Re: Some continuum-jpa branch updates
Its seems TopLink can do Criteria Queries (using Expressions and ExpressionBuilders, correct me if I am wrong). It seems quite a few JPA implementations provide some sort of Criteria Query API extension. Hibernate does that too ! Damien
Re: Some continuum-jpa branch updates
I would have liked this thread to merge with Continuum 2.0 discussion thread, but anyway... Its seems TopLink can do Criteria Queries (using Expressions and ExpressionBuilders, correct me if I am wrong). It seems quite a few JPA implementations provide some sort of Criteria Query API extension. And from what I gather online, its quite likely that JPA 2.0 would standardize a Criteria API. So, no more performance overhead of String concatenations ;-) Rahul Christian Edward Gruber wrote: You can still use parameterized queries dynamically, you just use strings that contain ? and they get turned into pre-compiled queries in the db. However, named queries can be further optimized by Hibernate before it even gets to the db (pre-compiling at load, etc.) Criteria queries are the other way to go. They're programmatically constructed and they can get a lot of the jdbc benefits of named queries. Christian. On 21-Jan-08, at 16:59 , Emmanuel Venisse wrote: As Christian said, named queries are pre-compiled to SQL. With dynamic queries, perf can be not good because for each execution, the JPQL request is recompile to SQL, so parsing, creation of the JPQL tree then SQL generation, and with your solution, you concatenate lot of String. It isn't important for one request but with lot of request, you use more time and cpu, for string concatenation, it is better to use StringBuilder that is more performant than String addition or StringBuffer. An other argument for named queries is that with dynamic queries, if they aren't written correctly (it isn't the case for your code ;) ), it is easy to introduce some malicious SQL code with parameters my two cents. Emmanuel On Jan 18, 2008 9:57 PM, Christian Edward Gruber [EMAIL PROTECTED] wrote: You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep the core Store interface lean and mean (read extensible). The
Re: Some continuum-jpa branch updates
Nice! On 6-Feb-08, at 00:31 , Rahul Thakur wrote: I would have liked this thread to merge with Continuum 2.0 discussion thread, but anyway... Its seems TopLink can do Criteria Queries (using Expressions and ExpressionBuilders, correct me if I am wrong). It seems quite a few JPA implementations provide some sort of Criteria Query API extension. And from what I gather online, its quite likely that JPA 2.0 would standardize a Criteria API. So, no more performance overhead of String concatenations ;-) Rahul
Re: Some continuum-jpa branch updates
On Jan 22, 2008 3:06 AM, Rahul Thakur [EMAIL PROTECTED] wrote: A Query object that wraps up criteria and is built programmatically affords us the ability to keep Store APIs lean and stable. That is the motivation behind building up queries programatically. IMHO, the current ContinuumStore is a bunch of methods that don't even vary that much underneath. I think the same can be easily achieved by using Query. With named queries, queries are cached in the persistence context so they don't need to be parsed each time. With named queries, an other good thing is that they can be overriden in the xml file if needed for performance for a specific DB and we can add query hints. The last thing is that with named queries, we know exactly which requests we execute so we can optimize the DB schema with some index, it isn't easy to do with dynamic queries. I don't say we won't use dynamic queries but only that it must be the majority of our requests and it's a JPA best practices. I am not sure if StringBuilder will be more performant than StringBuffer when you are concatenating only a few Strings. I think what is more important is a goal of a lean, test'able and clean API. It isn't important for a concatenation of few strings, but in your code, you do it in the Query generator. The concatenation will executed a lot because we execute lot of requests in all pages, so the benefit of StringBuilder is very important. I can't really comment on named queries (probably need to toy around with them a bit), and not sure how the implementation would end up making use of named queries, but if anyone else has any opinions, I am keen to understand. Cheers, Rahul Emmanuel Venisse wrote: As Christian said, named queries are pre-compiled to SQL. With dynamic queries, perf can be not good because for each execution, the JPQL request is recompile to SQL, so parsing, creation of the JPQL tree then SQL generation, and with your solution, you concatenate lot of String. It isn't important for one request but with lot of request, you use more time and cpu, for string concatenation, it is better to use StringBuilder that is more performant than String addition or StringBuffer. An other argument for named queries is that with dynamic queries, if they aren't written correctly (it isn't the case for your code ;) ), it is easy to introduce some malicious SQL code with parameters my two cents. Emmanuel On Jan 18, 2008 9:57 PM, Christian Edward Gruber[EMAIL PROTECTED] wrote: You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering
Re: Some continuum-jpa branch updates
