CHAPTER. Introduction to the Oracle Application Development Framework

Transcription

1 CHAPTER 4 Introduction to the Oracle Application Development Framework

2 104 Oracle JDeveloper 10g Handbook Your scheme must be the framework of the universe; all other schemes will soon be ruins. Henry David Thoreau ( ), A Week on the Concord and Merrimack Rivers A s use of the Java language matures and more and more technologies are based upon Java, designing, developing, and deploying Java-based applications becomes more and more complex. The use of Java has progressed from its early days, when Java programs were primarily command-line utilities, through the days of GUI windowed controls to today, when many new applications using Java are deployed on the Web. New technologies with Java at their core, such as those included in the Java 2 Platform, Enterprise Edition (J2EE, discussed in Chapter 7), offer many benefits to the enterprise, but require additional program components and introduce much additional complexity. Although J2EE suggests and specifies high-level technologies (BluePrints) and low-level techniques (design patterns), it does not define a development method for business applications. Developers and architects are left with the task of selecting the appropriate method and making decisions about all of the choices. Vendors have addressed the complexity of developing J2EE applications by creating Integrated Development Environment (IDE) tools, such as JDeveloper. IDEs can automate many of the tasks required to set up a particular style of development and deployment. A key part of a complex technology is the program files and code units that connect one component to another and to the appropriate application and database servers. Without the proper assistance, creating this part of the application, often called the plumbing, takes a significant amount of time and effort. To be more universally accepted, an IDE needs not only to assist with the plumbing but also to offer a clearly defined method for developing applications. JDeveloper 10g introduces an architecture mentioned in Chapter 1, called Oracle Application Development Framework (ADF), that assists in managing the complexity of developing and deploying applications, by addressing both these issues. This chapter explores the concept of frameworks and development frameworks; it then explains ADF further and provides a basis for understanding how ADF guides and assists in the development work you perform in JDeveloper 10g. This chapter contains a general set of steps for using ADF; other chapters contain hands-on practices that include more detailed steps for using ADF to create various types of code. Since ADF is the heart of JDeveloper 10g, it is important to understand its concepts. Therefore, throughout the chapter are references to where to look for more information. NOTE JDeveloper allows you to create code without using the Application Development Framework, but ADF has many benefits in productivity and is a main reason to use JDeveloper over other Java IDEs. What Is a Framework? Programmers have long incorporated the principles of code reuse into their program designs. After you have created an application using a certain technology, you usually want to think about how to leverage the code you have written for the next project. Applications often have many

3 Chapter 4: Introduction to the Oracle Application Development Framework 105 aspects in common. If you can abstract and standardize common routines so that they can serve multiple applications, you can reduce the time and effort required to create new applications. Therefore, you end up collecting these common routines into code libraries that can be plugged into each new application. Over time, you make improvements and add features to make the code more flexible and useful for different types of applications. As the code grows, its complexity and size have the potential to overwhelm developers who use it. However, if the reusable code is well designed and well documented, it can become a solid foundation that saves significant development time. A framework builds upon the idea of code reuse by offering well-designed code libraries, documentation, and often development tools. It supplies a complete system that accomplishes a specific task such as page flow (as with the Struts framework) or business services (as with the ADF Business Components framework). A framework provides (or simplifies) the implementation of a high-level architecture. You have limitless choices when developing applications; a framework applies a structure to the development process. In the context of the Java environment, framework code consists of a complete set of interrelated, highly integrated Java classes. The base classes are written to perform in a certain way by default, and they handle the details of the architecture such as communication between objects, data access, and UI presentation. Some frameworks take custom information about your application primarily from metadata in XML files that use an XML schema (definition of the XML tag elements and their attributes) readable by the base classes. With this category of frameworks, the primary work that you perform in a framework consists of defining the metadata that will customize the behavior of the framework base classes for your needs. In addition, you can extend the base classes to add or override the functionality of the framework if defining metadata is not sufficient. The proper way to use a framework is to stay as close as possible to its intention. This intention could include the definition of metadata that applies the framework to a particular business application, and defining this metadata can be considered working within the framework. However, writing massive customizations outside of the framework requires much time and effort and may even be less productive than writing the application from scratch without a framework. NOTE A downside to using any framework, whether it is vendor-supplied or home-grown, is that it is proprietary in nature. Vendor-supplied frameworks usually offer support, documentation, and available developer talent that home-grown solutions do not offer. Migrating from one framework to another framework may be difficult but also is normally not necessary. Investing time in proven frameworks, such as those used by JDeveloper, will minimize the risks of obsolescence. Why Use a Framework? Applications that you develop with frameworks contain very little customized code compared to the code within the framework libraries, and most of this code is defined as XML metadata. You reuse the same framework base classes for each project. Therefore, the promise of code reuse making application programming easier and faster, often not realized in the past, is the major benefit of using frameworks. Developers are more productive when they use a framework properly.

