Hacking so Existing

Here is a task to challenge myself: Find the first k digits prime number. And k would be 16, 32, 64, 256, 1024, 8096, 65536, or even bigger.

And the most challenging thing would be most of key calculations will be performed in JavaScript engine hosted inside browsers. And a distributed algorithm will be designed. Algorithm which is similar to Google’s Map/Reduce will be designed. And Apache Hadoop’s Map/Reduce is also in references.

Any comments about this challenge? Or join me to design the algorithm! Or join the distributed computing game.

Keep tuned for how big the number k would be!

PS: After searching around Internet for existed prime number theories, I find out that k=16 is already a challenge for me! There are algorithms to find prime number in format of 2^p+1, whose digits may be bigger than 1000000. But there are not the 1st k-digits algorithms. According to theories, I should have to find out all prime numbers less than given n. But the count of prime numbers less than n is about n / ln (n), which is huge number already for k=16! So my first challenge would be 16.

Actually, Google Talk Client’s Java SWT desktop copy is the original source for Google Talk Client’s JavaScript copy.

And now it is available for download. Please take a trial.

Sources of Java2Script Google Talk will be available in the next week. Keep tuned.

http://demo.java2script.org/gtalk/

Here is the screenshot:

En, in beta …

I am writing Java2Script’s Google Talk, and it uses a mode of continuation (also known as “Comet” application). In order to implement continuum data transfer between browser and server ( Tomcat in the backend ), I kept the HTTP connection blocked waiting for data to be available. In the middle, Apache httpd server is used and mod_jk is used to connect the two server.

But I met a ridiculous problem between servlet container and http server. When the browser is assigned to connect servlet directly, it can obtain data from the connection, but it can not obtain a bit when it is piped through Apache httpd server.

I tried to add “Transfer-Encoding: chunked” or “Content-length: 0″ but with no helps. And I modified jk.conf with “JkOptions +FlushPackets”, still with no helps. Finally, I remove a line of “writer.flush();” from my servlet source, and things all went correctly.

The line of “writer.flush();” was located in the the line when there is no data written to the response. And I considered that when there are no data in the response, calling flush method will hang mod_jk connector up. And the whole later data transfer will be disturbed.

More details about mod_jk, I recommend you to read “Tunning apache and tomcat for web 2.0 comet application“.

Update:
Finally I found out that “JkOptions +FlushPackets” works for me. #flush method problem is a fake problem. Only after I restart both Tomcat and Apache server do “JkOptions +FlushPackets” begin to work.