Components in Java

Component

 

1) In programming and engineering disciplines, a component is an identifiable part of a larger program or construction. Usually, a component provides a particular function or group of related functions. In programming design, a system is divided into components that in turn are made up of modules . Component test means testing all related modules that form a component as a group to make sure they work together.

2) In object-oriented programming and distributed object technology, a component is a reusable program building block that can be combined with other components in the same or other computers in a distributed network to form an application. Examples of a component include: a single button in a graphical user interface, a small interest calculator, an interface to a database manager. Components can be deployed on different servers in a network and communicate with each other for needed services. A component runs within a context called a container . Examples of containers include pages on a Web site, Web browsers, and word processors.

Sun Microsystems, whose JavaBeans application program interface defines how to create component, defines "a component model" as typically providing these major types of services:

• Component interface exposure and discovery. Thus, during application use, one component can interrogate another one to discover its characteristics and how to communicate with it. This allows different companies (possibly independent service providers) to create components that can interoperate with the components of other companies without either having to know in advance exactly which components it will be working with.
• Component properties. This allows a component to make its characteristics publicly visible to other components.
• Event handling. This allows one component to identify to one or more other components that an event (such as a user pressing a button) has occurred so that the component can respond to it. In Sun's example, a component that provided a button user interface for a finance application would "raise" an event when the button was pressed, resulting in a graph-calculating component gaining control, formulating a graph, and displaying it to the user.
• Persistence. This allows the state of components to be preserved for later user sessions.
• Application builder support. A central idea of components is that they will not only be easy and flexible for deploying in a distributed network, but that developers can easily create new components and see the properties of existing ones.
• Component packaging. Since a component may comprise several files, such as icons and other graphical files, Sun's component model includes a facility for packaging the files in a single file format that can be easily administered and distributed. (Sun calls their component package a JAR (Java Archive) file format.)

My rage! My passion! My despiration

Our tuition sir was very handsome and rich, most of females used to die for him. He is my favourite sir, I liked his intelligence. He is creating now a very novel frame work. I worship him as a Teacher, he guided me all through my career. He is my idol. He got mesmerized at my passion on Java. He says, "I have never seen a female who is so dedicated to the Java as you are." He was available all the time for me. He used to wake up at 3:00Am in the morning and just to solve my queries.

5 years back, one of my male classmate said, "Females are meant to be in kitchen, they can only love a male and write a lot in notes and fit for nothing. They can't do the job, and Java forget it. Females are pathetic little creatures."





That changed my destiny!

Totally changed my thoughts:

I got this rage,
I got this desperation,
I got this anger.

Fear of failing and letting every female was growing in me. I was scared if I fail he will win. Most of males still think in that way. Make fun of females. Come on, give me a break. I have that rage even now, that helped me to work like hell. Working became my only passion. I wanted to prove those disgusting, filthy, jealous, creepy, gross, envious males that females can do more than cooking. We can do everything. In fact you males are pathetic.

At home we are humble and at work we are perfect. I tried to create this rage in every female I meet. I wanted every female to grow aggressive in her career. It's my bad, that I found some of males who work in IT industry still think females are fit for nothing but just a tool in making others work. Come on!

There are males who are worse than a normal female in intelligence. I have seen such a pathetic males at work. I was like saying Jesus! They are stupids. Males you have to learn respecting females. Technology is growing to unimaginable heights but your minds are not growing according to the Technology. I have this passion because of that one male who said "females are useless." No we are not. In India, we are sacrifices, we are invisible, but we are the pillars of a family.

In India, a wife decides a fate of a family. If she is intelligent that family shines, if she is stupid, that family is in ruins. Without females contribution you males are nothing but mere beasts. Oh! Ya I have that anger still in me.

I will achieve something, I will never stop until and unless I establish a giant organization. I will fight until my last breath. I would rather try and fail than give up.

Sequences in 10G RAC

Sequences in 10G RAC

Recently we migrated our application to Oracle 10g RAC (3 Instance) and ended up with sequences created as out of order at each Instance.