4 106 Oracle JDeveloper 10g Handbook A framework is a compromise between a 4GL and a 3GL. 4GLs (such as Oracle Forms Developer) are primarily declarative programming tools with which you create objects and assign property values. The runtime code is derived from metadata you define in the builder and you have no chance to see or modify the runtime code outside of the metadata. A 3GL requires you to write each line of code that creates the runtime program, but it gives you ultimate control because you directly manipulate the runtime code. A framework combines these two concepts and allows you to work in a declarative way but also allows you to modify the basic functionality of the system. In defining the framework metadata, you are working in a 4GL way; in modifying the framework base classes, you will be writing 3GL code. In addition, a good framework delivers complete, working code as an infrastructure to your business code, as well as the flexibility to easily modify the framework s behavior. Maintenance and upgrades of a legacy application that uses a framework are, in concept, easier too because learning the system code is a matter of understanding the framework and examining a small amount of metadata and custom code. The task of learning a framework may be non-trivial but the framework is likely to offer more documentation and to have more user community support than a custom-built code library. User community support is an important aspect to any product because the wider the use, the more examples of successful implementations and techniques will be available. Also, if the user base is strong, it is likely that there will be input based on experience that guides improvements in future versions of the framework. NOTE Well-built frameworks make clear distinctions between welldocumented API code, which you can extend, and the internal plumbing code, which you do not call or extend. What Is a Development Framework? A development framework adds several layers around the idea of a framework and, in addition to base library classes of the framework, includes the following aspects: A development method The development framework defines a set of steps that you can use to create applications with the framework libraries. A method is implied when you are using frameworks, but a development framework documents the method explicitly. A development tool The development framework will be supported by a software tool that helps you complete the steps in the method. As with a framework, working with a development framework consists mainly of following a set of steps in a tool to extend or customize the default behavior and mechanisms in the framework code libraries. Therefore, you need to learn its development method and adjust your development style to fit the framework. Why Use a Development Framework? The benefits of a development framework are the same as those for a framework in general. You benefit from using a base set of framework libraries that are easily extensible and flexible, and

5 Chapter 4: Introduction to the Oracle Application Development Framework 107 that save you from writing a large amount of foundation code for your application. You also benefit from the development method implied by the libraries because this method should be (and often is) easier than creating the application from scratch. The framework gives you a starting point for code and for the development method. In addition to flexibility and extensibility of the code and ease of use of the development method, another important aspect of a development framework is that it saves time and effort, which makes the developer more productive. A key to productivity lies in a tool that supports the framework and makes learning and using the framework fast and relatively understandable. The tool must take care of the plumbing so the developer can concentrate on fulfilling the business requirements of the application. The tool must also assist in generating the customized, businessspecific portions of the application. Support for the Framework Frameworks can be measured by the extent of user community support and the quality of information available. A framework without a clear definition of its development path will limit its adoption. Documentation about the development path as well as detailed descriptions and examples are keys to a successful framework. Technical Support and User Community Support It is also important that frameworks have good technical support other than documentation and tools. This can be supplied as formal product support through the framework vendor or a third party, but these sources are usually not enough. A broad user community is also essential. When you are in the middle of developing an application, you need to be able to ask questions of other framework users. This need can be fulfilled by Internet mail list servers, online discussion forums, and vendor and third-party white papers. The Java community is a prime example of a broad, extensive user community. Technical support for Java is available on the Sun Microsystems website in user discussion forums, technical white papers, tutorials, and detailed specifications. In addition, third-party websites such as user groups extend this support by offering specialized views of a particular technology. A quick search for a Java technology in any web search engine will yield many available websites. What Is Oracle Application Development Framework? Oracle Application Development Framework is a full-featured development framework for creating application program code in JDeveloper. ADF contains all aspects of a true development framework as just discussed highly integrated code libraries, a well-documented development method, and a full-featured IDE to support it. It also offers an architecture model that explains the concepts of the framework. ADF combines a number of Oracle frameworks available in previous JDeveloper releases: ADF Business Components (ADF BC), formerly called Business Components for Java (BC4J); ADF UIX (formerly UIX or User Interface XML); and ADF JClient (used for Java client applications). Also, ADF includes built-in integration with the Struts framework for web controller functions and data binding. In addition, ADF supports work with JSP technology as a view alternative. The primary strength and uniqueness of ADF is in its handling of business services (data sources). Much thought and effort have gone into providing a seamless method for connecting the various

