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DRY Your Code

Rexleed — Sun, 01 Nov 2009 00:00:00 +0000

Don’t Repeat Yourself (DRY, also known as Single Point of Truth) is a process philosophy aimed at reducing duplication, particularly in computing. The philosophy emphasizes that information should not be duplicated, because duplication increases the difficulty of change, may decrease clarity, and leads to opportunities for inconsistency. DRY is a core principle of Andy Hunt and Dave Thomas’s book The Pragmatic Programmer. They apply it quite broadly to include “database schemas, test plans, the build system, even documentation.” When the DRY principle is applied successfully, a modification of any single element of a system does not change other logically-unrelated elements. Additionally, elements that are logically related all change predictably and uniformly, and are thus kept in sync.

The DRY code philosophy is stated as “Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.” This philosophy is also prevalent in model-driven architectures, in which software artifacts are derived from a central object model expressed in a form such as UML. DRY code is created by data transformation, which allows the software developer to avoid copy and paste operations. DRY code usually makes large software systems easier to maintain, as long as the data transformation are easy to create and maintain. Tools such as XDoclet and XSLT are examples of DRY coding techniques. Examples of systems that require duplicate information are Enterprise Java Beans, which requires duplication not just in Java code but also in configuration files. Examples of systems that attempt to reduce duplicate information include the Ruby on Rails application development environment.

Data transformation skills are not taught in most junior-level software engineering courses. Current computer science curricula tend to be heavily weighted toward procedural skills such as Java, C++, or C#. The use of DRY code becomes increasingly important as developers create applications that use multi-tier architectures. The model-view-controller architectural pattern also challenges software developers to use data transformations. Developments in some language features, such as Java annotations, may allow additional metadata to be stored within object class definitions and accessed at run time, allowing features such as automatic view generation directly from models.

Reference: http://en.wikipedia.org/wiki/Don’t_repeat_yourself

Enabling a repository as a global registry

Rexleed — Sat, 04 Jul 2009 02:53:44 +0000

To enable a repository as a global registry after configuration, you must activate the

dm_bof_registry user.

1. Access Documentum Administrator in a browser and connect to the repository.

2. Navigate to Administration > User Management > Users.

3. Locate the user named dm_bof_registry and select View > Properties > Info to access

the User Properties – Info page.

4. Verify that the username attribute is set to dm_bof_registry.

The value dm_bof_registry is required.

5. Optionally, change the user login name to a new value.

6. Change the user’s password.

7. Set the dm_bof_registry user’s status to Active.

8. Click OK to save the user.

9. During DFC installation on client machines, such as the Webtop or Documentum

Administrator hosts, provide the user login name and password.

This updates the dfc.properties file and enables that DFC installation to contact

the global registry as required.

10. To manually modify the dfc.properties file to designate a global registry repository

and user credentials:

a. On the DFC host, navigate to $DOCUMENTUM/config (UNIX or Linux) or

%DOCUMENTUM%\config (Windows).

b. From a command prompt, execute the following command to generate the

encrypted form of the global registry user’s password:

java -cp dfc.jar com.documentum.fc.tools.RegistryPasswordUtils

password_of_user

where password_of_user is the global registry user’s clear-text password. In step

d, enter the encrypted form of this password in the dfc.properties file.

c. Open the dfc.properties file in a text editor.

d. Modify the following attributes:

dfc.globalregistry.repository=global_registry_repository_name

dfc.globalregistry.username=user_login_name

dfc.globalregistry.password=encryped_password_of_user

where encryped_password_of_user is the encrypted password you generated in

step b.

e. Save the dfc.properties file.

2009-Feb-19

I helped redtead to change the global registry repository on her machine. DQLs were used:

select user_state from dm_user where user_name= ‘dm_bof_registry’
update dm_user object set user_state=0 set user_login_name = ‘dm_bof_registry’ set user_password=’test’ set home_docbase=’’ where user_name=’dm_bof_registry’

Caution: we should clean the dmcl cache to make this effective

Cabinet and Folder

Rexleed — Fri, 26 Jun 2009 05:13:19 +0000

What’s cabinet

Objects in the Docbase are organized by placing them within cabinets and folders. Cabinets form the highest level of organization and contain folders, documents and other objects. Objects can reside within cabinets or within folders. Folders are present within cabinets or within other folders.