Here is the snippet of code to demonstrate that.

rajesh@ORA10GR2-01> SELECT INST_ID,
  2    INSTANCE_NUMBER,
  3    INSTANCE_NAME
  4  FROM GV$INSTANCE
  5  ORDER BY INST_ID;

   INST_ID INSTANCE_NUMBER INSTANCE_NAME
---------- --------------- ----------------
         1               1 ORA10GR2-01
         2               2 ORA10GR2-02
         3               3 ORA10GR2-03


 rajesh@ORA10GR2-01> create sequence s CACHE 30;

Sequence created.

Elapsed: 00:00:00.07
rajesh@ORA10GR2-01> select SEQUENCE_NAME,ORDER_FLAG,CACHE_SIZE
  2  from user_sequences
  3  where sequence_name ='S'
  4  /

SEQUENCE_NAME                  O CACHE_SIZE
------------------------------ - ----------
S                              N         30

Elapsed: 00:00:00.17
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01> select s.nextval from dual;

   NEXTVAL
----------
         1

Elapsed: 00:00:00.14
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01> select s.nextval from dual;

   NEXTVAL
----------
         2

Elapsed: 00:00:00.25
rajesh@ORA10GR2-01>

When connecting back to Instance02 I found the sequence values different.

rajesh@ORA10GR2-01> connect rajesh/oracle@ORA10GR2-02
Connected.
rajesh@ORA10GR2-02> select s.nextval from dual;

   NEXTVAL
----------
        31

Elapsed: 00:00:00.48
rajesh@ORA10GR2-02>
rajesh@ORA10GR2-02> select s.nextval from dual;

   NEXTVAL
----------
        32

Elapsed: 00:00:00.15
rajesh@ORA10GR2-02>

When connecting back to Instance03 I found the sequence values different again.

rajesh@ORA10GR2-02> connect rajesh/oracle@ORA10GR2-03
Connected.
rajesh@ORA10GR2-03> select s.nextval from dual;

   NEXTVAL
----------
        61

Elapsed: 00:00:00.21
rajesh@ORA10GR2-03> select s.nextval from dual;

   NEXTVAL
----------
        62

Elapsed: 00:00:00.14
rajesh@ORA10GR2-03>
The reason for this out of order sequence at each instance is the sequence cache is in the shared pool, therefore sessions on the same node can share the cached entry, but sessions on different nodes cannot.

The solution to solve this sequence running out of order at each instance is to create sequence using ORDER option. which will guarantee the order in which numbers are generated.

rajesh@ORA10GR2-01> create sequence s CACHE 30 ORDER;

Sequence created.

Elapsed: 00:00:00.09
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01> select SEQUENCE_NAME,ORDER_FLAG,CACHE_SIZE
  2  from user_sequences
  3  where sequence_name ='S'
  4  /

SEQUENCE_NAME                  O CACHE_SIZE
------------------------------ - ----------
S                              Y         30

Elapsed: 00:00:00.10
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01> select s.nextval from dual;

   NEXTVAL
----------
         1

Elapsed: 00:00:00.17
rajesh@ORA10GR2-01> select s.nextval from dual;

   NEXTVAL
----------
         2

Elapsed: 00:00:00.34
rajesh@ORA10GR2-01>
Connecting back to Instance02.

rajesh@ORA10GR2-01> connect rajesh/oracle@ORA10GR2-02

Connected.
rajesh@ORA10GR2-02> select s.nextval from dual;

   NEXTVAL
----------
         3

Elapsed: 00:00:00.17
rajesh@ORA10GR2-02>
rajesh@ORA10GR2-02> select s.nextval from dual;

   NEXTVAL
----------
         4

Elapsed: 00:00:00.17
rajesh@ORA10GR2-02>
Connecting back to Instance03.

rajesh@ORA10GR2-02> connect rajesh/oracle@ORA10GR2-03
Connected.
rajesh@ORA10GR2-03> select s.nextval from dual;

   NEXTVAL
----------
         5

Elapsed: 00:00:00.14
rajesh@ORA10GR2-03>
rajesh@ORA10GR2-03> select s.nextval from dual;

   NEXTVAL
----------
         6

Elapsed: 00:00:00.17
rajesh@ORA10GR2-03>

We changed the sequence to "ordered" Now selecting on either node gets the next number as expected.