6 108 Oracle JDeveloper 10g Handbook layers of an application to its data. ADF handles the complexity of binding the user interface components to various sources of data. In addition to the ADF BC framework for business services, ADF also integrates business services implemented as Enterprise JavaBeans (EJBs), web services, and Java classes. Struts, JSP pages, EJBs, web services, and Java classes were all supported in Oracle9i JDeveloper, but ADF in JDeveloper 10g wraps them in a consistent architecture and development method. JDeveloper s visual editors, navigators, property inspectors, and modelers reduce the complexity of combining these different technologies and minimize the amount of code that you need to create. The motto of this release is Productivity with Choice. The choice comes from the many technologies, deployment platforms, and development styles that are supported. The productivity results from the ADF development method and architecture. In addition to feedback received from expert user testing and months of feedback from a public preview release available on OTN, ADF has been road tested for over four years by more than two thousand of Oracle s E-Business Suite application developers. From that standpoint ADF is a mature product even though it was just released to the public in JDeveloper 10g. Who Will Use ADF? In the early days of Java, IDEs provided an easy way to compile, run, and debug code without having to use the command line. As Java evolved, IDEs evolved and included more tools such as navigators, visual editors for GUI code, property inspectors, and deployment wizards. The current trend in Java IDE tools is toward model-driven architectures (MDA), which allow a developer to graphically represent the underlying design of an application and then generate code from it. Until the recent tools came along, work in a Java environment has been difficult for the non-expert Java developer. Today Java is a primary language taught in schools, which means that current graduates enter the workforce with Java skills. A Gartner study completed about two years ago ( Leading Languages for IT Portfolio Planning ) placed the use of Java in IT shops at 70 percent. Visual Basic had the same penetration; COBOL and C++ both were in 45 percent of IT shops, and other languages were 20 percent or under. However, there is much talk that a skills gap exists in Java programmers and many Java experts do not know as much as they should about important concepts. Although the exact figures should only be used as guidelines, the trends are noteworthy. Vendors such as Oracle are paying attention. Tools such as JDeveloper are trying to fill the gap in skills and target the majority market. ADF is aimed at all levels of Java developers. Developers who are in the expert category will find that the time-saving features of ADF (such as the data-binding mechanism) will assist their work. They will be able to perform their normal low-level code manipulation and use technologies with which they are familiar, such as EJBs. ADF is also targeted at the not-so-expert Java developer who is new to development languages or who has migrated from another tool such as Visual Basic, PowerBuilder, or Oracle Forms Developer. JDeveloper 10g offers support for more development options than Oracle Forms Developer offers. Because of the flexibility, it is not yet as developer-friendly as a 4GL such as Oracle Forms Developer, but ADF is a step in the right direction toward a tool that is as easy to use as Forms Developer. ADF provides more of a 4GL wrapper on 3GL Java code than any other previous release.

7 Chapter 4: Introduction to the Oracle Application Development Framework 109 NOTE A help topic About Oracle ADF Business Components: An Oracle Forms Developer s Perspective explains ADF BC concepts in the context of their counterparts in Oracle Forms Developer. Although developers familiar with tools such as Oracle Forms Developer will need study and training to understand the intricacies of the J2EE environment, they can still produce productionlevel code using JDeveloper and ADF. Those who have experience with Oracle Forms Developer will find many parallel tools in JDeveloper such as navigators, visual editors, and property inspectors. As ADF and JDeveloper mature further, the learning curve for non-java developers will decrease and developer productivity will increase. NOTE As mentioned in other parts of the book, JDeveloper makes creating J2EE code possible for non-expert developers, but your project still needs one or more Java experts to act as architects and leaders for J2EE technology. ADF User Community Support As mentioned, one consideration for frameworks is the extent of support available in the user community and resources outside of the framework documentation. ADF is a new technology so you will see its third-party support grow over time. However, because many of the frameworks and options that were rolled into ADF had existed in previous releases, the Oracle OTN website (otn.oracle.com) already offers extensive community support and other resources for detailed technical information. Discussion forums on OTN supply the voice of the user community and already have many questions and answers about ADF technology and techniques. In addition, how-tos (detailed instructions for a specific technique), tutorials, product tours and demonstrations (including video clips of working in the IDE), code samples, white papers, Frequently Asked Questions (FAQs), overviews, code samples, specifications, and product sheets extend the range of technical information about ADF. In addition, OTN offers links to JDeveloper partner websites for ADF extensions and tools. These resources started growing during the JDeveloper 10g preview release period and expanded greatly after JDeveloper 10g was placed into production. Development Frameworks in Previous JDeveloper Releases Before fully exploring the concepts and features of ADF, it is useful to briefly examine the evolution of frameworks in JDeveloper. Previous releases of JDeveloper offered frameworks such as UIX, JClient, and BC4J. The BC4J framework contained base classes, wizards, and editor support in the IDE. This method for creating BC4J was well supported and defined in the IDE wizards, Component Palette, Property Inspector, and editors. Other data access methods such as EJBs and web services were also supported but were not a major focus of the IDE. Other frameworks such as UIX and JClient had their own methods for developing the user interface part of the application. In JDeveloper 10g, all of these technologies are still separate components but have been reworked

8 110 Oracle JDeveloper 10g Handbook (refactored) to plug into the new ADF data-binding architecture (described in the Model section later in this chapter). ADF Architecture Model ADF is based on the J2EE design pattern Model-View-Controller (MVC). Chapter 7 explains MVC in the context of J2EE design patterns but a brief preview in this context is necessary as an introduction to the ADF architecture model. MVC For the purposes of this discussion, it is important to know that the Model-View-Controller design pattern defines three main layers of application code: Model This layer represents the data and values portion of the application. View This layer represents the screen and user interface components. Controller This layer handles the user interface events that occur as the user interacts with the interface (view), controls page flow, and communicates with the Model layer. In concept, these layers are independent so that you can switch code in one layer to another technology and use the other two layers without modification. For example, if you build your view layer on JavaServer Pages technology, you could switch ADF UIX into the application and retain the same model and controller layers. In practice, completely separating layers is difficult, but MVC is still useful as a guide and a goal. ADF Layers and Components The ADF architecture divides its components into four layers as shown in Figure 4-1. The Model, View, and Controller layers in ADF correspond to the MVC layers with those names. However, ADF splits the MVC Model layer into two layers: Model and Business Services. For the purposes of this discussion (and throughout the book), applications can exist in two main styles as follows: Java client This is a runtime alternative that runs code in a Java virtual machine on the client machine (such as for Java applications and applets). The Java Foundation Classes (JFC) Swing library (part of the Java Software Development Kit) provides components such as buttons, text items, containers, and windows for building the user interface. Although other component libraries exist, the examples in this book use the Swing library. Web client The web client style displays a user interface in the user s web browser and is run on a web tier server (as are servlets and JSP pages). The main idea of this type of client is that it is lightweight, so for the purposes of this book, mobile client (such as PDAs and cell phones) applications can be considered with this type of client. Business Services The Business Services layer of ADF provides a code layer for accessing data sources such as a database. Business services are responsible for persistence the physical storage of data for future

