網際網路應用系統設計 作業八( 5/23 Homework)

GreaseMoney Script definition, if you don’t follow the rules, will unable to install.

This is the javascript to reload after 60s.

// ==UserScript==
// @name reload
// @namespace
// @description reload webpage after 60sec
// ==/UserScript==

(function()

{

setTimeout("document.location.reload()",60000);

})
();

this test for hello and picasa 

網際網路應用系統設計 作業七 ( 5/9 Homework)

3.1秘密鑰匙系統有何優缺點?

Secret key or privacy key is a system that uses the same key to decryption and encryption.

Thumb up:

It can use for self-security for encrypting data on hard drive. People won’t have the chance to steal the key when transit. For example, compressed files can encrypt by secret key.

Thumb down:

Everyone who has the key can decrypt the message. It’s not so reliable when you want to tell the key to another. The key may be compromised when transit.

http://www.linktionary.com/s/secret_key.html

http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci518887,00.html

3.2公開金鑰系統如何防止第三者竊取資料?

In a public-key cryptosystem, a user makes use of a pair of keys: a public key and a private key.

The privacy key can keep by one. It’s not necessary to tell anyone else. So we don’t have the security problem to send the message though internet. The only way to decrypt the message is the privacy key which encrypt by corresponding public key.

http://www.webopedia.com/TERM/P/public_key_cryptography.html

http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci214299,00.html

網際網路應用系統設計 作業六 ( 5/16 Homework)

3.電腦硬體頻頻的升級會過度增加企業的營運成本，以Web為基礎的應用程式系統可否減低這種成本？為什麼？

似乎可以，但是在以WEB端為主的服務，等於是集中風險的服務，如果一旦伺服器端停擺，公司完全倚靠WEB服務，無法分散風險。所以必定要在穩定性、系統備份的地方下功夫，所以一般公司級的伺服器，穩定為第一考量，價格也十分昂貴，我想硬體的價錢並不會省多少。

可以節省的成本我想是在集中管理的方便性，集中管理可以讓整個系統簡單化，在WEB服務出問題的時候，也知道從哪裡開始除錯，節省人力和時間的成本我想比硬體升級來的多。

4.如下圖所示，瀏覽器支援Java, HTML，JavaScript，ActiveX Control，以及各式Plug-in，這些工具分別適合用來做哪些應用？

JAVA：

是一種較新的語言，採用OOP，更加容易撰寫。有跨平台的特性，適合在網路在做任何應用，只要有Java Applet就可以執行。

HTML：

網際網路的基本，以靜態網頁為主，但在現在仍是不可或缺。我想有百分之80以上的網頁都還是靜態網頁，主要還是以文字閱讀為主。

JavaScript：

現在很容易在網頁中發現JavaScript的蹤跡，網際網路已經不再是一成不變的靜態，更佳人性化的互動，可以讓瀏覽網頁更加有趣。網路上可以看到許多的JavaScript程式，便可略知一二。

JAVA & JavaScript?

ActiveX Control：

是Microsoft主導的整合平台，讓瀏覽者可以在internet執行應用程式，主要的開發是使用在Internet Explorer，一樣和JavaScript有動畫，增加網頁互動功能，但沒有跨平台的特性。

什麼是ActiveX？

網際網路應用系統設計 作業五( 5/2 Homework)

1.試解釋web技術演進是要解決什麼樣的問題?

依照課本的解釋方式，由第一階段的靜態網頁，慢慢演變成有動態存取的網頁，就是所謂的第二階段，但隨著動態網頁的執行，卻遇到系統負載的情形過重，就有必須改進的空間，便誕生解決第二階段問題的第三時期。利用效率較高的方法，來處理資源過度使用的問題。

第一階段HTML

解決問題：有了TCP/IP的協定之後，需要統一的文件格式，於是產生HTML。

發展初期以靜態網頁為主，由於頻寬的限制，以及使用的不普及，靜態網頁已經符合需求。但隨著人們對電腦的依賴，更新資料必須更為快速，到麼就要建立資料庫，但以HTML的網頁技術，和資料庫交換資訊的功能是缺乏的。

第二階段CGI

解決問題：增加網路存取的功能，讓靜態網頁動起來，WEB server透過CGI存取資料庫達成和使用者互動的功能。

CGI的出現，讓使用者透過瀏覽器能看到動態的資料，透過CGI介面，和有檔案存取功能的程式語言，與資料庫交換資料，動態的產生WWW網頁。

第三階段 Thread & Scripting

解決問題：網路的方便性，使用者的增加，在有限的資源底下，要負荷幾百到幾千人的存取，便要產生新的技術，來解決process所造成耗費過多系統資源的問題。

網站技術以Thread產生常駐的程式，並產生不同的優先權，較高的優先權，用來應付使用者即時的需求，一些優先權較低的執行緒，可以等到資源空閒的時候處理。

<還有>

隨著網路扮演著更多的功能，安全性的議題也是重要的階段，也就產生SSL(security socket layer)的安全機制。

XML，網路資料急速增加，搜尋和萃取資料的困難，就產生XML的標準。

等等…也許今天又有新的技術，可怕的網路。

2.以網站開發的角度來說,Script語言有什麼優勢?