However having the sequence with CACHE and ORDER would lead to some performance implications due to cluster synchronization. In Oracle 10g RAC, if you specify the "ordered" clause for a sequence, then a global lock is allocated by the node when you access the sequence. This lock acquisition happens only at the first sequence access for the node, and subsequent uses of the sequence do not wait on this lock.


rajesh@ORA10GR2-01> create sequence s order;

Sequence created.

Elapsed: 00:00:00.01
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01> select SEQUENCE_NAME,ORDER_FLAG,CACHE_SIZE
  2  from user_sequences
  3  where sequence_name ='S';

SEQUENCE_NAME                  O CACHE_SIZE
------------------------------ - ----------
S                              Y         20

Elapsed: 00:00:00.01
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01>
Connected.
rajesh@ORA10GR2-01>

I was running the below Pl/SQL block evenly across all the RAC Instance.

rajesh@ORA10GR2-01>  declare
  2             k number;
  3             l_start number;
  4             l_cpu_time number;
  5     begin
  6             l_start := dbms_utility.get_time;
  7             l_cpu_time := dbms_utility.get_cpu_time;
  8     for i in 1..500000
  9     loop
 10                     select s.nextval
 11                     into k
 12                     from dual;
 13     end loop;
 14
 15             dbms_output.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
 16             dbms_output.put_line (' Total CPU time = '|| (dbms_utility.get_cpu_time - l_cpu_time) );
 17     end;
 18  /

 Total Execution time = 82110
 Total CPU time = 7057

PL/SQL procedure successfully completed.

Elapsed: 00:13:40.99
rajesh@ORA10GR2-01>

And the AWR on Instance 1 is.

   SQL Id      Time (ms)
------------- ----------
9x2hyv1prpts9    802,038
Module: SQL*Plus
OUTPUT
--------------------------------------------------------------------------------
 declare k number; l_start number; l_cpu_time number; begin l_start :=
dbms_utility.get_time; l_cpu_time := dbms_utility.get_cpu_time; for i in 1..5
00000 loop select s.nextval into k from dual; end loop; dbms_outpu
t.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
          -------------------------------------------------------------
SQL ID: 9x2hyv1prpts9              DB/Inst: IRDST01/irdst011  Snaps: 3518-3519
-> 1st Capture and Last Capture Snap IDs
   refer to Snapshot IDs witin the snapshot range
-> declare k number; l_start number; l_cpu_time number; begin l...
OUTPUT
--------------------------------------------------------------------------------
    Plan Hash           Total Elapsed                 1st Capture   Last Capture
#   Value                    Time(ms)    Executions       Snap ID        Snap ID
--- ---------------- ---------------- ------------- ------------- --------------
1   0                         802,038             1          3519           3519
          -------------------------------------------------------------
Plan 1(PHV: 0)
--------------
OUTPUT
--------------------------------------------------------------------------------
Plan Statistics                    DB/Inst: IRDST01/irdst011  Snaps: 3518-3519
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Stat Name                                Statement   Per Execution % Snap
---------------------------------------- ---------- -------------- -------
Elapsed Time (ms)                           802,038      802,037.9    30.0
CPU Time (ms)                                70,597       70,597.3    93.7
Executions                                        1            N/A     N/A
Buffer Gets                                 149,976      149,976.0    56.6
Disk Reads                                        3            3.0     7.7
OUTPUT
--------------------------------------------------------------------------------
Parse Calls                                       1            1.0     0.0
Rows                                              1            1.0     N/A
User I/O Wait Time (ms)                          45            N/A     N/A
Cluster Wait Time (ms)                      186,959            N/A     N/AApplication Wait Time (ms)                        0            N/A     N/A
Concurrency Wait Time (ms)                   13,813            N/A     N/AInvalidations                                     0            N/A     N/A
Version Count                                     1            N/A     N/A
Sharable Mem(KB)                                 20            N/A     N/A
          -------------------------------------------------------------

And the AWR on Instance 2 is.