9 Chapter 4: Introduction to the Oracle Application Development Framework 111 FIGURE 4-1. ADF architecture model retrieval and object-relational mapping translating physical storage units such as rows and columns in relational database tables to object-oriented structures such as arrays of objects with property values. Business services code deployed into the J2EE Business Tier provides a place to code business logic for the application. ADF was designed around the idea of flexibility. For example, if you are accustomed to working with business services delivered in Enterprise JavaBeans, you can develop EJBs to act as business services within the ADF method. ADF supports the following business services technologies: EJB A standard J2EE structure for managing data from within a runtime container, consisting of entity beans, session beans, and message-driven beans. Web services Utility functions and other resources written by a provider that are available through an Internet address and that you can incorporate into your application.

10 112 Oracle JDeveloper 10g Handbook ADF Business Components ADF BC is an evolution of BC4J, which provides components that allow developers to design and code business objects and business logic. It offers easy interaction with business data though SQL statements. ADF BC uses declarative tools (property editors to create and maintain values in XML files) that define functions for persistence and object-relational mapping. Java classes You can code Java class files, also called Plain Old Java Objects (POJOs) or JavaBeans, that supply data stored in files or in Java objects. JDeveloper s TopLink utilities (available in the New Gallery s Business Tier\TopLink category) provide flexible mapping and persistence services to these Java classes. Chapters 8 13 of this book discuss ADF Business Components and Chapter 14 briefly explores other business services alternatives. The sidebar at the end of this chapter called About ADF BC Code provides an introduction to some concepts of ADF BC code. The upcoming sidebar A Note About Service-Oriented Architecture describes service-oriented architecture, which is closely related to business services. Model The Model layer in ADF architecture supplies the connection mechanism from the View layer to the data access components in the Business Services layer. It receives instructions from the Controller layer as requests for data retrieval and updating. The Model layer supplies data from the Business Services layer and sends a request to the View layer to update the display. For example, when the user submits a page in a web client application, the Controller layer requests an update of the data model through the Model layer. The Model layer communicates the data change to the View layer so the visual display can be updated when the page refreshes (in the case of a web client). The Model layer in ADF is composed of two aspects ADF Data Controls and ADF Bindings. Since these are core features of the new ADF development method and ADF architecture, they are worth a more detailed explanation. ADF Data Controls Data controls are definitions used to abstract one or more business services into a common layer. For example, business services that use ADF BC, EJBs, and web services in one project will all be available through a common set of ADF data controls. This is the reason that ADF can support so many business services with a consistent interface. Data controls appear as a list of interface components available to data model components. A data model is a representation of the business service objects available to a project. For example, if A Note About Service-Oriented Architecture Current industry thoughts about business services are focusing towards service-oriented architecture (SOA), which generalizes the idea of business services to just services. SOA services, like business services in ADF, provide a common interface to various service implementations (such as the different possible data sources in the ADF business services layer). SOA services can be data sources such as in ADF as well as any other code or data source. Although this concept is not used in ADF, it is primarily a widening of the ADF concept of business services.

11 Chapter 4: Introduction to the Oracle Application Development Framework 113 you create a business services layer using ADF Business Components, you can define a data model in the application module definition using the Application Module Editor as shown here: The left area of this editor shows the available data objects and the right side shows the data model objects selected for this application module. You can also use the business components diagram to modify or display the application module data model as shown here: This data model contains two master view object instances LocationsView1 and DepartmentsView1. It also contains a detail view object instance, DepartmentsView2, that links to LocationsView1. (You can change the names of the instances using the Application Module Editor.) The view object definitions and their attributes are available to the applications that reference the data model. Data controls standardize the interface to business services other than ADF BC. The properties of a data control (if any) are usually collections of values (like row sets). The Data Control Palette offers user interface controls that are appropriate to the kind of page or panel you are working on (for a web client or Java client, respectively). The interface controls presented also depend

12 114 Oracle JDeveloper 10g Handbook upon whether the data source is a collection of data (such as an ADF view object instance with multiple rows), a single value (such as an attribute in a view object instance), or a single structure (such as a row). Different binding objects are supported depending upon the type of data and the controls available in the Data Control Palette will change based on these considerations. The following lists some of the user interface components available for view object-level components such as LocationsView1 and DepartmentsView2: Java Client Table ComboBox Tree NavigationBar ScrollBar Web Client Read-Only Table Navigation Buttons Input Form Read-Only Form Select Row Link The next list shows some data model components that are available for attributes: Java Client TextField ComboBox CheckBox ScrollBar TextArea Web Client Value Label Text Field Password Field List of Values As you would expect, for each user interface style, different interface components are available for different types of data model components such as view object definitions and view object attributes. Data controls are available from the Data Control Palette, which appears automatically when you display a visual editor (or when you select View Data Control Palette). All data model objects defined for business services in the workspace will be available. When you select a data model object in this palette, the Drag and Drop As pulldown will display a list of available interface components. You add an interface component to the editor by selecting the data model component, such as DepartmentsView2 in the previous example, selecting an interface type from the pulldown, and dragging the data object node into the visual editor. After you release the mouse button, a component will appear in the editor. Figure 4-2 shows this action for a Read- Only Table built from the DepartmentsView2 detail view object definition. In addition to data value components, the Data Control Palette also offers operations such as Commit and Rollback to send the current data in the Model to the Business Services layer. Other navigational operations such as Create, Find, First, Next, Last, and Delete appear on the data set (ADF BC view object definition) level. In addition, you can drag Data Control Palette components into the Page Flow Diagram to create controller-level operations as methods. ADF Bindings Bindings are code or definitions that declare which data from a business service is connected to a user interface control or structure. One of the challenges in the classic definition

