Introducing hibernate-memcached

Some of you may, or may not (care), know I am a huge fan of memcached. Its combination of simplicity, elegance and performance make it fantastic choice for any real caching solution.

I've recently begun work on implementing a bridge for using memcached as a second-level cache for hibernate. The project is hosted at googlecode right now, and the code is currently available in the googlecode hosted subversion repositories. In the future I'll probably move it over to github, but subversion is much more accessible to the public at large still.

Adding hibernate-memcached to your hibernate based application is as simple as adding hibernate-memcached.jar, memcached.jar, and spy.jar to your classpath. This can also be done using Maven.

Enabling the hibernate-memcached cache is simple as adding two properties to your hibernate config.

hibernate.cache.provider_class=com.googlecode.hibernate.memcached.MemcachedCacheProvider
hibernate.memcached.servers=server1:11211 server2:11211


Property #1 tells Hibrnate to use the MemcachedCacheProvider. Property #2 tells the MemcachedClient in use what servers to use for the cache. It really is as simple as that.

There are many other configuration properties available to configure things like the default and per-region cache times, operation timeout, hash algorithm to use, and what key strategy to use.

The hibernate-memcached cache is working great for both individual entity caching and query caching. I currently have a lot of work to do around getting documentation up on the googlecode site. It is ready to play with and easy to setup, if anyone out there has the time to check out; please do! If you run into any questions or problems you can post them on the hibernate-memached google group, or open an issue at googlecode.

SAP Memory Analyzier

I know nothing about SAP, but they built a nice memory analyzer worth checking out.
Check it out

Scalability Principles

Author Simon Brown discusses 7 principles of scalability.

1. Decrease processing time
2. Partition
3. Scalability is about concurrency
4. Requirements must be known
5. Test continuously
6. Architect up front
7. Look at the bigger picture

Check it out

David Heinemeier Hansson at Startup School 08

David Heinemeier Hansson, creator of the Ruby on Rails framework and Partner at 37Signals gives insight into creating a profitable startup company.
Watch it

Better World Books

I found Better World Books a while back by reading a story I don't remember now. I had completely forgotten the name of the site and couldn't find it again, until now. I am selfishly blogging this so I don't have to look for it again :)

That being said, check out Better World Books next time you're looking to by some fat-ass technical book. Their mission statement sums it up pretty well...

Better World Books capitalizes on the value of the book to fund and support literacy initiatives locally, nationally, and around the world.

Pro Web 2.0 Application Development with GWT

Jeff Dwyer has just released his book on GWT. Jeff is a really bright guy and has done some extensive work with GWT. Aside from that, he's a good guy so throw him a bone and check it out...

Pro Web 2.0 Application Development with GWT

Distributed Version Control

I've recently done some work with git as a source control system. I was pretty impressed by its functionality and the overall concept of distributed version control.

In my career I've been exposed to a rather limited set of version control systems. I've used CVS, Subversion, SourceSafe and Accurev. Each of those systems are based on a central repository with many clients. The concept is a simple client-server model that is very easy to understand.

Git is a "Distributed Version Control" system. This means that everyone effectively has their own repository of the code that they can fork and merge as much as they'd like locally. DVCS systems like git work on a peer-to-peer model. This is a very powerful feature in that if I have some code that you would like to integrate with I can exchange it with you, and you alone. In a VCS system like Subversion or CVS, I would have to commit my changes to the central repository for you and everyone else to get. Sure, I could branch and put my changes there, but merging that back in is a huge pain in Subversion and CVS.

InfoQ just posted a lengthy article discussing Distributed Version Control Systems such as git, mercurial, and bazaar.

SpringSource Application Platform Details

Last week SpringSource announced their Application Platform project. It is an interesting attempt at slimming down the J2EE environment by tying things like Spring and OSGI together. On the SpringSource Team Blog, Rob Harrop begins an in-depth explanation of SpringSource Application Platform and it's features. Very interesting stuff...

Trying to get Git

I'm trying to patch some stuff in the java-memcached-client right now. The code is hosted at GitHub. I've never used Git in my life so this is a brand new experience for me. Boy did I screw this up :P
I've got branches gone wild and accidental reverts. I think I'm starting to get the hang of it now though. Thanks to this cheat sheet, and this tutorial.

SpringSource Application Platform

The guys over at SpringSource have created an "Application Platform" based on Tomcat, Spring, and OSGI. Interesting stuff, read more at InfoQ.

I'm gonna get my hands on the beta. Though if they intend to release it as Open Source anyway, why is there a beta sign up? Odd...

Mastering Grails

Scott Davis has posted "Mastering Grails: Many-to-many relationships with a dollop of Ajax" in the Mastering Grails series. If anyone can master Grails; it would be Scott Davis. Have a look.

Spring Security 2.0 Released

Spring Security 2.0 has been released into the wild. Tons of great new features, including OpenId Support!

http://www.springframework.org/node/627
http://forum.springframework.org/showthread.php?t=52640
http://www.nabble.com/-ANN--Spring-Security-2.0.0-Released-to16701081.html

Hibernate and Memcached

As I mentioned at the end of my last post, Cache Everything, I am working on building a library to use memcached from Hibernate as a second level cache. That project is hibernate-memcached and its in it's infancy over at googlecode.

