We've up­loaded a slideshare pre­sen­ta­tion on de­vel­op­ing trans­ac­tion­al ap­pli­ca­tions with Spring. En­joy!

Here is an­oth­er ex­cel­lent ar­ti­cle about the cost of ap­pli­ca­tion servers, and why a par­a­digm shift is need­ed with lighter-weight al­ter­na­tives:

http://www.tom­ca­t­ex­pert.com/blog/2010/06/03/mi­grat­ing-jee-ap­pli­ca­tions-tom­cat-mo­ti­va­tion-mi­grat­ing

In­ter­est­ing note: the au­thor used to work at Bea, so he def­i­nite­ly knows what he is talk­ing about;-)

Check out http://www.tom­ca­t­ex­pert.com/blog/2010/07/07/how-mi­grate-jee-ap­pli­ca­tions-tom­cat for a nice dis­cus­sion on how to mi­grate from jee to a light-weight al­ter­na­tive like Tom­cat - with Atomikos for JTA if need­ed.

Check out this cool blog en­try on how this can all work to­geth­er.

DISCLAIMER: the sug­gest­ed so­lu­tion has not yet been ver­i­fied by Atomikos...

2018 UPDATE: the link seems to be bro­ken by now - apolo­gies for that.

The cloud phe­nom­e­non is an in­ter­est­ing one, and a nat­ur­al evo­lu­tion of the out­sourc­ing mod­el. While a lot is go­ing on around cloud com­put­ing it­self, lit­tle is be­ing said about re­li­a­bil­i­ty.

Do clouds of­fer re­li­a­bil­i­ty? In a way yes: caching sys­tems like Ter­ra­cot­ta, Gem­stone or Or­a­cle's Co­her­ence of­fer a fail-safe mode for avail­abil­i­ty of your data in the form of caches. So if a cloud node goes down, chances are that a live copy of the data still ex­ists some­where else, which means that your process can con­tin­ue work­ing else­where.

All is fine (or most­ly fine) if you are work­ing with a sin­gle data­base and are pro­cess­ing, say, web re­quests in the cache. After all, if you only have one data­base and no oth­er re­sources then you don't even need some­thing like a trans­ac­tion man­ag­er (or Atomikos, for that mat­ter). There are at least two sit­u­a­tions where things change:

• If you queue cache up­dates to en­able write-be­hind, then you find your­self in a queu­ing sce­nario and are pro­cess­ing jobs from a queue to a data­base. En­ter dis­trib­uted trans­ac­tions.
• If you are not pro­cess­ing web re­quests but rather get queued re­quests from the start. En­ter dis­trib­uted trans­ac­tions.

In both cas­es you should at least con­sid­er us­ing a trans­ac­tion man­ag­er. In both cas­es, Atomikos is a good choice for the fol­low­ing rea­sons:

• It's open source (or at least our ba­sic ver­sion is)
• It's very light-weight and easy to de­ploy (mean­ing it lends it­self eas­i­ly to cloud-ori­ent­ed vir­tu­al­ized con­fig­u­ra­tions)
• It bun­dles over 10 years of ex­pe­ri­ence and mar­ket lead­er­ship
• It pro­vides full crash re­cov­ery and all oth­er bells and whis­tles - un­like many of the built-in so­lu­tions that you will find in a cache

So in that way, Atomikos pro­vides "re­li­a­bil­i­ty for the cloud".