13 Chapter 4: Introduction to the Oracle Application Development Framework 115 FIGURE 4-2. Dragging a component to the visual editor of MVC has been where to place the data-binding functionality. ADF Bindings act as the connection layer from the View components to Business Services components. Bindings are defined using XML files, which are created and maintained automatically by actions in the JDeveloper IDE. The binding attaches to data both at design time and at run time. When you drag a component from the Data Control Palette to a user interface surface, ADF binds the new interface component to the data control selected. For Java client controls, ADF sets the Swing component s model or document properties to the selected data control that connects to the business service component. For web client controls, ADF sets the appropriate data attribute for the element. Chapter 12 discusses the ADF Model layer in depth. Chapter 15 contains examples of binding for Java client code. Chapter 18 contains examples of binding for web client code. A white paper on OTN, Oracle ADF Data Binding Primer, discusses data bindings in more depth. NOTE Oracle has submitted the data-binding and data controls architecture to the Java Community Process as JSR-227 ( Controller The Controller layer in ADF is used only for web client code as shown in Figure 4-1. For a web client, the Controller layer defines page flow which page is presented when an action occurs on another page as well as the processing actions that occur between pages (such as a database query). Since the Controller handles the order in which pages appear, a page need not have a

14 116 Oracle JDeveloper 10g Handbook hard-coded link to the next page. This makes the page flow design more flexible because the Controller can apply conditional logic to determine the next page to be displayed. The Controller layer is also responsible for sending data entered in the View layer to the Model layer where it can be processed. Although you can use any controller mechanism (even one you write yourself) for web client code you create in JDeveloper, the tools in the current release of JDeveloper 10g support the Struts controller framework the most fully. Struts The Struts framework is an open source project of the Apache Software Foundation (struts.apache.org) that is used for Controller layer functionality. Struts support is installed with JDeveloper, and JDeveloper contains many powerful features, such as the Page Flow Diagram, that help you create the controller metadata (included in the struts-config.xml file). This metadata determines page flow and the chain of actions in a web application. The Struts controller layer interfaces well with existing view and model technologies. Chapter 17 discusses Struts in JDeveloper in more detail. What About the Controller for Java Client Code? Java client applications use components such as those from the Swing library; these components perform the Controller functions on the client tier through event handlers. Event handlers are triggered by user events such as a button click or field navigation and can affect the component, the form (a collection of components), or the navigation between forms (a parallel concept to page flow in a web client). Although the controller mechanism is built into the component event handlers and is not part of ADF, writing code for events is well supported in JDeveloper. ADF JClient provides the link from the Swing model layer to the Model layer s data bindings and data controls. Swing contains a visual aspect (View layer), event handlers aspect (Controller layer), and model aspect (Model layer). Figure 4-1 shows all Swing MVC layers, along with the ADF JClient binding API inside the View layer because the MVC layers use ADF JClient to communicate with the ADF Data Bindings and Data Controls that are part of the Model layer. View The View layer in ADF includes Java client and web client technologies that are used to render user interfaces. Java Client As mentioned, Java client technology is a runtime alternative that runs code in a Java virtual machine on the client machine. It does not require application servers because all application code is stored and runs on the client machine (although it may access business services code such as ADF BC that is deployed on a web tier server as EJB session beans). A primary function of Swing controls is to present user interface objects an MVC view aspect. As explained in the preceding section What About the Controller for Java Client Code Swing event handlers supply a controller function and JClient supplies a link from the Swing component model layer to the Model layer components in ADF (as shown in Figure 4-1). Web Client ADF supports a number of web client view technologies that display in a browser. Although you can use any view technology, the following technologies are supported the most fully by the JDeveloper tools:

