Package org.dspace.importer.external.service.components

Class AbstractRemoteMetadataSource

  • Direct Known Subclasses:
    AbstractImportMetadataSourceService
    public abstract class AbstractRemoteMetadataSource
extends Object
    This class contains primitives to handle request timeouts and to retry requests. This is achieved by classifying exceptions as fatal or as non fatal/retryable. Evidently only subclasses can make the proper determination of what is retryable and what isn't. This is useful in case the service employs throttling and to deal with general network issues.
    Author:
    Roeland Dillen (roeland at atmire dot com), Antoine Snyers (antoine at atmire dot com)

    • Field Detail

      • lastRequest

        protected long lastRequest

      • interRequestTime

        protected long interRequestTime

      • maxRetry

        protected int maxRetry

      • retry

        protected int retry

      • operationId

        protected String operationId

      • warning

        protected String warning

    • Constructor Detail

      • AbstractRemoteMetadataSource

        protected AbstractRemoteMetadataSource()
        Constructs an empty MetadataSource class object and initializes the Exceptionhandlers

    • Method Detail

      • initExceptionHandlers

        protected void initExceptionHandlers()
        initialize the exceptionHandlersMap with an empty LinkedHashMap

      • getWarning

        public String getWarning()
        Return the warning message used for logging during exception catching
        Returns:
        a "warning" String

      • setWarning

        public void setWarning​(String warning)
        Set the warning message used for logging
        Parameters:
        warning - warning message

      • getRetry

        public int getRetry()
        Return the number of retries that have currently been undertaken
        Returns:
        the number of retries

      • getMaxRetry

        public int getMaxRetry()
        Return the number of max retries that can be undertaken before separate functionality kicks in
        Returns:
        maximum number of retries

      • setMaxRetry

        public void setMaxRetry​(int maxRetry)
        Set the number of maximum retries before throwing on the exception
        Parameters:
        maxRetry - maximum number of retries

      • getOperationId

        public String getOperationId()
        Retrieve the operationId
        Returns:
        A randomly generated UUID. generated during the retry method

      • getError

        public Exception getError()
        Retrieve the last encountered exception
        Returns:
        An Exception object, the last one encountered in the retry method

      • setError

        public void setError​(Exception error)
        Set the last encountered error
        Parameters:
        error - exception to set

      • retry

        protected <T> T retry​(Callable<T> callable)
               throws MetadataSourceException
        Command pattern implementation. the callable.call method will be retried until it either succeeds or reaches the try limit. Maybe this should have a backoff algorithm instead of waiting a fixed time.
        Type Parameters:
        T - return type. Generics for type safety.
        Parameters:
        callable - the callable to call. See the classes with the same name as the public methods of this class.
        Returns:
        The result of the call
        Throws:
        MetadataSourceException - if something unrecoverable happens (e.g . network failures)

      • handleException

        protected void handleException​(int retry,
                               Exception exception,
                               String operationId)
                        throws MetadataSourceException
        Handles a given exception or throws on a MetadataSourceException if no ExceptionHandler is set
        Parameters:
        retry - The number of retries before the exception was thrown on
        exception - The exception to handle
        operationId - The id of the operation that threw the exception
        Throws:
        MetadataSourceException - if no ExceptionHandler is configured for the given exception

      • throwSourceException

        protected void throwSourceException​(int retry,
                                    Exception exception,
                                    String operationId)
                             throws MetadataSourceException
        Throw a MetadataSourceException
        Parameters:
        retry - The number of retries before the exception was thrown on
        exception - The exception to throw
        operationId - The id of the operation that threw the exception
        Throws:
        MetadataSourceException - if no ExceptionHandler is configured for the given exception

      • throwSourceExceptionHook

        protected void throwSourceExceptionHook()
        A specified point where methods can be specified or callbacks can be executed

      • init

        public abstract void init()
                   throws Exception
        Attempts to init a session
        Throws:
        Exception - on generic exception

      • setInterRequestTime

        public void setInterRequestTime​(long interRequestTime)