2006年9月20日

Install Oracle 11g R2 on Ubuntu

Ubuntu is not an official supported linux version from Oracle, so I still get some errors during the install process even with required configuration, anyway, it can work and what i'm doing here is try to setup an experiment environment, it's enough to me, any one who want to deploy Oracle in product mode should have supported linux platform like RedHat, OK, following is the steps i have to install it:

1. If you were in multihomed enviroment, set the ORACLE_HOSTNAME variable:
    export ORACLE_HOSTNAME=machine_name.domain_name

2. Create create OSDBA (dba) group, Oracle Inventory group (oinstall)  and a user "oracle" which has "dba" as its login group and oinstall as its 2nd group.

3. Modify /etc/sysctl.conf, set kernel parameter:

kernel.shmall = 2097152
kernel
.shmmax = 2147483648
kernel
.shmmni = 4096
kernel
.sem = 250 32000 100 128
fs
.file-max = 65536
net
.ipv4.ip_local_port_range = 1024 65000
net
.core.rmem_default = 1048576
net
.core.rmem_max = 1048576
net
.core.wmem_default = 262144
net
.core.wmem_max = 262144

4. Modify /etc/security/limits.conf to improve the "number of process" and "number of open file"  performance for oracle:
oracle              soft    nproc   2047
oracle              hard    nproc   
16384
oracle              soft    nofile  
1024
oracle              hard    nofile  
65536

5. Modify /etc/pam.d/login, add:
session    required     /lib/security/pam_limits.so
session    required     pam_limits
.so

6. Modify /etc/profile:
if [ $USER = "oracle" ]; then
        
if [ $SHELL = "/bin/ksh" ]; then
              ulimit 
-16384
              ulimit 
-65536
        
else
              ulimit 
-16384 -65536
        fi
fi

7. Change user to oracle if you haven't done it yet

8. Create base directory, for me it's "/app/oracle"

9. Export ORACLE_BASE, ORACLE_SID
export ORACLE_BASE=/app/oracle
export ORACLE_SID
=orcl

10.  If you're trying to install oracle with a X window:
DISPLAY=your.ip.address:0.0 ; export DISPLAY

11. run installer:
./runInstaller

12. Oracle should start, if the installer GUI cannot be start, check the error messages, most time it's because a wrong X window configuration, if you are running X window with Xming, just like me, please do make sure to check the "No Access Control" check box in the launch, otherwise, Xming will reject the connection.

13. Now the GUI shoudl open, like what you did in the Windows system, fullfill required value and click next, ingore all errors if there is any condition that is not match, click finish in the last step, it should start install process.

14. After install oracle, the installer GUI will ask you to run two .sh files, run it with a root role.

15. You can try to visit https://you.ip.address:1158/em to see is that OK for you.

16. How to start oracle:
export ORACLE_BASE=/app/oracle
export ORACLE_HOME
=/app/oracle/product/11.2.0/dbhome_1
export ORACLE_OWNR
=oracle
export ORACLE_SID
=orcl
export PATH
=$PATH:$ORACLE_HOME/bin


lsnrctl start

sqlplus 
/nolog
connect /as sysdba
startup
quit

emctl start dbconsole


Reference
http://download.oracle.com/docs/cd/B19306_01/install.102/b15660/pre_install.htm#BABDFJAE

posted @ 2010-03-16 15:57 Find it, try it, experience it 阅读(575) | 评论 (0)编辑 收藏

How to connect Reliance Modem AC2726 on Linux Ubuntu 9.10

1. Type command: lsusb
Bus 002 Device 003: ID 19d2:fff5 ONDA Communication S.p.A.
2. Install "usb-modeswitch", then re-plugin modem again and input command "lsusb" again, you should get the following output
Bus 002 Device 003: ID 19d2:fff1 ONDA Communication S.p.A.
3. Notice in step #2, the product code has been changed from "fff5" to "fff1".
4. Install package "wvdial" which is used to dail up
5. Type command: "sudo modprobe usbserial vendor=0x19d2 product=0xfff1", don't forget the "sudo"
6. Type command: "sudo wvdialconf", again don't forget the "sudo", this will detect your modem
7. Modify file "/etc/wvdial.conf", following is what I have:

[Dialer Defaults]
Init1 
= ATZ
Init2 
= ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Modem Type 
= Analog Modem
ISDN 
= 0
New PPPD 
= 1
Phone 
= #777
Modem = /dev/ttyUSB0
Username 
= yourName
Password 
= yourPassword
Baud 
= 921600
Stupid Mode 
= 1
Tonline 
= 0

