4.6.1.1. 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.

<!-- ... -->
<session>
    <ejb-name>ASessionBean</ejb-name>
    <!-- ... -->
    <env-entry>
        <description>The maximum number of tax exemptions allowed </description>
        <env-entry-name>maxExemptions</env-entry-name>
        <env-entry-type>java.lang.Integer</env-entry-type>
        <env-entry-value>15</env-entry-value>
    </env-entry>
    <env-entry>
        <description>The tax rate </description>
        <env-entry-name>taxRate</env-entry-name>
        <env-entry-type>java.lang.Float</env-entry-type>
        <env-entry-value>0.23</env-entry-value>
    </env-entry>
</session>
<!-- ... -->

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