RE: Entity creation at Runtime
You can use Serp -- a bytecode manipulation library -- (http://serp.sourceforge.net/). OpenJPA itself uses it to enhance class files. To enhance the dynamically defined class and register it to OpenJPA persistence unit requires few considerations. The attached example demonstrates these steps with a simple example that a) defines a class dynamically b) enhances c) defines database mapping for it d) pouplates instance of the defined class and finally persists it. Pinaki Poddar BEA Systems 415.402.7317 -Original Message- From: James Hang [mailto:[EMAIL PROTECTED] Sent: Monday, May 14, 2007 1:18 PM To: open-jpa-dev@incubator.apache.org Subject: RE: Entity creation at Runtime Thanks for the reply Marc. Is there a third party tool that can generate classes with annotations? Or is there something in OpenJPA that can do that? I noticed a CodeGenerator class that can generate classes from metadata. Can I use that? I'll take a look at the PCClassFileTransformer class like you suggested. Thanks for your help! James -Original Message- From: Marc Prud'hommeaux [mailto:[EMAIL PROTECTED] On Behalf Of Marc Prud'hommeaux Sent: Monday, May 14, 2007 10:30 AM To: open-jpa-dev@incubator.apache.org Subject: Re: Entity creation at Runtime James- It should be possible. The easiest way (and the most implementation- agnostic) would be to simply generate the classes with the appropriate mapping annotations, and then just load them at runtime. The somewhat tricky part would be to ensure they get enhanced by the system when they are loaded. You could just run the - javaagent:openjpa.jar flag with no arguments, and I believe it will scan all loaded classes for annotations, but that can slow things down quite a bit. A faster solution would be to run your generated classes through the enhancer. Take a look at the code for org.apache.openjpa.enhance.PCClassFileTransformer ... if you can't use that directly, then it might be good to use as a starting point. On May 14, 2007, at 10:00 AM, James Hang wrote: > Hi, > > I'm curious if it's possible to create and map new entities at > Runtime? > We have an application which allows users to design new data models at > runtime. When new tables are being created in the database, we would > like to make OpenJPA aware of them. We are currently doing this in > Hibernate by generating the POJO classes dynamically using CGLIB, > adding dynamically generated xml mappings to the Hibernate runtime > configuration and re-initializing the SessionFactory. Is there a way > to do something similar in OpenJPA? > > Thanks, > > James > > > Notice: This email message, together with any attachments, may > contain information of BEA Systems, Inc., its subsidiaries > and affiliated entities, that may be confidential, proprietary, > copyrighted and/or legally privileged, and is intended solely for the > use of the individual or entity named in this message. If you are not > the intended recipient, and have received this message in error, > please immediately return this by email and then delete it. Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
Re: Entity creation at Runtime
Also, depending on how you have things configured, OpenJPA can lazily discover classes for a given EntityManager. So, you shouldn't necessarily need to re-initialize / reload anything in particular. -Patrick On 5/14/07, Marc Prud'hommeaux <[EMAIL PROTECTED]> wrote: James- The CodeGenerator just generates .java file, so I don't think it will be useful for your purposes. Well, I suspect that if if you are currently generating classes using CGLIB, then the easiest thing would be to just use CGLIB to add the annotations as well. Alternately, you could instead generate a separate orm.xml mapping file conforming to the JPA specification, which would allow you to define the mappings separately. On May 14, 2007, at 11:18 AM, James Hang wrote: > Thanks for the reply Marc. > > Is there a third party tool that can generate classes with > annotations? > Or is there something in OpenJPA that can do that? I noticed a > CodeGenerator class that can generate classes from metadata. Can I > use > that? > > I'll take a look at the PCClassFileTransformer class like you > suggested. > > Thanks for your help! > > James > > > > -Original Message- > From: Marc Prud'hommeaux [mailto:[EMAIL PROTECTED] On > Behalf Of > Marc Prud'hommeaux > Sent: Monday, May 14, 2007 10:30 AM > To: open-jpa-dev@incubator.apache.org > Subject: Re: Entity creation at Runtime > > James- > > It should be possible. The easiest way (and the most implementation- > agnostic) would be to simply generate the classes with the > appropriate mapping annotations, and then just load them at runtime. > > The somewhat tricky part would be to ensure they get enhanced by the > system when they are loaded. You could just run the - > javaagent:openjpa.jar flag with no arguments, and I believe it will > scan all loaded classes for annotations, but that can slow things > down quite a bit. A faster solution would be to run your generated > classes through the enhancer. > > Take a look at the code for > org.apache.openjpa.enhance.PCClassFileTransformer ... if you can't > use that directly, then it might be good to use as a starting point. > > > > On May 14, 2007, at 10:00 AM, James Hang wrote: > >> Hi, >> >> I'm curious if it's possible to create and map new entities at >> Runtime? >> We have an application which allows users to design new data >> models at >> runtime. When new tables are being created in the database, we would >> like to make OpenJPA aware of them. We are currently doing this in >> Hibernate by generating the POJO classes dynamically using CGLIB, >> adding >> dynamically generated xml mappings to the Hibernate runtime >> configuration and re-initializing the SessionFactory. Is there a >> way to >> do something similar in OpenJPA? >> >> Thanks, >> >> James >> >> >> Notice: This email message, together with any attachments, may >> contain information of BEA Systems, Inc., its subsidiaries >> and affiliated entities, that may be confidential, proprietary, >> copyrighted and/or legally privileged, and is intended solely for >> the use of the individual or entity named in this message. If you >> are not the intended recipient, and have received this message in >> error, please immediately return this by email and then delete it. > > > Notice: This email message, together with any attachments, may > contain information of BEA Systems, Inc., its subsidiaries > and affiliated entities, that may be confidential, proprietary, > copyrighted and/or legally privileged, and is intended solely for > the use of the individual or entity named in this message. If you > are not the intended recipient, and have received this message in > error, please immediately return this by email and then delete it. -- Patrick Linskey 202 669 5907
