数码天地 今日: 0|主题: 4756|排名: 52 

最后发表： 四香油饼
回复内容：
真的是中国发明的？很不错啊

最后发表： coredump
回复内容：
OAuth-Authentication-Flow

最后发表： coredump
回复内容：
http://decentralyze.com/2010/03/09/rdf-meets-nosql/
March 9, 2010
On Thursday, I have 20 minutes to address 200 people (plus a video audience) at [url=]NoSQL Live … from Boston[/url]. My self-appointed mission is to start building bridges between theNoSQL community and the Linked Data/RDF/W3C community. These are two sets of people working on different problems, but it’s pretty clear to me they are heading in the same direction, in similar spirit, and could gain a lot from working together.
I’m organizing my talk around the question of standardization for NoSQL, and I’ll talk about W3C process and such, but the interesting part is where NoSQL touches RDF. So here are some of my thoughts on that, written for an audience already familiar with RDF. I’d love to get some feedback on the basic ideas now, to make my talk better.

• While they both want to move beyond SQL, their reasons are different. I understand the key for NoSQL is:
  
  • SQL doesn’t scale big enough. Once your read-write dataset gets too big for a single machine, you have to develop and maintain a messy sharding system. (But see below.) Sometimes it’s an economy/efficiency thing; if you don’t need ACID, a NoSQL solution might give you better performance on cheaper hardware.
  Meanwhile, I see two big motivation for the RDF folks:
  
  • Decentralization. On the open Web, data comes from many different sources, mostly beyond your control. Everyone might be providing data to everyone, and no one has the authority to run a central database, ever if they had the technology and the iron.
  • Inference. Some people find formal semantics and well defined inference to be very useful. (How is this different from triggers and views? Good questions.)
    
• There’s a freedom, a joy, and in some case enormous practicality to not having to pre-create your database schema. Nearly all NoSQL and RDF systems are schemaless or allow a fully dynamic schema. (But I understand most bigtable systems have fixed column families. That could be a problem in using a bigtable as an RDF store.)
• Both tend follow Web Architecture, using HTTP and often using REST.
• Reading about CouchDB and MongoDB (JSON document databases), as well as Neo4j (a graph database), I noticed an undercurrent about SQL being awkward to program against. I guess this is theO/R Impedance Mismatch, especially thestructural differences. RDF’s design is very close to the relational model, so it doesn’t help on this front. Within the RDF community, however, there are some systems which attempt to partly bridge this gap, including node-centric APIs (which I happen to prefer, myself). I would also argue that duck typing closes the gap from the programming-language side.
• I don’t see NoSQL going anywhere near linked data or having a vocabulary ecosystem. I expect it will want to, someday. Decentralization is a key difference in requirements.
• I only see RDF dealing with inference. Why is this? My first thought is that the RDF community has a lot of AI roots, and the NoSQL community doesn’t. But maybe it’s about economics and motivations: formalizing the notion of inference makes it possible, in theory, to easily deploy very sophisticated data transformation (and making them complete before the sun goes out). At NoSQL scale, folks are much more concerned about techniques for being able to run even simple transformations (and making them complete before the power bill comes due). I note that AllegroGraph manages to be in both communities, with a very practical, high-performance Prolog element; I don’t know how parallel it is. A few RDF folks are working on using map/reduce. Presumably, with the rise of multi-core systems, even single-user inference engines will want to be made parallel.
• How many of the reasons for NoSQL rejecting SQL also apply to SPARQL? Does the scaling issue apply? Actually, does the scaling issue really apply to SQL? Michael Stonebraker (more or less the Voice of God) claims automatic sharding can and should be done while still using SQL. Some people reply: Perhaps, but in Enterprise-Grade Open Source? Also, maybe “SQL” is a euphemism for ACID, and that’s really what doesn’t scale and/or is too expensive. Perhaps that issue needs to be settled before considering SPARQL? Actually, the state of ACID in SPARQL is an [url=]open issue[/url] right now; maybe NoSQL can inform that decision.
• RDF is standardized. Some would argue it’s more standardized than SQL; that case will be stronger when SPARQL 1.1 is done. Here’s a diagram Steve Harris made, which I reformatted. “KV” refers to key-value stores, the simplest, most scalable kind of NoSQL database.
  
