Raible Designs

[DJUG] Ship it! and Distributed Teams by Jared Richardson

Jared's first book is called Ship it! and it's been wildly successful (translated into several different languages). During the first hour, Jared talked about his book and practices defined in it.

Ship it! is an attempt to talk about the holistic process of software development: techniques, infrastructure and process. For Techniques, there's a Technical Lead, The List, Code Reviews, Code Change Notifier and Daily Meetings. Infrastructure involves Version Control, Script Builds, Continuous Builds, Track Issues, Track Features and Writing/Running Tests. Process is Propose System Objects -> Propose Interfaces -> Connect Interfaces -> Add Functions -> Refactor, Refine, Repeat.

Martin Fowler's definition of Architecture: anything that is difficult to change later.

The majority of Jared's talk was about implementing TDD, continuous integration and many other things driven by audience questions. I didn't take notes because it was more of a conversation than a presentation. Jared's second talk was on Distributed Teams and my notes from this talk are below.

Agile is not XP or Scrum, those are implementations of Agile. The Manifesto for Agile Software Development is the interface for Agile Development. It contains the following principles:

• Individuals and interactions over processes and tools
• Working software over comprehensive documentation
• Custom collaboration over contract negotiation
• Responding to change over following a plan

To re-word these principles: Agility is...

• People interacting
• Software that runs
• Fast Feedback
• Frequent Change

Scrum principles are often not about developing software, they're about making people talk. The important thing is to get people in the habit of communicating. The best way to get people interacting is to do Daily meetings. One to two minutes per person. Same time. Three questions (what did you do yesterday, what today and any blockers?). Scrum style.

How do you do a daily meetings when you're remote? Conference calls are the most common, but don't let anyone local dial-in or they will get in the habit of doing it. Video is best, but it's often expensive to setup. One good strategy for daily meetings is IM. The beauty of this is that there's a transcript of the daily meeting that others can read. Conference calls are usually bad b/c you can only hear the guys that are close to the phone. It's even worse when the speaker phone is a cell phone. Whatever you do, you should never skip the daily meetings.

Peer Code Reviews are another good way to get people interacting. The first rule of code reviews is that anyone can refuse to do one. If you're not doing code reviews or pair programming, you'll end up with inefficiencies and broken windows. Address the behavior head-on. Peer Code Reviews remotely: e-mail, Skype headset, IM, VNC or SubEthaEdit (works awesome). NetBeans (collaboration module) and Eclipse (communication framework) have plugins that allow SubEthaEdit-style functionality.

How do you keep software running? Continuous integration and automated testing. Keep a list of atomic features. Prioritize. Don't let people work for 2 months. All tasks should be broken down into small chunks. Tests are a good way to communicate. Don't tell me you're done because you think you're done. Show me a test that proves you're done. Don't allow broken windows. Broken windows give the impression that no one cares and more bugs happen because of this. Continuous integration is essential for remote teams.

What's the best to get fast feedback? Fast compiles, fast tests, running CI 24/7. Another good strategy is the The List. Make sure and get feedback from your Tech Lead and from your Customers (they like to be involved). If you have a list that doesn't change after 6 weeks, you're working for a team who's list is dead.

There's nothing wrong with documentation and a plan, but its the things on the left that are more important. Offsite teams should have a single tech lead. Writing Tests might be better than writing requirements. When the tests pass, you'll get what you asked for. If you care about the design, write unit tests. If you don't care about how it looks, but want it to work, use integration/MCT for functional tests. Don't separate development and QA. To deal with time zones, make the tech lead stay up and rotate. For documentation, DRY out your Docs. Generate documentation instead of manually creating them.

"Docs are a cache ... flush often"

For Customer Feedback, have the tech lead translate.

I really enjoyed Jared's talks. The first one (on Ship it!) didn't provide much new information for me, but that's likely because I've worked on several open source projects and I've tried to bring those procedures and practices into any company I've worked at. I'm very grateful that LinkedIn does a good job with continuous integration (Hudson), bug tracking (JIRA) and documentation/planning (Confluence).

The 2nd talk on Distributed Teams was enjoyable because I'm in the heart of that - managing a remote team in Denver. We've experienced the awful conference calls where you can't hear anything or when we're on speaker on a cell phone. We do have all the video conferencing equipment purchased (10K worth) and sitting in our office, but haven't set it up because we're waiting on IT to setup a persistent VPN (which is a requirement to make it work). I've had some communications issues with my boss (mostly related to him not knowing what we're working on). We do daily stand-ups and use many of the practices recommended by Jared. One thing I think we can do to increase communication with headquarters is to start doing our daily meetings over IM and posting the transcript to a wiki page.

