fan's technical blog

2007年6月6日星期三

RESTful Web development

What RESTful means? I found this document : RESTful Rails development is very clear to express this point. And It is also quickly to test it in Rails. Soon you will find the amazing of RESTful. It just used HTTP GET, POST, DELETE, PUT to manage the resource and some likes JDBC CRUD implement. And more it is a new RPC implement. It has been used widely in web service. So a web service can be invoked by RESTful URL. And I think it make web service more powerful. In some traditional web application, for example a struts or JSF application, RESTful just provides nice URL format.

But obviously RESTful will be more important when application need to invoke 3rd party functions

2007年6月2日星期六

Visual library of NetBeans

Today I evaluated Visual library of NetBeans org. There are not too much information about it on Sun's site. And it is a part of NetBeans 6 M9. I guest it was just separated from Netbeans as a standalone project. It's many feature is same as JGraph which has been used by many users. But I think this library provides more about UI design but not only concerning on graph as done by JGrah. For example, it has a feature "ComponentWidget - AWT/Swing components on scene". So you can do this:

JButton button = new JButton();
button.setText("xixi");
ComponentWidget widget = new ComponentWidget(this,button);

Then I have a question: Is Visual Web (netbeans) developed on this library? If so, Visual Library is very cool! (From this post, just page flow navigator is based on Visual Library.)
There is a video which created a demo on Visual library. You can find that a JasperReports tool called jarvis is also base on this library. It looks powerful.

2007年5月7日星期一

Question on JSF state saving

JSF state is restored or used in "Restore View" of JSF life cycle. These state can be stored in 2 places:client and server. There are some links about the difference of them:

http://www.jroller.com/page/mert?entry=state_saving_method_client_side
http://www.jroller.com/page/cagataycivici?entry=jsf_state_saving_best_of
http://www.jroller.com/page/cenkcivici?entry=changing_default_state_management_method

These states are used to store data about the JSF component tree(the elements in f:view), including components and component id. They can be seen between 2 request. That is the difference from backend bean. At first thought most of components have no state, or just have a value which presents its state. A text field has state? But YES. Disable/Enable is a common state. In the component implement java code, saveState and restoreState methods deal all these work: choose some attributes and save them to an object which can be found as a hidden field named javax.faces.ViewState in client's browser source code. It was Base64 encoding. And of course, the view state has been configurated to be stored in the client. In Sun's webui implement, many attributes are stored in view state, such as javascript event method and style.

Some component such as Table can be very complex and has its own states such as the current page number and ordered column. If these states doesn't be stored in component tree, we have to save them in hidden input field.

Myfaces even has a component t:saveState just for storing data. See here.

This technology is powerful when user's action is within one page. When page is refreshed, all he has done are saved. If he just jumps between page, navigate from one page to another page, then the state of a page is discarded, and more it is useless. In one page scenario, AJAX is also a good choice. They all improve user's experience.

Somebody provides stateless approach.

There is a cool tool called FacesTrace to monitor JSF application. It displays not only session data, but also the whole JSF life cycle dynamically.

2007年5月4日星期五

test code and use Microsoft Writer

test code
if (component instanceof ValueHolder && (null != (converter = ((ValueHolder)

the css please refers here. make sure that css code block should be placed in <head> and started with .post.

In your blog, you should enbrace your code with <code> tag in HTML view. And in your code block, you cann't use <> these simble. You change it into HTML code by some tools like phpfi. It also provides highlighting feature.

But this approach is some boring. Later I found M$ Live Writer. It is cool. You can edit blog on offline mode and post it when online. You also can download blog item, modify it, and update it to Blogger. You also can delete blog by Writer although Writer didn't remind you. The editor is css-enable. And more interesting it is extensible.

It's disadvantage I found until now is that it cann't upload image file(Blogger does not support it). It can just add a image link.

(6.4 add)Today Writer beta2 is released. It has many nice feature. The biggest imprement is that my article can use tag. Well Done! It looks really cool! I think Microsoft will let it more powerful.

The reason of Writer's existen is:1)It provide offline edit mode; 2)It is WYEIWYS editor; 3) web editor is not so much convenient until now. You will find these problem specially when the article is some long.

2007年5月3日星期四

use ajax4jsf

Ajax4JSF is a framework which inserts AJAX function to JSF. It is easy to transform orginal JSF code to Ajax-able. Ajax4JSF just changed the way of http message.
It's document is here. It has a simple example. Look at blow code:

the reRender property points out whose data in JSF component tree should be return from server. After JSF engine renders that component, Ajax4JSF then sends response. So this approach didn't do harsh to JSF. We can code in JSF bean:
private HtmlOutputText rep2 = new HtmlOutputText(); ...... String style="border-color: rgb(204, 0, 255); backgroun....."; this.rep2.setStyle(style);
We can see the benefit of JSF component model. But this model don't consider the position of the javascript or it is hard to add javascript function. For example, if we want to hightlight the outputText, Should I write a new class extends HtmlOutputText which has a cool appearance? Maybe a Decrtor Pattern is better. No matter which approach we use, we should encapsulate the javascript into JSF component and give user a consistent usage. On the other hand, If we have a JSF component which is not ajax-able but provides hightlight function, we can use it directly in Ajax4JSF. So the problem is the matter of JSF instead of Ajax4JSF.

2007年4月4日星期三

why Ruby over Java

这个帖子很不错，可以参照来学习Ruby。总结来说Ruby的优点在于：
* closures
* multiple implementation inheritance via mixins (simplifies a lot designs where we would use decorators and factories in java)
* messages to objects as if they were first class methods (natural way of doing AOP, used a lot in ActiveRecord). This actually also counts for the famous java properties support planned for java 7...
缺点在于没有了Java的类型检查，而这是提高Java开发效率的关键：通过编译就可以排除大部分的错误，也提高了系统的安全性。但是在开发一个完整的 Java应用时，经常会遇到DSL语言的地方，比如jsp, sql，这些都是没有办法进行类型检查的地方（DSL的特点吗？）。再比如对Session的处理不可避免的会用到类型cast。
在RJS里面，html, rjs, rb这些文件之间存在的变量type和name的合约（或契约）更多，而只能手工检查。
疑问：Ruby里面method的参数的类型会在运行时进行类型检查？
那JRuby会起到一个粘合剂的作用吗？这会提高系统的复杂性，而且一个系统中使用两种语言也少见，除非是一个遗留系统。

2007年3月31日星期六

Sun的一些新动向

最近忙于找工作，荒疏了一些东西。
1.pet store 2.0发布了。看上去好像是web 2.0的跟风作品，AJAX，RSS，TAG，SEARCH都用上了，还没来仔细研究。用了不少开源的库，可以借鉴下。
2.一则netbeans有了新的插件：Visual Web Pack，看上去很不错的东西，应该是从creator里面提取出来的，这样比较eclipse的web开发，netbeans强了很多。记得原来使用 creator时，由于deploy服务器只能使用sun application server，速度很慢，还设法过把部署环境改为tomcat，这下方便多了。
产品的定位跟Microsoft visual web developer express类似。
相比下，eclipse的可视化编辑界面就差了很多，VE发展到现在还是个小玩具。个人感觉Swing比较swt可能难看点，但是灵活性更好些。
3.新的application server增加了很多SOA的支持，比如REST，BPEL。有个netbeans演示BPEL开发过程的Video，图形拖放的方式，很是cool。