No, a tier does not mean a physical machine. It is actually a logical portioning. Each tier can have one or more physical servers. Vice versa, a physical server can accommodate one or more different tier. For example, a middle tier can be configured in 2-3 different servers and one server can accommodate a database and web server.
How will someone access Oracle Applications, if the client software is not installed in his/her desktop PC?
The client desktop accesses Oracle Applications through Java-enabled client browser with JInitiator and forms client applet.
What is forms client applet?
For running forms from client desktop, forms client applet must run in the client desktop. It’s a collector of JAR (Java Archive files) files. These JAR files contain all the classes, required to run the presentation layer of Oracle Applications. It supports all Oracle Application forms including custom forms.
Which servers are hosted from Application tier?
The following six servers constitute the application tier:
- Oracle HTTP server (Apache)
- Forms server
- Reports server
- Admin server
- Concurrent processing server
- Discoverer server
Oracle HTTP server is the Web server which is used by Oracle Applications. It processes all the requested received from the clients. The Web server includes additional components like Web listener, Jserv (Java Servlet Engine) and JSP (Java Server Pages).
What is difference between Apache and Oracle HHTP server?
Oracle HTTP server is the customized form of Apache. Oracle has customized the Apache Web server as per its own requirement which is known as Oracle HTTP server.
What is the function of Oracle HTTP (Apache) server?
The Web listener accepts the HTTP requests coming from the client browsers, and the Web server services the request. If the URL needs further processing, it forwards the request to the server engine, which in turn contacts the database for processing the request, and returns back to Web listener.
How does Oracle HTTP (Apache) server work?
The Web server works in the following way:
- The user clicks a hyperlink on his desktop.
- The browser contacts the Web listener with the URL. If possible, HTTP listener services the request itself by returning a simple HTML page. If it needs a JSP parsing then
- Web listener redirects the request to the Servlet Engine (Jserv) for running a JSP
- The JSP, in turn, contact the metadata dictionary in the database where it gets the information from the application tables to construct the HTML page.
- Web server returns the resulting HTML page back to the browser.
The main configuration files are httpd.conf, apps.conf, httpd_pls.conf, oprocmgr.conf and oracle_apache.conf. These files are located in $IAS_ORACLE_HOME/Apache/Apache/conf directory. In case of shared APPL_TOP, these are located in $IAS_CONFIG_HOME/ Apache/Apache/conf directory.
Whenever autoconfig is run, all the customizations that were done to config files like apps.conf, httpd.conf are overwritten. How can we prevent it?
To overcome this problem, go to $FND_TOP/admin/template directory. You can see template files for the configuration files here. Make a directory "custom" in this directory and copy all the files where you want to do customization from $FND_TOP/admin/template to $FND_TOP/admin/template/custom directory and do the customization in the files in the custom directory. Now if you run autoconfig, customizations will be read from the files in the custom directory.
How can you check version of Apache?
It can be checked using the below command:
$IAS_ORACLE_HOME/Apache/Apache/bin/httpd -v
What is plsql cache and what is it's use?
The mod_pls component of Apache caches some database content to file. The plsql cache (database cache) is of the type session and plsql cache. The session cache is used to store the session information and the plsql cache is used to store the plsql cache which is used by mod_pls. It is stored in $IAS_ORACLE_HOME/Apache/modplsql/cache directory.
What is admin server?
The admin server is that node of the APPL_TOP from which all the maintenance acticities for Oracle Applications are performed.
What is concurrent processing server?
When an Oracle Application user submits a request to run a a program, it's called concurrent requests. Concurrent manager are the programs responsible for running the concurrent requests. Concurrent requests are processed from concurrent processing server.
What is forms server?
the forms server is that server from which the forms are hosted. The forms server can be hosted from more than one node of the middle tier and the load balancing can be implemented with the forms.
What is load balancing?
Load balancing is a server process that monitors loading on all of the forms servers. Each of the forms servers runs a load balancing client which keeps the load balancing server apprised of its load.
What is reports server?
Reports server is a component of middle tier and is hosted in the same node of the concurrent processing server. Reports server is used to produce business intelligence reports. Reports server is started by executable rwmts60 which is located in $ORACLE_HOME/bin.
How can you find how manhy forms users are connected to the application system from the operating system level?
It can be done by counting the f60webmx processes.
ps -fu <osusername>|grep f60webmx|wc -l
What is appsweb.cgf file and what is its significance?
appsweb.cgf file defines the parameter values used by forms Web CGI. It is the main configuration file used by the forms. It is located at $OA_HTML/bin. It contains the following details:
To overcome this problem, go to $FND_TOP/admin/template directory. You can see template files for the configuration files here. Make a directory "custom" in this directory and copy all the files where you want to do customization from $FND_TOP/admin/template to $FND_TOP/admin/template/custom directory and do the customization in the files in the custom directory. Now if you run autoconfig, customizations will be read from the files in the custom directory.
