Scala on .NET via IKVM

This post will show you how to get started with writing Scala code and running it on the Mono and .NET runtimes, using a JDK re-implementation called IKVM.

So the Scala language has been gaining a lot of traction lately, mostly due to Twitter adopting it for their Kestrel messaging back-end as well as other open source projects. Another major reason why Scala is becoming increasingly relevant is the lack of velocity with which the Java community process has been incorporating various trendy language features, such as delegates, closures, and many more. There are many advantages you get when migrating from Java to Scala. So how about getting all of those and sticking close to your platform of choice, .NET?

Apparently an attempt was made to allow Scala to run over .NET, called Scala.NET. It is basically far from being production ready and only supports Scala 1.4, whereas what I'm going to show is verified to run on Scala 2.8 RC7.

1) Download the latest IKVM from SourceForge (I used 0.42.0.6)
2) Download the latest Scala from scala-lang (I used 2.8 Release Candidate 7)
3) Download a recent Java JDK and JRE (I used v1.6).
4) Write a Scala application in your favorite IDE, e.g. Netbeans
(Note: Use plugin manager in Netbeans to download Scala IDE support)
A typical app looks like this:

package myscalaapp

object Main{
def main(args: Array[String]): Unit = {
println("Hello Scala on .NET!!!")
}}


5) Build your project to create myscalaapp.jar
6) Copy myscalaapp.jar and scala-library.jar to your IKVM folder
7) Execute

ikvmc -target:exe -recurse:scala-library.jar myscalaapp.jar

8) Run myscalaapp.exe

Hello Scala on .NET!!!

Good times.

NHibernate with csharp-sqlite embedded C# database

Following my [NH-2120] post on JIRA, I decided to make another post here, just in case I need it in the future. Maybe for instance my driver does not get accepted for whatever reason.

So what I have done is created a driver for the managed embedded SQLite C#/.NET re-implementation database called C#SQLite (see csharp-sqlite project) and have tested this with the latest versions of csharpsqlite and NHibernate (2.1.2.GA using the SQLiteDialect).

This database re-implementation is really bringing together a number of very attractive things, such as fully managed code, .NET 2.0 requirement only, multi-platform support via Mono, OK performance, embeddable, etc, etc. So download a copy of the latest database and ADO.NET provider first.

Then you need the NHibernate sources. Open them up and create a new driver file in NHibernate.Driver called CsharpSqlite.cs

Once the driver file (link 1, link 2) is included/pasted in the project, I had to recompile NHibernate and NHibernate.Bytecode.LinFu (you may want to recompile the bytecode provider of your own choice e.g. Castle). I'm using it with 2.1.2.GA currently and C#-SQLite version 3.6.22 (latest at the moment) without problems. EDIT: The very latest version (3.6.23) is broken, I'm investigating this and will submit a patch. In the mean time, use my 3.6.22 binary.

For your own project, the usual NHibernate libraries need to be referenced, consult NHibernate documentation for this. But make sure you include the assemblies "Community.CsharpSqlite" (SQLite managed implementation) and "Community.CsharpSqlite.SQLiteClient" (the ADO.NET provider), both available from noah.hart's csharp-sqlite webpage (EDIT: use my binary above!).

Some of these libraries (e.g. CSharp SQLite itself as well as the Client) appear to target .NET 3.5, but setting them all to .NET 2.0 caused no compilation errors and they worked just fine for me.

Enjoy!

NHibernate embedded managed C# database

I was looking for an embedded cross-platform managed database to use for a C# .NET 2.0 project of mine and I was surprised to find out how difficult it was to find one. After you read this post, I hope that you will have discovered a new and exciting choice.

In my search I encountered the following posts:

(sources: Embedded database for .NET SO question, C#/.NET single user database SO question, Good "mobile" database .NET database SO question, Observations on embedded databases by Ayende, as well as many others)

The major options available seemed not good enough for various reasons:

SQLite: It's basically a native library with a x86-only requirement.
SQL Server CE: It's not thread safe and hangs periodically.
VistaDB: Commercial database.
SharpHSQL: No NHibernate support as of yet.
Firebird: Windows only.

The list goes on. Basically all available options either lacked a NHibernate support, or were not cross platform, or required installation, etc.

So when I stumbled upon this little gem called C#Sqlite (csharp-sqlite) which is a C# re-implementation of the latest SQLite database, I thought that my search was over. Alas, this embedded, managed, cross-platform (.NET/Mono) database (which also has an OK performance) was not possible to use with NHibernate, due to the lack of a driver.

I have posted an NHibernate driver for CsharpSqlite [NH-2120], so there, now you can use NHibernate with this wonderfully compact database which fits the bill for all of the above requirements.

I hope you enjoy it!