Oracle forms les02

Editor's Notes

• #3: Introduction Overview It is essential that you understand the environment of the form operator before designing and building your own applications. In this lesson you run an existing application on the Web in order to familiarize yourself with the run-time interface of the Oracle Forms Developer.
• #4: Testing a Form with OC4J What Is OC4J? Oracle Application Server Containers for J2EE (OC4J) is Oracle’s Java 2 Enterprise Edition (J2EE) container that executes on any Java Virtual Machine (JVM), which is the Java interpreter that is provided on each operating system and hardware platform. It is implemented completely in Java, making it lightweight and easy to install. At the same time, it provides complete support for J2EE applications, including servlets, Enterprise JavaBeans, JavaServer Pages, and so on. OC4J is ideally suited to run Forms applications. It is included in Oracle Developer Suite to enable you to test your applications, if desired, on the same machine where you are running Forms Builder. In other words, you do not need to install Oracle Application Server to test your applications.
• #5: Testing a Form: Starting OC4J To use OC4J on Windows, start it by executing the batch file provided, called startinst.bat. This file is located in the j2ee\DevSuite\ subdirectory of the Developer Suite home directory. If you will be testing your applications on your client machine, it is a good idea to set up a shortcut to this batch file, and also to the batch file called stopinst.bat, which stops the OC4J instance. Alternatively, you can call these batch files from the Windows Start menu: Programs > Oracle Developer Suite – iDS10g > Forms Developer > Start [Shutdown] OC4J Instance. The batch file executes in a separate window; you can minimize this window if desired. Do not close this window, or you will abort the OC4J instance. When you no longer need to run OC4J you can execute the batch file called stopinst.bat to stop the OC4J instance.
• #6: Running a Form Deploying form applications to the Web is implemented by the three-tier architecture of Oracle Application Server. Application logic and the Forms Services Runtime Engine reside on the middle-tier application server. All trigger processing occurs on database and application servers, while user interface processing occurs on the Forms client. End users can run Forms Developer applications in a Web browser. Users request an application in their Web browsers by entering a URL that points to the application. Forms Services then generates an HTML file that downloads a Java applet to the client machine. This small applet is capable of displaying the user interface of any form, while the application logic is executed on the middle tier.
• #7: Running a Form: Browser The URL to invoke an application must have the following format: http://host[:port]/forms servlet or html file[parameters] (optional portions of URL enclosed in brackets) Summit’s URL consists of the following components:
• #8: The Java Runtime Environment The Web browser can run a Java applet because it provides a Java Runtime Environment (JRE). However, not all Web browsers are able to natively run the Forms client. On Windows platforms, Oracle provides a plug-in called JInitiator that provides an alternative JRE capable of running the Forms applet. JInitiator provides several benefits: It is able to incrementally download the Java ARchive files (JAR files) needed for the Forms client, providing faster application startup. It caches the JAR files locally, so that they do not need to be downloaded again. It improves application performance within a browser session by applet instance caching. When a user navigates from the current page in the browser, the running Forms application is cached. When the user comes back to the page containing the applet, the applet that was running is automatically fully restored, including all of the data entered in the application. It is automatically configured to run the Forms application in trusted mode. This enables the application to have access to resources that the Java sandbox model normally prohibits it from using, such as print services.
• #9: Starting a Run-Time Session Starting a Run-time session involves the following steps: 1.The user accesses the URL that indicates that a Forms application should be run. 2.The Oracle HTTP Server or OC4J receives an HTTP request from the browser client and contacts the Forms Servlet. 3.The Forms Servlet dynamically creates an HTML page containing all the information to start the Forms session.
• #10: Starting a Run-Time Session (continued) 4.The Oracle HTTP Server or OC4J downloads a generic applet to the client after checking that it has not already been downloaded. The client caches the applet so that it can run future Forms applications without downloading it again. 5.The client applet contacts the Forms Listener Servlet to start the session. The Forms Listener Servlet starts an instance of the Forms Runtime Engine on the Forms Server (middle tier). If included in the HTML file, Forms Runtime command-line parameters (such as form name, user ID and password, database SID, and so on) and any user-defined Forms Builder parameters are passed to the process by the Forms Listener Servlet. 6.The Forms Listener Servlet establishes a connection with the Runtime Engine, which connects to the database if needed and loads application executable files.
• #11: Starting a Run-Time Session (continued) 7.The Forms applet displays the user interface of the application in the main window of the user’s Web browser. 8.The Forms Listener Servlet, working through OC4J or the HTTP Server, manages communication between the Forms applet and the Runtime Engine. Technical Note More information about the Oracle Forms Listener Servlet is available in the Oracle white paper: Oracle Application Server Forms 10g (9.0.4) Technical Overview.