As Christian said, named queries are pre-compiled to SQL. With dynamic queries, perf can be not good because for each execution, the JPQL request is recompile to SQL, so parsing, creation of the JPQL tree then SQL generation, and with your solution, you concatenate lot of String. It isn't important for one request but with lot of request, you use more time and cpu, for string concatenation, it is better to use StringBuilder that is more performant than String addition or StringBuffer. An other argument for named queries is that with dynamic queries, if they aren't written correctly (it isn't the case for your code ;) ), it is easy to introduce some malicious SQL code with parameters my two cents. Emmanuel On Jan 18, 2008 9:57 PM, Christian Edward Gruber [EMAIL PROTECTED] wrote: You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep the core Store interface lean and mean (read extensible). The Store interface[3] now has 4 methods: lookup() save() delete() query() The lookup(), save() and delete() act on single model Entity, while query() will filter and obtain matching Entities from the underlying database based on the Query specified. Query implementations control how a resulting JPQL gets constructed and which matching entities get pulled, and can be easily extended. To preserve compatibility with the existing Store interface, we can mimick the existing ContinuumStore interface operations by having a facade that can prepare requisite queries and delegate to a Store instance. 3) Misc. There are a few I am investigating: 1) Spring/Guice under the hood. 2) JUnit 4.4 (and Hamcrest library) , but these are still in early stages. I am keen to get a feedback on
Re: Some continuum-jpa branch updates
I think it would be good to introduce some partial object like ProjectGroupWithoutProjects that we can use in JPQL request so we won't use non detached fields and we'll know exactly what we use and where. Emmanuel On Jan 21, 2008 10:59 PM, Emmanuel Venisse [EMAIL PROTECTED] wrote: As Christian said, named queries are pre-compiled to SQL. With dynamic queries, perf can be not good because for each execution, the JPQL request is recompile to SQL, so parsing, creation of the JPQL tree then SQL generation, and with your solution, you concatenate lot of String. It isn't important for one request but with lot of request, you use more time and cpu, for string concatenation, it is better to use StringBuilder that is more performant than String addition or StringBuffer. An other argument for named queries is that with dynamic queries, if they aren't written correctly (it isn't the case for your code ;) ), it is easy to introduce some malicious SQL code with parameters my two cents. Emmanuel On Jan 18, 2008 9:57 PM, Christian Edward Gruber [EMAIL PROTECTED] wrote: You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep the core Store interface lean and mean (read extensible). The Store interface[3] now has 4 methods: lookup() save() delete() query() The lookup(), save() and delete() act on single model Entity, while query() will filter and obtain matching Entities from the underlying database based on the Query specified. Query implementations control how a resulting JPQL gets constructed and which matching entities get pulled, and can be easily extended.
Re: Some continuum-jpa branch updates
You can still use parameterized queries dynamically, you just use strings that contain ? and they get turned into pre-compiled queries in the db. However, named queries can be further optimized by Hibernate before it even gets to the db (pre-compiling at load, etc.) Criteria queries are the other way to go. They're programmatically constructed and they can get a lot of the jdbc benefits of named queries. Christian. On 21-Jan-08, at 16:59 , Emmanuel Venisse wrote: As Christian said, named queries are pre-compiled to SQL. With dynamic queries, perf can be not good because for each execution, the JPQL request is recompile to SQL, so parsing, creation of the JPQL tree then SQL generation, and with your solution, you concatenate lot of String. It isn't important for one request but with lot of request, you use more time and cpu, for string concatenation, it is better to use StringBuilder that is more performant than String addition or StringBuffer. An other argument for named queries is that with dynamic queries, if they aren't written correctly (it isn't the case for your code ;) ), it is easy to introduce some malicious SQL code with parameters my two cents. Emmanuel On Jan 18, 2008 9:57 PM, Christian Edward Gruber [EMAIL PROTECTED] wrote: You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep the core Store interface lean and mean (read extensible). The Store interface[3] now has 4 methods: lookup() save() delete() query() The lookup(), save() and delete() act on single model Entity, while query() will filter and obtain matching Entities from the underlying database based on the Query specified. Query implementations control how a resulting JPQL gets constructed and which matching entities get pulled, and can be easily extended. To preserve compatibility with the existing Store interface, we can mimick the existing
Re: Some continuum-jpa branch updates
(Sorry if this is a duplicate post; for some reason this didn't make it to the list earlier) A Query object that wraps up criteria and is built programmatically affords us the ability to keep Store APIs lean and stable. That is the motivation behind building up queries programatically. IMHO, the current ContinuumStore is a bunch of methods that don't even vary that much underneath. I think the same can be easily achieved by using Query. I am not sure if StringBuilder will be more performant than StringBuffer when you are concatenating only a few Strings. I think what is more important is a goal of a lean, test'able and clean API. I can't really comment on named queries (probably need to toy around with them a bit), and not sure how the implementation would end up making use of named queries, but if anyone else has any opinions, I am keen to understand. Cheers, Rahul Emmanuel Venisse wrote: As Christian said, named queries are pre-compiled to SQL. With dynamic queries, perf can be not good because for each execution, the JPQL request is recompile to SQL, so parsing, creation of the JPQL tree then SQL generation, and with your solution, you concatenate lot of String. It isn't important for one request but with lot of request, you use more time and cpu, for string concatenation, it is better to use StringBuilder that is more performant than String addition or StringBuffer. An other argument for named queries is that with dynamic queries, if they aren't written correctly (it isn't the case for your code ;) ), it is easy to introduce some malicious SQL code with parameters my two cents. Emmanuel On Jan 18, 2008 9:57 PM, Christian Edward Gruber [EMAIL PROTECTED] wrote: You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep
