Author Archives: maxdemarzi

Permission Resolution with Neo4j – Part 1

i_can_haz_permissions

People produce a lot of content. Messages, text files, spreadsheets, presentations, reports, financials, etc, the list goes on. Usually organizations want to have a repository of all this content centralized somewhere (just in case a laptop breaks, gets lost or stolen for example). This leads to some kind of grouping and permission structure. You don’t want employees seeing each other’s HR records, unless they work for HR, same for Payroll, or unreleased quarterly numbers, etc. As this data grows it no longer becomes easy to simply navigate and a search engine is required to make sense of it all.

But what if your search engine returns 1000 results for a query and the user doing the search is supposed to only have access to see 4 things? How do you handle this? Check the user permissions on each file realtime? Slow. Pre-calculate all document permissions for a user on login? Slow and what if new documents are created or permissions change between logins? Does the system scale at 1M documents, 10M documents, 100M documents?
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A Peek behind the Neo4j Lucene Index Curtain

wizard-of-oz

Did you know you can write Javascript in the Neo4j console to access the Neo4j API?
Try it. Open up your Neo4j Web Admin Console and type:

neo4j-sh (0)$ eval db
EmbeddedGraphDatabase [data/graph.db]

OMG! I know, Neo4j is crazy. So much to play with, I’ve been at it for a few years and I haven’t even dug into this area. What else can we do here?
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Neo4j and Gatling sitting in a tree, Performance T-E-S-T-ing

neo4j_loves_gatling

I was introduced to the open-source performance testing tool Gatling a few months ago by Dustin Barnes and fell in love with it. It has an easy to use DSL, and even though I don’t know a lick of Scala, I was able to figure out how to use it. It creates pretty awesome graphics and takes care of a lot of work for you behind the scenes. They have great documentation and a pretty active google group where newbies and questions are welcomed.

It ships with Scala, so all you need to do is create your tests and use a command line to execute it. I’ll show you how to do a few basic things, like test that you have everything working, then we’ll create nodes and relationships, and then query those nodes.
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Facebook Graph Search with Cypher and Neo4j

Update: Facebook has disabled this application

Your app is replicating core Facebook functionality.

neo_graph_search_screen_shot

Facebook Graph Search has given the Graph Database community a simpler way to explain what it is we do and why it matters. I wanted to drive the point home by building a proof of concept of how you could do this with Neo4j. However, I don’t have six months or much experience with NLP (natural language processing). What I do have is Cypher. Cypher is Neo4j’s graph language and it makes it easy to express what we are looking for in the graph. I needed a way to take “natural language” and create Cypher from it. This was going to be a problem.
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Setting up a Neo4j Cluster on Amazon

There are multiple ways to setup a Neo4j Cluster on Amazon Web Services (AWS) and I want to show you one way to do it.

Overview:

  1. Create a VPC
  2. Launch 1 Instance
  3. Install Neo4j HA
  4. Clone 2 Instances
  5. Configure the Instances
  6. Start the Coordinators
  7. Start the Neo4j Cluster
  8. Create 2 Load Balancers
  9. Next Steps

We’ll start off by logging on to Amazon Web Services and creating a Virtual Private Cloud:


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Pathfinding with Neo4j Unmanaged Extensions

In Extending Neo4j I showed you how to create an unmanaged extension to warm up the node and relationship caches. Let’s try doing something more interesting like exposing the A* (A Star) search algorithm through the REST API. The graph we created earlier looks like this:
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Extending Neo4j

One of the great things about Neo4j is how easy it is to extend it. You can extend Neo4j with Plugins and Unmanaged Extensions. Two great examples of plugins are the Gremlin Plugin (which lets you use the Gremlin library with Neo4j) and the Spatial Plugin (which lets you perform spatial operations like searching for data within specified regions or within a specified distance of a point of interest).

Plugins are meant to extend the capabilities of the database, nodes, or relationships. Unmanaged extensions are meant to let you do anything you want. This great power comes with great responsibility, so be careful what you do here. David Montag cooked up an unmanaged extension template for us to use on github so lets give it a whirl. We are going to clone the project, compile it, download Neo4j, configure Neo4j to use the extension, test the extension and tweak it a bit.
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CrunchBase on Neo4j

NeoTechnology was featured on TechCrunch after raising a Series B round, and it has an entry on CrunchBase. If you look at CrunchBase closely you’ll notice it’s a graph. Who invested in what, who co-invested, what are the common investment themes between investors, how are companies connected by board members, etc. These are questions we can ask of the graph and are well suited for graph databases.
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Matches are the New Hotness

How do you help a person without a job find one online? A search screen. How do you help a person find love online? A search screen. How do you find which camera to buy online? A search screen. How do you help a sick person self diagnose online? I have no idea, I go to the doctor. Doesn’t matter, what I want to tell you is that there is another way.
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Hubway Data Visualization Challenge with Neo4j

Michael Hunger imported the Hubway Challenge dataset into a Neo4j graph database, and made it available for us to play with.
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