If you get a chance to hear Jared speak, I highly recommend it. He has a style that's very conversational and fun to listen to. You feel like you're a part of a self-help group rather than listening to someone preach about how you should be developing software.

Happy Birthday Jack!

Jack's birthday was last Thursday (August 28th) and only now am I getting a chance to wish him a Happy Birthday on this blog. I told you it was a busy week last week.

Happy Birthday Jack!

On his birthday, I picked him up from Kindergarten at 11 and let him run the show for the day. Needless to say, we had a good time.

On Saturday, we had a party to celebrate at my house. It was a great time with many old friends and lots of crazy kids.

I woke up to quite the disaster area the next day. I was also quite impressed when Abbie showed up with her ears pierced.

The rest of the weekend I spent quite a bit of time enjoying A Taste of Colorado. When work began on Tuesday, the week intensified as I was the "Release Owner" for LinkedIn this week. We made a number of backend changes to reduce statefulness and improve performance. I'm proud to say it was one of the smoothest releases I've been a part of, mostly because of the high quality people involved.

As far as my schedule for the rest of the year, it seems like I'm going to be busier than ever. I have to complete my presentations for CSS this week. In two weeks, I'm speaking at the Colorado Springs Open Source User Group Meetup. The following week I'm heading to Munich for Oktoberfest. If I live through that, I'll be implementing Memcached, speaking at CSS, hunting with my Dad, celebrating Abbie's birthday, traveling to Costa Rica/Panama and keynoting the JavaEdge Conference in Israel. If you happen to be in Colorado Springs, Munich, Mountain View, Keystone, Montana, Costa Rica, Panama or Israel in the next few months, maybe we can enjoy a beer together. Cheers!

What's wrong with JSF

The developers of Seam have come up with a list of major issues with JSF. I'm assuming many of these issues are fixed by Seam, but it's interesting to note how they've somewhat admitted that JSF has many flaws. Note that there's a lot of references to Struts and WebWork.

Hopefully many of these will be fixed in JSF 2. If REST support is an important feature for web frameworks, it'll be be interesting to see how the component frameworks handle it. It'd be great if they provided native support. Oh wait, then they'd be action-based frameworks.

EhCache Project Busy this Summer

The EhCache project appears to be having a very busy summer. EhCache 1.5.0 (a major new version) was released on July 12th. In addition, a new (SOAP-based) EhCache Server was released at the end of July. You might ask yourself why you'd need such a beast. I think Greg explains it best:

Why am I doing this? There are lots of theories that have made their way on to the ehcache mailing list. The prosaic truth is that a large US corporate using ehcache for their Java apps on 200+ servers also wants to use it for their C++ apps. And they are prepared to sponsor development. The Web Services API lets them do it. That's it.

As to the larger question of how interesting this is to the world at large, my view is not very. However having to jump through all the hoops to get a server infrastructure done, I thought that the world at large may be interested in a RESTful, resource oriented ehcache server.

The next day, Greg announces EhCache for JRuby on Rails. A few days later, RESTful, resource-oriented caching becomes available in ehcache-server.

I guess this helps answer the question about OSCache vs. EhCache. OSCache hasn't had a release in over a year and EhCache is pumping out new releases and new products. Well done, Greg!

At LinkedIn, we use EhCache for many of our caching needs. However, it's likely we'll be moving to Memcached in the future. Since I'll be part of the team that implements Memcached, it'll be interesting to see which one performs better.

Maven Plugin for Running Integration Tests against Multiple Containers

Don Brown has created a pretty cool Maven plugin that allows you to run integration tests on multiple containers in one go. I learned about it on the Struts 2 Dev List:

I've started adding functional tests to Struts 2 by adding a few to the REST showcase application, running against Tomcat 5.x, Jetty 6.x, JBoss 4.2.x, and Resin 3.x. The magic happens through a new Maven 2 plugin I developed called maven-itblast-plugin, which enables multiple integration test runs against multiple containers in one go. For more info, see http://github.com/mrdon/maven-itblast-plugin/wikis/home.

You might notice that this plugin is hosted on GitHub. If you want to learn how to use GitHub with Maven, you might want to see Don's entry on Maven-enabled project hosting with GitHub. Thanks Don - good stuff.