Organizing objects within cabinets and folders can help us categorize the content better and enables faster searching for critical information.

Cabinet object type in Documentum is dm_cabinet and folder object type is dm_folder. It should

be noted that dm_folder is a supertype of dm_cabinet object type.

Create cabinet and folder by DQL, API and DFC

Any user can create folders. Creating cabinets requires the Sysadmin, Superuser, or Create Cabinet privileges.

It is easiest to create folders and cabinets using Documentum Administrator. You can also use DQL, API and DFC methods.

DQL

CREATE dm_cabinet OBJECT

SET object_name = ‘myCabinet’,

SET title = ‘My Cabinet’,

SET owner_name = (select distinct(owner_name) from dm_docbase_config),

SET acl_domain = (select distinct(owner_name) from dm_docbase_config),

SET acl_name = ’some_acl’

CREATE dm_folder OBJECT

SET object_name = ‘folder1′

LINK ‘/cabinet name’

WHERE r_object_id = ”

API

create,c,dm_cabinet

set,c,l,object_name

Cabinet Name Here

save,c,l

create,c,dm_folder

set,c,l,object_name

Folder Name Here

link,c,l,/Cabinet Name Here

save,c,l

DFC

Cabinet:

IDfFolder cabinet = null;

cabinet = (IDfFolder) session.newObject(“dm_cabinet”);

cabinet.setObjectName(“test_cabinet”);

cabinet.save();

Folder:

IDfFolder folder = null;

folder = (IDfFolder) session.newObject(“dm_folder”);

folder.setObjectName(“test_folder”);

folder.save();
This is from YC’s study note.

Time zone and timestamp in Oracle

Rexleed — Fri, 12 Jun 2009 11:12:08 +0000

There are two kinds of timezone:

1. DBTIMEZONE you can set the time zone for database by “alter database set time_zone=’+08:00′”. To make
this take effect, you should reboot the database. But if you have a column that is of TIMESTAMP WITH TIME ZONE/LOCAL TIME ZONE, you will not be able to change the DBTIMEZONE. SYSTIMESTAMP is used to get the current database timestamp with time zone information. BTW, SYSDATE is used to get the current date without time zone information.

2. SESSIONTIMEZONE you can set time zone at the session level
e.g. you can issue “alter session set TIME_ZONE=’+08::00′;” to change the timezone for current session. CURRENT_TIMESTAMP is used to get the current session timestamp with time zone infomation.

There are three types of timestamp:

1. timestamp

2. timestamp with time zone

3. timestamp with local time zone

The key point is “The main idea to grasp here is that the column with datatype TIMESTAMP WITH TIME ZONE stores and displays the explicit time supplied from the INSERT statement. The column with datatype TIMESTAMP WITH LOCAL TIME ZONE stores the explicit time supplied but will display a value that is relative to the current session time zone. This means that if you want hard and fast TIMESTAMPS with time zone information stored, you should use the TIMESTAMP WITH TIME ZONE datatype. If you are concerned more with giving date and time information to customers in different time zones and represented in their local time, you should use the TIMESTAMP WITH LOCAL TIME ZONE datatype.”

references:

http://www.dbasupport.com/oracle/ora9i/TimeZone.shtml

http://toolkit.rdbms-insight.com/tz.php

P.S. you can get all valid timezone name by “select tzname, tzabbrev from V$TIMEZONE_NAMES”

Tomcat Out of Memory

Rexleed — Sun, 08 Feb 2009 06:27:34 +0000

We always get out of memory error on Tomcat when the system occupy many memory resource. To avoid this,

we can dedicate how much memory tomcat can use.