How can you check version of Apache?
It can be checked using the below command:
$IAS_ORACLE_HOME/Apache/Apache/bin/httpd -v
Sample output:
$IAS_ORACLE_HOME/Apache/Apache/bin/httpd -v
Server version: Oracle HTTP Server Powered by Apache/1.3.19 (Unix)
Server built: Jul 23 2003 18:41:23 (iAS 1.0.2.2.2 rollup 4)
I have deleted DBC file accidently. Can it be recreated?
Yes. It can be created by either running autoconfig or by running adgendbc.sh script located at $COMMON_TOP/admin/install directory.
What is plsql cache and what is it's use?
The mod_pls component of Apache caches some database content to file. The plsql cache (database cache) is of the type session and plsql cache. The session cache is used to store the session information and the plsql cache is used to store the plsql cache which is used by mod_pls. It is stored in $IAS_ORACLE_HOME/Apache/modplsql/cache directory.
What is admin server?
The admin server is that node of the APPL_TOP from which all the maintenance acticities for Oracle Applications are performed.
What is concurrent processing server?
When an Oracle Application user submits a request to run a a program, it's called concurrent requests. Concurrent manager are the programs responsible for running the concurrent requests. Concurrent requests are processed from concurrent processing server.
What is forms server?
the forms server is that server from which the forms are hosted. The forms server can be hosted from more than one node of the middle tier and the load balancing can be implemented with the forms.
What is load balancing?
Load balancing is a server process that monitors loading on all of the forms servers. Each of the forms servers runs a load balancing client which keeps the load balancing server apprised of its load.
What is reports server?
Reports server is a component of middle tier and is hosted in the same node of the concurrent processing server. Reports server is used to produce business intelligence reports. Reports server is started by executable rwmts60 which is located in $ORACLE_HOME/bin.
How can you find how manhy forms users are connected to the application system from the operating system level?
It can be done by counting the f60webmx processes.
ps -fu <osusername>|grep f60webmx|wc -l
What is appsweb.cgf file and what is its significance?
appsweb.cgf file defines the parameter values used by forms Web CGI. It is the main configuration file used by the forms. It is located at $OA_HTML/bin. It contains the following details:
- Forms Server Name, Server Port, Domain Name
- Database Connection Parameters.
- JInitiator version
What is DBC file and what is its significance?
DBC (Database Connection) file is responsible for establishing connection between the database and the APPL_TOP. It stores all the information required for successful connection to the database. It contains the value of GWYUID, FNDNAM, TWO_TASK and GUEST_USER_PWD. It is located at $FND_TOP/secure.
What is the difference between GWYUID and GUEST_USER_PWD?
GWYUID (Gateway User ID) is used by thick clients (forms) to connect to the database. It should have APPLSYSPUB/PUB as User ID/Password. GUEST_USER_PWD is used by JDBC thin client.
How do you find the DBC file that is used by the application system, in case there are multiple DBC files at $FND_TOP/secure location?
It can found out by querying profile "Application Database ID". If the profile value is SID, then SID.dbc is used by the application.
What are the tables which store information about application users and passwords?
FND_USERS and FND_ORACLE_USERID.
Can you delete an application user?
No. Application user cannot be deleted. But you can put an end date to the application user, thus making the user inactive.
In case of multi-mode installation, how can you check which service is running from which node?
It can be checked by either checking the CONTEXT_FILE or by querying FND_NODES table. FND_NODES table has columns SUPPORT_CP, SUPPORT_FORMS, SUPPORT_WEB, SUPPORT_ADMIN, SUPPORT_DB.
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DBC (Database Connection) file is responsible for establishing connection between the database and the APPL_TOP. It stores all the information required for successful connection to the database. It contains the value of GWYUID, FNDNAM, TWO_TASK and GUEST_USER_PWD. It is located at $FND_TOP/secure.
What is the difference between GWYUID and GUEST_USER_PWD?
GWYUID (Gateway User ID) is used by thick clients (forms) to connect to the database. It should have APPLSYSPUB/PUB as User ID/Password. GUEST_USER_PWD is used by JDBC thin client.
How do you find the DBC file that is used by the application system, in case there are multiple DBC files at $FND_TOP/secure location?
It can found out by querying profile "Application Database ID". If the profile value is SID, then SID.dbc is used by the application.
What are the tables which store information about application users and passwords?
FND_USERS and FND_ORACLE_USERID.
Can you delete an application user?
No. Application user cannot be deleted. But you can put an end date to the application user, thus making the user inactive.
In case of multi-mode installation, how can you check which service is running from which node?
It can be checked by either checking the CONTEXT_FILE or by querying FND_NODES table. FND_NODES table has columns SUPPORT_CP, SUPPORT_FORMS, SUPPORT_WEB, SUPPORT_ADMIN, SUPPORT_DB.
Click below links for more Oracle APPS DBA Interview Questions and Answers
Oracle APPS DBA Interview 2