15 Chapter 4: Introduction to the Oracle Application Development Framework 117 JSP technology This is a popular J2EE coding style that combines HTML and JSP tags. You can also embed Java scriptlets that perform programming functions such as conditional processing and iteration. JSP files run on an application server and usually output HTML to the client browser. ADF UIX ADF UIX is an Oracle framework that defines a page using XML code. A unique feature of UIX is its rich container model, which allows you to easily create a standard look-and-feel for your application. Since the page definition is XML metadata, the page can be rendered using different viewers such as mobile devices or a desktop browser. Oracle s E-Business Suite (Oracle Applications) uses UIX technology for its self-service applications. UIX has many features in common with JSF technology. For web client applications, the code is run on an application server and generates a page that is displayed in the client s display device (such as a web browser). These technologies are primarily coded with tag languages that are supported by various Java class libraries (called tag libraries). These libraries present the user interface using standard controls for the appropriate device (such as HTML in a web browser). When the user submits a web page that contains input values, the page is processed by the Controller layer. JavaServer Faces Another view technology that deserves a mention (although it is not shown in Figure 4-1 because it has no native support yet in JDeveloper 10g), is JavaServer Faces (JSF) technology. JSF technology is a Sun initiative that developed from the Java community process as Java Specification Request (JSR) 127. This JSR has recently been released in its final form and has a reference implementation (code proving the specification can be built). Since it is a new technology, not all development frameworks support it yet. JSF adds a cleaner separation between logic and HTML presentation to JSP technology. The JSF API and JSP tag libraries offer Controller functions that you can use instead of Struts as well as a standard way to manage the server-side processing of user interface components (for example, for data validation, page navigation, and events). JSF handles different client devices such as mobile clients and desktop clients more easily than JSP technology. Even though JDeveloper does not offer JSF support natively, you can still work with JSF using some of the JDeveloper tools as explained in the sidebar A Word About JSF Technology in JDeveloper. A Word About JSF Technology in JDeveloper Although JSF is not automatically installed in JDeveloper, you can download the reference implementation from the Sun website (java.sun.com/j2ee/javaserverfaces) and register JSF tag libraries in JDeveloper. You can then develop JavaServer Faces code using some of the same tools you use for JSP and UIX files. The JDeveloper help system contains information about how to get started (search for JSF in the Index page) and a link to the OTN website where a How To white paper discusses details of using JSF in JDeveloper. The Sun Microsystems website also offers the J2EE 1.4 Tutorial (java.sun.com/j2ee/tutorial), which contains a thorough introduction to JSF. To learn more about the future of JSF in JDeveloper, refer to OTN for the white paper Roadmap for the ADF UIX technology and JavaServer Faces.

16 118 Oracle JDeveloper 10g Handbook NOTE View technology alternatives are discussed further in Chapter 7. Chapter 15 discusses Swing and JClient further, Chapter 18 describes JSP pages, and Chapter 19 discusses ADF UIX pages. ADF Code Libraries As with any framework, ADF provides a set of base libraries that you can extend and customize. These libraries are the core of the application that you create using JDeveloper tools and a specific development method. The application-specific code that you add in JDeveloper uses the ADF libraries for basic functionality. Therefore, you will very rarely need to know details about how the libraries work unless you need to replace or supplement a specific mechanism. However, you will need to know what functionality the libraries offer so that your code can take advantage of that functionality and so that you do not waste time writing code for functionality that the framework offers by default. Also, should you need to modify the way in which the libraries work, you will need to refer to the JDeveloper online documentation and Javadoc for the appropriate class. The main libraries in ADF consist of many proven technologies. The code is based on J2EE design patterns and is deployable in any J2EE-compliant server or environment. The code, as with all Java code, is platform independent so it will run under any operating system. It is also nonspecific to a particular database product, although ADF Business Components contain some features (like automatic sequence generators) that work best with an Oracle database. See the help system topic Limitations of Developing Oracle ADF Business Components for Oracle9i Lite and Non- Oracle Datasources for more information; in the table of contents node, navigate to Building J2EE Applications\Working with the Business Tier\Developing Oracle ADF Business Components\ Developing Oracle ADF Business Components for Oracle9i Lite and Non-Oracle Datasources. NOTE ADF runtime libraries are included in the cost of the JDeveloper license. Deploying the runtime libraries to a J2EE server (for web client code) requires no additional runtime license. Some ADF Libraries Since the ADF libraries are automatically used by the IDE, a full list of the libraries and their contents would not be helpful outside the realm of a reference manual. However, the following is a list of some of the libraries available in the Libraries node of the Project Properties dialog: ADF Controller Runtime ADF Designtime API ADF EJB Runtime ADF Model Runtime ADF JSP Tag Library ADF TopLink Runtime ADF UIX Runtime ADF Web Runtime BC4J Client BC4J EJB Client BC4J EJB Runtime BC4J HTML BC4J Struts Runtime JClient Runtime

17 Chapter 4: Introduction to the Oracle Application Development Framework 119 You can access the Project Properties dialog by double clicking a project node in the Application Navigator and selecting the Libraries page under Profiles\Development as shown here: Selecting a library name shows the archive files that it is composed of under the Available Libraries area. You can also click the Edit button in this dialog to display the Edit Library dialog, which contains information about the library. The Edit Library dialog also contains a View button to the right of the Class Path field that shows the View Class Path dialog, which contains a list of archive files in the library as shown here: NOTE Information about the ADF libraries can be found in the JDeveloper online help system. The table of contents node contains a Reference node (book) that contains Javadoc for a number of ADF libraries such as ADF BC (the library is called Oracle Business Components for Java ), ADF UIX (the library is called UIX ), and the ADF Controller.