• #12: The Forms Servlet The Forms Servlet is a Java servlet that creates a dynamic HTML file by merging information from the following sources: The Forms Web configuration file The Forms base HTML file The application’s URL parameters
• #13: The Forms Client? The Forms Client is a generic Java applet. Forms Services dynamically downloads this applet and automatically caches it on the client machine. The Forms Client consists of a set of Java classes. At startup, only those Java classes that are necessary to initialize the application are downloaded. Additional class files are downloaded dynamically, as needed, to support additional user interface activity. You do not have to deploy a separate Java applet for each application. The same generic applet is used to run any Forms Services application, regardless of its size and complexity. Responsibilities of the Forms Client The Forms Client represents the user interface layer and has three primary functions: To render the Forms Services application display for the user To efficiently process user interaction back to Forms Services To process incoming messages from Forms Services and translate them into interface objects for the end user efficiently
• #14: The Forms Listener Servlet? The Forms Listener Servlet is a Java servlet that runs in a Web server equipped with a servlet engine, such as OC4J. The Web server directs HTTP requests for the Forms Listener Servlet directly to the servlet instances. The Forms Listener Servlet is in charge of: Managing the creation of the Forms Runtime process for each client Managing the network communications that occur between the client and its associated Forms Runtime process, through the Web server This means that the client sends HTTP requests and receives HTTP responses from the Web server process itself. Since the Web server acts as the network endpoint for the client, there is no need to expose additional server machines and ports at the firewall.
• #15: The Forms Runtime Engine? The Forms Runtime Engine is a process on the Application Server that is started by the Forms Listener Servlet. You cannot start the runtime engine directly. The Forms Runtime Engine handles all the application logic and Forms functionality and executes the code written into the application. It manages requests from the Forms Client and sends metadata to the client to describe the user interface. It connects to and communicates with the Oracle database via Oracle Net Services, the replacement for Net8 and SQL*Net.
• #16: What You See at Run Time At run time, you will see the following components: 1.Browser window 2.Java applet (contained within browser window) 3.Default menu (contained within applet) 4.Menu toolbar (contained within applet) 5.Console (contained within applet) What is the Default Menu? The Default menu, which is part of all Oracle Forms Developer applications, is an alternative to keystroke operations. You can replace or customize the Default menu to introduce your own functionality into a form module. What is the Menu Toolbar? The Menu toolbar contains buttons corresponding to menu items. At run time, it appears above any user-defined toolbars. It executes the same code as menu items, and it is a shortcut to menu commands that does not duplicate code or effort.
• #17: What You See at Run-Time (continued) What is the Console? The console is the generic name for the standard features that provide information at run time. The console is displayed at the bottom of the window and consists of: The message line that displays both Forms and application-specific messages. The status line that displays a variety of indicators to reflect the current state of the form module.
• #18: Identifying the Data Elements A Forms application may contain many different kinds of data elements: 1.Prompts 2.Text Items 3.Boilerplate graphics 4.Check boxes 5.Boilerplate text 6.Display items 7.List items 8.Push buttons 9.Image items 10.Radio groups Not Pictured: Hierarchical tree items Chart items Custom items
• #19: Navigating a Forms Application The Default Menu The Default menu is automatically available in a form, unless it is disabled or replaced with a customized menu. Select options from the menu by using the mouse or function keys. At run time, use the menu to perform the following tasks: Move the cursor and navigate between data blocks, records, and items. Save or clear all changes. Execute queries. Insert new records or delete existing records. Invoke Help. The Menu Toolbar You can use the Default menu toolbar buttons to perform the following operations also available through the Default menu: Save all changes. Exit the form. Execute queries. Navigate between data blocks or records.
• #20: Navigating a Forms Application (continued) The Menu Toolbar (continued) Insert new records or delete existing records. Invoke Help to see properties of an item. The Mouse You can use the mouse to navigate and to perform many user operations in a bitmapped environment without needing to learn the function keys. Use the mouse to perform the following actions: Move the cursor. Select from a menu. Select from an LOV. Select or clear a check box. Select a button, including a radio button. Switch to an open window. Respond to an alert. Scroll records or lines by using a data block or item scroll bar. Manipulate a custom item. Buttons Web applications often use buttons as a means of navigation. You can click buttons with the mouse. Use buttons to perform the following tasks: Move input focus. Display a list of values. Invoke an editor. Invoke another window. Commit data. Issue a query. Perform calculations. Exit the form. Function Keys In addition to navigating with the mouse, you can move from item to item in sequence with function keys. Use function keys to perform the following tasks: Navigate between data blocks, records, and items. Execute queries. Insert new records or delete existing ones. Invoke Help. To view a list of keys and the functions they perform, select Help > Keys, or press [Ctrl]+K.
