db4o

db4o 是一款优秀的面向对象数据库， German Viscuso最近在DZone上发表了一篇介绍它的文章，该文可以视为是db4o在主要语言和框架中的一次巡演 。 作为一个关注Groovy的站点，我们的兴趣当然是其中和Groovy相关的部分：“在Giffon框架中使用db4o”。在这一小节，作者向读者展示了Griffon的db4o插件。 在Griffon工程中安装db4o插件后，会产生两个文件：Db4oConfig.groovy，包含数据源的定义；BootstrapDb4o.groovy，类似Grails中的BootStrap.groovy。同时，对于控制器，会注入一个名为withDb4o的动态方法，让你可以访问com.db4o.ObjectContainer实例，通过该对象你可以对数据库进行操作。 简单的例子由3部分组成： 领域类： class Person { int id String name String lastname } 在BootstrapDb4o.groovy中初始化数据： class BootstrapDb4o { def init = { db4o -> db4o.store(new Person(id: 1, name: "Danno" , lastname: "Ferrin")) db4o.store(new Person(id: 2, name:

I'm playing around with db4o, and I have the Object Manager viewer thingy for Visual Studio. It seems okay, but not exactly on par with tools like HeidiSQL/SQL Studio/etc., not to mention that it locks the db4o file--I can't use my db4o app and Object Manager at the same time. Maybe I'm using it wrong, but regardless, I'd like to know what else is out there. What tools would you recommend for looking at and manipulating db4o files? UPDATE: I've been using LINQPad. There is some yak-shaving involved, but it's working pretty well. It still leaves a lot to be desired in terms of the functionality

领先的开源面向对象数据库提供厂商db4objects宣布db4o已可以顺利运行于Android平台。先前的InfoQ新闻“Db4Objects发布Db4o 7.0，支持透明激活”中曾经报道db4objects公司和爱好者积极推进db4o运行于Google Android平台，以期待让db4o成为Android上的首选数据库平台，现在db4o已经成功走出了这一步。 Android是Google宣布成立的“开放手机联盟”的移动开发平台。开发者拿到的Andorid SDK是一个包含完整的移动设备开发工具包，包括应用程序框架、开发环境和工具（基于Eclipse）、调试和虚拟运行环境，默认的开发语言是Java，让开发者可以使用熟悉的面向对象方式开发移平台动应用程序。Andorid平台的操作系统使用Linux内核，其上架设了基于C/C++编写的OpenGL、字体、编解码器、SQLite和用于Web渲染的Webkit。更多细节，可以回顾新闻“Google Android SDK舍弃Java ME，支持Java Lite和Apache Harmony”。在这个SDK发布之后，其Dalvik虚拟机背离标准Java虚拟机的基于寄存器的实现，而且配合使用了Apache的Harmony基础类库，这种选择说明了Google实现开放联盟的决心，虽然引发了是否会造成Java移动开发平台的分裂的争议

I'm currently trying out db4o (the java version) and I pretty much like what I see. But I cannot help wondering how it does perform in a real live (web-)environment. Does anyone have any experiences (good or bad) to share about running db4o? We run DB40 .NET version in a large client/server project. Our experiences is that you can potentially get much better performance than typical relational databases. However, you really have to tweak your objects to get this kind of performance. For example, if you've got a list containing a lot of objects, DB4O activation of these lists is slow. There are

I am trying the db4o object databse and so far I quite like what I am seeing, but I also read this post on stackoverflow db4o experiences? indicating that not everything that seems so easy is easy. Right now, I have some questions regarding on how db4o is used in real world apps. So if you have any experience in working (especially in web app context) with db4o, I would love to hear them. Here are my questions: How do you manage object identity when working with db4o stored objects?** Coming from RDBMS background where you normally always have a primary key / identity column for every table, I

What is the difference between graph-based databases ( http://neo4j.org/ ) and object-oriented databases ( http://www.db4o.com/ )? I'd answer this differently: object and graph databases operate on two different levels of abstraction. An object database's main data elements are objects, the way we know them from an object-oriented programming language. A graph database's main data elements are nodes and edges. An object database does not have the notion of a (bidirectional) edge between two things with automatic referential integrity etc. A graph database does not have the notion of a pointer

Is there any way to completely disable Java security manager? I'm experimenting with source code of db4o. It uses reflection to persist objects and it seems that security manager doesn't allow reflection to read and write private or protected fields. My code: public static void main(String[] args) throws IOException { System.out.println("start"); new File( DB_FILE_NAME ).delete(); ObjectContainer container = Db4o.openFile( DB_FILE_NAME ); String ob = new String( "test" ); container.store( ob ); ObjectSet result = container.queryByExample( String.class ); System.out.println( "retrieved (" +