1. add JAVA_OPTS=’-Xms1024m -Xmx1024m’ in catalina.sh

2. add set JAVA_OPTS=-Xms128m -Xmx350m in catalina.bat

3. use tomcat service(tomcat.exe) which read JAVA_OPTS from regedit table. add -Xms1024m -Xmx1024m in item HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Tomcat Service Manager\Tomcat5\Parameters\Java\Options or HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Procrun 2.0\Tomcat5\Parameters\Java\Options

Reference:

http://gcgmh.javaeye.com/blog/291234

ESB Study Resource

Rexleed — Sun, 08 Feb 2009 06:17:06 +0000

Architecture of Open ESB
https://open-esb.dev.java.net/AboutOpenEsb.html

A 60 mins tutorial
https://open-esb.dev.java.net/60mintutorial/index.html

基于Open ESB的网上商城系统（You can get scource code there）
http://developers.sun.com.cn/blog/jasonhuang/entry/%E5%9F%BA%E4%BA%8E_open_esb_%E7%9A%84%E7%BD%91%E4%B8%8A%E5%95%86%E5%9F%8E%E7%B3%BB%E7%BB%9F

Why ESB
http://www.sonicsoftware.com/solutions/service_oriented_architecture/enterprise_service_bus/index.ssp

Site of Open ESB
https://open-esb.dev.java.net/

Model and build ESB SOA frameworks
http://www.ibm.com/developerworks/web/library/wa-soaesb/

Tom Barrett’s Open ESB and Mural Tutorials
http://wikis.sun.com/display/OpenESBTutor/Tom+Barrett’s+Open+ESB+and+Mural+Tutorials

Upgrade Oracle 10.2.0.1 to 10.2.0.3

Rexleed — Sun, 08 Feb 2009 06:13:28 +0000

I. Download patch set p5337014_10203_WINNT.zip

II. To install the Oracle Database 10g patch set interactively:

Log on as a member of the Administrators group to the computer on which you are going to install Oracle components. If you are installing on a Primary Domain Controller or a Backup Domain Controller, log on as a member of the Domain Administrators group.

Start Oracle Universal Installer located in the unzipped area of the patch set. For example, Oracle_patch\setup.exe.

On the Welcome screen, click Next.

In the Specify Home Details Screen, select the name of the Oracle home that you want to update, or select the Path that you want to update from the list, then click Next

If you are installing the patch set on an Oracle RAC cluster, click Next when the Selected Nodes screen appears.

On the Summary screen, click Install.

When the installation is complete, the End of Installation screen appears.

On the End of Installation screen, click Exit, then click Yes to exit from Oracle Universal Installer.

MSVCR71.DLL is in use during Oracle patch installation

If you are trying to upgrade the Oracle Client and an error message is displayed telling you that msvcr71.dll is in use, try the following:

1) Verify that all Oracle services are stopped.

2) Stop the Distributed Transaction Coordinator – In most cases this will solve the issue.

3) Run Process Explorer

a) In the Find menu, click on “Find Handle or DLL” (CTRL F)

b) Type msvcr71.dll and click on Search

c) Go through the list and close the listed applications

III Start upgrade

1. Start all services
2. Connect sys user
C:\> sqlplus /NOLOG
SQL> CONNECT SYS/SYS_password AS SYSDBA
3. Enter the following SQL*Plus commands:
SQL> STARTUP UPGRADE
SQL> SPOOL patch.log
SQL> @ORACLE_BASE\ORACLE_HOME\rdbms\admin\catupgrd.sql
(Ukoom: It takes a long time to run this script, so have a cup of coffee )
SQL> SPOOL OFF
Review the patch.log file for errors and inspect the list of components that is displayed at the end of catupgrd.sql script.
This list provides the version and status of each SERVER component in the database.
If necessary, rerun the catupgrd.sql script after correcting any problems.