18 120 Oracle JDeveloper 10g Handbook ADF Development Method and IDE Support Two major features of a development framework are the development method used to create applications and the IDE support for that development method. In JDeveloper, the development method is bound to the IDE. Therefore, it is necessary to explain the development method and IDE support together. The purpose of framework support in an IDE is to make the job of learning the framework easier and to allow you to create applications more quickly. Framework tools allow you to work within a declarative environment and let you focus on the business requirements instead of the details of writing 3GL code and the plumbing needed to connect application components. The objective is to use the declarative tools to create as much application code as possible and spend the least amount of time writing custom code. This will allow you to spend more time writing code that adds business value to the application and less time writing code for plumbing. The more you know about the framework, the closer you will be to achieving this objective. This section provides an overview of these steps using ADF and a description of the tools that support these steps. Chapter 1 provides a summary of how to create applications in JDeveloper and hands-on practices to demonstrate the steps. Chapters 2 and 3 discuss the JDeveloper IDE more fully so this discussion will focus on how the IDE tools support ADF instead of all features of all tools. Individual tasks in the ADF development method are well documented in the online help system and in documents on the Oracle Technology website (otn.oracle.com). JDeveloper is oriented toward using ADF to create code and all tools support work within the ADF method. NOTE Understanding a framework completely is not a prerequisite to producing workable code. You can start working in JDeveloper and ADF after a brief overview; however, the more you know about the framework, the better chance you have of using it in the right way and of being more productive. All work in JDeveloper creates plain ASCII text files, some of which may need to be compiled but most of which will be deployed into a production environment. JDeveloper keeps track of all files (such as server configuration files) even if you are not aware of them so that the deployment package is complete. (Chapter 7 discusses details about J2EE deployment.) Developers who use JDeveloper 10g must still be aware of how the plumbing works so that they can perform any required customizations, but they do not have to create or maintain the files that connect to or configure the client, the application server, and the database server. They do need to consider how the application should look and act and how it will implement business requirements. This is the most proper use of a developer s time and expertise finding programmatic solutions for business problems. The Steps The steps for creating code are slightly different for each type of technology (for example, Java client or web client). However, the ADF development method is very similar for all. This section summarizes the high-level steps needed to create an ADF BC model and JSP view application. The general steps are similar for a Java client. Refer to the hands-on practices throughout this book for detailed steps. In addition to outlining the high-level steps you follow when creating

19 Chapter 4: Introduction to the Oracle Application Development Framework 121 such an application, this section also describes some of the tools and ADF concepts you will employ for each step. The method consists of the following general phases: I. Create an application workspace using an application template II. Create the Business Services and Model layers III. Create the View and Controller layers IV. Test, debug, and deploy the application The steps for creating the Model layer are contained within the phase that creates the Business Services layer. The steps for creating the Controller layer are contained within the phase that creates the View layer. Details of how each project is created are specific to the type of code that you are building. I. Create an Application Workspace Using an Application Template As explained in Chapter 1, JDeveloper organizes code files into projects that contain similar types of code for an application. Projects are contained within application workspaces. When you start work on an application, you need to create an application workspace using the Create Application Workspace dialog shown next: Application Template This dialog contains an Application Template pulldown where you select a specific application template. This pulldown contains pre-defined templates (described in Chapter 1). Using a specific template to create a workspace will create a set of projects, each of which is set up for a specific technology scope.

20 122 Oracle JDeveloper 10g Handbook Technology Scope Each project created by an application template will be oriented toward a specific technology scope. Technology scopes are a way to reduce the enormous number of options available in the JDeveloper IDE to just the options that apply to the application you are developing. A technology scope in this context refers to the following behavior: A set of code libraries will be placed into the CLASSPATH for the application runtime and for coding the application. Specific user interface and controller components will be accessible using the Component Palette pages in a project. A specific style of business services will be available to the workspace. Specific configuration files will be created in the project, for example, a web.xml file for web client applications. The New Gallery item list will be filtered appropriately. New Gallery Item Filtering As an example of filtering in the New Gallery, if you select the Web Application [Default] template, ADF will create a workspace containing a Model project for business services, and a ViewController project for the view (JSP or UIX code) and the controller (Struts) code. The New Gallery for the Model project will display items that are applicable to the technologies defined for the project, such as Business Components, as shown in the following illustration:

21 Chapter 4: Introduction to the Oracle Application Development Framework 123 The list of categories is filtered to those that will likely be required for a model project. The ViewController project for this workspace would show New Gallery categories and items that are applicable to the technologies defined for the project as shown here: The Filter By pulldown at the top of the New Gallery allows you to select All Technologies in case an item you need to create does not appear. After you select an item or category outside the technology list and return to the New Gallery, that item or category will be available even if the pulldown in the New Gallery is Project Technologies. You can add technologies to a project using the Technology Scope page of the Project Properties dialog (accessed by right-clicking the project node). TIP If in each project you create, you find yourself selecting the same New Gallery category or item that is outside of the project technology, you should create your own application template modeled after the default template that contains the appropriate technologies. Managing Application Templates You can examine the definitions of the default templates and add your own templates by clicking the Manage Templates button (if the Create Application Workspace dialog is displayed) or by selecting Tools Manage Application Templates to display the Manage Application Templates dialog shown in Figure 4-3.

22 124 Oracle JDeveloper 10g Handbook FIGURE 4-3. Manage Application Templates dialog You can view the technologies that apply to a particular project within the application template by clicking the project node under a template name, as Figure 4-3 shows. Selecting the Application Templates node and clicking New allows you to define your own application template. NOTE In addition to limiting the options available in the IDE by using technologies, you can use the Extension Manager to temporarily disable options that you will not use. You can access the Extension Manager using the Extension Manager page of the Preferences dialog (Tools Preferences). II. Create the Business Services and Model Layers After creating an application workspace with an empty Model project, you need to define the business services in that project. This task relies on ADF wizards, dialogs, or modelers to create default objects that you can modify. The following example describes a path for creating the default objects using ADF wizards. Part II of this book contains examples of using the Business Components Modeler to create ADF BC components.