                Elapsed
   SQL Id      Time (ms)
------------- ----------
9x2hyv1prpts9    818,718
Module: SQL*Plus
OUTPUT
--------------------------------------------------------------------------------
 declare k number; l_start number; l_cpu_time number; begin l_start :=
dbms_utility.get_time; l_cpu_time := dbms_utility.get_cpu_time; for i in 1..5
00000 loop select s.nextval into k from dual; end loop; dbms_outpu
t.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
          -------------------------------------------------------------
SQL ID: 9x2hyv1prpts9              DB/Inst: IRDST01/irdst012  Snaps: 3518-3519
-> 1st Capture and Last Capture Snap IDs
   refer to Snapshot IDs witin the snapshot range
-> declare k number; l_start number; l_cpu_time number; begin l...
OUTPUT
--------------------------------------------------------------------------------
    Plan Hash           Total Elapsed                 1st Capture   Last Capture
#   Value                    Time(ms)    Executions       Snap ID        Snap ID
--- ---------------- ---------------- ------------- ------------- --------------
1   0                         818,718             1          3519           3519
          -------------------------------------------------------------
Plan 1(PHV: 0)
--------------
OUTPUT
--------------------------------------------------------------------------------
Plan Statistics                    DB/Inst: IRDST01/irdst012  Snaps: 3518-3519
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Stat Name                                Statement   Per Execution % Snap
---------------------------------------- ---------- -------------- -------
Elapsed Time (ms)                           818,718      818,718.5    31.7
CPU Time (ms)                                72,017       72,017.1    97.5
Executions                                        1            N/A     N/A
Buffer Gets                                 149,898      149,898.0    81.6
Disk Reads                                        0            0.0     0.0
OUTPUT
--------------------------------------------------------------------------------
Parse Calls                                       1            1.0     0.0
Rows                                              1            1.0     N/A
User I/O Wait Time (ms)                           0            N/A     N/A
Cluster Wait Time (ms)                      135,191            N/A     N/A
Application Wait Time (ms)                        0            N/A     N/A
Concurrency Wait Time (ms)                   14,768            N/A     N/A
Invalidations                                     0            N/A     N/A
Version Count                                     1            N/A     N/A
Sharable Mem(KB)                                 20            N/A     N/A
          -------------------------------------------------------------

And the AWR on Instance 3 is.

                Elapsed
   SQL Id      Time (ms)
------------- ----------
9x2hyv1prpts9    816,826
Module: SQL*Plus
OUTPUT
--------------------------------------------------------------------------------
 declare k number; l_start number; l_cpu_time number; begin l_start :=
dbms_utility.get_time; l_cpu_time := dbms_utility.get_cpu_time; for i in 1..5
00000 loop select s.nextval into k from dual; end loop; dbms_outpu
t.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
          -------------------------------------------------------------
SQL ID: 9x2hyv1prpts9              DB/Inst: IRDST01/irdst013  Snaps: 3518-3519
-> 1st Capture and Last Capture Snap IDs
   refer to Snapshot IDs witin the snapshot range
-> declare k number; l_start number; l_cpu_time number; begin l...
OUTPUT
--------------------------------------------------------------------------------
    Plan Hash           Total Elapsed                 1st Capture   Last Capture
#   Value                    Time(ms)    Executions       Snap ID        Snap ID
--- ---------------- ---------------- ------------- ------------- --------------
1   0                         816,826             1          3519           3519
          -------------------------------------------------------------
Plan 1(PHV: 0)
--------------
OUTPUT
--------------------------------------------------------------------------------
Plan Statistics                    DB/Inst: IRDST01/irdst013  Snaps: 3518-3519
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Stat Name                                Statement   Per Execution % Snap
---------------------------------------- ---------- -------------- -------
Elapsed Time (ms)                           816,826      816,826.4    97.8
CPU Time (ms)                                68,859       68,858.5    90.9
Executions                                        1            N/A     N/A
Buffer Gets                                 133,660      133,660.0    28.3
Disk Reads                                        0            0.0     0.0
OUTPUT
--------------------------------------------------------------------------------
Parse Calls                                       1            1.0     0.0
Rows                                              1            1.0     N/A
User I/O Wait Time (ms)                           0            N/A     N/A
Cluster Wait Time (ms)                       25,148            N/A     N/A
Application Wait Time (ms)                        0            N/A     N/A
Concurrency Wait Time (ms)                    8,942            N/A     N/A
Invalidations                                     0            N/A     N/A
Version Count                                     1            N/A     N/A
Sharable Mem(KB)                                 20            N/A     N/A
          -------------------------------------------------------------

Due to the less CACHE sequence value and ORDER attribute and since the same sequence is shared across all Instance we ended up with Clustered & Concurrency waits.

