New JSP 2.0 Mailer Taglib

Updated: 2004-08-12

2004-08-12:
Mailer2 has been added to Jakarta Taglibs Sandbox. A nightly build can be downloaded from the Jakarta site.

Introduction

I did a complete rewrite of the mailer taglib 1.1 to make it a JSP 2.0 mailer taglib.

Features

• Send simple plain text e-mails
• Attach local (file) or external (url) attachments to a message
• Create HTML formatted messages
• Create multipart/alternative HTML and plain text messages
• Save messages in a scope for later use
• Send messages in a background thread for better response times, or directly to get better feedback
• Use JSTL 1.1 EL throughout
• PLAIN or LOGIN SMTP authentication
• Configure server, port, username and password from your web.xml
• Load previously stored messages, or save messages to disk
• S/MIME encrypt and/or sign messages using a Legion of the Bouncy Castle implementation of the S/MIME protocol

Documentation

• Javadoc
• Tag Library Documentation

Download

• Source
• Tag Library for JSP 2.0

Why a new taglib?

• JSP 2.0 and JSTL 1.1 allow a more flexible way of configuring and using a taglib
• Create a mailer taglib with JSTL and EL in mind
• No need to use custom EL Evaluators that are unnecessary in a JSP 2.0 environment
• Some features are missing from the 1.1 version: multipart mail, background or foreground sending of mail, better tag lifecycle management, saving messages, configuration, signing and/or encryption of mail messages
• Because it is a maintenance nightmare to maintain both a 1.2 and 2.0 version of the same tag library, a tool is used to create an EL'ified 1.2 version of the original 2.0

Requirements

• JDK 1.4 or higher
• mail.jar and activation.jar from a J2EE 1.4 or JEE 5 distribution
• If you want to use signing and/or encryption:
  • bcprov-jdkX-Y.jar and bcmail-jdkX-Y.jar from http://www.bouncycastle.org where X is the JVM version and Y is the current BC version, e.g. bcprov-jdk15-137.jar and bcmail-jdk15-137.jar
• For the JSP 2.0 version:
  • JSP 2.0 container, like Tomcat 5.0, 5.5 or 6.0 or Resin 3.x
• For the JSP 1.2 version:
  • JSP 1.2 container, like Tomcat 4.x or Resin 2.x
  • standard.jar and jstl.jar from the JSTL 1.0.x distribution.

How to deploy the examples

• Unzip mailer2.zip
• Copy build.properties.sample to build.properties
• Update build.properties and set the location of the required jar files
• For the 2.0 version:
  • ant war
  • Deploy mailer2.war in your favorite JSP 2.0 container
• For the 1.2 version:
  • ant war12
  • Deploy mailer2_12.war in your favorite JSP 1.2 container

Creating a 1.2 tag library version from a 2.0 version

• Read the 2.0 taglib JAR file
• Read the TLD file inside the JAR
• For every <tag> in the TLD:
  • Create a new class in a new package that ends with "_12" that extends the original 2.0 tag class
  • Create new setter methods for the EL for every attribute in the TLD
  • Create a doStartTag() function that evaluates all these EL attributes and stores the result in the corresponding properties in the superclass
  • If the tag implements javax.servlet.jsp.tagext.BodyTag, create a function doAfterBody() that sets the body property with the evaluated version of the BodyContent

This tool is run with ant generate12.

The example JSPs and Javadoc should give a good overview of what is possible and how the library can be used.

Have fun,

Jeroen van Vianen
jeroen at vanvianen dot nl

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