23 Chapter 4: Introduction to the Oracle Application Development Framework 125 Wizards and Editors The Model project created using the Web Application [Default] template shows ADF Business Components in the New Gallery. Selecting Business Components from Tables in this dialog starts the Business Components Project Initialization dialog shown here: This dialog creates some ADF BC configuration files and starts the Create Business Components from Tables Wizard. This wizard steps you through the process of defining which tables will be the source of entity object definitions, which view object definitions to create from the entity object definitions, and how the application module is named. After running this wizard, you will see objects in the Application Navigator for the components you specified in the wizard such as the following for the DEPARTMENTS and LOCATIONS tables: In addition to the objects shown in the Application Navigator, the wizard creates configuration and property files. For example, the Model project created using the Create Business Components

24 126 Oracle JDeveloper 10g Handbook from Tables Wizard will include the bc4j.xfcg, model.xml, and Model.jpx files. These configuration files are visible under the project s node in the System Navigator. In addition to the wizards that create default code objects, ADF provides various editors. In this example of a Model project, double clicking an object such as the Locations entity object definition displays an editor such as the following: This editor modifies the XML file associated with the entity object definition. You cannot edit the XML file directly in a code editor within JDeveloper. This editor can also create Java class files that allow you to extend the default entity object behavior, and these Java files may be edited directly in the Code Editor. Chapter 10 discusses entity object definition editing. Diagrams For model components, you can also create diagrams such as the business components diagram shown in Figure 4-4 for the Locations and Departments application module. The Component Palette offers elements that you can add to the diagram as shown in the excerpt from the Component Palette for an ADF BC diagram in Figure 4-4. As with all diagrams, the Thumbnail window shows a version of the page you are editing and allows you to navigate around the window by dragging a viewport rectangle. Other types of business services offer diagrams, wizards, and editors that are similar to this example. Structure Window The Structure window displays the contents of business services objects such as the example in Figure 4-4 for an ADF BC entity object definition. You can view or edit most elements shown in the Structure window by double clicking the element or by selecting Edit from the right-click menu on the element s node.

25 Chapter 4: Introduction to the Oracle Application Development Framework 127 Business Components Diagram Component Palette Structure window FIGURE 4-4. Some Business Services tools III. Create the View and Controller Layers The ViewController project is the container for code in the View and Controller layers of the application. It uses the same Code Editor as the Model project objects. It also uses the same Structure window although the Structure window objects represent elements appropriate to the View and Controller components. The Component Palette contains the components appropriate to the View and Controller layers.

26 128 Oracle JDeveloper 10g Handbook Page Flow Diagram ADF supports the Struts controller by default, and some Struts files are automatically created when you specify the Web Application [Default] application template. You can see these files, namely ApplicationResources.properties and struts-config.xml, in the Application Navigator as shown under the default ViewController project here: The Page Flow Diagram is the starting point for creating user interface code such as JSP and UIX code. It is available by double clicking the struts-config.xml or by selecting Open Struts Page Flow Diagram from the right-click menu on the ViewController project. If the project does not contain a struts-config.xml file, you can create one using the New Gallery s Web Tier\Struts category. After opening the diagram, you drop components on it from the Component Palette. A simple Page Flow Diagram is shown here: Notice that action components (cogwheel symbols) that represent the Controller layer as well as page components (rectangular box page symbols) that represent the View layer are displayed on the same diagram. The Component Palette for a Struts Page Flow Diagram contains all elements that would normally appear on this diagram. The Structure window and Property Inspector display the applicable elements and properties, respectively, for a selected component. JSP/HTML Visual Editor and Data Control Palette The next step in creating a View project is to add user interface components to the pages defined in the Page Flow Diagram. Double clicking the page symbol opens a dialog that allows you to name the file associated with the Struts page symbol. The file extension you use in this dialog (.jsp or.uix) determines what type of editor will open when you click the OK button in the dialog. For a JSP file, the JSP/ HTML Visual Editor will open as shown in Figure 4-5. (For a UIX file, the UIX Visual Editor will open.) As in other steps, you will also see the Component Palette and Structure window. In addition, the Data Control Palette will appear containing the business services objects and a pulldown listing the appropriate user interface components. (Data controls are explained earlier in this chapter, as well as in Chapter 17.)

27 Chapter 4: Introduction to the Oracle Application Development Framework 129 FIGURE 4-5. JSP/HTML Visual Editor and supporting tools Next, you select a node in the Data Control Palette, select the appropriate component from the Drag and Drop As pulldown, and drop the component on the visual editor. This action binds the component to the selected business services object such as the LocationsView1 view object instance in this example. You can also add components using the Component Palette but this does not set the data-binding properties, so you will need to set them manually if the component represents business services data. You can use the JSP/ HTML Visual Editor to edit the HTML portion of the JSP file including the style sheet (selected by clicking the visual editor and selecting the style sheet from the Component Palette), boilerplate text such as headings and labels, and other HTML elements such as tables. The visual editor allows you to view and edit the components (without data) in an emulation of the runtime display. Property Inspector and Structure Window After dropping the required components onto the page, you can set details of an object by selecting it in the visual editor and using the Property Inspector.