some experiments with ratpack and neo4j

Back in May this year I’ve attended the Gr8conf in Copenhagen. As always this conference added couple of things to my personal “take-a-look-at-this” list. The most exciting thingy for me was ratpack, a lean toolkit for building web applications on the JVM. Ratpack is powered by Netty and provides an event driven network engine as […]

nice addition back in Neo4j 1.9.1: closeable ExecutionResult

When using Cypher from Java code one instantiates a ExecutionEngine and calls execute to get a instance of ExecutionResult. ExecutionResult is an Iterable and therefore provides access to an iterator() method. Up to Neo4j 1.9 it is recommended to fully consume the iterator until hasNext() returns null, otherwise it’s not guaranteed that all resources are […]

assigning UUIDs to Neo4j nodes and relationships

TL;DR: This blog post features a small demo project on github: neo4j-uuid and explains how to automatically assign UUIDs to nodes and relationships in Neo4j. A very brief introduction into Neo4j 1.9’s KernelExtensionFactory is included as well. a little rant on Neo4j node/relationship ids In a lot of use cases there is demand for storing a […]

configuring a Neo4j GraphDatabaseService via Spring

Starting with Neo4j 1.9 the constructors for EmbeddedGraphDatabase and HighlyAvailableGraphDatabase were deprecated. The recommended way to instantiate those from Java is by using factory classes as documented in the reference manual. In the case of HighlyAvailableGraphDatabase use a different factory class HighlyAvailableGraphDatabaseFactory. If you’re using Spring for wiring components or Spring Data Neo4j then it’s up to […]

how to use Cypher over JDBC from Groovy

Groovy has a very convenient to use API for accessing databases over JDBC. My colleagues at Neo Technology brought up a JDBC driver for Cypher. It’s very easy to bring these two together. The only ugly thing here is that you have to use a class called “Sql” to emit Cypher statements. [gist id=”6094267″] Dependency […]

upgrading an old Neo4j database using Groovy

In a project I’m involved with there is still a very old Neo4j 1.0 database used. Now this database should be used with an up-to-date version of Neo4j (1.7.2 as of this writing). Following Neo4j docs, upgrades are done incrementally with every x.y in-between version by starting up and shutting the DB. For upgrading, a […]

update on Grails Neo4j GORM plugin

The milestone release 1.0.0.M2 of the  Neo4j Grails GORM plugin was published a couple of days ago. The plugin provides a GORM compliant implementation backed by a Neo4j datastore. This means you can switch any Grails application to use Neo4j by simply exchanging the GORM plugin used. Plugin documentation can be found at There […]

project setup for Grails with customized plugins using git submodules

Starting with it’s initial version a couple of years ago, Grails comes with a very nice predefined project structure, e.g. domain classes go into grails-app/domain. Every artefact has its well defined location. Almost every Grails application doing a little more than a simple “Hello world” will use at some extend one or more of the […]

embedding the git/hg/svn’s revision number inside a grails application

When your application goes to production, you should be prepared for handling bugs. Users and customers will find them and hopefully report them. I’ve been multiple times in a situation where a well written bug report including a stacktrace doesn’t help me much because the stacktrace doesn’t match the current development state of the […]

a perfect team: Grails Taggable plugin and JQuery Tagit

In a recent Grails project the customer asked for support of a tagging functionality for some domain classes. In order not to clutter the tagspace too much auto-complete should be available when editing the tags. In fact there is a very simple and elegant solution for this. On the application’s side, there’s the Grails Taggable […]