Update: Don has posted more information about this plugin on his blog.

OSCON 2008 Wrapup

This week, I attended OSCON 2008 in Portland, Oregon. I talked to someone who thought the conference had a very small Java presence. I noticed this too, but that's how it's always been. Interestingly enough, they also thought it had a small Ruby showing. I guess Perl, Python and PHP will always dominate OSCON. Of course, there's nothing wrong with that. I've always admired OSCON for the diversity of developers and languages.

Below is a list of my entries for all the sessions I attended.

• The Keynote with Tim O'Reilly, Christine Peterson and Dirk Hohndel
• An Introduction to Ruby Web Frameworks by Ryan Carmelo Briones
• Google XML Pages (GXP) by Harry Heymann and Laurence Gonsalves
• Caching and Performance: Lessons from Facebook by Lucas Nealan
• Web Frameworks of the Future: Flex, GWT, Grails and Rails (my presentation)
• The State of Lightning Talks
• CSS for High Performance JavaScript UI by Gavin Doughtie
• Even Faster Web Sites by Steve Souders

If you attended OSCON, did you enjoy the show? What was your favorite session? I'd love to hear other's impressions of the conference and how it could be improved.

[OSCON 2008] The State of Lightning Talks

From this session's detail page:

As a repeat of the last 2 years, 15 open source project leaders will be given five minute lightning talk slots to bring the audience up to date on their projects.

This year’s speakers and projects include: Brian Aker: Memcached, Glynn Foster: OpenSolaris, OSI: Danese Cooper, MySQL: Monty Widenius, PostgreSQL: Bruce Momjian, GNOME: Dave Neary, Gentoo: Donnie Berkholz, OpenOffice.org: Louis Suarez-Potts, Jabber: Peter Saint-Andre, Mozdev: Brian King, OpenID: Scott Kveton, Open Scrum: James Dixon, and Cliff Schmidt for the Talking Book Project. A couple more projects may be added later.

Each speaker has exactly 5 minutes, and we use various “fun” tools to make sure they stick to their time. The session usually ends with a “zinger” presentation worth staying for.

Unlike the description above, apparently there's 17 projects instead of 15. This session is 95 minutes long (spans 2 normal sessions). I figure this will be the most challenging event for me to blog, so here we go!

OSI (Open Source Initiative), Danese Cooper
Danese has been on the board of OSI since 2001 and will be on the board for another 3 years. This year, they've been asking themselves "What are the ways to make OSI more effective?" The best answer they've come up with is that they should run OSI more like an open source project (with lots of transparency). Minutes are posted publicly on website and they have a public blog. They're also transferring their archives to a searchable system. They'll be using Trac to do more objective tracking of all the issues that've been brought to their attention.

They're also going to establish (formal) membership. They're going to use Apache as a model and allow Charter, Individual, Organizational and have an Annual Members Meeting. ASF currently has 300 members and these folks are in charge of making decisions for the foundation. There's a good chance you'll recognize all the Charter Members of OSI. The names will be announced in the next couple months (I believe). There will be opportunities to be individual or organizational members.

There's new board members this year with an international focus: Nnenna (Africa), Harshad Gune ...honk... out of time.

Open Scrum, James Dixon
James is the founder and Chief Geek at Pentaho. Pentaho recently took their products open source and they're releasing Open Scrum as an agile methodology for managing open source projects. Open Source is not a methodology, it is a set of principles.

Some agile principles are used in open source, but some are not. For instance, trusting developers and face-to-face contact can be difficult with open source projects. Simplicity sometimes comes out of open source projects, but usually only for projects with a large developer base. There's a 45% good fit between Agile and Open Source.

Open Scrum is based on Scrum, but geared towards open source projects. It's simple and flexible and template driven. It scales from single-geek, part-time, single-projects to massively multi-geek full-on and multi-layered undertakings.

MySQL, Monty Widenius
Monty is the Chief Fonder of MySQL and he's talking about what's new in MySQL. There's been no new releases for users, but internally they've been doing lots of bug fixes in 5.1. He expects to have a reasonable GA of 5.1 in 3-5 months. 5.0 will include online backup and optimizer changes for faster joins and sub queries. 5.1 has an InnoDB Plugin.

MySQL was acquired by Sun for $1 billion and 6 months later, life is good. MySQL Backup was announced to be crippleware by MySQL management, but later changed to be open source.

