Package de.aristaflow.adept2.base.communication.invocation

Class InvocationHandler<T>

  • Type Parameters:
    T - The type is the interface this invocation handler will handle invocations for, i.e. the type of the service (getComponent()) and the type of the stub representing the service.
    All Implemented Interfaces:
    InvocationHandler
    public class InvocationHandler<T>
extends Object
implements InvocationHandler
    This InvocationHandler handles invocations to a ADEPT2 service through the API-Interface designated by the type parameter T in a distributed environment. It catches the API method calls to the proxy object that represents the service to the caller (i. e. the client) and delegates them to the communication submodule that is responsible for doing the remote calls on the remote service the proxy object is a proxy for.

    If a callback object is passed within a parameter to the requested method, then the handler creates a callback URI, associates this URI with the passed callback object and passes this URI to the skeleton responsible for the execution of the requested method on server side instead of the callback object itself.

    With this URI the receiver skeleton can create a stub/proxy object intended to do remote callback invocations on the callback object associated with the given callback URI.

    The invocation handler only delegates calls to methods of the service interface, which are neither annotated with ProxyIgnore nor with ProxyFollow.

    Calls to methods which are annotated with ProxyIgnore, are dismissed.

    Calls to methods which are annotated with Replaces will be replaced by the method described in the annotation. All further then applies to the replacing method, i. e. using cached values for an immutable (replacing) method or following the proxy. Replacing methods may switch from virtual to static invocation (i. e. from an instance method to a class method). In this case the parameter values are shifted by one and the first parameter will be the provided object instance. The replacing method has to consider this appropriately, i. e. the first parameter has to be of the appropriate type (of the object instance).
    Additionally, replacing may take place locally. In this case the method call on the proxy will not be forwarded but executed locally instead of remote.

    The return value of methods annotated with Immutable will cached internally using a WeakReference. Consecutive calls will then use this cached value if it is still present.

    Calls to methods which are annotated with ProxyFollow, are replied with another proxy object.

    • Field Detail

      • logger

        protected final Logger logger
        My logger.

      • proxyAnnotCache

        protected final Map<Class<?>,​Boolean> proxyAnnotCache
        The cache containing whether a class has a proxy annotation (ProxyAllow, ProxyCallback or ServerSideProxyAllow). This is shared across different invocation handlers. null if no caching should be used.
        See Also:
        checkIface(Class)

    • Constructor Detail

      • InvocationHandler

        public InvocationHandler​(InvocationTarget invTarget,
                         AtomicLong invId,
                         long lazyTime,
                         URI remoteIdentifier,
                         URI registeredIdentifier,
                         Class<T> remoteInterface,
                         boolean callback,
                         Map<Class<?>,​Boolean> proxyAnnotCache,
                         Logger logger)
        Create a new invocation handler.
        Parameters:
        invTarget - The invocation target providing the callback export and the invocation delegate to send messages to.
        invId - The count of each invocation to each have its unique ID.
        lazyTime - The time span in milliseconds which a lazy method is considered immutable.
        remoteIdentifier - The service URI of the ADEPT2 component this object is a proxy for.
        remoteInterface - The interface of the ADEPT2 component, with T defining the generic type of this handler.
        registeredIdentifier - The original URI identifying the remote service to call, in case a URI mapping was applied on the original URI.
        callback - Whether this invocation handler is a callback object, that is, it is a stub that has been created for a callback parameter in an invocation message.
        proxyAnnotCache - The cache containing whether a class has a proxy annotation (ProxyAllow, ProxyCallback or ServerSideProxyAllow). This is shared across different invocation handlers. null if no caching should be used.
        logger - The class-specific logger for this invocation handler.

      • InvocationHandler

        protected InvocationHandler​(InvocationTarget invTarget,
                            AtomicLong invId,
                            long lazyTime,
                            URI remoteObjectIdentifier,
                            URI registeredIdentifier,
                            boolean callback,
                            Stack<Method> preceder,
                            Map<Class<?>,​Boolean> proxyAnnotCache,
                            Logger logger)
        Create an invocation handler for the configured component name, following the provided methods to the interface this is a proxy for.

        Invocation handler for ProxyFollow objects are created automatically within this class.

        Parameters:
        invTarget - The invocation target providing the callback export and the invocation delegate to send messages to.
        invId - The count of each invocation to each have its unique ID.
        lazyTime - The time span in milliseconds which a lazy method is considered immutable.
        remoteObjectIdentifier - The service URI of the ADEPT2 component this object is a proxy for.
        registeredIdentifier - The original URI identifying the remote service to call, in case a URI mapping was applied on the remote object identifier.
        callback - Whether this invocation handler is a callback object, that is, it is a stub that has been created for a callback parameter in an invocation message.
        preceder - The stack of methods of the component, to reach the object this is a proxy for.
        proxyAnnotCache - The cache containing whether a class has a proxy annotation (ProxyAllow, ProxyCallback or ServerSideProxyAllow). This is shared across different invocation handlers. null if no caching should be used.
        logger - The class-specific logger for this invocation handler.

    • Method Detail

      • getComponent

        public T getComponent()
        Returns:
        The component (i.e. a Proxy).

      • nextInvocationId

        protected long nextInvocationId()
        Generates unique invocation IDs.
        Returns:
        A new invocation ID.