8. Repeat step #5 again and then if you with not bad luck type in command "sudo wvdial", you should connect in.
9. If bad luck with you, click right-upper corner, there is a connection configuration menu, you can create "Mobile Broadband" connection yourself here, don't forget input the phone number "#777" (for China Telcom) and your username password, after that click connect, this works for me.
10. Good luck with you.
11. BTW, if it still cannot work, try to re-plug in the modem.

posted @ 2010-03-12 18:03 Find it, try it, experience it 阅读(380) | 评论 (0)编辑 收藏

Oracle Tips Part Two

1. It will not get data from DB when just open the cursor, data will be loaded as an ongoing basis.

2. SCN: System Change Number/System Commit Number

3. FLASH BACK AS OF SCN;

4. You can also flash back table: FLASHBACK TABLE SOME_TABLE TO SCN :SCN_NUM;

5. But before you do a flash back operation on a table, do make sure you have already enbale ROW MOVEMENT on that table.

posted @ 2010-03-07 18:03 Find it, try it, experience it 阅读(161) | 评论 (0)编辑 收藏

Oracle Tips One

1. Do use oracle "Bind variable", it can increase the speed by 90 percent in 10g release1.

2. Understand how to use "lock", read never block write,  vice verse.

3. There is a side effect from oracle regarding to the "lock", if you do want to control the access to one row at a specify time (like doing an if 'this row belong to some search condition' then 'modify this row' action), you have to write some logic yourself, for example use the "for update" statement, like: "select * from x where x.id = 1 for update", so that you can lock the row only with id equals to '1' and then modify this row, so that some orther concurrence requests should execute the same sql first, yes, with the same 'for update' statement, and because you already have locked this row(id = 1), orther requests cannot get the access to it, and you get the access control to this row.

4. Regardint to item 3, it will not decrease the concurrence level, because first you only lock the item with id equals to 1 and there maybe thousands of items in your table, second, it will not block the read request.

posted @ 2010-03-06 21:25 Find it, try it, experience it 阅读(213) | 评论 (0)编辑 收藏

算法求解!如何判断一个单向链表是否有环路?

这该死的问题让我竟然没有想到解决方案...脑子生锈了?呵呵,算了...

该问题最经典的解答,简直是一句话惊醒梦中人啊

“用两个指针,一个的步长为 1,另外一个的为 2,从表头开始一起往前走,如果相遇,表明有环路,否则就是没有了。”

下来,不用说什么了吧,用JAVA实现的话,声明两个Iterator A 和 B,A 每次调用两个NEXT,B只调用一次,如果他们能够相遇,就是有环...我操

posted @ 2009-03-02 14:15 Find it, try it, experience it 阅读(595) | 评论 (0)编辑 收藏

Something you may ingore when to use Hibernate and JPA.

The first is about identity generator, this is something I ingored and find really interesting later when I read back the document.

    When you choose "native" (for plain hibernate) or "AUTO" (for JPA which use hibernate as provider) as identity generator, it (actually they are the same identity generator but with different name in different scope) will pick other identity generators like identity, sequence, or hilo, depending on the capabilities of the underlying database. Use this generator to keep your mapping metadata portable to different database management systems.
    If your underlying DB is oracle, it will automatically create a sequence for you which means choose the sequence as identity generator, that's really interesting, at least for me for the first time when it comes to me.

The second is about the flush and close session operations when to use hibernate with JTA transaction.

    You should manually flush your operation by call flush method and close your session by calling close method when you try to use JTA transaction instead of hibernate Transaction API, these is because hibernate Transaction API does thoes operations automatically for you. But, with following configuration, it can also be done automatically for you by hibernate, though you are still with JTA transaction.

    hibernate.transaction.flush_before_completion=true
    hibernate.transaction.auto_close_session=true

The third is about an interesting code snatch listed as follow:
   
1     Session session = sessionFactory.openSession();
2     session.beginTransaction();
3     session.save(new Item());
4     session.close();

    What happen if you don't commit the transaction? It's depends on the underlying DB, for oracle it will commit any uncommited transactions, but for many other DB vendors, they will roll back any pending transactions.
   

posted @ 2008-04-03 16:32 Find it, try it, experience it 阅读(894) | 评论 (0)编辑 收藏

A "Hello" program on EJB3 with Jboss server 4.2.2GA (PART 3) - EJB3 Timer service.