4. Restart the database:
SQL> SHUTDOWN
SQL> STARTUP
5. Compile Invalid Objects
Run the utlrp.sql script to recompile all invalid PL/SQL packages now instead of when the packages are accessed for the first time. This step is optional but recommended.
SQL> @ORACLE_BASE\ORACLE_HOME\rdbms\admin\utlrp.sql
SQL> select * from utl_recomp_errors;
SQL> select * from v$version;

SQL> show user

SQL> select tablespace_name, bytes from dba_data_files

6. Popular data dictionary (it should be optional)

SQL> @ ORACLE_BASE\ORACLE_HOME /rdbms/admin/catalog.sql
SQL>shutdown immediate
SQL>startup

Reference:

http://idbasolutions.com/installing-oem-10g-r4-on-windows/

http://babudba.blogspot.com/2007/11/upgrade-oracle-10202-to-10203.html

http://blog.csdn.net/yjz0065/archive/2008/02/27/2124778.aspx

http://sabdarsyed.blogspot.com/2007/03/upgrading-oracle-database-server-10g.html

http://blog.nominet.org.uk/tech/2007/03/16/some-issues-with-oracle-10203-patchset/

upgrade-oracle-10201-to-10203.zip

Sqlnet.ora

Rexleed — Sun, 08 Feb 2009 05:40:10 +0000

Sqlnet.ora is a text file that provides SQL*Net with basic configuration details like tracing options, default domain, encryption, etc. This file can be found in the ORACLE HOME\NETWORK\ADMIN directory.

It can be used to enable/disable trace.

Reference:
http://www.orafaq.com/wiki/Sqlnet.ora#Sample_sqlnet.ora_files
http://users.handysoft.co.kr/~jelong/net_para.txt
http://www.dba-oracle.com/t_tns_12560_protocol_adapter_error.htm

TNS-12560: TNS:protocol adapter error

Rexleed — Sun, 08 Feb 2009 05:36:11 +0000

The error “TNS-12560: TNS: protocol adapter error” is usually related to a configuration issue with the listener:

TNS-12560 TNS:protocol adapter error

Cause: A generic protocol adapter error occurred.

Action: Check addresses used for proper protocol specification. Before reporting this error, look at the error stack and check for lower level transport errors. For further details, turn on tracing and re-execute the operation. Turn off tracing when the operation is complete.

The “TNS-12560: TNS:protocol adapter error” sometimes a transient error on a SQL*Net (Oracle*Net) client, happening sporadically. To turn-on tracing for the ORA-12560, use these settings. Also check /var/log/messages (Linux) for errors:

TRACE_LEVEL_<> = admin
TRACE_DIRECTORY_<> = <>
TRACE_TIMESTAMP_<> = true

Possible fixes for the TNS-12560 include:

1 – Get the latest patches for the SQL*Net client software.

2 – Check your $ORACLE_HOME and $PATH variables

3 – Check file permissions on the PC client

4 – Ensure that TNS_ADMIN is set properly

5 – Check for network firewall issues

6 – In Windows, Verify that the database service is started. · Verify that the ORACLE_SID parameter is correctly set in the registry.

Reference:

http://www.dba-oracle.com/t_tns_12560_protocol_adapter_error.htm

ORA-01758 when trying to alter table

Rexleed — Sun, 08 Feb 2009 05:29:37 +0000

If you are trying to add a new Not NULL columns to a table and you get the following error:

ORA-01758: table must be empty to add mandatory (NOT NULL) column

Since the values in the new column are null (after all, you just added the column) the new constraint can not be satisfied.

There are several option to overcome ORA-01758:

1) provide a default value for the column.

ALTER TABLE table-name ADD column-name VARCHAR2(15) DEFAULT ‘X’ NOT NULL

If you don’t want the default value you can remove it after the column will be populated with the new data.

2) Add the column without the NOT NULL constraint,

ALTER TABLE table-name ADD (column-name VARCHAR2(15));

– add the data

UPDATE table-name set column-name=’x’;

– apply the NOT NULL constraint.

ALTER TABLE table-name MODIFY (column-name NOT NULL)

3) Empty the table, apply the NOT NULL and add the data back to the table

UKoom » Rexleed

DRY Your Code

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