An Introduction to RDF and the Jena RDF API

http://jena.sourceforge.net/tutorial/RDF_API/

XAuth - an introduction from Chris Messina

XAuth - an introduction from Chris Messina on Vimeo.

CentOS: find out what network ports are in use

To get a quick idea of what ports you have open on your local box, you can use nmap.

[root@api1dev /usr/local/bin]nmap localhost
Starting Nmap 5.00 ( http://nmap.org ) at 2010-05-10 03:02 EDT
Interesting ports on vmlinux-testing1 (127.0.0.1):
Not shown: 991 closed ports
PORT     STATE SERVICE
21/tcp   open  ftp
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
389/tcp  open  ldap
631/tcp  open  ipp
726/tcp  open  unknown
8009/tcp open  ajp13
8080/tcp open  http-proxy

For more detailed information, try netstat:

netstat -an

You’ll get a breakdown of every socket open on your machine – useful for figuring out who’s connected and from where.

Interesting articles about Ad-Exchange and RTB

The Ad-Exchange Model (Part I)
RTB Part I Followup
RTB Part II: Supply supply supply!
RTB Part III: Cookies & User Data!

Alternative to HBase + Map-Reduce

mongoDB

Combining the best features of document databases, key-value stores, and RDBMSes.

MongoDB (from "humongous") is a scalable, high-performance, open source, schema-free, document-oriented database. Written in C++, MongoDB features:

• Document-oriented storage (the simplicity and power of JSON-like data schemas)
• Dynamic queries
• Full index support, including secondary indexes, inner-objects, embedded arrays, geospatial
• Query profiling
• Fast, in-place updates
• Efficient storage of binary data large objects (e.g. photos and videos)
• Replication and fail-over support
• Auto-sharding for cloud-level scalability
• MapReduce for complex aggregation
• Commercial Support, Training, and Consulting

MongoDB bridges the gap between key-value stores (which are fast and highly scalable) and traditional RDBMS systems. Many companies are using MongoDB in production today.

Quick Links

• Downloads
• Follow @mongodb on Twitter
• Use Cases | Philosophy
• Hosting Center
• Drivers
• Source Code
• Blog | Articles
• Tutorial | Try MongoDB in the Browser
• Licensing | Example Snippets | BugDB (Jira)

Support

• Support forums: mongodb-user | more...
• IRC: irc.freenode.net/#mongodb
• Commercial support: 10gen
• Training: 10gen

LAMP on EC2 : Setting up Amazon Web Services

http://goo.gl/z1Zb

http://goo.gl/xhqB

Web performance in seven steps: Summary and Conclusions

Web performance in seven steps: Summary and Conclusions

Previous time I blogged about the last step of the seven steps, step 7: Share the responsibility for the whole chain, a non-technical but rather a communication and behavior thing which I found crucial for success. We now have reached the end of this series and I'll sum up the topics we've dealt with and draw some conclusions.

In this growing on line world with demanding customers it has become essential that services provided on the web are always available and always fast enough. This is often challenging to developers and operators: performance problems manifest themselves in various ways, like in frustration, loss of revenue and disruption of development; and just adding hardware is a doubtful solution.

The question is: how can we as developers and operators assure that our web site is always available and always fast? My answer is: you need the right approach. I present that approach: measure, don’t guess; seven steps to performance success. These seven steps are as follows:

• Step 1: Define performance requirements;
• Step 2: Execute a proof of concept;
• Step 3: Test representatively;
• Step 4: Test continuously;
• Step 5: Monitor and diagnose;
• Step 6: Tune based on evidence;
• Step 7: Share the responsibility for the whole chain.

This approach provides a pro-active way of working which my customers appreciate as valuable. It can actually be leveraged to assure high performance all the time, for virtually any on- and off-line application.

This blog series has been an interesting journey for me. Some time ago we presented our EJAPP Top 10 of performance problems. Now we have added this approach of seven steps to help assure your applications performance.

It has worked for us and our customers. How does this all work for you in practice? We’d like to hear your feedback.