1.j2ee提出了规范,给出了一个标准。On the other hand, I feel it has come up short on a number of measures.j2ee也确实降低了企业应用级项目的失败。
2.任何规范和特定的实现都没有一个技术思想重要。如同重构的时机一样:OO原则,针对接口编程;将任何特定的规范已经实现尽量隐藏一般特性之后,比如ejb的接口隐藏在pojo之后。
3.在我自己的技术选择中,几乎都是选择OpenSource社区的,很少受到规范驱动或者vendor驱动的影响。正好相反,也vendor driven才造就今天的我们。:)
4.项目成功,检验架构的标准:
simplicity
productivity
the fundamental importance of object orientation
the primacy of business requirements
the importance of empirical process
the importance of testability
5.一切皆来源于经验过程。spring比Expert One-on-One J2EE还要早。(没有working code就无法写出这本书。)springframework是Rod Johnson几个商业项目的经验而产生的。开发这个framework也应该是在模式大量复用中找到了突破点,如果一些模式大量的被复用,那么把这些模式的职责转嫁给framework来做,dry原则。当然,必须优先考虑模块化的原则,比方说对于log4j的如何集成到framework的方式。
6.Architecture and implementation should always be undertaken with clear goals in mind.
Productivity
1.framework不断抽象,不断重构产生的,framework与代码生成的转换:If we see a requirement for boring repetitive code, we should apply an OO solution and abstract it into a framework,rather than generate it and live with the resulting duplication.
2.代码生成技术在解决生产率中扮着十分重要的角色。在j2ee开发中涉及到代码生成的层次很多。从dll,database schema到jsp.
3.There shouldn’t be vast amounts of repetitive plumbing code in J2EE applications.Better architectural choices and better frameworks can virtually eliminate such code,meaning that nearly all application code can be hand-authored.(注:framework形成的时机之一。)I’m not saying that code generation is a bad technology in general—merely that,when properly designed and built on appropriate frameworks, most J2EE applications should not contain enough boilerplate code to justify it and outweigh its negatives.
4.关于代码生成以及MDA作者的观点:The natural path of our industry is toward higher levels of abstraction. Perhaps one day MDA-powered code generation will prove to be an appropriate abstraction. However, I feel that this is 10–15 years away, if it ever happens.
5.Better Solutions for Higher Productivity:
Architecture
Avoid unnecessary architectural complexity.
Avoid unnecessary use of EJB.
Use abstraction layers to hide the complexity of core J2EE and J2SE APIs.
If possible, use an O/R mapping product to simplify the persistence layer.
Use a good application framework.
Focus and methodology
Focus! Know what problems you should be solving, and concentrate on them.
Use a reference architecture and start from a template application.
Use an agile development process.
Use appropriate tools.
6.Different developers do the same thing in different ways, wasting
valuable development time and complicating maintenance.程序设计始终要做的就是不发生这样的事情。
7.Know What Problems to Solve 生产率即是知道要解决得是什么问题,将主要是domain problems而不是generic problems.
8.Use Reference Architectures and Templates一旦选择了技术,将着手reference architecture.begin work using a skeleton application that establishes the overall plumbing.
9.And remember that the more upfront effort before arriving at a working prototype, the greater the risk of inadequate performance or an unworkable architecture. 项目组也应该精化,微型化。
10.J2EE developers are fortunate in that all these requirements can be met by free, open source tools, such as Eclipse, JUnit, Ant, a good Eclipse XML plugin, CVS, and the standard Eclipse JUnit and CVS integration.
OO
1.本身OO是一种范式,是一个模型,在SICP中对于讲到代换模型的理论:In general, when modeling phenomena in science and engineering, we begin with simplified, incomplete models. As we examine things in greater detail, these simple models become inadequate and must be replaced by more refined models.关于OO的讨论算是一个检查考虑问题的讨论。
2.作者提出的实践中运用oo的四个方面:封装domains concepts;运用polymorphism将共性和差异分离;代码复用;extensibility.
3.j2ee应用的对象常常都是一些fake objects,即是不具备objects的某些特征:identity,state,behavior.
4.oo针对接口编程的优点和误区。
The importance of business requirements
1.这个问题因不同的角色而已。就我而言,如同我一样的普通程序员,对于generic technical problems常常都是难题,故而在这方面的需要长足的学习和提高的;对于我们而言,我们domain problems就是如何具备了generic technical方面的强大能力只是第一步。
The Importance of an Empirical Process
1.Always develop a vertical slice to validate your application’s architecture early in the project. Don’t trust our advice or anyone else’s without establishing that it’s appropriate to your needs.验证自己的想法。