Why not to use stateful EJBs as data caches: http://www.onjava.com/pub/a/onjava/2001/10/02/ejb.html
--- Tim Fox <[EMAIL PROTECTED]> wrote: > c below > > > -----Original Message----- > > From: Evan Ireland [mailto:[EMAIL PROTECTED]] > > Sent: 24 October 2001 21:28 > > To: Tim Fox > > Cc: [EMAIL PROTECTED] > > Subject: Re: Server-side data caching > > > > > > Tim Fox wrote: > > > > > This may work in practice - specifically (and > probably only if) > > your ejbs > > > are all running in the same JVM. > > > This will probably be true in most cases - but > there is nothing > > in the spec. > > > that prevents an EJB server from using multiple > JVMS, or even clustering > > > across multiple machines - in those cases you > are going to have problems > > > with this approach. > > > > > > What would be the problem with having multiple > copies of the cache? > > If your data is read-only then nothing. > > If you're writing to the table too - then you have > the classic dirty cache > problem - you'll need to ensure cache consistency by > some means. > (Multi-casting your changes or whatever). > > So basically I'd use this technique if the data is > invariant/ref data (like > US states), but not in the general case. > > > > > >>-----Original Message----- > > >>From: A mailing list for Enterprise JavaBeans > development > > >>[mailto:[EMAIL PROTECTED]]On Behalf Of > Victor Langelo > > >>Sent: 23 October 2001 21:10 > > >>To: [EMAIL PROTECTED] > > >>Subject: Re: Server-side data caching > > >> > > >> > > >>Ken, > > >> > > >>Assuming this is read only data, I would use a > stateless session > > >>bean that loaded > > >>that table and saved it in a static collection. > I know that > > >>static attributes are > > >>supposed to be final, but I cannot see nor have > I experienced any > > >>problem using this > > >>technique. Read the table whenever the attribute > is null (or an > > >>empty collection if > > >>you initialize it). That way you won't need a > static initializer > > >>which might cause > > >>problems in some servers. > > >> > > >>You can follow the letter of the spec by > declaring the attribute as: > > >> > > >>final static List usStates = new ArrayList(); > > >> > > >>--Victor > > >> > > >> > > >>"Kenneth D. Litwak" wrote: > > >> > > >> > > >>> If I wanted to have the equivalent of a whole > table of data, > > >>> > > >>liek the names of > > >> > > >>>U.S. states, cached in a J2EE application, > liike in the EJB > > >>> > > >>container, and I > > >> > > >>>wanted this data available to every EJB that > wanted it, what > > >>> > > >>would be a good > > >> > > >>>design approach? A plain Java object > implemented as a > > >>> > > >>SIngleton? A stateful > > >> > > >>>session bean with ahandle taht any caller could > lookup and use? > > >>> > > >>If the latter, > > >> > > >>>how would you get around the restriction > against multiple > > >>> > > >>callers on an EJB? > > >> > > >>>Thanks. > > >>> > > >>> Ken > > >>> > > >>> > > > >>================================================================== > > >>========= > > >>To unsubscribe, send email to > [EMAIL PROTECTED] and include > > >>in the body > > >>of the message "signoff EJB-INTEREST". For > general help, send email to > > >>[EMAIL PROTECTED] and include in the body of > the message "help". > > >> > > >> > > > > > > > > > ================================================================== > > ========= > > > To unsubscribe, send email to > [EMAIL PROTECTED] and include > > in the body > > > of the message "signoff EJB-INTEREST". For > general help, send email to > > > [EMAIL PROTECTED] and include in the body of > the message "help". > > > > > > > > > > > > > > > > > > =========================================================================== > To unsubscribe, send email to [EMAIL PROTECTED] > and include in the body > of the message "signoff EJB-INTEREST". For general > help, send email to > [EMAIL PROTECTED] and include in the body of the > message "help". > ===== Nicholas Whitehead Home: (973) 377 9335 Cell: (973) 615 9646 Work(@ JP Morgan): (212) 235 5783 [EMAIL PROTECTED] __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. http://personals.yahoo.com =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff EJB-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
