how to prevent multi-access

[john_woo]

Hi,

I'm thinking of, let's say when caller A reading data via ejb3, and caller B updates same record, then A wants to update, how can we inform A that the record has just been updated?

Can we

1. in ejb xml descriptor file, for somehow specify the transaction level, allowing like non-repeatable read;

2. in coding, for somehow
get cachedRowSet

3. using annotation....

Can anyone have idea?

Thanks
John

[wolfc]

Use the @Version annotation, see EJB 3 Persistence 9.1.17.

@Version
@Column(name="OPTLOCK")
protected int getVersionNum() { return versionNum; }

[john_woo]

"wolfc" wrote:
Use the @Version annotation, see EJB 3 Persistence 9.1.17.

@Version
@Column(name="OPTLOCK")
protected int getVersionNum() { return versionNum; }

Thanks for the reply. but where is the document?

further question:
what's the mechanism using @version? I meant we don't have to do it that way, ex. we can use like timestamp field, and treat that field as just regular field, before modifying a record, simply compare the timestamp values.

John

[wolfc]

http://jcp.org/en/jsr/detail?id=220

The mechanism is explained in EJB 3 Persistence 3.4.