• #21: Modes of Operation Forms Builder has two main modes of operation: Enter-Query mode and Normal mode. The third mode of operation, Query mode, occurs while Forms is processing a query; the user cannot interact with the form while processing is taking place. Enter-Query Mode Use Enter-Query mode to enter search criteria for a database query. In Enter-Query mode, your keystrokes are interpreted as search criteria for retrieving restricted data. What you can do in Enter-Query mode Retrieve all records Retrieve records by using selection criteria Retrieve records by using the Query/Where dialog box Obtain the number of records that will be retrieved before fetching them from the database by using Query > Count Hits What you cannot do in Enter-Query mode Navigate out of the current block Exit from the run-time session Use certain functions, such asNext Record
• #22: Normal Mode Use Normal mode to insert and alter records in the database. In Normal mode, your keystrokes are interpreted as either the entering of new records or the altering of existing ones. What you can do in Normal Mode Retrieve all records. Insert new records. Update records. Delete records. Commit (Save) records. Rollback (Clear) records. Navigate outside of the current data block. Exit the run-time session. What you cannot do in Normal Mode Retrieve a restricted set of records. Invoke the Query/Where dialog box.
• #23: Retrieving Data You can use a form module to retrieve information from the database without knowing any SQL syntax. However, if you are an experienced SQL user, you may want to supplement Oracle Forms Developer default processing with your own SQL predicates. There are two general types of queries: Performing an Unrestricted Query You can retrieve unrestricted data by performing one of the following actions: Select Query > Execute. Press the appropriate function key. Click the Execute Query button. Note: You cannot perform a query while you have unsaved updates, inserts, or deletes. Either save or undo the changes before you continue with the query.
• #24: Performing a Restricted Query You can use any one of the following methods to perform a restricted query: Matching values Matching patterns (wildcards) A Query/Where dialog box for user entry of SQL predicates Valid Search Criteria
• #25: Performing a Restricted Query (continued) How to Perform a Restricted Query You can perform a restricted query with the following steps: 1.Perform one of the following: Select Query > Enter. Click the Enter Query button. Press the appropriate function key. 2.Enter-Query displays on the status line. 3.Enter search criteria into appropriate items. 4.Perform one of the following: Select Query > Execute. Click the Execute Query button. Press the appropriate function key. Note: Forms Builder constructs a select statement by using the AND operator for all specified conditions.
• #26: Using the Query/Where Dialog Box In the Query Where dialog box you can enter complex search criteria by using raw SQL. To use the Query/Where dialog box effectively requires knowledge of SQL. Use Query/Where to perform the following tasks: Write complex search conditions. Write queries with OR predicates. Order the result of a query. Note: Forms Builder logically uses the AND operator to append the Query/Where conditions to any other search criteria (including those imposed by the form designer) and constructs a SELECT statement. The Query/Where dialog box does not work in an item whose name differs from the name of its corresponding database column. Example 1.To restrict the query to orders with a Sales Rep ID (:S) of 11 or an Order ID (:O) between 100 and 200, enter the following in the Query/Where dialog box: :S = 11 OR :O between 100 and 200 2.To sort the data by Sales rep ID (:S), enter the following in the Query/Where dialog box: ORDER BY :S
• #27: How to Use the Query/Where Dialog Box To use the query/where box to enter query criteria: 1.Perform one of the following: Select Query > Enter. Click Enter Query. Press the appropriate function key. 2.Enter a colon (:) followed by a unique character variable name in one or more items. 3.Perform one of the following: Select Query > Execute, click Execute Query, or press the appropriate function key.Note: You can select Query > Count Hits if you simply want to know how many records will match your criteria. 4.The Query/Where dialog box is displayed. Enter the search criteria by using variables, SQL, and logical operators. Click OK.Note: To perform a query without any variables, type only the colon (:) and execute the query. Doing so also displays the Query/Where dialog box. If you enter an ORDER BY at run time, it overrides any ordering defined by the designer.
• #28: Inserting, Updating, and Deleting Records Upon entering a typical form module you are in Normal mode. This means that Forms Builder regards anything that you type into a blank record as an insert and anything that you type over an existing record as an update. How to Insert a Record To insert a record, perform the following steps: 1.Ensure that you have the cursor positioned on a blank record by performing one of the following steps: Scroll down until you find a blank record (always the last in the block). Select Record > Insert. Click Insert Record (green +). Press the appropriate function key. 2.Enter the data into the relevant items.