Switched to use Bazaar and Launchpad to increase community participation. Started public bug hunt for MySQL 5.1. Started using case competition for new features in 5.1. There's also a new MySQL forge. Please help MySQL get better by filing bugs!

Maria engine 1.0 and 1.5; now crashsafe and multi-versioned. Transactional part to follow soon.

OpenID, Scott Kveton
Scott is on the board of the OpenID Foundation and his son is on stage with him (with a Twitter shirt on). In terms of adoption, they have a hockey stick graph with the big upturn starting in February 2007. OpenID is only 3 years old and there's over 20,000 sites that now support it. There's about ~500 million OpenIDs (including every AOL, Yahoo, MySpace and LiveJournal user).

OpenID 2.0 was released as final 12/7/2007. What's next: usability (currently sucks), security (PAPE), integration with other protocols, more than just providing, and possibly OpenID 3.0. One of the biggest problems with usability is people just can't remember URLs, so they're trying to figure out a URL -> e-mail mapping.

OpenID Foundation has added 5 corporate board seats and has 7 community board seats and elections are in August. You can get code at openidenabled.com and you can get involved at openid.net.

Gentoo, Donnie Berkholz
Donnie is one of 7 people that's on the council that tries to make sure Gentoo is going in a good direction. In the last year, they've been struggling with community and releasing. Gentoo is just getting old enough where people are quitting and new developers are coming on board. In 2005, they had a lot of voters for their council. 2006 and 2007 were bad years from a community participation standpoint. This year, they've fixed "poisonous people" and participating is back up.

Rather than voting for single candidates, they use a "rank all the candidates" voting system. Community is very important and they've recently kicked out 3 people that didn't think community was important. They released 2008.0 a few weeks ago. It was supposed to be released in February. When they released, they made the front page of Digg, which made Donnie very happy. Gentoo news announcements were way down in 2007, but now they're back up.

Recommended books for community building: Good to Great, The No Asshole Rule, Getting to Yes.

PostgreSQL, Bruce Momjian
Bruce is a PostgreSQL core developer and works for EnterpriseDB. The future for PostgreSQL is going to be a lot different than the past. PostgreSQL's path to the future isn't a straight line. Rather, it's a meandering path like a road up a mountain with switchbacks. People would like a catapult to put features into to get things in, but it's not that easy. It's difficult to improve software that's been around for 20 years.

Companies have very clearly defined goals that usually revolve around money. With open source, it's a lot different. Goals are usually for a feature set, for adoption of open source or for the challenge and fun of it.

PostgreSQL 8.0 was released in January 2005 and had a lot of enterprise features: Win32, Savepoints, Point-In-Time Recovery, Tablespaces. The latest release (8.3 in February) was much different and much more exotic features. In the future, they're going to expand on running queries on multiple CPUs and maintaining their leadership in the open source database space.

Bazaar, Mark Shuttleworth
Mark's interest in distributed version control predates his interest in Ubuntu. If we can elevate our process of version control, we can elevate the entire open source community. Bazaar is a distributed version control system that's developed in Python. It focuses relentlessly on a couple of key values:

• Cross-platform: Linux, Windows, Mac OS X
• Performance: sub-second status on > 10,000 files
• Being adaptive to the way that people want to work (can use it like Subversion if you want or you can have distributed branches or have a team checkout)
• Extensibility and embeddable - has a plugin system
• Python Hackable - people can easily modify

Projects that use Bazaar: GNU, MySQL, Twisted and Ubuntu.

Memcached, Alan "Dormando"
Memcached is a very simple project with a mailing list with very simple people on it that run very simple websites. They haven't had a release in 6 months. Memcached was written by a guy named Fitz that wrote it and left. They've only recently created a developer community that's all over the globe. Alan didn't bring any slides, but he did release 1.2.6 RC1 as he was standing on stage. They also hope to release 1.3.1 this week, but there's not a lot of documentation.

People fork Memcached a LOT, mostly because they need a new backend. They've added a new storage engine that's pluggable to hopefully fix the forking problem. Also, their new binary protocol should make it a lot faster for high traffic web sites.

The Talking Bridge Project, Cliff Schmidt
While the network at OSCON has been slow, the folks that live in rural areas around the world have an incredibly slow means of getting information. Their network is often roads that people travel on to communicate with each other.