Re: Some continuum-jpa branch updates
You can get some benefit from named queries in terms of query pre- compilation and caching on the underlying database. However, most database flavors and hibernate providers turn criteria queries into named queries (parameterized SQL) which is then cached, so, on the surface I suspect the performance characteristics will be similar. Christian. On 18-Jan-08, at 14:35 , Rahul Thakur wrote: Thanks Emmanuel! Responses inlined... Emmanuel Venisse wrote: Hi Rahul, After few days to look at JPA, I'm sure now it would be good to use it instead of the actual JDO/JPOX (I know JPOX 1.2 support JPA). The code is very easy to write and to read with JPA. About your continuum-jpa branch, I have few remarks: - I don't think it's good to use directly some OpenJPA APIs. If possible, I'd prefer to use only standard JPA APIs so we'll can choose later the implementation we want to use (OpenJPA, TopLink, JPOX...) Agree. The only place where OpenJPA APIs are being used directly currently are the unit tests. - why do you use some Spring code? Experimental. Spring has a good transaction management framework out of the box. - we don't need to store the model encoding (CommonUpdatableModelEntity class) Sure. Easily fix'able. :-) - can you explain dateCreated/dateUpdated fields? How are they managed? These are for audit puposes, and can be used as range search query criteria for fetching entities. These were an extension I thought will be good. 'dateCreated' gets set when an entity is first inserted into the underlying store, subsequent updates update the 'dateUpdated'. - all the model is fectched eagerly and it isn't acceptable for performance Yes, the model does needs review and tweaks to annotations where we know we don't need to fetch 'eagerly'. - I'm not sure your Query pattern is good. I'd prefer to use named queries but maybe you have a reason I think using a Query like we have on the JPA branch nicely provides for a flexible construction of queries (i.e, only the criteria passed in contributes to the query). I am not sure if such is available with named queries; but I am interested to know why named queries might be better. Cheers, Rahul That's all for the moment. Emmanuel On Jan 16, 2008 11:30 PM, Rahul Thakur [EMAIL PROTECTED] wrote: Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep the core Store interface lean and mean (read extensible). The Store interface[3] now has 4 methods: lookup() save() delete() query() The lookup(), save() and delete() act on single model Entity, while query() will filter and obtain matching Entities from the underlying database based on the Query specified. Query implementations control how a resulting JPQL gets constructed and which matching entities get pulled, and can be easily extended. To preserve compatibility with the existing Store interface, we can mimick the existing ContinuumStore interface operations by having a facade that can prepare requisite queries and delegate to a Store instance. 3) Misc. There are a few I am investigating: 1) Spring/Guice under the hood. 2) JUnit 4.4 (and Hamcrest library) , but these are still in early stages. I am keen to get a feedback on what others think. Cheers, Rahul [1] - http://svn.apache.org/repos/asf/maven/continuum/branches/continuum-jpa/ [2] - http://openjpa.apache.org/ [3] - http://svn.apache.org/repos/asf/maven/continuum/branches/continuum-jpa/continuum-model-jpa/src/main/java/org/apache/maven/continuum/store/api/Store.java
Re: Some continuum-jpa branch updates
Just wondering if anyone else got to the changes? Emmanuel Venisse wrote: I don't have the time to look at it these days but I'll do it asap (maybe in few weeks :( ) Emmanuel Rahul Thakur a écrit : Hi All, Scribbling some quick notes on some of the toying around I have been doing with OpenJPA, Generics etc on the continuum-jpa branch[1]: 1) Use JPA for persistence Motivation behind this has been to investigate how this compares to JPOX/JDO for managing the model - both in terms on performance and ease of use (Store APIs). Continuum model classes are annotated with JPA annotations on the branch. However, this needs a review as there are some elements (for example 'configuration' typed as Map) that I am not sure yet how to persist yet. The provider used is OpenJPA [2]. 2) Refactorings to Store interface Main motivation has been to keep the core Store interface lean and mean (read extensible). The Store interface[3] now has 4 methods: lookup() save() delete() query() The lookup(), save() and delete() act on single model Entity, while query() will filter and obtain matching Entities from the underlying database based on the Query specified. Query implementations control how a resulting JPQL gets constructed and which matching entities get pulled, and can be easily extended. To preserve compatibility with the existing Store interface, we can mimick the existing ContinuumStore interface operations by having a facade that can prepare requisite queries and delegate to a Store instance. 3) Misc. There are a few I am investigating: 1) Spring/Guice under the hood. 2) JUnit 4.4 (and Hamcrest library) , but these are still in early stages. I am keen to get a feedback on what others think. Cheers, Rahul [1] - http://svn.apache.org/repos/asf/maven/continuum/branches/continuum-jpa/ [2] - http://openjpa.apache.org/ [3] - http://svn.apache.org/repos/asf/maven/continuum/branches/continuum-jpa/continuum-model-jpa/src/main/java/org/apache/maven/continuum/store/api/Store.java
