Introduction

This document describes changes made to WebObjects between release 4.5 and 4.0. It describes changes made to existing features and describes new features you may want to start using in your applications

Compatibility with WebObjects 4.0

WebObjects 4.5 is compile-compatible with WebObjects 4.0. You should be able to run most WebObjects 4.0 applications by simply rebuilding them using WebObjects 4.5. Note that Direct To Web and Java Client applications require some additional effort to convert to WebObjects 4.5; see the WebObjects 4.5 Post-Installation Instructions for more information on converting your existing applications.

Changes in WebObjects 4.5

This section describes the primary changes to WebObjects for the 4.5 release, including Enterprise Objects Framework (EOF), which is considered part of WebObjects 4.5.

Platform and Language Support

WebObjects makes the following improvements to platform and language support in release 4.5:

• WebObjects applications written in Java are now supported on HP-UX.
• WebObjects now supports JDK 1.1.8 on Windows NT and on Solaris (1.1.7 on HP-UX).
• On Solaris and HP-UX, WebObjects no longer needs to be installed into /opt/Apple.

Deploying WebObjects Applications

In addition to the changes listed under Platform and Language Support (above), the following changes have been made to ease the deployment of WebObjects applications:

• Web server adaptors can now get their configuration information from a file on the local machine, a file on another machine running a web server, from wotaskd (the replacement for MonitorProxy), or from other machines on the subnet running WebObjects via a new multicast mechanism.
• Many of the responsibilities formerly assumed by Monitor are now handled by wotaskd (each host involved in a WebObjects deployment now runs wotaskd). Monitor now simply changes settings in your deployment environment.

Profiling and Tuning Applications

WebObjects 4.5 provides many new features to help you profile applications, decrease their memory usage, and increase their speed. This section provides an overview of the features and tells you where to go for more information.

Profiling

WebObjects 4.5 introduces a new feature to help you profile your applications. event logging. A new event logging system records and displays how long certain operations in an application take. The measurements allow you to profile an application and optimize its execution time. For this, the EOF and WebObjects frameworks instrument key portions of their code to measure the elapsed time of functions and methods. You can instrument key portions of your code as well. To learn how to use this feature, see "Event Logging" in the chapter What's New in Enterprise Objects Framework.

Tuning

There are many new features to help tune your application. They are:

• Object sharing
  
  EOF 4.5 introduces a new technique for sharing read-only enterprise objects. The new subclass of EOEditingContext, EOSharedEditingContext, defines a mechanism that allows editing contexts to share enterprise objects for reading. This mechanism can reduce both the number of fetches an application makes and the amount of redundant data it requires. See the section "Object Sharing" in the chapter What's New in Enterprise Objects Framework.
  
  
• Subclassing EOGenericRecord
  
  EOF 4.5 adds a new option for creating custom enterprise objects: rather than creating a subclass of EOCustomObject (Java) or NSObject (Objective-C), you can now subclass EOGenericRecord.
  
  This feature is most significant in applications that use the Java bridge. By default, a subclass of EOGenericRecord stores its properties in a dictionary on the Objective-C side of the bridge instead of in individual instance variables on the Java side. This allows EOF to access enterprise object properties with many fewer trips across the bridge, which reduces memory usage and improves performance.
  
  See the section "Subclassing EOGenericRecord" in the chapter What's New in Enterprise Objects Framework.
  
  
• Deferred faulting
  
  EOF uses faults as stand-ins for objects whose data has not yet been fetched. Although fault creation is much faster than fetching, fault instantiation still takes time. To improve performance, EOF 4.5 has the ability to use deferred faults (which are more efficient) for enterprise object classes that enable the feature. See the section "Deferred Faulting" in the chapter What's New in Enterprise Objects Framework.
  
  
• Snapshot reference counting
  
  This is a new feature that removes snapshots from an EODatabase when they are no longer used by any enterprise objects in an application. This feature reduces the memory footprint of WebObjects applications. See the section "Snapshot Reference Counting" in the chapter What's New in Enterprise Objects Framework.

Tools Improvements

• WebObjects Builder's user interface has been significantly enhanced and should now be even easier to use. See the chapter "WebObjects Tools Changes" .
• EOModeler supports synchronization of a database schema with the current state of a model. See the section "Schema Synchronization" in chapter What's New in Enterprise Objects Framework.

Object Modeling Improvements

EOF 4.5 adds the following features that improve object modeling:

• Better handling of missing faults
  
  When a fault fires but doesn't have a corresponding row in the database, an exception isn't automatically thrown. An exception is thrown only if the application attempts to make changes to the missing fault. See "Handling Missing Faults" .
  
  
• Handling of ambiguous to-one relationships in Java
  
  If you enable deferred faulting-a new feature in EOF 4.5-you can have to-one relationships to non-leaf entities in an inheritance hierarchy. This arrangement was impossible without workarounds in earlier versions. See "Deferred Faulting" .
  
  
• Enterprise object classes are more flexible and easier to maintain
  
  You can now subclass EOGenericRecord, which can benefit the design of your enterprise objects. See "Subclassing EOGenericRecord" .
  
  

Managing Stale Data

EOF 4.5 adds a snapshot timestamping feature to help you keep your application's data fresh. It updates snapshots when fetching and allows an editing context to request that the snapshots used to build enterprise objects are no older than a particular timestamp. This has the effect of refreshing snapshots periodically, keeping the application's view more up-to-date with the database. See "Snapshot Timestamping" .

Automatic Database Reconnection

In EOF 4.5, a concrete adaptor can now implement methods that cause EOF to automatically attempt to reconnect to a database server when a connection is unexpectedly dropped. This behavior handles the problem of transient communication failures. By default reconnection is attempted by all of the adaptors that ship with EOF 4.5. See the section "Automatic Database Reconnection" in the chapter What's New in Enterprise Objects Framework.

Direct to Web

Direct to Web now allows you to create your own visual style and exposes a great deal of new API. For more information, see the section "Direct to Web Changes" in the chapter WebObjects Tools Changes.

Java Client

Java Client has been extended considerably, including the following:

• The foundation layer (com.apple.client.foundation) contains a new number formatter based on NSNumberFormatter and adds an NSUndoManager class, which is analogous to the server side class.
• The control layer (com.apple.client.eocontrol) is more complete.
• The distribution layer (com.apple.client.eodistribution on the client side and com.apple.yellow.eodistribution on the server side) now provides support for encrypted client/server communication and for managing user defaults.
• The interface layer (com.apple.client.eointerface) adds support for table cell editing and for displaying images and QuickTime media.

Additionally, Java Client now has a new user interface generation layer, Direct to Java Client, which is comparable to WebObjects' Direct to Web.

For more information on changes to Java Client, see the chapter "What's New in Java Client" .

LDAP Adaptor

EOF 4.5 comes with a new sample adaptor: the LDAP adaptor. The adaptor provides a simple way to verify a user's password on the Web with an LDAP server. For more information, see the section "LDAP Adaptor Example" in the chapter What's New in Enterprise Objects Framework.