Now repeting the same test with Increased CACHE size.

rajesh@ORA10GR2-01> create sequence s CACHE 100000 order;

Sequence created.

Elapsed: 00:00:00.03
rajesh@ORA10GR2-01>
rajesh@ORA10GR2-01> select SEQUENCE_NAME,ORDER_FLAG,CACHE_SIZE
  2  from user_sequences
  3  where sequence_name ='S';

SEQUENCE_NAME                  O CACHE_SIZE
------------------------------ - ----------
S                              Y     100000

Elapsed: 00:00:00.01 

rajesh@ORA10GR2-01>  declare
  2             k number;
  3             l_start number;
  4             l_cpu_time number;
  5     begin
  6             l_start := dbms_utility.get_time;
  7             l_cpu_time := dbms_utility.get_cpu_time;
  8     for i in 1..500000
  9     loop
 10                     select s.nextval
 11                     into k
 12                     from dual;
 13     end loop;
 14
 15             dbms_output.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
 16             dbms_output.put_line (' Total CPU time = '|| (dbms_utility.get_cpu_time - l_cpu_time) );
 17     end;
 18  /

 Total Execution time = 32396
 Total CPU time = 3418

PL/SQL procedure successfully completed.

Elapsed: 00:05:23.96
rajesh@ORA10GR2-01>

AWR at Instance-01 shows

                Elapsed
   SQL Id      Time (ms)
------------- ----------
9x2hyv1prpts9    316,430
Module: SQL*Plus
OUTPUT
--------------------------------------------------------------------------------
 declare k number; l_start number; l_cpu_time number; begin l_start :=
dbms_utility.get_time; l_cpu_time := dbms_utility.get_cpu_time; for i in 1..5
00000 loop select s.nextval into k from dual; end loop; dbms_outpu
t.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
          -------------------------------------------------------------
SQL ID: 9x2hyv1prpts9              DB/Inst: IRDST01/irdst011  Snaps: 3520-3521
-> 1st Capture and Last Capture Snap IDs
   refer to Snapshot IDs witin the snapshot range
-> declare k number; l_start number; l_cpu_time number; begin l...
OUTPUT
--------------------------------------------------------------------------------
    Plan Hash           Total Elapsed                 1st Capture   Last Capture
#   Value                    Time(ms)    Executions       Snap ID        Snap ID
--- ---------------- ---------------- ------------- ------------- --------------
1   0                         316,430             1          3521           3521
          -------------------------------------------------------------
Plan 1(PHV: 0)
--------------
OUTPUT
--------------------------------------------------------------------------------
Plan Statistics                    DB/Inst: IRDST01/irdst011  Snaps: 3520-3521
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Stat Name                                Statement   Per Execution % Snap
---------------------------------------- ---------- -------------- -------
Elapsed Time (ms)                           316,430      316,429.6    91.0
CPU Time (ms)                                34,199       34,198.8    87.9
Executions                                        1            N/A     N/A
Buffer Gets                                     118          118.0     0.9
Disk Reads                                        0            0.0     0.0
OUTPUT
--------------------------------------------------------------------------------
Parse Calls                                       1            1.0     0.1
Rows                                              1            1.0     N/A
User I/O Wait Time (ms)                           0            N/A     N/A
Cluster Wait Time (ms)                            4            N/A     N/AApplication Wait Time (ms)                        0            N/A     N/A
Concurrency Wait Time (ms)                        8            N/A     N/AInvalidations                                     0            N/A     N/A
Version Count                                     1            N/A     N/A
Sharable Mem(KB)                                 20            N/A     N/A
          -------------------------------------------------------------

