ejb-ql
When will Orion have full-support for ejb-ql? It would be nice to specify the finder-queries by ejb-ql instead of specifying the queries in orion-ejb-jar.xml System Developer Michael Østergård Jensen CIM Industrial Systems A/S Kildegården 3 DK-7600 Struer Denmark Phone +45 96 84 05 00 Mobile +45 61 39 31 19 Fax +45 97 84 10 11 mailto:[EMAIL PROTECTED] http://www.cim.as
Entity relationship and EJB QL thoughts
Hi, I'm a bit disappointed about Entity relationships and EJBQL. What used to seem to be simple, now it is a nightmare. How can I achieve lazy loading of related EBs in Orion? For instance, there's an EB (EB1) that has 1..N relationship to another (EB2). If I lookup an instance of EB1 do all the related instances of EB2 load at the same time, even if I do not need to access them? A bit off-topic (as EJB QL is not available in Orion so it is impossible to develop something general, really portable), but I'm curious about the issue: Do you think that Entity relationships and EJB QL could be as optimized as smart finder methods? I wish I could supply finders with SQL SELECTs... Unfortunately, you have the drawback of EJBQL that you're limited to refer to EBs (abstract schemas). So, a more complex case: I have to model the following situation: M..N relationship between Users and Countries. Each country belongs to one region (region id is a column in the country table). I have to lookup those countries that belong to the regions of the countries mapped to a user. So it's not only a simple relationship between users and countries, but I'd need a countr-country 1..N relationship over the region id. Therefore the EJB QL would look like this for a finder method: SELECT OBJECT(rc) FROM User AS u, IN(u.countries) c, IN(c.regionCountries) rc WHERE u.userID = ?1 With one smart SQL SELECT it would be possible to retrieve the result set but how will servers manage the above situation? regards, please give me a hint with the first Orion-specific question, thanks, Tibor
Orion and EJB2.0 (EJB QL)
Hi, currently I have to decide wich way to go with a new EJB Project. We need some App-Server independance so we have to decide if we should use CMP with the EJB2.0 Relationships and QL or BMP with our own SQL-Statements. Is there any information available when Orion will support EJB2.0 and EJB QL (Query language)? I can also use a Beta Release for the next 3 Months so I'm not sticked on official Releases. Regards Stefan
RE: Orion and EJB2.0 (EJB QL)
Is there any information available when Orion will support EJB2.0 and EJB QL My thoughts on CMP vs BMP: On my project I went with BMP + DAO patterns + business deligates at the client tier that deligate reads to the much more efficient DAO's (direct access to the DB) and updates to transactional components (entities mediated by session beans). With CMP you don't have the higher performance choice at the client business deligate level to go directly to the DB via DAO's, all reads have to go through the transactional tier (for no good reason except to boost the stock of your appserver and hardware vendors). My personal opinion about CMP, that I'd like to hear other's experience on is that you'll spend almost as much time developing and debugging QL as you would DAO+SQL. You'll loose the much higher performance direct access to the DB for read operations. Given that most web site pages are doing read, (display of catalogue pages) use of CMP for reads through entities makes no sense unless a slow web site is desired. Any thoughts? thanks, curt
Re: EJB-QL in 1.4.7
No. --On Monday, February 12, 2001 11:02 PM -0600 Christian Billen [EMAIL PROTECTED] wrote: Is there any implementation of EJB-QL at this time in the 1.4.7 code? Thanks, Christian
EJB-QL Support
It doesn't look like Orion 1.3.8 supports EJB-QL. If true, are there any plans to make this available? When? = __ 5.5 cents calls with 6-second billing no fees. Free toll-fre numbers. No other charges 4 cents Domestic calls with no fees: 5 cents per minute International calls also available http://globetrot.hypermart.net e-mail: [EMAIL PROTECTED] __ __ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/
Re: EJB QL and container managed relationships
Hello Jeff, EJB QL is not supported yet, the EJB 2.0 PD support is just partial so far. When EJB QL is available we will announce it. Regards, Karl Avedal Jeff Schnitzer wrote: Hello folks. Once again I have some questions, this time about EJB QL. The quick version is: How sophisticated is the current Orion support for EJB QL? I want to define a finder query on a field which is the mapping field of a CMR relationship, but it doesn't seem to work. Here's the long version: I'm using EJB 2.0 CMR fields to map a relationship between two entity beans, called Member and MemberName. The primary key for the MemberName is (not surprisingly) a string, and every Member has a MemberName as defined by the following relation: ejb-relation ejb-relation-name Member-canonical-MemberName /ejb-relation-name description This is a unidirectional one-to-one mapping from Member to MemberName. Members have a single canonical MemberName. /description ejb-relationship-role ejb-relationship-role-name Member-has-canonical-MemberName /ejb-relationship-role-name multiplicity one /multiplicity role-source ejb-name MemberEJB /ejb-name /role-source cmr-field cmr-field-name memberName /cmr-field-name /cmr-field /ejb-relationship-role ejb-relationship-role ejb-relationship-role-name MemberName-is-canonical-for-Member /ejb-relationship-role-name multiplicity one /multiplicity role-source ejb-name MemberNameEJB /ejb-name /role-source /ejb-relationship-role /ejb-relation Just a quick side-note, which I think was brought up before: the EJB2.0 spec (pd2) seems to indicate that the cmr-fields should _not_ also be defined as cmp-fields in the entity descriptor. Orion 1.3.8 seems to require this. In any case... The table which is created for Member has the memberName field which is of course a string (the MemberName's primary key). Good. Now I want a finder method on MemberHome which is public Member findByName(String name); I can imagine two ways of going about this. The simple one would be to pretend that Member's memberName is a cmp-field. The query would be: query query-method method-name ejbFindByName /method-name method-params method-param java.lang.String /method-param /method-params /query-method ejb-ql FROM MemberEJB memb WHERE memb.memberName = ?1 /ejb-ql /query While this works for actual cmp-fields, this does not seem to work for cmr-fields. Not surprising, since the spec doesn't mention this as an option (although it doesn't eliminate it, either). The "proper" way to write the query, if I'm reading the spec right, is: query query-method method-name ejbFindByName /method-name method-params method-param java.lang.String /method-param /method-params /query-method ejb-ql FROM MemberEJB memb, n IN memb.memberName WHERE n.name = ?1 /ejb-ql /query But I'm not wholly certain, because all the relational EJB QL examples in the spec are for one-to-many relationships, not one-to-one. In any case, when I try this, I get the same results that I do for the first query, which is to say wholly incorrect results :-) The failure mode is bad, too; rather than failing to find the Member, it seems to just return a random existing Member. So am I just pushing the edge of Orion's implementation of the EJB2.0 spec, or am I defining my queries wrong? If this is heading into unimplemented space, should I log bugs in Bugzilla or just assume that the authors are busily working on this very problem and don't need yet another monkey on their backs? :-) Is anyone else working with EJB2.0 beans? Thanks, Jeff Schnitzer [EMAIL PROTECTED] mailto:[EMAIL PROTECTED]
EJB QL and container managed relationships
Hello folks. Once again I have some questions, this time about EJB QL. The quick version is: How sophisticated is the current Orion support for EJB QL? I want to define a finder query on a field which is the mapping field of a CMR relationship, but it doesn't seem to work. Here's the long version: I'm using EJB 2.0 CMR fields to map a relationship between two entity beans, called Member and MemberName. The primary key for the MemberName is (not surprisingly) a string, and every Member has a MemberName as defined by the following relation: ejb-relation ejb-relation-name Member-canonical-MemberName /ejb-relation-name description This is a unidirectional one-to-one mapping from Member to MemberName. Members have a single canonical MemberName. /description ejb-relationship-role ejb-relationship-role-name Member-has-canonical-MemberName /ejb-relationship-role-name multiplicity one /multiplicity role-source ejb-name MemberEJB /ejb-name /role-source cmr-field cmr-field-name memberName /cmr-field-name /cmr-field /ejb-relationship-role ejb-relationship-role ejb-relationship-role-name MemberName-is-canonical-for-Member /ejb-relationship-role-name multiplicity one /multiplicity role-source ejb-name MemberNameEJB /ejb-name /role-source /ejb-relationship-role /ejb-relation Just a quick side-note, which I think was brought up before: the EJB2.0 spec (pd2) seems to indicate that the cmr-fields should _not_ also be defined as cmp-fields in the entity descriptor. Orion 1.3.8 seems to require this. In any case... The table which is created for Member has the memberName field which is of course a string (the MemberName's primary key). Good. Now I want a finder method on MemberHome which is public Member findByName(String name); I can imagine two ways of going about this. The simple one would be to pretend that Member's memberName is a cmp-field. The query would be: query query-method method-name ejbFindByName /method-name method-params method-param java.lang.String /method-param /method-params /query-method ejb-ql FROM MemberEJB memb WHERE memb.memberName = ?1 /ejb-ql /query While this works for actual cmp-fields, this does not seem to work for cmr-fields. Not surprising, since the spec doesn't mention this as an option (although it doesn't eliminate it, either). The "proper" way to write the query, if I'm reading the spec right, is: query query-method method-name ejbFindByName /method-name method-params method-param java.lang.String /method-param /method-params /query-method ejb-ql FROM MemberEJB memb, n IN memb.memberName WHERE n.name = ?1 /ejb-ql /query But I'm not wholly certain, because all the relational EJB QL examples in the spec are for one-to-many relationships, not one-to-one. In any case, when I try this, I get the same results that I do for the first query, which is to say wholly incorrect results :-) The failure mode is bad, too; rather than failing to find the Member, it seems to just return a random existing Member. So am I just pushing the edge of Orion's implementation of the EJB2.0 spec, or am I defining my queries wrong? If this is heading into unimplemented space, should I log bugs in Bugzilla or just assume that the authors are busily working on this very problem and don't need yet another monkey on their backs? :-) Is anyone else working with EJB2.0 beans? Thanks, Jeff Schnitzer [EMAIL PROTECTED] mailto:[EMAIL PROTECTED]
EJB QL support
Is there any in the current (1.3.8) server? john d