They've created a Talking Book device that is an MP3 player that costs $5-10. They're also creating kiosks that people in rural areas can interact with to download new information (i.e. podcasts and other educational content). It also has a microphone and can be found at literacybridge.org. They're creating open source projects to help build the device and content around it. They'd love to have open source developers join their projects and help them make access to information easier for rural societies.

Open Source Lab at Oregon State University, Lance Albertson
Lance is a Kansas native and grew up on a farm. He's a Gentoo developer and joined OSL a year ago. OSL was created in 2003 to utilize "extra" unused bandwidth. They provide managed and co-located hosting for open source software projects. They also provide on-the-job learning opportunities for students in system administration and development.

In addition to hosting, they have a development and outreach side. They have 12 student employees that are given developers/sys admins are given real world practical opportunities. Their work is seen and used by many people and students are given extraordinary amounts of responsibility. They're working on a couple external OSS projects: Oregon Virtual School District and One Laptop Per Child.

Outreach wise, they have an Open Source Education Lab and they've been doing Drupal training for OSU employees. They've also helping organize GOSCON, which is an open source conference for governments.

They currently offer hosting for over 70 OSS projects. Services include, email relays, databases, web hosting, file mirroring and code repositories. Notable clients: ASF, Drupal, kernel.org (master), OpenOffice, Freenode, Gentoo Linux & Debian, phpBB and many others. Datacenter currently has 50 racks; they'll be moving to 75 in the near future.

OpenOffice
They've had 150 million downloads and believe there's around 1 million users. There's 350 committers and most of them work from Sun. Presently, their biggest focus is Desktop. In the future, they'll focus on the Web. The idea is that people will want to use OpenOffice from their mobile devices. ODF is a format that can be expressed by any application. OO 3.0 is about extensions, not bloat. They're adding linkage to a free PIM (Outlook replacement). They're also adding better interoperatbility with other suites and formats (e.g., Microsoft Office 2007). They're adding productivity tools and adding toolkits to make things easier for developers. In the next year, they expect to go way beyond 150 million downloads. They also expect to expand greatly internationally.

Mozdev, Brian King
Brian has been in the Mozilla Community since 1999. Mozdev.org is a community site that provides free hosting for Mozilla applications and extensions since 2000. Established as a non-profit organization in 2004. It has over 250 active projects today and there's over 500 developers discussing issues on the [email protected] list.

Services provided: source code hosting, bug tracking (Bugzilla), communication tools (lists, newsgroups, blogs, forums), file management tools, project tagging, wiki, statistics, permissions system and public planning.

They've experienced some grown pains in the last few years, but they're mostly solved now. They've added developer resources to help develop their site, but they need more. Up until Firefox, they were the #1 place to go for Mozilla projects. They're still working on letting people know that they're around and have projects that are interested. They're looking for new avenues for funding.

Moving forward: they'll be add more items to roadmap, making it easier for less technical folks to host and create extensions, solving the funding issue, and developing deeper relationship with Mozilla (MoFo and MoCo). Quite simply, they want to continue with their goal of supporting developers in order to proliferate Mozilla technologies.

Glen Foster, OpenSolaris
Hey - I had a beer with this guy last night at Kells! Rather than focusing on the older Solaris users, they want to move to focus on getting kids to learn and use it. A couple of months ago, they released 200805 and reduced 5 CDs down to a single live CD. The packaging system is now network based. They changes the default shell to bash and changed to GNU tools as they default as well.

They introduced a new site - opensolaris.com. Since Sun released the source code 3 years ago, they've had a long evolution of getting the source out the door. They were using Teamware and doing much of the development behind the door. Early next month, they're moving to Mercurial and they'll be moving all the source outside the firewall. They'll be using Bugzilla as their bug tracking system.

Similar to Gentoo, they've had quite a few people in their community that don't like change. They're working on fixing this and have had good progress. Several years ago, they created a governance system before they had a community. This was a mistake and their new community-driven governance system should work much better.

GNOME, Dave Neary
GNOME is a desktop environment and set of utilities. It's the default on Ubuntu and Fedora. It's the face of Linux on the Desktop. It's also a platform for development. They have a vibrant ISV community that includes Adobe, VMWare and IBM. In addition to desktop, GNOME is also a mobile platform. They also act as a big tent that provides an infrastructure for projects that are part of the GNOME ecosystem.