AWR at Instance-02 shows

--------------------------------------------------------------------------------
 declare k number; l_start number; l_cpu_time number; begin l_start :=
dbms_utility.get_time; l_cpu_time := dbms_utility.get_cpu_time; for i in 1..5
00000 loop select s.nextval into k from dual; end loop; dbms_outpu
t.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
          -------------------------------------------------------------
SQL ID: 9x2hyv1prpts9              DB/Inst: IRDST01/irdst012  Snaps: 3520-3521
-> 1st Capture and Last Capture Snap IDs
   refer to Snapshot IDs witin the snapshot range
-> declare k number; l_start number; l_cpu_time number; begin l...
OUTPUT
--------------------------------------------------------------------------------
    Plan Hash           Total Elapsed                 1st Capture   Last Capture
#   Value                    Time(ms)    Executions       Snap ID        Snap ID
--- ---------------- ---------------- ------------- ------------- --------------
1   0                         320,198             1          3521           3521
          -------------------------------------------------------------
Plan 1(PHV: 0)
--------------
OUTPUT
--------------------------------------------------------------------------------
Plan Statistics                    DB/Inst: IRDST01/irdst012  Snaps: 3520-3521
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Stat Name                                Statement   Per Execution % Snap
---------------------------------------- ---------- -------------- -------
Elapsed Time (ms)                           320,198      320,198.1    96.7
CPU Time (ms)                                36,561       36,561.4    92.0
Executions                                        1            N/A     N/A
Buffer Gets                                      59           59.0     0.7
Disk Reads                                        0            0.0     0.0
OUTPUT
--------------------------------------------------------------------------------
Parse Calls                                       1            1.0     0.1
Rows                                              1            1.0     N/A
User I/O Wait Time (ms)                           0            N/A     N/A
Cluster Wait Time (ms)                           12            N/A     N/A
Application Wait Time (ms)                        0            N/A     N/A
Concurrency Wait Time (ms)                        9            N/A     N/AInvalidations                                     0            N/A     N/A
Version Count                                     1            N/A     N/A
Sharable Mem(KB)                                 20            N/A     N/A
          -------------------------------------------------------------

AWR at Instance-03 shows

--------------------------------------------------------------------------------
 declare k number; l_start number; l_cpu_time number; begin l_start :=
dbms_utility.get_time; l_cpu_time := dbms_utility.get_cpu_time; for i in 1..5
00000 loop select s.nextval into k from dual; end loop; dbms_outpu
t.put_line (' Total Execution time = '|| (dbms_utility.get_time - l_start) );
          -------------------------------------------------------------
SQL ID: 9x2hyv1prpts9              DB/Inst: IRDST01/irdst013  Snaps: 3520-3521
-> 1st Capture and Last Capture Snap IDs
   refer to Snapshot IDs witin the snapshot range
-> declare k number; l_start number; l_cpu_time number; begin l...
OUTPUT
--------------------------------------------------------------------------------
    Plan Hash           Total Elapsed                 1st Capture   Last Capture
#   Value                    Time(ms)    Executions       Snap ID        Snap ID
--- ---------------- ---------------- ------------- ------------- --------------
1   0                         318,115             1          3521           3521
          -------------------------------------------------------------
Plan 1(PHV: 0)
--------------
OUTPUT
--------------------------------------------------------------------------------
Plan Statistics                    DB/Inst: IRDST01/irdst013  Snaps: 3520-3521
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Stat Name                                Statement   Per Execution % Snap
---------------------------------------- ---------- -------------- -------
Elapsed Time (ms)                           318,115      318,115.2    92.6
CPU Time (ms)                                31,745       31,745.2    83.8
Executions                                        1            N/A     N/A
Buffer Gets                                      47           47.0     0.0
Disk Reads                                        0            0.0     0.0
OUTPUT
--------------------------------------------------------------------------------
Parse Calls                                       1            1.0     0.1
Rows                                              1            1.0     N/A
User I/O Wait Time (ms)                           0            N/A     N/A
Cluster Wait Time (ms)                           11            N/A     N/A
Application Wait Time (ms)                        0            N/A     N/A
Concurrency Wait Time (ms)                        5            N/A     N/AInvalidations                                     0            N/A     N/A
Version Count                                     1            N/A     N/A
Sharable Mem(KB)                                 20            N/A     N/A
          -------------------------------------------------------------

Now the Cluster Wait Time & Concurrency Wait Time got reduced due to Increased CACHE size. which leads to less synchronization across RAC Instances.

