Oracle Application Framework (OAF) and Application Development Framework (ADF)
As of R12, OAF can only be used for Oracle Applications development/extensions.
Oracle ADF is an end-to-end J2EE framework. ADF is currently not used for Oracle Apps. Development / extensions. It is expected to be the case in Fusion and is a part of the Oracle Fusion Middleware。
OAF和ADF是Oracle的兩個不同的産品。
ADF是在OracleAS産品線中的一個通用的應用開發架構，而OAF是OracleEBS中的技術元件，是EBS中所有網頁功能采用的應用架構。
通常ADF會采用最近的技術，如果你做J2EE的開發的話，在應用采用ADF。如果你需要在OracleEBS上擴充和開發新的功能，則需要采用OAF。
ADF和OAF在很多技術上是相似的，比如OAF中采用BC4J的業務層元件，而在ADF中BC4J（ADFBC）僅僅是其中的一個選項。
當然了，如果你要學習ADF的話，OTN網站是一個很好的資源站點。如果學習OAF的話，資料相應會少一些，OAF自帶的開發工具中會帶一個Guide，也是比較詳細的，我還沒有發現其他資源站點。
至于ADF是否會取代OAF的問題，我想這本身不是一個問題。從技術的層面上來講他們兩個應該是一種技術，隻不過适用的對象不同而已。
OAF provides you with automatic, seamless integration with the EBS applications in terms of EBS menus, security, look and feel, flexfields, personalization, attachments,
and so on. These integrated EBS features aren't part of ADF.
OAF Technology Stack for E-Business Suite R12：
OAF is a model-view-controller technology stack that is fully oriented towards EBusiness Suite application development. The OAF stack is comprised of underlying technologies like UIX and BC4J, that respectively form the core of the view and model layers（UIX是vier層的核心；BC4J是model層的核心）.It
includes Application Object Library (AOL) that provides common E-Business Suite artifacts such as menus, functions, messages, profiles, flexfields and attachments, and common services like function and data security.
MDS is used for metadata management. And finally, the OAF design time is integrated with Oracle JDeveloper 10g to provide a comprehensive integrated
development platform.
ADF 10g Technology Stack：
ADF is a comprehensive, model-view-controller technology stack that is oriented towards general-purpose application development. The ADF stack allows users to
select among several choices of UI and business services technologies. The ADF stack is primarily comprised of ADF Faces (which is based on industry standard
JSF technology), ADFm (m for model - the data control layer that implements JSR-227) and ADFbc (bc for business components – formerly BC4J). Early
releases of ADF contained UIX. Oracle then developed the ADF Faces set of components, based on UIX functionality, but conforming to the JSF standard. The
ADF Faces components now replace UIX as the preferred（優先選擇的） view technology for ADF applications. ADF design time is also integrated with JDeveloper 10g.
更多參考：http://download.csdn.net/detail/changyanmanman/7330013