Advice for multi-DAO, nested objects, connection mgt, Spring config, for Click webapp

[Tim Colson <ti...@yahoo.com>]

Hi!

The team I'm working with has been experimenting with Empire DB in a small Apache Click webapp for managing a Confluence wiki. 
Our experience so far with no-strings has been good, but we'd appreciate advice on how to best use Empire DB persistence patterns. 

The webapp has five model objects, persisted to h2 for development /  Oracle in production. Maven, Spring for DI only, liquibase for DB migration,  TestNG/Surefire. We created a PersistenceManager class just like the Spring example, and injected it with WikiMgtDB (extends DBDatabase), a DataSource, and the Empire DB Driver. The PM class grew large with get/search/updates for the business objects, so we created DAO classes for each model object and injected each with WikiMgtD via Spring. 

The PersistenceManager is injected into the Apache Click action classes for the webapp and can retrieve/store objects, but is not much more than a proxy that gives each DAO classes a Connection (see example).

PersistenceManagerImpl {
….
  public SpaceSummary getSpaceSummary(String serverName, String spaceKey) {
        Connection conn = getConnection();
        spaceSummaryDAO.setConnection(conn);
        SpaceSummary ss = spaceSummaryDAO.getSpaceSummary(serverName, spaceKey);
        releaseConnection(conn);
        return ss;
    }

This pattern seems wrong, and test cases cannot be written against the DAO objects directly because they don't have a Connection.
(A related puzzle is connection and transaction management which has been problematic with @Transactional annotations across updates involving more than one DAO. )

I've looked over most all of the sample code, found a lot of good ideas, but I need advice on EmpireDB patterns with more than one DAO, patterns for retrieving nested objects, proper connection management, and also how to best handle "paged" retrieval of 90,000 records.

Thanks in advance for any/all comments/feedback…and I'm happy to provide more details and contribute lessons back into more example code. (ex, a sample Apache Click + Empire DB)

Thanks!
Tim

 

Re: Advice for multi-DAO, nested objects, connection mgt, Spring config, for Click webapp

[Harald Kirsch <Ha...@raytion.com>]

Interestingly we had a long discussion among developers yesterday here 
over the differences between a solution with Hibernate/JPA and EmpireDB. 
We came to the conclusion that

JPA puts the Java object into focus and wants to "just store it 
somewhere", ideally completely shielding whatever underlying storage 
technology is used, while

EmpireDB puts the relational database with all its functions and 
features into focus. And a database is not just to store stuff and read 
it back. It has lots of dedicated functionality to very efficiently work 
with the data.

Consequently to me it seems to be wrong to see EmpireDB as a way to 
persist objects. Rather it is a smooth interface to a database.

And if you rather need a database than "just get me these objects 
stored", exploit the database and don't just focus on persistence.

I know this is not a very specific answer to your question, but maybe a 
new perspective helps to figure out a better way to use EmpireDB --- or 
rather something completely different, depending on what your data 
really needs.

Just my personal opinion,
Harald.

On 29.08.2013 01:09, Tim Colson wrote:
> Hi!
>
> The team I'm working with has been experimenting with Empire DB in a small Apache Click webapp for managing a Confluence wiki.
> Our experience so far with no-strings has been good, but we'd appreciate advice on how to best use Empire DB persistence patterns.
>
> The webapp has five model objects, persisted to h2 for development /  Oracle in production. Maven, Spring for DI only, liquibase for DB migration,  TestNG/Surefire. We created a PersistenceManager class just like the Spring example, and injected it with WikiMgtDB (extends DBDatabase), a DataSource, and the Empire DB Driver. The PM class grew large with get/search/updates for the business objects, so we created DAO classes for each model object and injected each with WikiMgtD via Spring.
>
> The PersistenceManager is injected into the Apache Click action classes for the webapp and can retrieve/store objects, but is not much more than a proxy that gives each DAO classes a Connection (see example).
>
> PersistenceManagerImpl {
> ….
>    public SpaceSummary getSpaceSummary(String serverName, String spaceKey) {
>          Connection conn = getConnection();
>          spaceSummaryDAO.setConnection(conn);
>          SpaceSummary ss = spaceSummaryDAO.getSpaceSummary(serverName, spaceKey);
>          releaseConnection(conn);
>          return ss;
>      }
>
> This pattern seems wrong, and test cases cannot be written against the DAO objects directly because they don't have a Connection.
> (A related puzzle is connection and transaction management which has been problematic with @Transactional annotations across updates involving more than one DAO. )
>
> I've looked over most all of the sample code, found a lot of good ideas, but I need advice on EmpireDB patterns with more than one DAO, patterns for retrieving nested objects, proper connection management, and also how to best handle "paged" retrieval of 90,000 records.
>
> Thanks in advance for any/all comments/feedback…and I'm happy to provide more details and contribute lessons back into more example code. (ex, a sample Apache Click + Empire DB)
>
> Thanks!
> Tim
>
>
>

-- 
Harald Kirsch
Raytion GmbH
http://www.raytion.com