Java Messaging Service - Consumer / Subscriber

package oc.test.olivia;


import javax.jms.*;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;

/*
 * @author Olivia Cassandrae
 */
public class Consumer {

    public static void main(String[] args) throws JMSException {
        ConnectionFactory connectionFactory
            = new ActiveMQConnectionFactory(url);
        Connection connection = connectionFactory.createConnection();
        connection.start();
        Session session = connection.createSession(false,
            Session.AUTO_ACKNOWLEDGE);
        Destination destination = session.createQueue(subject);
        MessageConsumer consumer = session.createConsumer(destination);
        Message message = consumer.receive();
        if (message instanceof TextMessage) {
            TextMessage textMessage = (TextMessage) message;
            System.out.println("Received message '"
                + textMessage.getText() + "'");
        }
        connection.close();
    }
   
    // URL of the JMS server
    private static String url = ActiveMQConnection.DEFAULT_BROKER_URL;
    private static String subject = "GROUNDOPS.PSCS.IROPS.BRIDGE.QUEUE";
}

Url: http://localhost:8161/admin

Java Messaging Service - Producer / Publisher

Exception:


ConnectionFactory is ::: org.apache.activemq.ActiveMQConnectionFactory
javax.jms.JMSException: Could not connect to broker URL: tcp://PDCHCL-TRAX9:61616. Reason: java.net.ConnectException: Connection refused: connect
at org.apache.activemq.util.JMSExceptionSupport.create(JMSExceptionSupport.java:35)
at org.apache.activemq.ActiveMQConnectionFactory.createActiveMQConnection(ActiveMQConnectionFactory.java:278)
at org.apache.activemq.ActiveMQConnectionFactory.createActiveMQConnection(ActiveMQConnectionFactory.java:222)
at org.apache.activemq.ActiveMQConnectionFactory.createQueueConnection(ActiveMQConnectionFactory.java:185)
at com.test.IROPSQueueApacheMQProducer.main(IROPSQueueApacheMQProducer.java:58)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at org.apache.activemq.transport.tcp.TcpTransport.connect(TcpTransport.java:414)
at org.apache.activemq.transport.tcp.TcpTransport.doStart(TcpTransport.java:380)
at org.apache.activemq.util.ServiceSupport.start(ServiceSupport.java:50)
at org.apache.activemq.transport.TransportFilter.start(TransportFilter.java:57)
at org.apache.activemq.transport.TransportFilter.start(TransportFilter.java:57)
at org.apache.activemq.transport.WireFormatNegotiator.start(WireFormatNegotiator.java:72)
at org.apache.activemq.transport.TransportFilter.start(TransportFilter.java:57)
at org.apache.activemq.transport.TransportFilter.start(TransportFilter.java:57)
at org.apache.activemq.ActiveMQConnectionFactory.createActiveMQConnection(ActiveMQConnectionFactory.java:258)
... 3 more

This is the very first exception I got when I started to code my first JMS code. Due to wrong Listener Connection (IN red and green (my mistake of taking 9))


package oc.messageQ.olivia;

import java.io.File;
import java.io.FileInputStream;
import java.util.Hashtable;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueReceiver;
import javax.jms.QueueSender;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;

public class IROPSQueueApacheMQProducer {

/**
* @author O Cassandrae
* @param args
*/
public static void main(String[] args) {
MessageProducer producer = null;
Connection conn = null;
Session jmsSession = null;

try {
Hashtable<String, String> env = new Hashtable<String, String>();
env.put(Context.INITIAL_CONTEXT_FACTORY,"org.apache.activemq.jndi.ActiveMQInitialContextFactory");
                        //env.put(Context.PROVIDER_URL,"tcp://PDCHCL-TRAX9:61616");
env.put(Context.PROVIDER_URL,"tcp://PDCHCL-TRAX6:61616");
InitialContext context = new InitialContext(env);
ConnectionFactory cf = (ConnectionFactory) context
.lookup("ConnectionFactory");
System.out.println("ConnectionFactory is ::: "
+ cf.getClass().getName());