    Timer service in EJB3 with anotation is fairly simple, I give you an example as follow, and it's really simple and self-explanation:
 1 package com.ramon.expejb3.session.impl;
 2 
 3 import javax.annotation.Resource;
 4 import javax.ejb.Stateless;
 5 import javax.ejb.Timeout;
 6 import javax.ejb.Timer;
 7 import javax.ejb.TimerService;
 8 
 9 import com.ramon.expejb3.session.Greeting;
10 
11 @Stateless(name = "Greeting")
12 public class GreetingBean implements Greeting {
13     
14     @Resource
15     TimerService ts;
16 
17     /* (non-Javadoc)
18      * @see com.ramon.expejb3.session.Greeting#greeting(java.lang.String)
19      */
20     public void greeting(String name) {
21         System.out.println("Hello " + name + ".");
22         ts.createTimer(1 * 10005 * 1000, name);
23         System.out.println("Create timer for " + name + ".");
24     }
25     
26     @Timeout
27     public void timeout(Timer timer) {
28         String name = (String)timer.getInfo();
29         System.out.println(name + " TIME OUT.");
30         //timer.cancel();
31     }
32 }
33
    It's the "GreetingBean" I introduced in part one of this series article with TimerService injected, @Resource anotation inject the time service we want, it's totally free which is supported by the J2EE container that means we do not need any further steps to get the powerful schedule service. In the line 22, I crate a new timer, I think this could be more fit if it was called Task instead, there are several "createTimer" methods with different parameters, the one I used here describe the task should be execute 1 second delay and every 5 second one time in the future, the third parameter can be anything you want to pass in to the task, it can be get back use method Timer.getInfo() like line 28 does here.
    Another important anotation here is the @Timeout anotation, this anotation tell container which method will be called when timeout for this task to be executed, you can only specify one timeout method for each Bean, if there is no @Timeout anotation at all, you will get some exception like "No timeout method specified" in Jboss server. Something funny here is that you should mark the timeout method as "public", otherwise, you will get the same error as no timeout method does, I do NOT think it's necessary, because the time out method should only be called by the container, "private" signature is enought for that, with "private" signature container still has the right to access this method with java reflection, nevertheless timer service in EJB3 is still a good tools for use.
    I summarize what good/bad for timer service in EJB3 as follow:
    Good news:
  •     It's free, it's supported by the EJB container.
  •     It's portable, it's supported by the EJB container as specified in EJB3 specification.
  •     It's easy to use, no need to learn more.
    Bad news:
  •     The feature of EJB3 timer sevice is not as powerful as some third party timer service such as Quartz, but it's enough with EJB3 for ordinary daily job.
  •     There is no UI for you to monitor the timer you created.

posted @ 2008-03-26 13:30 Find it, try it, experience it 阅读(1158) | 评论 (0)编辑 收藏

A "Hello" program on EJB3 with Jboss server 4.2.2GA (PART 2) - EJB3 MDB with Jboss server.

     摘要:     MDB is the MVP(most valuable player) both in previous EJB version and EJB3. Although coding with MDB is simple in EJB2.x, EJB3 make it much more friendly to you. Let's get to the ...  阅读全文

posted @ 2008-03-25 17:42 Find it, try it, experience it 阅读(1103) | 评论 (0)编辑 收藏

A "Hello" program on EJB3 with Jboss server 4.2.2GA.

    Recently I did some research on EJB3 programming, find that it's really simple than programming with previous EJB version. Coding in EJB2.X or previous version is really a nightmare for most developers, maybe for this, EJB3 gives me much more impression than Spring when it first comes to me, this article is the first one of these series articles which record the new knowledge I find interesting in EJB3.

    Well, let's begin.

    EJB3 is simple with AOP and DI, there is no Home interface any more, only with Service Interface and your Service implementation you can create an typical EJB3 application. I will create a simple hello world program in this article, the service interface as follow:

 1 package com.ramon.expejb3.session;
 2 
 3 import javax.ejb.Remote;
 4 
 5 @Remote
 6 public interface Greeting {
 7     
 8     /**
 9      * say hello test
10      * @param name
11      */
12     void greeting(String name);
13 
14 }