The most important thing to Dave is the shared vision of universal access to anyone and everyone. Very important things to the GNOME project: usability, internationalization and localization, accessibility (Sun and IBM have done a lot of work). Accessibility is something they've really focused on in the last year. They've created an Outreach Project for Accessibility and have gotten funding from Mozilla, Canonical and Google. Mozilla has done a lot to fund them and help provide accessibility for Rich Internet Applications. To see if a website is accessible, try it in lynx.

Subversion, John Mark Walker
John is the Community Manager for openCollabNet and is not a Subversion developer. Subversion 1.4 was released in September 2006. There was much anticipating for 1.5 and was released last month. The people rejoiced.

What's new in 1.5? Merge tracking: easier to merge changes from trunk to branch and vise versa. You can also do sparse checkouts (replaces -N). Interactive conflict resolution so you can do it from the command line client. It also add changelist support. svn:externals is no longer required to be absolute (sweet!) and you can add peg revisions in your URLs. FSFS repos never change a rev after written to disk. Clients many now perform chained copy/move operations locally. It also supports moving multiple sources for copy and move. Client operations are now significantly more responsive to canceling operations. "resolve" subcommand replaces "resolved" (deprecated). Delete (remove) now takes a --keep-local option.

Now it's time for the fun stuff...

Ken Drachnik had to leave for an emergency and is unable to give his talk on GlassFish. An audience member (Carl Fogel) volunteers to do his presentation. It's very funny, especially since he's not a Java Developer and has never heard of GlassFish. The only thing I got out of this presentation (besides lots of laughs) is that v3 will be released in June 2009.

Drizzle, Brian Aker
Stored procedures, triggers, prepared statements and many other things have been discarded. "One CPU to rule them, and in the query cache, bind them." If you have a query cache turned on in our database, turn it off or delete it.

Drizzle is currently ~420K. The Master Plan is to rethink everything and not assume everything was bad. Also, they can reuse many other libraries w/o writing them from scratch. They don't have to ship every library because many are present on operating systems. In with the new: C99, Posix, package-lib. They're moving to a MicroKernal design and moving code to the edge. No new features will be in core. To add interfaces you have to remove code so there's an equal amount of code.

Multi-Core support: no new locks, remove old locks. Think today (burn memory, messages scales). They can leverage Sun because they can build machines with more cores than anyone else.

Field Types: Less primitives - now there's just one "blob". Removed the 3 byte int and add UUID/IPV4(6). They dumped ACL because we authenticate in clouds. KISS.

You can get involved with Drizzle at http://launchpad.net/drizzle (bzr branch lp:drizzle) and http://launchpad.net/drizzle-discuss (mailing list).

[OSCON 2008] Web Frameworks of the Future: Flex, GWT, Grails and Rails

Below is the presentation I'm delivering at OSCON today. Unfortunately, I had to remove slides on GWT and Flex to fit w/in the 45 minute time limit. I hope to expand this presentation in the future, as well as continue to develop the side project I'm working on using these technologies.

[OSCON 2008] Google XML Pages (GXP) by Harry Heymann and Laurence Gonsalves

GXP is a templating system that Harry and Laurence developed at Google. It was original created by Laurence in late 2001 (Java run-time, compiler written in Python) as part of the AdWords rewrite. I'm attending this session because I heard from a Google employee that they were using WebWork + their proprietary templating framework for the view. My suspicion is that GXP is that framework. The presentation I'm listening to is available at the following URL:

http://docs.google.com/Present?docid=dcbpz3ck_8gphq8bdt

Google XML Pages has the following features:

• static type checking
• convenient parameter passing/modularization system
• partial markup validation
• automatic escaping of untrusted content
• encourages functional style, discourages side-effects
• internationalization support
• lightweight runtime

GXP is an open source project as of today and is available at http://gxp.googlecode.com. It's used by AdWords, AdSense, Checkout, Blogger, Analytics, Reader and many more.

HelloWorld.gxp:

<gxp:template name='com.google.sample.HelloWorld'
              xmlns:gxp='http://google.com/2001/gxp'>
Hello, World!
</gxp:template>

Output:

Hello, World!

GXP has compile-time markup validation as well as static-type checking. GXP has native data types: for text/html, text/plain, text/css and text/javascript. It supports loops, conditionals, abbreviations, internationalization (i.e. <gxp:msg>Hello, World</gxp:msg>) with placeholders. You can call GXP in the same package using <call:GXPName>. To call something outside a package, you can use <gxp:import> to import packages or classes. You can also use a qualified XML namespace to access another package.