A good site answers this question for me!

透過Script語言，網頁設計者可以在網頁上加入互動式或比較複雜的功能， 而這些功能以往只能出現在較進階的應用程式上。所謂的Script語言就是在文件中加入的一段程式碼，在執行時才會進行編譯動作。 也就是說，它可以使一般HTML文件中加上一些額外控制瀏覽器的文字。

3.程序(Process)和執行緒(Thread)對網站性能有什麼不同的影響?

If a user visit a web site, web server create a thread to the user. If another user takes the same service, the sever use another thread to the second user. The user does not need to wait the first the first. So the thread let the program to do different things at the same time. The web user can browse easily. And process can’t do those things.

網際網路應用系統設計 作業四( 4/25 Homework)

1. If Google Maps is available as web service,
propose at least five applications that can make use of this service.

a. 如果衛星照的角度來看，Google的服務可以跨到安全型服務，如果我要出國幾天，從網路可以監控我家附近的情況，”Google security guard” will release!!

b. 和GPS結合，網路比現在的衛星導航有更多的擴充性，再加上Google快速搜索引擎，一定是事倍功半。

c. Google travel，在地圖上可以利用Google引擎搜索出附近的店家資訊，旅館資訊，對於愛旅遊的人不用在對照地圖找地方，再上網找地址。

d. Google Weather，可以利用衛星照的功能，判斷地區天氣狀況，妳要去的地方會不會下雨，溫度是幾度。

e. 判斷交通狀況，在堵車的路段能避免，找出替代道路，節省時間。

JAVA 3/25 Homework

3. Hit the Internet and do a search. Based on the results you find, write a Cellular Phone Java Game market report on your own blog.

Java becomes a universal platform for mobile games. It’s the fifth major platform for games after PCs, consoles, handheld computers and the Internet. But the java games are not so popular in Taiwan. I think we need to consider some of the bottleneck.

1. Software is ready, but hardware is not.

Cell phones still do not have enough memory and powerful processor to carry high quality games. Java language is easy to access and learn and games can easily build by anyone who is interested.

2. Where is the standard?

Cell phones are build by different company, each of them owns their specifications. Java games should be able to run by any of the mobile phone. We need to check every handset can launch and control the games normally. It takes money and time to develop java game.

3. Price is the point!

Internet makes the game more addicting! Mobile phones take the advantage to surf on internet without wires. The carriers in Taiwan can’t lower down the price. The connection fee is higher than average people can afford. Java game has the good performance on internet (we can take a look of the website MLB), but the carriers block its way to dance on the stage.

網際網路應用系統設計 作業三 ( 3/14 Homework)

1. Use Google to search. List some of the critiques about Skype. Make comments on each of these critiques.

a. Are you fed up with contacts stored on local machine?

It depends. Although the new released beta version solved the problem, I still have some doubts. If the server is down, the log-in is a problem. For instance, the MSN sometimes does its maintenance, millions of people can’t chat.

b. Can 9 Million Skype Users Be Wrong?

I think this is an interesting article. When everybody is criticize the Skype’s security, however, I worried it’s too safe and it may be used by criminal to kidnap or other illegal usage. Unlike telephone or cell phone, polices can still check the communication record, but Skype is not regulated by any law.

2. RSS and Atom are two methods that can be used to support site feed. Explain RSS and Atom with examples.

RSS & Atom

What is RSS?

What is Atom?

Firstly, we can try to read the RSS history.

RSS is the milestone but not the best. From the Atom project, I find out that RSS has some problem not fixed. So the Atom Project tries to fix the mistake already exists on RSS.

Maybe simply concluded, Atom is the new concept the RSS. The Atom project would like to make different formats and protocols just one format (Atom) and one protocol (HTTP).

NO!

It’s not that simple! Resources on internet tell that it looks like a war between RSS and Atom. By the way, you can say two software giant’s war, SUN and Microsoft.

I’m not quite understood after I read “RSS, Atom, And The Syndication Standards Dance!”

Here are several links of RSS and Atom.

RSS powered

BCC

http://news.bbc.co.uk/rss/newsonline_world_edition/front_page/rss091.xml

CNN

http://rss.cnn.com/rss/cnn_topstories.rss

Sun Microsystems

http://www.sun.com/rss/news-rss.xml

Atom powered

AtomEabled

http://www.atomenabled.org/atom.xml

Both supported

Flickr

http://feeds.feedburner.com/Flickrblog

clickable link

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