    It's really simple, especially for you that are familiar with programing with Interface, after that is the service implementation code:
 1 package com.ramon.expejb3.session.impl;
 2 
 3 import javax.annotation.PostConstruct;
 4 import javax.annotation.PreDestroy;
 5 import javax.ejb.Stateless;
 6 
 7 import com.ramon.expejb3.session.Greeting;
 8 
 9 @Stateless(name = "Greeting")
10 public class GreetingBean implements Greeting {
11     
12     @PostConstruct
13     public void init() {
14         System.out.println("Init Greeting Bean.");
15     }
16     
17     @PreDestroy
18     public void destroy() {
19         System.out.println("Garbage collect Greeting Bean.");
20     }
21 
22     /* (non-Javadoc)
23      * @see com.ramon.expejb3.session.Greeting#greeting(java.lang.String)
24      */
25     public void greeting(String name) {
26         System.out.println("Hello " + name + ".");
27     }
28 }
29 
    Still simple and very self-explanation, @Stateless(name = "Greeting") specify the JNDI name for client invocation. OK, that's all for our EJB jar file, no more file needed for this simple hello application. Execute your ANT script make a jar for it, part of ANT script may look like:
 1     <target name="prepareexpejb3" description="Create exp_jsf distribution.">
 2         <mkdir dir="${dist.dir}" />
 3         <mkdir dir="${build.dir}" />
 4         <mkdir dir="${build.core.dir}"/>
 5     </target>
 6 
 7     <!-- ================================= 
 8           target: Compile expejb3 classes      
 9          ================================= -->
10     <target name="compileexpejb3" depends="cleanDist,prepareexpejb3">
11         <javac destdir="${build.core.dir}" debug="yes" deprecation="on" srcdir="${src.dir}">
12             <include name="${core.src.dir}/**" />
13             <classpath refid="expejb3.classpath" />
14         </javac>
15         
16     </target>
17 
18     <!-- ================================= 
19           target: Create EJB3 jar
20          ================================= -->
21     <target name="createEJB3Jar" depends="compileexpejb3">
22         <jar jarfile="${dist.dir}/${expejb3.core.name}.jar">
23             <fileset dir="${build.core.dir}"></fileset>
24         </jar>
25     </target>

    Put the EJB jar into jboss server server\default\deploy, you should see some log from jboss console like:
   
1 10:59:27,036 INFO  [JmxKernelAbstraction] creating wrapper delegate for: org.jboss.ejb3.stateless.St
2 atelessContainer
3 10:59:27,051 INFO  [JmxKernelAbstraction] installing MBean: jboss.j2ee:jar=expejb3core.jar,name=Gree
4 ting,service=EJB3 with dependencies:
5 10:59:27,208 INFO  [EJBContainer] STARTED EJB: com.ramon.expejb3.session.impl.GreetingBean ejbName:
6 Greeting
    Which mean that you have successfully deploy your EJB into jboss server, create a client code to invoke your EJB service:
 1 package com.ramon.expejb3.session;
 2 
 3 import java.util.Properties;
 4 
 5 import javax.naming.Context;
 6 import javax.naming.InitialContext;
 7 
 8 import junit.framework.TestCase;
 9 
10 public class ExpEJB3BaseTestCase extends TestCase {
11 
12     private Properties properties = null;
13     
14     private Context context;
15 
16     protected void setUp() throws Exception {
17         super.setUp();
18         properties = new Properties();
19         properties.put("java.naming.factory.initial""org.jnp.interfaces.NamingContextFactory");
20         properties.put("java.naming.factory.url.pkgs""org.jboss.naming:org.jnp.interfaces");
21         properties.put("java.naming.provider.url""localhost:1099");
22         context = new InitialContext(properties);
23     }
24 
25     protected void tearDown() throws Exception {
26         super.tearDown();
27         context = null;
28         properties = null;
29     }
30 
31     public final Context getContext() {
32         return context;
33     }
34 
35     public final void setContext(Context context) {
36         this.context = context;
37     }
38 
39 }
40 

 1 package com.ramon.expejb3.session.impl;
 2 
 3 import javax.naming.NamingException;
 4 
 5 import com.ramon.expejb3.session.ExpEJB3BaseTestCase;
 6 import com.ramon.expejb3.session.Greeting;
 7 
 8 public class GreetingBeanTest extends ExpEJB3BaseTestCase {
 9 
10     public void testGreeting() {
11         try {
12             Greeting greetService = (Greeting)this.getContext().lookup("Greeting/remote");
13             greetService.greeting("Ramon");
14         } catch (NamingException e) {
15             // TODO Auto-generated catch block
16             e.printStackTrace();
17         }
18     }
19 
20 }
21 
    That's really simple, right? What you should note is that you must include following jars into your classpath when you run this clien test case, otherwise you will get the annoying classNotFound Exception:
 1 concurrent.jar
 2 jboss-aop-jdk50.jar
 3 jboss-aspect-library-jdk50.jar
 4 jboss-common.jar
 5 jboss-ejb3.jar
 6 jboss-ejb3-client.jar
 7 jboss-remoting.jar
 8 jbossx-client.jar
 9 jboss-transaction-client.jar
10 jnp-client.jar


