JBoss.org Community Documentation Environment Entries

Environment entries are the simplest form of information stored in a component ENC, and are similar to operating system environment variables like those found on UNIX or Windows. Environment entries are a name-to-value binding that allows a component to externalize a value and refer to the value using a name.

An environment entry is declared using an env-entry element in the standard deployment descriptors. The env-entry element contains the following child elements:

  • An optional description element that provides a description of the entry

  • An env-entry-name element giving the name of the entry relative to java:comp/env

  • An env-entry-type element giving the Java type of the entry value that must be one of:

    • java.lang.Byte

    • java.lang.Boolean

    • java.lang.Character

    • java.lang.Double

    • java.lang.Float

    • java.lang.Integer

    • java.lang.Long

    • java.lang.Short

    • java.lang.String

  • An env-entry-value element giving the value of entry as a string

An example of an env-entry fragment from an ejb-jar.xml deployment descriptor is given in Example 4.5, “An example ejb-jar.xml env-entry fragment”. There is no JBoss specific deployment descriptor element because an env-entry is a complete name and value specification. Example 4.6, “ENC env-entry access code fragment” shows a sample code fragment for accessing the maxExemptions and taxRate env-entry values declared in the deployment descriptor.

<!-- ... -->
    <!-- ... -->
        <description>The maximum number of tax exemptions allowed </description>
        <description>The tax rate </description>
<!-- ... --> 

Example 4.5. An example ejb-jar.xml env-entry fragment

InitialContext iniCtx = new InitialContext();
Context envCtx = (Context) iniCtx.lookup("java:comp/env");
Integer maxExemptions = (Integer) envCtx.lookup("maxExemptions");
Float taxRate = (Float) envCtx.lookup("taxRate");

Example 4.6. ENC env-entry access code fragment