• #29: Inserting, Updating, and Deleting Records (continued) How to Update a Record To update a record, perform the following steps: 1.Select Query > Enter. 2.Enter the search criteria to retrieve the appropriate record. 3.Select Query > Execute to retrieve all records that satisfy your specific search criteria. 4.Scroll through the records, stopping at the record to be updated. 5.Update the record. How to Delete a Record To delete a record, perform the following steps: 1.Select Query > Enter. 2.Enter the search criteria to retrieve the appropriate record. 3.Select Query > Execute to retrieve all records that satisfy your specific search criteria. 4.Scroll through the records, stopping at the record to be deleted. Delete the record by taking one of the following actions: Select Record > Remove to clear the record and mark it for deletion. Click Remove Record (red X) to clear the record and mark it for deletion. Press the appropriate function keys.
• #30: Making Inserts, Updates, and Deletes Permanent To make any inserts, updates, or deletes permanent you must save (commit) them to the database. To do this, take one of the following actions: Select Action > Save. Click Save in the menu toolbar. Discarding Inserts, Updates, and Deletes To discard any inserts, updates, or deletes, you must clear the records (rollback) instead of saving. Perform a rollback by selecting Action > Clear All. Exiting a Run-Time Session You exit the run-time session by taking one of the following actions: Select Action > Exit. Click Exit. Press the appropriate function keys. Note: By default, you cannot exit the form while you have unsaved updates, inserts, or deletes. You need to either save or undo the changes before you can exit.
• #31: Displaying Errors If an Oracle error is displayed on the message line while you are operating a form application, you can view the underlying SQL code by selecting Help > Display Error. Example Here is the SQL statement in error and its corresponding error: SELECT order_id, order_date, order_mode, order_status, customer_id, sales_rep_id FROM orders WHERE (order_id in ('a','b')) ORA-01722: invalid number Note: Selecting Help > Display Error displays only those errors where the error on the message line is preceded by ORACLE error.
• #32: Summary This lesson introduced the operator interface of Forms Builder. The following concepts were covered in this lesson: Starting OC4J on the development machine The run-time environment for Forms: Running a form in a Browser Starting a run-time session: The Forms Servlet, the Forms Client, and the Forms Listener Servlet The data elements of a form
• #33: Summary (continued) Elements of a running form Navigation methods Modes of operation: Normal mode Enter-Query mode (There is also a Query mode that occurs when the form is fetching records; the operator cannot interact with the form in Query mode.) Retrieving data by performing: Restricted queries—you supply search criteria Unrestricted queries—you supply no search criteria
• #34: Summary (continued) Inserting, updating, and deleting records Saving or clearing changes Displaying database errors
• #35: Practice 2 Overview In this practice session, you start OC4J to function as a Web server on your local machine. You run the course application in a browser and execute both unrestricted and restricted queries. You navigate through the application and use it to insert, update, and delete records. Note: For solutions to this practice, see Practice 2 in Appendix A, “Practice Solutions.”
• #36: Practice 2 1.Start an instance of OC4J. Invoke Internet Explorer and enter the following URL:http://<machine>:<port>/forms90/f90servlet?form=customers.fmxYour instructor will tell you the machine name and port number to use. Select Help > Keys from the menu. Click OK to close the Keys window. Browse through the records that were returned by the unrestricted query that executed automatically when the form started. Execute a restricted query to retrieve information about the customer with the ID of 212. Execute a restricted query to retrieve the customer whose first name is “Meenakshi”. Try each of these restricted queries: a.Retrieve all cities starting with San. b.Retrieve all customers based in the USA with a low credit limit. Display the customer details for Harrison Sutherland and click Orders to invoke the Orders form module. Click Image Off and notice that the image item is no longer displayed. Click Image On and notice that the image item is displayed. Query only those orders that were submitted online. Move to the fourth record (Product ID 2322) in the Item block of Order 2355 and click Stock.The Inventory block is displayed in a separate window with stock information for that item. Close the Stock Levels window. For the customer Harrison Sutherland, insert a new record in the ORDER block, as detailed below.Notice that some items are already populated with default values. Enter the following: Insert a new record in the ITEM block with the following values:
• #37: Practice 2 (continued) Save the new records. Update the order that you have just placed and save the change.Note: You may receive a message indicating that there are no changes to save. This message is generated by the Customers form, because both forms are saved at the same time. Changes to the Orders form should be saved successfully, so you can acknowledge the message and then ignore it. Attempt to delete the order that you have just placed. What happens? Delete the line item for your order and save the change. Now attempt to delete your order and save the change. Exit the run-time session and close the browser window.