jdo | 易学教程

JDO vs JPA for Java on Google App Engine

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问题 I want to develop my project on Google App Engine with Struts2. For the database I have two options JPA and JDO. Will you guys please suggest me on it? Both are new for me and I need to learn them. So I will be focused on one after your replies. Thanks. 回答1: JPA is Sun's standard for persistence, JDO is IMHO dying (actually, it's dead but still moving). In other words, JPA seems to be a better investment on the long term. So I guess I'd choose JPA if both were new to me. 回答2: The GAE/J google

Validating jdoconfig with incorrect url

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问题 I am using jdo and configuring the persistence manager with jdoconfig.xml However everywhere I find documentation about jdoconfig.xml it states that http://java.sun.com/xml/ns/jdo/jdoconfig should be used for validation. <jdoconfig xmlns="http://java.sun.com/xml/ns/jdo/jdoconfig" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://java.sun.com/xml/ns/jdo/jdoconfig"> etc This url points to a nonexistent file and my xml validator reports an error. What is

How to use JDO persistence manager?

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I have two questions regarding how to create / use the JDO persistence manager (PM, hereafter). Say, in a Java web application, if I have 10 entities, which can be logically grouped into 2 groups (for example, 5 user related entities and 5 business related entities) Should I need two different PMs to manage these 2 groups or only one PM is enough? Regarding the initialization, shall I use singleton instance of a PM (which will be shared by all the user's using the app at a given point of time) or should I create a PM for each and every session? NamshubWriter According to the JDO Documentation

Hibernate vs JPA vs JDO - pros and cons of each? [closed]

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I'm familiar with ORM as a concept, and I've even used nHibernate several years ago for a .NET project; however, I haven't kept up with the topic of ORM in Java and haven't had a chance to use any of these tools. But, now I may have the chance to begin to use some ORM tools for one of our applications, in an attempt to move away from a series of legacy web services. I'm having a hard time telling the difference betweeen the JPA spec, what you get with the Hibernate library itself, and what JDO has to offer. So, I understand that this question is a bit open-ended, but I was hoping to get some

Datanucleus, JDO and executable jar - how to do it?

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问题 I am developing a desktop app with Datanucleus and JDO for embedded H2 database. It all works fine when I run it from Eclipse, but it stops working when I try to make executable jar out of it. I get a following error: org.datanucleus.exceptions.NucleusUserException: Persistence process has been specified to use a ClassLoaderResolver of name "jdo" yet this has not been found by the DataNucleus plugin mechanism. Please check your CLASSPATH and plugin specification. Of course it shows that I

How to use JDO persistence manager?

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问题 I have two questions regarding how to create / use the JDO persistence manager (PM, hereafter). Say, in a Java web application, if I have 10 entities, which can be logically grouped into 2 groups (for example, 5 user related entities and 5 business related entities) Should I need two different PMs to manage these 2 groups or only one PM is enough? Regarding the initialization, shall I use singleton instance of a PM (which will be shared by all the user's using the app at a given point of time

Hibernate vs JPA vs JDO - pros and cons of each? [closed]

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问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 4 years ago . I'm familiar with ORM as a concept, and I've even used nHibernate several years ago for a .NET project; however, I haven't kept up with the topic of ORM in Java and haven't had a chance to use any of these tools. But, now I may have the chance to begin to use some ORM tools for