• Response times for requests are usually less than 10 milliseconds (+network i/o e.g. TCP round trips coming from HTTP)
• The Graphity News Stream Server is a free open source software (GPLv3) and hosted in the metalcon git repository. (Please also use the bug tracker there to submit bugs and feature requests)
• It is running two Graphity algorithms: One is read optimized and the other one is write optimized, if you expect your application to have more write than read requests.
• The server comes with an REST API which makes it easy to hang in the server in whatever application you have.
• The server’s response also follows the activitystrea.ms format so out of the box there are a large amount of clients available to render the response of the server.
• The server ships together with unit tests and extensive documentation especially of the news stream server protocol (NSSP) which specifies how to talk to the server. The server can currently handle about 100 write requests in medium size (about a million nodes) networks. I do not recommend to use this server if you expect your user base to grow beyond 10 Mio. users (though we are working to get the server scaling) This is mostly due to the fact that our data base right now won’t really scale beyond one machine and some internal stuff has to be handled synchronized.

Koding.com is currently thinking to implement Graphity like algorithms to power their activity streams. It was for Richard from their team who pointed out in a very fruitfull discussion how to avoid the neo4j limit of 2^15 = 32768 relationship types by using an overlay network. So his ideas of an overlay network have been implemented in the read optimized graphity algorithm. Big thanks to him!
Now I am relly excited to see what kind of applications you will build when using Graphity.

If you’ll use graphity

Please tell me if you start using Graphity, that would be awesome to know and I will most certainly include you to a list of testimonials.
By they way if you want to help spreading the server (which is also good for you since more developer using it means higher chance to get newer versions) you can vote up my answer in stack overflow:
http://stackoverflow.com/questions/202198/whats-the-best-manner-of-implementing-a-social-activity-stream/13171306#13171306

How to get started

its darn simple!

1. You clone the git repository or get hold of the souce code.
2. then switch to the repo and type sudo ./install.sh
3. copy the war file to your tomcat webapps folder (if you don’t know how to setup tomcat and maven which are needed we have a detailed setup guide)
4. and you’re done more configuration details are in our README.md!
5. look in the newswidget folder to find a simple html / java script client which can interact with the server.

Get involved

There are plenty ways to get involved:

• Fork the server
• commit some bug report
• Fix a bug
• Subscribe to the mailing list.

Furhter links:

• git repository
• originial graphity blogpost
• graphity paper
• Stack overflow discussion on social activity streams (for voting thanks!)
• issue tracker

• People broke in our basement and stole some stuff
• Another time people broke in our basement and stored bikes there which did not belong to any of our neighbors.
• There is a hole from a gun in our front door.
• last but not least: I was about to leave our backyard when I saw a guy wearing my neo4j shirt.

Ok let me elaborate on the last one:
Neo4j the graph database is not known as the most famous fashion brand in the world. So I hardly recognized the shirt when I saw him wear it. But I somehow recognized the design of the shirts and decided to turn around in order to get a second look at the shirt. Who in my neighborhood would wear such a shirt and what connection would he have to this rather new piece of technology?
When i turned around things got even stranger. I saw the back of the guy and his shirt said:
“My stream is faster than yours” which certainly is a link to graphity
and also displayed the Cypher Query:
“(renepickhardt) <-[:cites]- (peter)”
I was so perplex that I didn’t realize that I was alone and the guy was standing there with 2 other men. I said: “Sorry, you are wearing my shirt!” And his friends came in and told my I was crazy and how I could come up with this idea. I insisted that my name was written on the shirt. In particular my full name! Especially I knew the quote which was exactly what Peter had planned to print on my shirt.
The guys started mocking me and telling me to f… off. But I somehow resisted and pointed out again that this was certainly my shirt. At that moment the door of the Kung Fu School opened and the coach Mr. Lai came out and asked if the guys again stole packages from our post box. At that moment the guy with my shirt had to turn around again so anybody could see my name. He stared telling me some weird lie about how he got this shirt as a present and just thought it was nice looking but he finally returned it to me. 
Most interestingly the police didn’t care. The policeman only said: “It’s your own fault when you move to a place like Koblenz Lützel.” I find this to be very disappointing. I always thought that our policemen should be objective and neutral. Stealing and opening other peoples mail is a crime in Germany. Also owning drugs or stealing bikes… It is said that the police refuses to help us with our situation.
Well anyway If you have an important message for me why don’t you use email rather than physical mail. My email is also potentially read by third parties but at least it is still safely delivered. Anyway big thanks to the guys from neo4j for my new shirt (:

