org.opentripplanner.datastore.base.DataSourceRepository Maven / Gradle / Ivy

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package org.opentripplanner.datastore.base;


import org.opentripplanner.datastore.CompositeDataSource;
import org.opentripplanner.datastore.DataSource;
import org.opentripplanner.datastore.FileType;

import javax.validation.constraints.NotNull;
import java.net.URI;

/**
 * It is an abstraction to reading of and writing to files whenever the file is located on the local
 * disk or is in the cloud.
 * 
 * This interface provide an abstraction layer for accessing OTP data input and output sources. It
 * is an abstraction for reading from and/or writing to files whenever the file is located on the
 * local disk or is in the cloud. The interface make it possible to implement alternative ways to
 * access data. In a cloud ecosystem you might find it easier to access the data directly from the
 * cloud storage, rather than first copy the data into your node local disk, and then copy the build
 * graph back into cloud storage after building it. Depending on the source this might also offer
 * enhanced performance.
 * 

 * The {@link org.opentripplanner.datastore.OtpDataStore} will manage all repositories
 * so there is no need to use the repository directly.
 */
public interface DataSourceRepository {

    /**
     * @return a description that identify the datasource which is helpful to the user in case an
     * error occurs when using the repository.
     */
    String description();

    /**
     * Open a connection to the data repository/storage. This method is called once before any read
     * operations.
     */
    void open();

    /**
     * Get the a data source for the given uri and type.
     * 

     * The source may or may not {@link DataSource#exists()}.
     *
     * @param uri  a uniq URI to get the data source.
     * @param type the file type to load.
     * @return the datasource wrapper that can be used to access the data source.
     */
    DataSource findSource(@NotNull URI uri, @NotNull FileType type);

    /**
     * Get the a composite data source (zip/directory) for the given uri and type.
     * 
     * The source may or may not {@link DataSource#exists()}.
     *
     * @param uri  a uniq URI to get the data source.
     * @param type the file type to load.
     * @return the datasource wrapper that can be used to access the data source.
     */
    CompositeDataSource findCompositeSource(@NotNull URI uri, @NotNull FileType type);
}