4J. I immediately felt that the library is actually quite heavy with a lot of ceremony to get things done. Some of the feedback I have been hearing from Neo Technology and the Neo4J list is that Neo4J is more of a low-level infrastructure component that is meant to be wrapped up in higher-level APIs.

Working with Groovy it should be possible to cut that ceremony down a bit and put a nicer front-end on things. The first thing I’ve tried is using closures to execute code in Neo database and transaction contexts.

If you have the three jars in your .groovy/lib directory you should be able to run this script from the Groovy Console and have it create a node in your directory. It will be the same node each time but I have some ideas for using builders for both nodes and traversers (which allow you to search the graphs) and I am going to work on (and post) them later.

Groovy, Programming, Software

Using Gant to build Java Projects

I know I said I would be taking a step by step introduction to Gant in my last post on the subject but sometimes the devil drives and you need things done in a less systematic way.

Recently I have been building Java and Scala projects with Gant. I think it has been a successful exercise so I am just going to jump on and show you some example buildfiles. The first one is going to be a Java project. This project is obviously toy code but I think if you just download the sample project and start filling in your own code (it’s an Eclipse project, Intellij and NetBeans should both import it successfully) you will be happy with how little you have to change the build file.

First have a look at the Gant file itself and then I am going to talk about the things that I think make Gant such a powerful and productive tool. The first thing to point out is the line count, this represents a complete build file for a Java SE project in under 100 lines. That includes the Hello World target I’ve left in as an echo test. Gant might have a slightly weird syntax if you are unfamiliar with Groovy but it isn’t verbose.

Targets and dependencies were in the last post so this time the new thing is using AntBuilder. Any method call that starts with Ant is a invocation of an Ant task. These are nothing but thin wrappers around the normal Ant task (and in fact I usually write them using the Ant Task documentation). Things that are attributes in Ant XML become hash properties in the parameter list. Things that would normally be nested elements are calls to the enclosing builder.

One area where Gant wins big is the way you can mix normal variables, Groovy string interpolation and Ant properties. Declaring the directory paths as Groovy variables near the head of the file allows me to create new paths via interpolation and assign the variable to the properties of an Ant task. Ant XML has properties and macro interpolation but this is both clearer and easier.

I am also using the Gant built-in clean task and in the course of using it, Groovy’s operator overloading for lists. I’m not a huge fan of operator overloading but if it’s clear enough here then it is great to have a DRY list assignment.

I also like the way that the directories are created in the init task. This kind of closure looping over a list again shows some of the power and conciseness that can be achieved by a language rather than a configuration file. If you don’t read Groovy then the each method iterates over the list its attached to and each item resulting from the iteration is stored in the whimsical “it” local variable.


Introduction to Gant

This post was started the day after a Geek Night, it was a very, very cool Night…

With every topic I wanted to talk more about it and I felt we didn’t have enough time to get all the buzz out but one thing that struck me was that not many people seem to have heard of Gant. This is a real shame as I have recently converted and therefore have all the zeal of the convert. This zeal leads me to try and convert those who have not seen the light (yet).

What is Gant? It is a Groovy wrapper around Ant tasks. Groovy comes with an Ant Wrapper so what’s the great shakes you might ask? When Gant handles all the target dependencies for the project. It is essentially the missing part of the puzzle that gives you all the Ant functionality and a lot more. Gant adds some methods to the base Groovy shell execution environment that allows you to say that a task A depends on task B.

Enough chat though let’s get on with some examples. Download the standalone gant installation and then invoke the gant script (for your environment) in a new empty directory. It will give you a moan about not being able to find a build.gant file. So let’s create one now.

My first gant file is on Pastebin, cut and paste into your build.gant (or retype it to really get the benefit).

Now when you call gant you should see Target A and Target B printed out in the order of their dependencies. Type gant b and just Target B should be printed.

To be honest this really is the core of Gant so it may seem trivial but it’s important to understand. After all if you have ever taken a crack at this Kata you will know that dependency resolution isn’t trivial.

So what should we take away from this small example? Well I think it is important to note that it is Groovy syntax, the attribute assignment in target is standard but note that we don’t need to quote the property on the left. The string is like the description attribute in standard Ant tasks.

The println call is not mapping onto Ant’s echo it is the Groovy println so all the normal stuff to do with GStrings (like interpolation) applies here. Similarly the block attached to the target is a normal closure.

Dependencies are listed by calling depends, why isn’t that in the target declaration like in Ant? Well because you can create a dependency at any point in the closure. That means you can dynamically define the dependency graph. Which when you think about it, is kind of mental.

I did not want to have a huge post so the next one is going to be about using that dynamic definition to DRY out my Gant file.

Web Applications, Work

The death of MVC

The MVC pattern is so embedded into the concept of modern web development I feel quite the heretic for declaring it over. Yet more and more I think we are moving away from it as a pattern. Views have been boiled down to a special case of templating and now Controllers are the next under the microscope. What does a Controller do? Well it marshalls the model and exposes it to the view.

However with the relentless march of REST how much controlling is the Controller really doing? The HTTP request tells you the format of the data, identifies the resource it is interested in. How much need is there for a controller for each request type? Surely the Uber Controller that responds to the HTTP request is all that’s required.

I have also been using Groovlets recently and when using them I feel like “why not mix your model lookup with the ‘view'”. In my Groovlets I essentially lookup the data for the view either directly via Groovy SQL or via the Service layer that is injected out of Guice. The view is then created using Markup Builder.

Since my scripts end up at around 50 lines of code I think that any benefit I might have in separating things is outweighed by the fact that the entire interaction is in one place and can be found, read and changed very easily.

MVC saved us from really painful web architectures but as we grow more sophisticated in the way we handle HTTP Requests and the more we understand the implications of HTTP and the less ceremonial our languages becomes the less benefit we get from it.

Groovy, Java, Programming, Scripting, Web Applications

Towards Groovier Projects

My latest project has witnessed an influx of Groovy. The project buildfile is run by Gant, there are Groovlets providing lightweight pages but it is in the test folders that the Groovy has made its most insidious advances.

Markup builder makes fragments of HTML to test, Groovy’s built-in Sql is beginning to setup and check the results of data operations at a functional level. Soon I plan to implement a Groovy Struts 2 result and then it will begin to replace Freemarker.

Groovy, Java, Programming, Scripting

A Groovy Dice Roller DSL Solution

I’ve been looking at Ruby Quiz 61 for a while and I decided to take a look at solving it in Groovy as well.

Here’s a rough draft of what a solution might look like. So what did I learn about doing DSL in Groovy?

Well overall I think the Ruby solution is probably more elegant but Groovy’s Categories make meta-programming easy for meta village idiots like myself. I really struggled at first though because the documentation is so poor. I had to refer to Groovy in Action to sort myself out.

The key issue was that a category must consist of static methods which have at least one parameter, the first parameter should be of the type you want to “attach” the method to (so in this example I want to add the method d to Integer). You then effectively form a closure on the block of code to be executed with the method use which takes a list of categories you want to have active in the block.

The Eval object acts as a kind of synonym for GroovyShell but is meant to remove the boilerplate. invokes the block with no pass-in parameters.

I think that Groovy does a decent job of providing solutions to problems like this but if you had a choice to make would you choose JRuby or Groovy? It ain’t easy. What I am convinced off is that both should be part of the library mix in any Java shop that is looking to the future.