15 Migrating Client-Server Applications to the Web

Guidelines for Migration

When migrating your applications from client-server deployment to the Web, note that a Web-based application:

• Supports JPEG and GIF image types only, so convert existing images to these formats.

• Supports the use of compressed JAR (Java Archive) files for file transfer, so use JAR files whenever the transfer of large files is required between the Forms Services and the Java client.

• Does not support ActiveX, OCX, OLE, or VBX controls in the user interface. Instead, use JavaBeans to duplicate functionality in the user interface. Any other Microsoft Windows user interface dependencies should also be replaced with JavaBeans. You can also use WebUtil to restore some of these functions.

• Does not support MouseMove triggers, such as When-Mouse-Enter, When-Mouse-Leave, and When-Mouse-Move.

• Does not natively support write access to the client hard drive. This can be accomplished by writing a JavaBean for the pluggable Forms user interface.

• Supports Java fonts only, so check applications for the types of fonts used. If necessary, switch to Java fonts. Java uses a font alias list, located in the Registry.dat file. The font aliases described in Table 15-1 are supported:

  Table 15-1 Font Support for Web-based Applications

  Java font	Windows font	XWindows font	Macintosh font
  Courier	Courier New	adobe-courier	Courier
  Dialog	MS San Serif	b&h-lucida	Geneva
  DialogInput	MS San Serif	b&h-lucidatypewriter	Geneva
  Helvetica	Arial	adobe-helvetica	Helvetica
  Symbol	Wingdings	itc-zapfdingbats	Symbol
  Times Roman	Times New Roman	adobe-times	Times Roman

  
  

• Has some Built-ins and packages that execute only in the application server, but not in the client browser:

  • TEXT_IO

  • HOST

  • ORA_FFI

  • GET_FILE_NAME

  • READ_IMAGE_FILE

  • WRITE_IMAGE_FILE

If the functionality of these Built-in and packages is required for the client, use JavaBeans as a replacement or WebUtil.

About Client-Server-Based Architecture

In the client-server-based implementation, shown in Figure 15-1, the Forms Server Runtime Engine and all application logic are installed on the user's desktop machine. All user interface and trigger processing occurs on the client, except for database-server-side triggers and logic that may be included in some applications.

Figure 15-1 Oracle Forms Client-Server Architecture

About Web-Based Architecture

In a Web-based implementation, shown in Figure 15-2, the Forms Services Runtime Engine and all application logic are installed on application servers, and not on client machines. All trigger processing occurs on the database and application servers, while user interface processing occurs on the Forms client, located on users' machines.

Figure 15-2 Oracle Forms Web Architecture