if (cf instanceof QueueConnectionFactory) {
conn = ((QueueConnectionFactory) cf).createQueueConnection();
jmsSession = ((QueueConnection) conn).createQueueSession(false,
Session.AUTO_ACKNOWLEDGE);
}
Destination dest = (Destination) context
.lookup("dynamicQueues/GROUNDOPS.PSCS.IROPS.BRIDGE.QUEUE");
System.out.println("dest is ::: " + dest);
            producer = ((QueueSession)jmsSession).createSender((Queue)dest);
            TextMessage message = jmsSession.createTextMessage();
            String AsmSource = "src/resources/IROPSFlightCancelled.xml";
            FileInputStream inputStream;
            byte[] readBytes;
            // build an asm  request
            inputStream = new FileInputStream(AsmSource);
            readBytes = new byte[Integer.valueOf(""+(new File(AsmSource)).length())];
            inputStream.read(readBytes);
            message.setText(new String(readBytes));
            //System.out.println("request: "+new String(readBytes));
            ((QueueSender)producer).send(message);
            //System.out.println("Message sent successfully!!!");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if(conn != null){
producer.close();
jmsSession.close();
conn.close();
}
} catch (JMSException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

Please do start the bat file: C:\Software\apache-activemq-5.5.1\bin\activemq.bat (activemq.bat) before executing the program.

TransientObjectException - Hibernate 2

Transient Object Exception occurs due to two reasons:

1.  The below article will explain it. 

               Transient State

2. It occurs due to passing null as primary key. Check the class you are passing into the table is not null due to any logic. Therefore check the logic of the class it is throwing the exception.

The conversion of the transient state to persistent state in the method getHibernateTemplate();

TransientObjectException - hibernate

org.hibernate.TransientObjectException: object references an unsaved transient instance – save the transient instance before flushing: com.swacorp.pcs.common.model.ServiceLevel
<class name=”com.xxx.A” table=”A” schema=”TESTSCHEMA”>
<id name=”aId” type=”java.lang.Long”>
<column name=”A_ID” precision=”29? scale=”0? />
</id>
…………………..
some more mapping elements
…………………..
…………………..
<many-to-one name=”bId” class=”com.xxx.B” fetch=”select”>
<column name=”B_ID” precision=”29? scale=”0? />
</many-to-one>
…………………..
A is referring to B using a primary key column of bId of B.
In that post I have mentioned that if B is a transient object and you don’t want to persist the value of B to A then just tell the hibernate to ignore that value by saying
update=”false” insert=”false” in the many to one mapping.
But what if you want to persist the value of foreign key in A.
Then the approach is different. You have to make sure that instance B is persistent not transient.
That is if your code says something like
A a = new A();
B b = new B();
a.setB(b);
…..
…..
session.save(a);
you are in trouble. Because B is in transient state. You have to attach b to the session.
There may be other ways of attaching this transient object to session. The approach I am following is simple. I am reading the value of B from the database using Hibernate. That way, hibernate attaches B to session and it is then a persistent object.
That is I do something like
A a = new A();
B b = session.get(B.class, new Long(1));
a.setB(b);
…..
…..
session.save(a);
Hibernate defines and supports the following object states:

  * Transient :- an object is transient if it has just been instantiated using the new operator, and it is not associated with a Hibernate Session. It has no persistent representation in the database and no identifier value has been assigned.

  * Persistent :- a persistent instance has a representation in the database and an identifier value. It might just have been saved or loaded, however, it is by definition in the scope of a Session.

  * Detached :- a detached instance is an object that has been persistent, but its Session has been closed. The reference to the object is still valid, of course, and the detached instance might even be modified in this state. A detached instance can be reattached to a new Session at a later point in time, making it persistent again.

My changes:
HibernateTemplate template = getHibernateTemplate();
   Session session = template.getSessionFactory().getCurrentSession();
   itmAndPaxItmEvntOccrs.paxItm.setSvcLvl((ServiceLevel)session.get(itmAndPaxItmEvntOccrs.paxItm.getSvcLvl().getClass(), new Long(1)));
   template.saveOrUpdate(itmAndPaxItmEvntOccrs.paxItm);