• a user base of 10’000 users.
• about 500 registered bands
• highly semantic and interlinked data base (bands, geographical coordinates, friendships, events)
• 624 MB of text and structured data about the mentioned topics.
• fairly good visibility in search engines.
• > 30k lines of code (mostly PHP)
• a bad scaling architecture (own OR-mapper, own AJAX libraries, big monolithic data base design, bad usage of PHP,…)
• no unit tests (so code maintenance is almost impossible)
• no music and audio files
• no processes for content moderation
• no processes to fight spam and block users
• a really bad usability (I could write tons of posts at which points the usability lacks)
• no clear distinction of features for users to understand
• …

When we built metalcon no one on the team had experience with high scaling web applications and we were about happy to get it running any way. After returning from china and starting my PhD program in 2011 I was about to shut down metalcon. Though we became close friends the core team was already up on new projects and we have been lacking manpower. On the other side everyone kept on telling me that metalcon would be a great place to do research. So in 2011 Jonas and me decided to give it another shot and do an open redevelopment. We set up a wiki to document our features and the software and we created a developer blog which we used to exchange ideas. Also we created some open source project to which we hardly contributed code due to the lacking manpower…
Well at that time we already knew of too many problems so that fixing was not the way to go. At least we did learn a lot. Thinking about high scaling architectures at that time I new that a news feed (which the old version of metalcon already had) was very core for the user experience. Reading many stack exchange discussions I knew that you wouldn’t build such a stream on MySQL. Also playing around with graph databases like neo4j I came to my first research paper building graphity a software which is designed to distribute highly personalized news streams to users. Since our development was not proceeding we never deployed Graphity within metalcon. Also building an autocomplete service for the site should not be a problem anymore.

Roadmap for the redesign

• Over the next weeks I hope to read as many interesting articles about technologies and high scalability as I can possibly find and I will be more than happy to get your feedback and suggestions here. I will start reading many articles of http://highscalability.com/ This blog is pure gold for serious web developers. 
• During a nice discussion about scalability with Heinrich we already came up with a potential architecture of metalcon. I will soon introduce this architecture but want to check first about the best practices in the high scalability blog.
• In parallel I will also collect the features needed for the new metalcon version and hopefully be able to pair them with usefull technologies. I already started a wikipage about features and planned technologies to support them.
• I will also need to decide the programming language and paradigms for the development. Right now I am playing around with ruby on rails vs GWT. We made some greate experiences with the power of GWT but one major drawback is for sure that the website is more an application than some lightweight website.

So again feel free to give input, share your ideas and experiences with me and with the community. I will be ver greatfull for every recommendation of articles, videos, books and so on.

• how to integreate a SuggestBox instead of a textfield into the GWT Starter project
• how to set up the neccessary stuff (extending a SuggestOracle) to fire a remote procedure call that requests suggestions if the user has typed something.
• how to override the necessary methods from the SuggestOracle Interface

So here we go with the second part of the screencast which you can of course directly download from wikipedia:

Feel free to ask questions, give comments and improve the screencast!

• overvew of current graph benchmakrs and designs
• benchmark principles and methods
• Query Languages (Cypher, Gremlin, SPARQL)
• Analysis and classification of Choke points (Supernodes, data generators)
• Benchmark transactions (which are in general very slow)
• Benchmark the complexity of queries
• Analysis (if anyone has data sets and usecases contact the LDBC, actually I think we have data comming from related work)
• Navigational benchmark (e.g. open streetmaps)
• Benchmarking design for pattern matching (e.g. SPARQL and Cypher)

As you could here from beside there is a huge discussion going on about query languages which i like. Creating a query language is a tough task. The more expressive a language is (like SPARQL) the less efficient this might become. So I hope the EU project will really create some good solid output. I am also happy that many different industry vendors are part of this project. In this sense the results will hopefully be objective and don’t suffer from the “Who ever puts it on wins” paradigm.
Interestingly the LDBC makes a speration between graph data bases and rdf stores which I am very pleased to see and have been thinking a lot.