[OSCON 2008] An Introduction to Ruby Web Frameworks by Ryan Carmelo Briones

Ryan is a Server Monkey / Code Sumari for Edgecase, LLC in Columbus, Ohio. A framework allows you to create re-usable code. Frameworks allow you to use encapsulation. Frameworks tend to be domain specific. For example, Rails works really for CRUD application, but not for others (i.e. Twitter).

Why Ruby?
Ruby has been Object Oriented since day 1. Ruby promotes Beautiful Code that's easy to read and maintain. Yes, MRI has performance issues. Matz has said "I'm a language designer" and has turned over the VM to others for Ruby 1.9. Another thing that might keep folks from using Ruby or its web frameworks is the libraries available. This is understandable, but it's being solved by alternative implementations. This includes YARV (the official 1.9 implementation), JRuby, IronRuby (not ready for production) and MagLev.

Rack
A framework that provides a minimal API for connecting web services and web frameworks. As a web application developer, this framework allows us to know about web services, but not worry about the details of talking to it. Below is a very simple Rack application.

class HelloWorld
  def call(env)
    [200, {"Content-Type" => "text/plain"}, ["Hello World!"]]
  end
end

Rack allows the handlers do the work and not worry about the web server abstraction. Handlers exist for WEBrick, LightSpeed, Mongrel, Fast-CGI and many others. As an application developer, it allows you to choose different architectures (threaded, evented, etc.). Ryan is talking about Rack first because it's used in all the other Ruby web frameworks.

Ruby on Rails
Rails is 4 years old now and was written by DHH when he was a contractor at 37Signals. Rails doesn't define and grand new ideas, everything has been done before (MVC, code generation, etc.). What Rails did is package everything in a unique way that makes it very easy to use. Rails has influenced a lot of what has come from web frameworks in the last few years. One of Rails' nicest feature is code generation. Ryan showed part of DHH's Create a weblog in 15 minutes video to demonstrate code generation. He noted that the minute he showed was picked because David said "Whoops!" and "Look at all the things I'm not doing". Rails popularized Convention over Configuration using naming conventions and load paths. While this is definitely a cool feature, I think most web frameworks have adopted CoC by now. Maybe not JSF, but who wants to use JSF w/o a framework on top of it anyway?

One warning about Rails: "The Golden Path" can get in your way. Rails is very Opinionated Software and that's how Rails works. As long as you follow that, you should be very productivity. If you decide to go off the Rails (i.e. namespaces), it can be difficult.

Rails uses a DSL in its models (i.e. has_many, has_one for relationships) and in the Rails router. It allows you to very simply map a URL to a controller/method. In addition to DSLs, Rails has first-class testing and its generators create stub tests for you.

Bad things about Rails: too much magic, moves to fast (too many releases).

Merb
Merb was originally developed by Ezra Zygmuntowicz to run alongside a Rails app to handle file uploads. It grew from there and became it's own beast. Merb is very much about using only what you need. It has "package repos" that allow you to add additional features. For example, merb-core doesn't contain an ORM framework, just a web framework. Merb also allows you to choose your ORM. It's standardized on Rack, so it can run on just about any web server. It also included "deferred actions" that allow you to send some URLs to evented web servers and others to threaded web servers. Merb eschews the "magic" that Rails has. It tries to stay away from making it's code a "monument to personal cleverness". Simple code scales better and runs faster.

One of the downers to Merb is that it's flexibility allows you to get down to the nitty gritty. However, it can be less productive than Rails because of its flexibility. Another downside is its documentation and examples are sparse. Merb is not recommended if you're just getting into Ruby.

Camping
Camping is a micro framework (< 4K) developed by why the lucky stiff. It's designed to develop small applications. You can do everything in one file and create prototypes very quickly. It uses Markaby to write HTML code in a builder-style fashion.

Since a Camping application is all in one file, it can be difficult to develop large applications. The solution is to write small apps and mount them in the same URL space. The only issue with small apps sharing the same space is they have to use the same database. One downside to Camping is there is no standard test framework. Mosquito was developed as a solution, but doesn't seem to be maintained.

Sinatra
Simple. Fast. Effective. It's designed to allow creating REST applications with minimal dependencies. Similar to Camping, it has one file for the entire application. Unlike Camping, Sinatra doesn't follow MVC conventions, so it may be difficult to port a Sinatra application to another framework.