R12.2 ARCHITECTURE

Oracle Application have three tier architecture:

• The Client (Desktop) Tier
• The Application Tier
• The Database Tier

All major services are started out of the Fusion Middleware ORACLE_HOME.

Client Tier:

Application Tier:

There are two oracle home:

FMW ORACLE_HOME (sometimes referred to as the Web or Java ORACLE_HOME)(replaced OracleAS 10.1.3 home).

10.1.2 ORACLE_HOME (sometimes referred to as the Tools, C, or Developer ORACLE_HOME).

• Manage communication b/w database tier and client tier.
• Consist of two oracle home(FMW Oracle Home and oracle As 10.1.2)
• Consist of HTTP,Java, Forms and Concurrent processing manager.
• Oracle E-Business Suite modules (packaged in the file formsapp.ear) are deployed out of the OracleAS 10.1.2 ORACLE_HOME, and the frmweb executable is also invoked out of this ORACLE_HOME.
• fmwweb, FOrm executable, invoked out of FMW.
• formsapp.ear,collection of form based module.
• Http/web listener for all client request.
• oacore> Core functionality.
• Two architecture to support form based application(form servlet and socket mode),servlet is default mode and communicate with database using oracle net.
• A server is an instance of WebLogic Server that runs in its own Java Virtual Machine (JVM) and has its own configuration. And there five WebLogic instances these are ;

1. Admin(Server)
2. oacore (also cluster)
3. oafm (also cluster)
4. forms (also cluster)
5. forms–c4ws  (also cluster)

Another View:

Another View:

Client request :

Requests received from the desktop clients over n/w is processed by Web services component which includes the following major components (Web Listener (Oracle HTTP Server powered by Apache)  and Java Servlet Engine (Oracle WebLogic Server, WLS)).

The Web listener component of the Oracle HTTP server accepts incoming HTTP requests (for particular URLs) from  client browsers, and routes the requests to WLS.

If possible, the Web server services the requests itself, for example by returning the HTML to construct a simple Web page. If the page referenced by the URL needs advanced processing, the listener passes the request on to the servlet engine, which contacts the database server as needed.

HTTP and Oracle WebLogic Server configuration files are not stored under the $INST_TOP.

When compare 12.2 with previous R12 versions, we can’t not see any changes for Forms Services .No changes in Form Listener Servlet .They are still connecting database with Oracle Net networking infrastructure.But! Weblogic manages this processes.

Weblogic services are replaced with OC4J (Oracle Container for Java) as new Servlet Engine. All HTML-Based Applications and Oracle Application Framework (OAF) is still using Java servlets provided by Apache Jserv module and BC4J patterns (Business Components for Java) but Oracle Weblogic provides connection to database and application-specific functionality such as flexfields via WLS service. Weblogic is integrated with this tier planning to create hybrid applications using OAF-ADF and optimizing clustring performances . I think possible further requirements in the future for EBS to Fusion evolution is also key reason for Oracle’s decision on this change.

In 12.2 , OA Framework Architecture includes Weblogic services such as WLS,UIX,Java Controller, Metadata UI. And it looks like this:

Oracle Applications 12.2 have two file system:

FS1 : Production File System used by users
FS2 : Copy of production File System used by patching tools (adop : More on adop later)
Both  fs1 and fs2 which alternates between ‘run’ and ‘patch’ with every patching cycle at the end, means after cutover.
FS1 and FS2 can switch role i.e. FS2 will become production File system and FS1 will become File System for Patching at Cutover Phase of online patching (ADOP).
fs_ne non-editioned filesystem which is used to store files needed across all filesystems like log files, patch files etc.fs_ne stores data on filesystem like log, out, data import/exportfiles.

Dual File system

Two application tier ORACLE_HOMEs:

An OracleAS 10.1.2 ORACLE_HOME that was used in previous 12.x releases. 
An Oracle Fusion Middleware (FMW) ORACLE_HOME that supports Oracle WebLogic Server (WLS) and supersedes the Java (OracleAS 10.1.3)ORACLE_HOME that was used in previous releases.Oracle E-Business Suite R12 (12.2) uses Oracle Fusion Middleware 11g R1 PS3 (11.1.1.4) including WebLogic 10.3.4 as its application server (Note: In previous version of R12 i.e. 12.0.X and 12.1.X this is 10g R3 i.e. 10.1.3.X). Oracle HTTP Server (OHS) in R12 (12.2) is 11.1.1.4
The use of these two ORACLE_HOMEs enables Oracle E-Business Suite to take advantage of the latest Oracle technologies.

Application tier manage communication between client and database and consist of HTTP,java,form and concurrent processing.
HTTP/web listener for client request.
formsapp.ear:Collection form based modue.
frmweb:Executable for form. Invoked out of FMW.
The Oracle E-Business Suite modules (packaged in the file formsapp.ear) are deployed out of the OracleAS 10.1.2 ORACLE_HOME, and the frmweb executable is also invoked out of this ORACLE_HOME.
Oacore:core functionality.

Two architecture to support form based application.

• form listener servlet
• form soket mode

form listener servlet id default one and communicate with database using oracle net.







The Web services component of Oracle Application Server processes requests received over the network from the desktop clients, and includes the following major components:
• Web Listener (Oracle HTTP Server powered by Apache)
• Java Servlet Engine (Oracle WebLogic Server, WLS)
The Web listener component of the Oracle HTTP server accepts incoming HTTP requests (for particular URLs) from  client browsers, and routes the requests to WLS.
If possible, the Web server services the requests itself, for example by returning the HTML to construct a simple Web page. If the page referenced by the URL needs advanced processing, the listener passes the request on to the servlet engine, which contacts the database server as needed.

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Rapid Install deploys one WebLogic domain for Oracle E-Business Suite, with four different application types being provisioned out of the box:

oacore - Used to provide core functionality in Oracle E-Business Suite application tier Java code, including OAF-based functionality for Oracle E-Business Suite products.

oafm - Used for web services, Secure Enterprise Search, Oracle Transport Agent, and other components.

forms - Serves all Oracle Forms functionality.

forms-c4ws - Exposes Oracle Forms-based functionality as web services.

An additional application type, which is not deployed out-of-the-box, may be provisioned if additional Oracle applications are installed:

oaea: Used when installing additional Oracle applications such as Oracle E-Business Suite AccessGate, eKanban, and Spatial.

https://docs.oracle.com/cd/E26401_01/doc.122/e22953/T174296T589913.htm#:~:text=oacore%20-%20Used%20to%20provide%20core,Transport%20Agent%2C%20and%20other%20components.