 

   

posted @ 2008-03-21 16:02 Find it, try it, experience it 阅读(1784) | 评论 (0)编辑 收藏

编码字符集与Java -Java World乱码问题根源之所在。

     摘要: 本文介绍了编码字符集的概念以及Java与编码字符集之间的关系,文章的内容来自于本人工作过程中的经验积累以及网络中的相关文章介绍,如果文章中有任何纰漏欢迎读者指正,让我们共同讨论学习J1.      字符字符是抽象的最小文本单位。它没有固定的形状(可能是一个字形),而且没有值。“A”是一个字符,“€”(德国、法国和许多其他欧洲国家通用货币的标志)也是一个字符。“中”“国”这是两个汉字字符。字符仅仅代...  阅读全文

posted @ 2006-09-24 00:08 Find it, try it, experience it 阅读(9341) | 评论 (5)编辑 收藏

计算机中[1]和[-1]的趣事.

首先感谢南老师!

      在计算机里的有符号数,最高位的1用来表示负号,所以,用 0000 0001表示正1,1000 0001表示-1,确实对人来说很直观。但其实,计算机里的数是用“补码”表示的。其中正数的补码就是原来的数(称为原码),而负数的补码是这么算的,我用倒推的来说:
      补码 = 反码 + 1
      反码 = 原码按位取反(1变0,0变1)
      所以,-1就是1取补码,过程如下:
      先取反 0000 0001 ---> 1111 1110 
      然后加1得补码: 1111 1110 + 1 = 1111 1111 
    (当然这里为了方便,就取了8位,其实整数现在都是32位了,结果是32个1)。

     现在,你知道如何计算-2了吗? 为什么要搞反码,补码这么个转换呢? 这个原因要说长就很长的,但简单地讲,这又是一个在人的直观和机器的高效之间取一个平衡:
     我们先来看一个10进制的数运算:
     1 + (-1) = 0 //10进制中,1加负1应为0.
     然后,假如用1000 0001来表示-1的话。按照计算机计算加法的规则,它是每位加的,结果是:
     0000 0001 + 1000 0001 = 1000 0010  //-2
     结果变成-2了,其中后面两个0001 相加变成2,而前面的用于表示负号的1,被“继承”下来了……显然,原来计算机最直观的(对人来说也很直观的)算法,不灵了!怎么办?痛苦

    但更痛苦的事还在0这个数上。按10进制,0和-0可是完全相等的。但如果用二进制,0000 0000 和 1000 0000 参加起运算,可是完全不同。或许可以通过电路设计,来强制让计算机去实现一个规则: 碰到1000 0000就先转换为0000 0000。但可要知道加减法计算是计算机计算一切的基础,如果从这最底层就必须有一个转换会极大影响性能!何况前面那个问题也必须有个强制规则!规则最好越简单越好,那就是规定前面的补码转换规则,这个转换过程对于计算机来说很迅速的逻辑电路转换。

    你看,第一个问题 1 + (-1)
    0000 0001 + 1111 1111 = 0000 0000 
    看明白这个计算过程吗?其实就是最低位的两个1相加后,造成每一位都进位,最高位直接溢出(丢了)。如果你还算不清,就算算这个10进制的:
    1 + 999 =  1000 (最高位1丢失,就成0了)
    然后是第二个问题,0的表示。如果您把0当成正数,那么它是这样表示的:
    0000 0000
    如果你当它是负数,那么
    取反 1111 1111 ,再加1,以求补 ,哈哈又成 0000 0000这回在逻辑上没有错误了!明白了吧?当补我在学习这一段知识时,只能说:高,实在高! 想出补码的前辈,真是高人啊。

posted @ 2006-09-20 20:59 Find it, try it, experience it 阅读(209) | 评论 (0)编辑 收藏

<2006年9月>
272829303112
3456789
10111213141516
17181920212223
24252627282930
1234567

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