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Java Forum / JavaBeans / January 2004EJB CMP : generating an ID
Hello everybody, I would like to create a custom number identifier for a CMP bean. I would like just work with a sequencial number begining to 1 an step by 1. How can I do implement that ? I would like also when the EJB server crashes, thant this sequence is automoticaly set to the max number + 1. Thanks everybody > I would like to create a custom number identifier for a CMP bean. I would > like just work with a sequencial number begining to 1 an step by 1. Many times you can do this in the database itself. (MySQL: AUTO_INCREMENT; PostgreSQL: serial) Which database are you using? I'm using a MySQL DataBase at this time. And how can I get the id generated by the database for the current bean. Thanks Bernard > > I would like to create a custom number identifier for a CMP bean. I would > > like just work with a sequencial number begining to 1 an step by 1. > > Many times you can do this in the database itself. (MySQL: > AUTO_INCREMENT; PostgreSQL: serial) Which database are you using? > I'm using a MySQL DataBase at this time. > And how can I get the id generated by the database for the current bean. I don't remember if you're using JBoss.... I am and the trick with it is to use an entity-command. If you look in standardjbosscmp-jdbc.xml, there's something defined as "mysql-get-generated-keys". (I'm using the equivalent PostgreSQL version at the moment.) I assume other servers have other ways of dealing with it. Thank you ! Yes I use the jBoss Server ... I'm going to try your solution. And I repost a message if I have any other problems Bernard > > I'm using a MySQL DataBase at this time. > > And how can I get the id generated by the database for the current bean. [quoted text clipped - 5 lines] > > I assume other servers have other ways of dealing with it. Hello, And how can I do if I prefer to stay independent from the platform server ? Bernard > > I'm using a MySQL DataBase at this time. > > And how can I get the id generated by the database for the current bean. [quoted text clipped - 5 lines] > > I assume other servers have other ways of dealing with it. > And how can I do if I prefer to stay independent from the platform server ? > > Bernard I don't know if it is a MUST for your project to have numeric ids. If you can use strings, look at these resources: http://www.google.com/search?q=java+UUID+generation Bye, Jens -- Jens Kutschke http://www.j-dimension.com It's a very long key ... I prefere to use an Integer or a Double field into my database. Bernard > > And how can I do if I prefer to stay independent from the platform server > ? [quoted text clipped - 12 lines] > Jens Kutschke > http://www.j-dimension.com > And how can I do if I prefer to stay independent from the platform server ? Well, you could create the number as a field in some table, load it at startup into an application-scope bean and have a single instance of that bean manage the number. (If you're worried about crashes, you could validate it at startup as well.) If you can get away with non-sequential numbers, you can base your key on a startup timestamp and then you don't have to worry about validations after crashes. But, part of the logic for having deployment descriptors is to allow deployment variables to change. If you are using any files called jboss*.xml, then you're already not completely independent from the server. Please, Could you send me a sample code to illustrate the first method, including the ejb-jar, ... needed ? Thank you very much Bernard > > And how can I do if I prefer to stay independent from the platform server ? > [quoted text clipped - 11 lines] > jboss*.xml, then you're already not completely independent from the > server. Hi everbody, It's possible to have some code to illustarte your solutions ? Thank you all Bernard Koninckx > Hello everybody, > [quoted text clipped - 5 lines] > > Thanks everybody Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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