  
                                 
  登录/注册后可看大图
  
  

So… What does that all boil down to?
Bottom line: RDF could learn a lot from NoSQL about scaling and ease-of-programming; NoSQL could learn a lot from RDF about decentralization and inference.
Some closing questions, ideas….
Can someone make a SPARQL endpoint with Cassandra’s performance and scaling properties? I haven’t studied this idea much, but I’m afraid the static column families will make it impossible to get much performance without building the store for a particular set of SPARQL queries. But it could still be useful, even with that drawback. Or maybe some SPARQL endpoint is already there; has anyone really tried a comparative benchmark?
How does the SPARQL endpoint description and aggregation work compare to database sharding. Are there designs for doing it automatically?

最后发表： ubuntuhk
回复内容：
强悍的Google

最后发表： key
回复内容：
还可以把图打印出来，再扫描进去，然后再做处理。

最后发表： fatfish_cc
回复内容：
crashplan?

最后发表： procoder
回复内容：

可以自己刷ROM。

最后发表： coolmate
回复内容：

我觉得你对Qt和boost两个东西的用处上面的理解有偏差。Qt终究还是着重于GUI方面的东西，而且是着眼于外观的多一点。

boost是个广泛的C++函数库。二者截然不同。

最后发表： xblues
回复内容：
RC到最后也是过期啊。Experess版本好像还没出来呢。我考虑撞到虚拟机上玩玩。

最后发表： wancyzhang
回复内容：
不想聊VPN内部如何加密，如何建立通道，就像分析一下如何找到主机

主机地址不能是唯一的，也不能是一个内置的列表，那么有可能是一个算法生成。

有这个算法在运行时生成一系列的IP和端口号，每次不同。当发现这个算法找到服务器的比例小于一个特定值是，应当会自动下载更新算法。

这样，没有IP,没有端口号，协议也可以不固定。这个VPN就有点意思了。

当然，这个就需要大量的服务器，而且这些服务器的IP应当还可以变。

恩，如果有CISCO从路由器层面配合，会更简单一些，不是说了吗，全世界的路由器有那么十几二十台处于核心地位。。。。。

有意思，有点道高一尺，魔高一丈的感觉。

想起了黑客帝国中的老式电话了。呵呵

最后发表： yuba
回复内容：
还是那句话，以后用啥语言开发都行

最后都用汇编级的优化，有个日本人不就是这个厉害吗

支持汉编，希望能细化成上海编，粤编，牛鞭。。。

最后发表： shenzy
回复内容：
google, my favorite  

最后发表： black_zerg
回复内容：
也就用在自动测试上，对我来说没太大用。对一般人也没大用，个人对测试不感冒所以可能有偏见。这个可以包装成测试工具卖钱，还是很不错的创意。

[ 本帖最后由 black_zerg 于 28-1-2010 10:50 编辑 ]

最后发表： shenzy
回复内容：
好玩。。。。。。可惜只有阿姆斯特丹的数据

最后发表： xblues
回复内容：
有多达十余种放屁风格可选，由于声音过于逼真，请小心使用！


http://gallery.live.com/liveItem ... 4&bt=1&pl=1

最后发表： laowantong
回复内容：
haha, 俺就是XPSP3 + IE6.0的组合
懒得更新..

哪里有恶意网站? 也过过攻击谷歌的瘾

最后发表： 四香油饼
回复内容：
interesting invention!
I like it

最后发表： black_zerg
回复内容：
don't agree. Personally I like swing more, but JavaScript won't die soon.
The fact is, because of the market and the competition of those big companies, JavaScript is becoming the most popular and cross-platform language. Now if we want to play with RIA,  Rich JavaScript framework is something we must learn and master.

JQuery is even simpler than JavaScript itself. it can be used to enhance web page, it has so many plugins and fits web page requirements, it will never die.   other heavier frameworks like ext-js can create very complicated enterprise level application. GWT maybe attractive to Java developer, i tried some small projects with it. Now I prefer native JavaScript way because that's more flexible and extensible.

Now the JavaScript engine is becoming so fast and some people believe JS is better than Java. I can't tell which is better. What I can tell is they are all easy to learn.

Recently i found Qooxdoo is very interesting. it's based on a nice OOP design. So you can create you classes and widgets through an elegant way.

And what I would like to point out is, AJAX has been thriving since 2005. My guess will be the server assisted MVC like struts will die. JSF2 is coming, probably still a rubbish one.

