[scopes] render-scope vs flash-scoped vs codi scopes

frameworks like seam provide a so called render-scope e.g. to use beans after a redirect for rendering the next page. that's very often not enough because beans are usually also needed on a subsequent request to the same page. the flash scope is also not the best solution because it's usually also used to overcome the redirect issue of request scoped beans. therefore, myfaces codi introduced the view-access-scope which keeps beans as long as they are accessed by a view (also supports any kind of ajax scenarios). however, if you really need the behaviour of @RenderScoped, you can use e.g. the @PostRenderView callback to terminate beans (which have one of the codi scopes) manually or you can provide a custom marker and you terminate all beans with this marker automatically in a phase-listener. the needed information is available in the wiki (or just contact the myfaces mailing list, if you need further information about it).

[myfaces] setup of codi and extval

in the last weeks i saw a lot of users looking for information about setting up and/or configuring extval and/or codi.

the simple answer: both don't required configuration by default.
zero config allows you to add the jar files you would like to use to your project and that's it.
(in case of codi you have to ensure that you have configured the cdi implementation of your choice correctly. in case of the bv module of extval, you have to ensure that you added the bv implementation of your choice.)

information about the libs is available in the corresponding wiki which is liked on the official website of each project. please check the wiki and/or send a mail to the mailing list.

8th release of myfaces-extensions-cdi

The Apache MyFaces team is pleased to announce the 8th release of Apache MyFaces Extensions CDI (aka CODI). It's v1.0.1!

[scopes] view-scope vs view-access-scope

a lot of people were looking for this information.
you can find the information in the wiki of codi.

however, the short answer is:
the view-scope of jsf2+ is bound to a concrete jsf page. that means: as soon as you navigate to a different page, the state gets lost. that's better than nothing, but not useful for a lot of use-cases. the main use-case which needs it are ajax-requests on a page and the data used by them aren't needed on other pages, but it's pretty easy to break it e.g. with a browser-refresh on a page which stores the data in a view-scoped bean and has no form with input components. (in a previous blog post i described how to use the infrastructure provided by codi to create a session based view-scope to overcome such disadvantages cause by storing view scoped beans as part of the tree-state.)

like with the view-scope view-access-scoped beans are available on a page, but they also exist for the next page. that means: they are forwarded to the next page and get destroyed autom. if they don't get used during the first request of the next page. that's e.g. useful for wizards. if you have a wizard page which doesn't use the bean or you have to support the possibility to interrupt a wizard, you can use the grouped-conversation scope (and even the window-scope) provided by codi. however, due to the powerful api of codi you can also destroy the scope manually at any time (if needed).

[benchmark] boost myfaces codi scopes with owb v1.1.1

this is my last blog-entry about the performance of cdi implementations and codi scopes which is planned for the next months. why? you will see it in a minute.

within the last weeks we gave the weld team some hints how they can tweak the performance of their scopes. as you can see in the following benchmark, they improved the performance of std. scopes in weld a lot. the performance of the std. scopes is now pretty much the same as with owb. all differences are within the tolerance. however, the owb team (special thx to mark) is again one step ahead. the next release of owb (v1.1.1) will allow to use a very fast instance cache for custom scopes. based on this feature, i implemented the scope-boost add-on for codi. the result/s you can see in the chart: codi scopes are as fast as the request scope of owb. a nice detail about that: since owb v1.1.1 is faster than v1.1.0, codi scopes (+ add-on) in combination with owb v1.1.1 are faster than the (already very fast) request scope of owb v1.1.0 (you might remember the awesome results of the previous benchmarks).

as you know the results depend on a lot of parameters. anyway, the following charts should give you a basic impression about the difference. on my system i can reproduce the overall results (tolerance: <0,25ms). all application servers were started without changes in the configuration. for producing the other results i used again tomcat v7.0.19. in this benchmark the servers aren't that important, because there is no class of those servers between the method call and the final method of the bean (just the proxies used by the cdi implementation). that means jboss as7 as well as glassfish v3 are just slower because they don't ship the latest version of weld. for sure - if you upgrade your server, you will get a better performance with those servers.

the result:
as mentioned before std. scopes in weld (the currently latest release) and owb have about the same performance. in case of custom scopes owb can be way faster in combination with special add-ons for the corresponding custom scopes. the add-ons are needed to reset the cached instances, if the scope ends before the request ends. in case of codi you still have all advantages of codi-scopes as well as the performance of the request scope. that's possible due to the awesome concepts in owb as well as the UnscopeBeanEvent of codi. (please notice that weld v1.1.2 which is called "standalone" in this chart is a newer version compared to weld v1.1.2 shipped with jboss as7 out-of-the-box. the newer version already has the performance improvements mentioned before. that's the reason for the difference (and it isn't related to jboss as7))

(the lower - the better)

for this benchmark i used the simple benchmark which i used for my first post (as well as the same steps to measure the performance). in the previous benchmark i switched to jmeter because users were interested in the overall impact. this time i (again) used the simpler version because of some fluctuations with jmeter tests. besides the typical parameters which can influence the results, load tests are less reproducible e.g. because of several features of modern cpus. however, the previous posts are still valid. after publishing them i re-tested the benchmarks with different systems as well as different jdk implementations, operating systems,... . for sure the results differed a bit, but the overall result was more or less the same (esp. the ranking). however, as mentioned in the previous posts as well as in this post, these benchmarks should give you a basic impression. you might see a bit different results on your system, but the overall result is usually the same - esp. the basic messages illustrated by this benchmark:

- owb is innovative, pluggable and fast
- owb + codi == just awesome
- weld got a lot faster in the latest release
- servers which bundle old versions of weld are slower because they depend on the performance of those versions -> update the versions as soon as you can and you will increase the performance of your applications deployed to those servers for free!