Enhydra 3.0.1 Release Notes

These release notes include:

Platform, System, and Install Requirements
New Features
Known Problems
Additional Notes
Documentation Errata
Reporting Bugs and Feature Requests

Changes Since Enhydra 3.0

There was a bug in the HttpRequestProcessor, which would cause problems when a post was done with keepalive. The postParams object was not cleared by the next() method, causing the same data to be return if another post came in on a keepalive connection. This bug has been fixed in the 3.0.1 release.
Enhydra Director documentation was cleaned up to improve readability and remove references to old, non-existent files.

Platform, System, and Install Requirements

Installation

The Windows InstallShield program will only work on systems where Windows has been installed to the C drive.
WinZip 5.6 may have problems with the long file names. Use Jar, WinZip 6.0 or higher, or another zip extraction tool.

Platform Support

Through the open source development process, Enhydra has been used on a wide variety of platforms and with many different JDBC-supported databases, but only the specific configurations listed below are fully tested

Enhydra 3.0.1 Multiserver

Red Hat Linux 6.1
VA Linux 2.2.13-0.7smp
Windows NT Server 4.0 SP5
Solaris 2.7

Enhydra Director

Apache 1.3 web server on Solaris 2.7 and Red Hat Linux 6.1
Netscape (iPlanet) Enterprise Server 4.0 on Solaris 2.7 and NT Server 4.0SP5
Microsoft Internet Information Server 4.0 on NT Server 4.0SP5

Databases

Oracle 8i on Solaris 2.7 with the Oracle JDBC Driver.
PostgreSQL 6.5.3 with the PostgreSQL JDBC Driver.
Microsoft SQL Server 7.0 with the JTurbo 2.0 JDBC Driver.

JDKs

Sun JDK 1.1.8, 1.2.2 (Note: there are problems with using Sun JDK 1.1.6 and on Windows).
IBM JDK 1.1.8
BlackDown 1.2.2 RC4

Note that JREs cannot be used with Enhydra due to XMLC and JSP dynamic page re-compilation.

System Requirements

The minimum recommended system configuration is:

Intel 200 MHz processor or Sparc-compatible processor
64 MB or RAM or more
259 MB of disk space (less if you don't install the Enhydra source)

New Features

General

Enhydra Director provides load-balancing and server failover. Installation and configuration instructions are provided in the online document, Using Enhydra Director.
Support for Java Servlet 2.2 API and Java Server Pages (JSP) 1.1 API.
Multiserver now fully supports the Java Servlet 2.2 interface and Java Server Pages (JSP 1.1).
Session persistence is now configurable to use URL rewriting instead of cookies. This eliminates the need for clients to have cookies enabled.
Kelp Tools improvements: You can now automatically invoke the XMLC tool in the IDE's build process. Kelp also supports all XMLC options through XMLC options files, and you can open XMLC Property Pages directly from the project navigator's short-cut menu.

XMLC

XMLC is now built on the Xerces DOM implementation from the Apache XML Project. This implementation provides DOM level 2 support. The W3C DOM allowed copying a Node from one document to another, which is illegal operation. In Xerces, you can accomplish the same thing by using document.importNode( ).
XMLC now supports dynamic re-compilation. You can modify HTML pages at runtime, and your application can use the new content without stopping your application. You must use the XMLC_AUTO_COMP flag when compiling the application. You must also be sure to use the proper method calls in your application. Use

myPageHTML = (myPageHTML)comms.xmlcFactory.create(myPageHTML.class)

comms

HttpPresentationComms

myPageHTML = new MyPageHTML()

automatic re-compilation.

Wireless/WML Support: You can use Wireless Markup Language (WML) pages in your application by using the DOM Factory class WMLDomFactory. This will produce WMLDocument classes. To do this, use the following command-line syntax:

xmlc -dom-factory org.enhydra.wireless.wml.WMLDomFactory

Support for X-Catalogs; this enables you to specify DTDs that are local, rather than via HTTP.
XMLC now handles internal DTD subsets.
There is a new formatting package, org.enhydra.xml.io, that enables you to format DOMs into documents.

Application Wizard

The application wizard now creates presentation objects that use methods that support XMLC dynamic recompilation.

Known Problems

Enhydra Specific

ContentType for static files is compiled into the application and is not defined in a configuration file.
Application Names in the Multiserver Administration Console must be alphanumeric.
Selecting the Connections tab in the Multiserver Administration Console Status page incorrectly changes the text on the disabled tab from "Servlet" to "Application".
Internet Explorer 4.0 users should not use the option to set each window as a seperate instance, as this may cause problems with some applications that use popups or multiple windows.
Enhydra does not currently compile on Windows 95, resulting in system crashes. This problem does not occur on Windows 98 and Windows NT.

Platform Specific

A performance degradation occurs on Windows platforms if an Enhydra application is generating a lot of debug or log messages which are displayed on the screen. This problem does not occur if the window displaying the output is minimized. To work around this Windows problem, either remove debug messages or minimize the window.
On Windows platforms without an active network connection, the first access to Enhydra through localhost can result in a delay serving the first page due to the initial DNS lookup.
On some platforms and JVMs, when Enhydra is first started, there is a delay before the first page is served. This is a result of the initial loading of the classes by the JVM.

Additional Notes

Multiple Connection Methods

Enhydra applications and Servlet 2.2 contexts (a "web app") can be accessed through multiple URLs. This is achieved by creating more than one connection method. In the case of Servlet 2.2 Web applications there is a restriction that each connection method must have the same URL path prefix (the port number may be different).

In general, multiple connection methods are discouraged. They are useful for providing a "special" access path to an application for debugging or for privilaged admin access to an application designed for such purposes.

DODS GUI

The GUI interface to the Enhydra Object-to-releational mapping technology is provided as a convenience. It does not prevent the operator from creating illegal mappings that cannot be automatically built or that can cause errors in the tool. Careful use of the tool can prevent these errors. The user is envouraged to edit the DOML (XML specification file created by the DODS GUI) directly and run DODS in command line mode to avoid these problems. See the latest DODS documentation at the Enhydra.org web site.

MultiServer Debugger

When debugging Servlet 2.2 applications you may occasionally see seemingly duplicate entries. This is caused by the Servlet 2.2 internal redirection mechanism or "server side redirect" and correspond to a single client request. Each of these requests are picked up by the debugger hence the two entries.

Documentation Errata

In Getting Started with Enhydra, Chapter 4, section titled "Creating Data Objects," in following the instructions for step 3, you will encounter a known problem with the DODS GUI; it does not allow you to add data objects directly to sub-packages. So if you have:

simpleApp ( package )
   data( package )
      person( package )
          Person( data object you made )

You have to add the object Person to the data or simpleApp package and then drag it down into the person package.

In Getting Started with Enhydra, Appendix B, "Using the Multiserver Administration Console," you must perform some additional steps to manage an application with the administration console:

In the application configuration file, change the line

Server.ClassPath[ ] =/<your_app_root>/lib/appName.jar

After you click the ADD button and select the name of your application from the dropdown list, click "Connection" to transfer to the Connection status display for your new application.
Click the Create button to establish the connection.

Reporting Bugs and Feature Requests

Send bug reports and feature requests via email to: bugs@enhydra.org. Please include the JDK vendor, version number, operating system, and Enhydra version.