[ 本帖最后由 black_zerg 于 31-12-2009 23:16 编辑 ]

最后发表： combread
回复内容：
try
    {
        打酱油;
        speak;
        speak freely;
        speak freedom;
    }
    catch (Exception 河蟹)
    {
        被喝茶;
        被躲猫猫;
        被上吊;
    }
    finally
    {
        if (!dead)
            移民;
    }

最后发表： coredump
回复内容：
祝软件版网友平安夜里梦不到写代码

最后发表： yuba
回复内容：
还有Spring Framework 3.0

最后发表： coredump
回复内容：
Google Chrome开始支持Web Socket标准

Slashdot/Solidot报道： http://it.solidot.org/article.pl?sid=09/12/11/0315211&;from=rss

Web Sockets Now Available In Google Chrome
例子：

1. if ("WebSocket" in window) {
   
2. var ws = new WebSocket("ws://example.com/service");
   
3. ws.onopen = function() {
   
4. // Web Socket is connected. You can send data by send() method.
   
5. ws.send("message to send"); ....
   
6. };
   
7. ws.onmessage = function (evt) { var received_msg = evt.data; ... };
   
8. ws.onclose = function() { // websocket is closed. };
   
9. } else {
   
10. // the browser doesn't support WebSocket.
    
11. }
    

复制代码

IETF WebSocket协议草案

W3C WebSocket API标准

W3C WebSocket标准中的WebSocket 接口

1. [Constructor(in DOMString url, in optional DOMString protocol)]
   
2. interface WebSocket {
   
3. readonly attribute DOMString URL;
   
4. 
   
5. // ready state
   
6. const unsigned short CONNECTING = 0;
   
7. const unsigned short OPEN = 1;
   
8. const unsigned short CLOSED = 2;
   
9. readonly attribute unsigned short readyState;
   
10. readonly attribute unsigned long bufferedAmount;
    
11. 
    
12. // networking
    
13. attribute Function onopen;
    
14. attribute Function onmessage;
    
15. attribute Function onclose;
    
16. boolean send(in DOMString data);
    
17. void close();
    
18. };
    
19. WebSocket implements EventTarget;

复制代码

最后发表： cndpan
回复内容：
同感 ,也许没有朋友一起用

最后发表： gdzack
回复内容：
直接上google申请啊，不到30秒钟。It's too simple, sometimes naive

最后发表： mayabin
回复内容：
过不过时用事实来说话吧。
我在2个项目里用过Hibernate，缺点是性能；优点是用HQL，不用考虑SQL和后台数据库。

所以，我的观点是，适合你的项目就是好的。不适合的也别硬往里整。
这年头，有喜欢穿唐装的，也有喜欢穿西服的，个人喜好不同而已。

最后发表： earthengine
回复内容：
注意：以下内容为本人原创，首发本论坛。这不是论文，只是一个简介，希望抛砖引玉。

设计模式：Parser （处理器）
目的：经常遇到的一种情况是，程序需要根据成文的协议进行处理。协议会规定各种封包或者对象的格式，然后程序需要根据接收到的数据生成相应的对象。这时候，我们可能需要一种灵活的方式以便适应对协议的修改。

实现：通过组合一些经典的设计模式，可以设计一种非常灵活的方式来实现以上功能。首先，Factory Method可以用以最终生成对象。其次，由于封包类型可能是递归的（即一个特定的包类型可以递归地包含自己），那么可以选择使用Composit来表达这种递归关系，这样很方便对生成的对象进行后续处理。然后，关键的一点是，每种对象必须负责自己的生成，这可以使用Responsibility Chain来实现。整体上，这种根据数据生成对象的方法可以看作是Interpretor的实例。

例子：在本人做的一个项目里，利用本模式实现了对电子邮件的处理。

最后发表： zycbob
回复内容：
就1年~~

最后发表： wwjia
回复内容：
看一下看一下．

最后发表： coredump
回复内容：
FROM:http://www.blogjava.net/hhj/archive/2006/05/17/46688.html
一个很好的关于semantic web的资源list

最后发表： coredump
回复内容：


没听说过，对我是个新名词。

------
Clojure is a dialect of Lisp   这年头函数式编程风起云涌啊.不过说起STM实现的最优雅的还是Haskell，函数式编程天生和STM容易结合，因为本来在函数式编程中的函数就没有副作用，没有共享变量。