Re: Entity creation at Runtime
James- The CodeGenerator just generates .java file, so I don't think it will be useful for your purposes. Well, I suspect that if if you are currently generating classes using CGLIB, then the easiest thing would be to just use CGLIB to add the annotations as well. Alternately, you could instead generate a separate orm.xml mapping file conforming to the JPA specification, which would allow you to define the mappings separately. On May 14, 2007, at 11:18 AM, James Hang wrote: Thanks for the reply Marc. Is there a third party tool that can generate classes with annotations? Or is there something in OpenJPA that can do that? I noticed a CodeGenerator class that can generate classes from metadata. Can I use that? I'll take a look at the PCClassFileTransformer class like you suggested. Thanks for your help! James -Original Message- From: Marc Prud'hommeaux [mailto:[EMAIL PROTECTED] On Behalf Of Marc Prud'hommeaux Sent: Monday, May 14, 2007 10:30 AM To: open-jpa-dev@incubator.apache.org Subject: Re: Entity creation at Runtime James- It should be possible. The easiest way (and the most implementation- agnostic) would be to simply generate the classes with the appropriate mapping annotations, and then just load them at runtime. The somewhat tricky part would be to ensure they get enhanced by the system when they are loaded. You could just run the - javaagent:openjpa.jar flag with no arguments, and I believe it will scan all loaded classes for annotations, but that can slow things down quite a bit. A faster solution would be to run your generated classes through the enhancer. Take a look at the code for org.apache.openjpa.enhance.PCClassFileTransformer ... if you can't use that directly, then it might be good to use as a starting point. On May 14, 2007, at 10:00 AM, James Hang wrote: Hi, I'm curious if it's possible to create and map new entities at Runtime? We have an application which allows users to design new data models at runtime. When new tables are being created in the database, we would like to make OpenJPA aware of them. We are currently doing this in Hibernate by generating the POJO classes dynamically using CGLIB, adding dynamically generated xml mappings to the Hibernate runtime configuration and re-initializing the SessionFactory. Is there a way to do something similar in OpenJPA? Thanks, James Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
RE: Entity creation at Runtime
Thanks for the reply Marc. Is there a third party tool that can generate classes with annotations? Or is there something in OpenJPA that can do that? I noticed a CodeGenerator class that can generate classes from metadata. Can I use that? I'll take a look at the PCClassFileTransformer class like you suggested. Thanks for your help! James -Original Message- From: Marc Prud'hommeaux [mailto:[EMAIL PROTECTED] On Behalf Of Marc Prud'hommeaux Sent: Monday, May 14, 2007 10:30 AM To: open-jpa-dev@incubator.apache.org Subject: Re: Entity creation at Runtime James- It should be possible. The easiest way (and the most implementation- agnostic) would be to simply generate the classes with the appropriate mapping annotations, and then just load them at runtime. The somewhat tricky part would be to ensure they get enhanced by the system when they are loaded. You could just run the - javaagent:openjpa.jar flag with no arguments, and I believe it will scan all loaded classes for annotations, but that can slow things down quite a bit. A faster solution would be to run your generated classes through the enhancer. Take a look at the code for org.apache.openjpa.enhance.PCClassFileTransformer ... if you can't use that directly, then it might be good to use as a starting point. On May 14, 2007, at 10:00 AM, James Hang wrote: > Hi, > > I'm curious if it's possible to create and map new entities at > Runtime? > We have an application which allows users to design new data models at > runtime. When new tables are being created in the database, we would > like to make OpenJPA aware of them. We are currently doing this in > Hibernate by generating the POJO classes dynamically using CGLIB, > adding > dynamically generated xml mappings to the Hibernate runtime > configuration and re-initializing the SessionFactory. Is there a > way to > do something similar in OpenJPA? > > Thanks, > > James > > > Notice: This email message, together with any attachments, may > contain information of BEA Systems, Inc., its subsidiaries > and affiliated entities, that may be confidential, proprietary, > copyrighted and/or legally privileged, and is intended solely for > the use of the individual or entity named in this message. If you > are not the intended recipient, and have received this message in > error, please immediately return this by email and then delete it. Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
Re: Entity creation at Runtime
James- It should be possible. The easiest way (and the most implementation- agnostic) would be to simply generate the classes with the appropriate mapping annotations, and then just load them at runtime. The somewhat tricky part would be to ensure they get enhanced by the system when they are loaded. You could just run the - javaagent:openjpa.jar flag with no arguments, and I believe it will scan all loaded classes for annotations, but that can slow things down quite a bit. A faster solution would be to run your generated classes through the enhancer. Take a look at the code for org.apache.openjpa.enhance.PCClassFileTransformer ... if you can't use that directly, then it might be good to use as a starting point. On May 14, 2007, at 10:00 AM, James Hang wrote: Hi, I'm curious if it's possible to create and map new entities at Runtime? We have an application which allows users to design new data models at runtime. When new tables are being created in the database, we would like to make OpenJPA aware of them. We are currently doing this in Hibernate by generating the POJO classes dynamically using CGLIB, adding dynamically generated xml mappings to the Hibernate runtime configuration and re-initializing the SessionFactory. Is there a way to do something similar in OpenJPA? Thanks, James Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