The Hibernate second level cache is used to cache items between session invocations. Hibernate always uses it's session as a first level cache, but if you want to avoid database hits between sessions you need a second level cache. If you want these caches to stay in synch between several instances of your application, you need a distributed second level cache.

Memcached is a fantastically fast distributed cache, so why not use that? Once I build a jar of the hibernate-memcached project you'll be able to include it in your application and tell Hibernate to use it. Telling Hibernate to use it means adding the cache_provider property to your hibernate.cfg.xml, or your Spring LocalSessionFactoryBean if you're using that. The hiberante.cfg.xml looks like this...

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.cache.provider_class">com.googlecode.hibernate.memcached.MemcachedCacheProvider</property>
        <mapping class="com.yadda.yadda.Something"/>
    </session-factory>
</hibernate-configuration>

Then, in your mappings you tell Hibernate that you want instances of your persistent objects to be cached, or collections from relation ships to be cached. Once Hibernate knows what you want cached you can watch it pump stuff into memcached, which is good clean geeky fun. Fire up memcahed (on windows or linux) using the -vv command line option to make it run "very verbose". You can see it storing and responding for each operation taken.

You can play with the code straight out of subversion at google code. It will actually work and cache stuff, but it is currently hardcoded to look only at localhost:11211 for a memcached instance. I'll get around to making it configurable. To build the code you'll need Maven2. I highly recommend using Don Brown's no-suck port of maven2 actually.

More to come...

Cache Everything

So I'm working on this Web Service project and its time to consider scalability. Which means its time to setup memcached. If you haven't looked at using memcached, you should.

Memcached is a totally stupid-simple distributed memory object cache. It's this super tiny application that slices off a chunk of RAM and listens on a port. Yeah, that's about it :)

It gets cool to talk about when you start talking about making it "distributed". When you start talking about "Distributed Caches" people start thinking about Coherence and other hugely complicated and hugely expensive enterprise applications. It really dosen't have to be so hard.

Here's what you do. Get a couple cheap boxes with one or two gigs of ram in them. Install the Linux flavor of your choise. Install memcached and run it with "memcached -d -m 1024". This will start memcached on it's default port (11211) and allocate 1gb of ram to the cache. If you do this on three boxes, you now have a 3gb distributed cache.

There are client libraries available for most popular languages. If you're using Java I'd highly recommend using spymemcached from Dustin Sallings.

So you give the clients a list of servers to connect to and they will basically treat that big distributed cache you created as a huge hashtable. Each get/set operation has a string key that is hashed and used to decide what "partition" of the cache to read/write to. If an instance goes down the client just begins distributing reads/writes to the other instances until the missing member comes back.

Using any of the client libraries, in just about any language, your usage looks like this:

• Check the cache for your object.


• If your object is not null, return the object.


• Otherwise, read the object from the database or what have you.


• Put the object in the cache.


• Return the object.

Memcached uses a very light and fast binary protocol which makes it usable by just about any language. There are pre-built packages in apt if you're using Ubuntu, you can easily build it from source for just about any other *nux flavor. There's even a windows port. I've only used that for dev at this point though.

I'm working on writing a second level cache for hibernate that uses memcached. It is super simple, but I just started work on it last night (seriously). Check it out if you want. I plan to work on it over the next few nights and get it ready for prime time :)

Open Source Licensing: WTFPL

I think I'm going to start using this license for any open source stuff I do...
WTFPL

Battlefield Heroes

I can't wait to play this!

Grails 1.0 Released

Graeme Rocher, from G2One Inc., announced the release of Grails 1.0 this morning. The release notes are available from grails.org.

If you're a Java person and aren't familiar with Grails or Groovy for that matter, you should definitely check out Grails. Grails is a rapid web application development framework based on convention over configuration. It is designed MUCH like Ruby-on-Rails, but built using Groovy as a language. The main benefits of this approach is that Groovy is based on Java; which means it looks and feels like Java. This helps introduce it to a team and lower the learning curve. The other benefit is that it builds down to a WAR file that you can deploy into any old application server. No special hackery required. This is important when deploying it into a very 'enterprisey' environment.

Also, the internals of Grails and how it works are not based on it's own invented voodoo. Grails uses Spring, Hibernate, and Acegi internally. Good stuff...

Out of the Sandbox: Spring-Security OpenID Support

I just finished moving the OpenID support For Acegi/Spring-Security out of the sandbox and out into it's own module. It is in dire need of documentation, but the code itself is pretty solid.
Here's the post to the mailing list.

Save Windows XP

InfoWorld has started a petition aimed at getting Microsoft to keep Windows XP support around past the June 30th end-of-life date.

To summarize, here's why I like XP...

• XP is simply the best OS Microsoft has produced. I realize that doesn't say much, but it's true.


• I am a gamer. I'd gladly run Ubuntu or Fedora Linux, but I am not down with playing Pac-man, Super-pacman, or one of 200 Tetris clones.


• I'd love to get a Macbook, but they're really expensive, and again, I don't like pacman.


• Vista blows

So, sign the SaveXP Petition at SaveXP.com

Sun to Buy MySQL

This is huge news! MySQL has to be the single most popular open-source database in the world.