最后发表： 向往自然
回复内容：
Windows / Mac / Linux版本的Chrome Dev同时更新到了3.0.195.1，主要更新内容如下：
表单建议收缩正常,扩展可以自动更新了,中文字体大小默认设定为12号，日语，韩语，阿拉伯语和泰语为10号.Mac版支持了将URL，纯文本，HTML拖拽进/出 内容显示区，支持文本域以及新标签页的预览图。URL也支持在Chrome和Finder / Desktop / Dock和外部程序之间拖来拖去。
Mac版修正清除下载列表时崩溃的问题。
Mac版加入了infobars。
Mac版在View->Developer菜单下面加入JavaScript Console功能。
Linux版可以将某个链接拖动到书签栏创建新的书签项目。
Linux版增加快捷键，(Ctrl-Enter, Shift-F5, Shift+Scroll Wheel)
Linux新增可以Dock的开发者工具。

点击这里查看完整的Release Note.

下载:Google Chrome 3.0.195.1

最后发表： justinli79
回复内容：
OpenCL可望实现这样的目标，让绘图处理器在电脑中不仅只用于绘图等相关应用上，而能执行各种不同的应用程式 .Khronos Group周二（12/9）宣布通过并公布OpenCL 1.0规格，该标准预计将首先在苹果下一代Mac OS X操作系统中采用。而周三的时候,NVIDIA与AMD也纷纷表示将支持最新的OpenCL1.0.

OpenCL（Open Computing Language，开放运算语言）是一个开放而免授权金的跨平台程式语言标准，专为当今个人电脑、伺服器，及手持和嵌入式装置的平行程式处理所设计。半年前苹果（Apple）提出了OpenCL的草案规格，并由Khronos Group完成开发，通过了该规格，可望首先用于即将推出的Snow Leopard作业系统内。Khronos Group成员包括了苹果、3DLABS、AMD、ARM、Intel、IBM、NVIDIA等重量级的科技业者。

OpenCL程式语言的设计，也是为了要让软体开发人员能够充份组合利用各种不同的多核心处理器、绘图处理器（GPU）、Cell架构，及其他平行处理器（如DSP）的效能。长久以来，业界就一直试图要把强大的绘图处理器运算能力运用在一般运算上，这个概念也就是所谓的GPGPU（general-purpose computation on GPUs，通用的GPU运算）。而OpenCL可望实现这样的目标，让绘图处理器在电脑中不仅只用于绘图等相关应用上，而能执行各种不同的应用程式。

对此，苹果软体工程资深副总裁Bertrand Serlet表示，苹果开发OpenCL好让下一代的Mac OS X作业系统Snow Leopard上的任何应用，都能够好好运用之前只有绘图应用能够使用的运算能力。

担任Khronos Group总裁并负责OpenCL工作小组的NVIDIA副总裁Neil Trevett则表示，做为一个开放而跨平台的标准，OpenCL是下一代软体发展的基础技术，并可望在明年见到该技术的建置。

最后发表： yuba
回复内容：
世界快大同了

最后发表： fargo
回复内容：

enterprise应用方面还不行,和Netapp还有差距，主要是Netapp有hardware controller,性能好。而且有battery，down机后，重启后会commit pending transtion，不会丢失数据

最后发表： 驁肆墜楽
回复内容：
不错，学习了

最后发表： ubuntuhk
回复内容：
是的，android只是google的一个小小的产品，不是它的主营业务，有点散漫。

iphone则是Apple的拳头产品，必然会倾力投入，而且有Jobs的天才领导把关，所以能以近乎完美的产品捕获用户的心。

最后发表： coredump
回复内容：
Javascript is tiny & smart, I like it.

最后发表： MacroJ
回复内容：
有什么用的啊？

最后发表： xblues
回复内容：
我推荐希捷7200.12 1TB，目前性能评测，所有产品中最好的。单碟500G的，转速达到7200的硬盘目前只有希捷一家。

可靠性嘛，7200.12代一经推出几个月了，没有出现7200.11代的问题，目前来看性能和稳定性还是非常好的。

西数的也不错，不过性价比就不如希捷了，而且性能的确也不如希捷。

最后发表： Tux
回复内容：
以前时不时看看PPA里的daily build，现在完成度更高，接近release了。