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@Environmental is different; it exposes a request-scoped, dynamically bound value

{footnote}. The term 

"Environmental" was chosen as the value "comes from the environment", whatever that means. A name more evocative of its function still has not occurred to the Tapestry team!{footnote}

• Request scoped: different threads (processing different requests) will see different values when reading the field.
• Dynamically bound: the value is explicitly placed into the Environment, and can be overridden at any time.

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In certain cases, Tapestry exposes a service (which can be injected) that is a proxy to the environmental; this is primarily for common environmentals, such as JavaScriptSupport, that may be needed outside of component classes. You can see this in TapestryModule:

    /**
     * Builds a proxy to the current {@link JavaScriptSupport} inside this thread's {@link Environment}.
     * 
     * @since 5.2.0
     */
    public JavaScriptSupport buildJavaScriptSupport()
    {
        return environmentalBuilder.build(JavaScriptSupport.class);
    }

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Yes, of course Tapestry is thread safe. The Request service is another special case, as seen in TapestryModule:

    public Request buildRequest()
    {
        return shadowBuilder.build(requestGlobals, "request", Request.class);
    }

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Also remember that @Inject on fields works for components and for service implementations or other objects that Tapestry instantiates, but not on arbitrary objects (that are created via Java's new keyword).

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