Interface ContentStore


  • @AlfrescoPublicApi
    public interface ContentStore
    Provides low-level retrieval of content readers and writers.

    Implementations of this interface should be soley responsible for providing persistence and retrieval of the content against a content URL.

    Content URLs must consist of a prefix or protocol followed by an implementation-specific identifier. See TimeBasedFileContentUrlProvider and VolumeAwareContentUrlProvider implementations of FileContentUrlProvider For example, default content URL format for file stores is store://year/month/day/hour/minute/GUID.bin

    • store://: prefix identifying an Alfresco content stores regardless of the persistence mechanism.
    • year: year
    • month: 1-based month of the year
    • day: 1-based day of the month
    • hour: 0-based hour of the day
    • minute: 0-based minute of the hour
    • GUID: A unique identifier

    Where the store cannot handle a particular content URL request, the UnsupportedContentUrlException must be generated. This will allow various implementations to provide fallback code to other stores where possible.

    Where a store cannot serve a particular request because the functionality is just not available, the UnsupportedOperationException should be thrown. Once again, there may be fallback handling provided for these situations.

    Since:
    1.0
    Author:
    Derek Hulley
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static ContentContext NEW_CONTENT_CONTEXT
      An empty content context used to retrieve completely new content.
      static java.lang.String PROTOCOL_DELIMITER
      The delimiter that must be found in all URLS, i.e ://
    • Method Summary

      All Methods Instance Methods Abstract Methods Default Methods 
      Modifier and Type Method Description
      boolean delete​(java.lang.String contentUrl)
      Deletes the content at the given URL.
      boolean exists​(java.lang.String contentUrl)
      Check for the existence of content in the store.
      default java.lang.String getDirectAccessUrl​(java.lang.String contentUrl, int expiryTime)
      Gets a presigned URL to directly access a binary content.
      ContentReader getReader​(java.lang.String contentUrl)
      Get the accessor with which to read from the content at the given URL.
      java.lang.String getRootLocation()
      Get the location where the store is rooted.
      long getSpaceFree()
      Calculates the remaning free space in the underlying store.
      long getSpaceTotal()
      Calculates the total storage space of the underlying store.
      ContentWriter getWriter​(ContentContext context)
      Get an accessor with which to write content to a location within the store.
      boolean isContentUrlSupported​(java.lang.String contentUrl)
      Check if the content URL format is supported by the store.
      default boolean isDirectAccessSupported()
      Checks if the store supports the retrieving of direct access URLs.
      boolean isWriteSupported()
      Check if the store supports write requests.
    • Field Detail

      • PROTOCOL_DELIMITER

        static final java.lang.String PROTOCOL_DELIMITER
        The delimiter that must be found in all URLS, i.e ://
        See Also:
        Constant Field Values
    • Method Detail

      • isContentUrlSupported

        boolean isContentUrlSupported​(java.lang.String contentUrl)
        Check if the content URL format is supported by the store.
        Parameters:
        contentUrl - the content URL to check
        Returns:
        Returns true if none of the other methods on the store will throw an UnsupportedContentUrlException when given this URL.
        Since:
        2.1
      • isWriteSupported

        boolean isWriteSupported()
        Check if the store supports write requests.
        Returns:
        Return true is the store supports write operations
        Since:
        2.1
      • getSpaceFree

        long getSpaceFree()
        Calculates the remaning free space in the underlying store.

        NOTE: For efficiency, some implementations may provide a guess.

        Implementations should focus on calculating a size value quickly, rather than accurately.

        Returns:
        Returns the total, possibly approximate, free space (in bytes) available to the store or -1 if no size data is available.
        Since:
        3.3.3
      • getSpaceTotal

        long getSpaceTotal()
        Calculates the total storage space of the underlying store.

        NOTE: For efficiency, some implementations may provide a guess.

        Implementations should focus on calculating a size value quickly, rather than accurately.

        Returns:
        Returns the total, possibly approximate, size (in bytes) of the underlying store or -1 if no size data is available.
        Since:
        3.3.3
      • getRootLocation

        java.lang.String getRootLocation()
        Get the location where the store is rooted. The format of the returned value will depend on the specific implementation of the store.
        Returns:
        Returns the store's root location or . if no information is available
      • exists

        boolean exists​(java.lang.String contentUrl)
        Check for the existence of content in the store.

        The implementation of this may be more efficient than first getting a reader to check for existence, although that check should also be performed.

        Parameters:
        contentUrl - the path to the content
        Returns:
        Returns true if the content exists, otherwise false if the content doesn't exist or if the URL is not applicable to this store.
        Throws:
        org.alfresco.repo.content.UnsupportedContentUrlException - if the content URL supplied is not supported by the store
        ContentIOException - if an IO error occurs
        See Also:
        ContentReader.exists()
      • getReader

        ContentReader getReader​(java.lang.String contentUrl)
        Get the accessor with which to read from the content at the given URL. The reader is stateful and can only be used once.
        Parameters:
        contentUrl - the path to where the content is located
        Returns:
        Returns a read-only content accessor for the given URL. There may be no content at the given URL, but the reader must still be returned.
        Throws:
        org.alfresco.repo.content.UnsupportedContentUrlException - if the content URL supplied is not supported by the store
        ContentIOException - if an IO error occurs
        See Also:
        exists(String), ContentReader.exists(), org.alfresco.repo.content.EmptyContentReader
      • getWriter

        ContentWriter getWriter​(ContentContext context)
        Get an accessor with which to write content to a location within the store. The writer is stateful and can only be used once. The location may be specified but must, in that case, be a valid and unused URL.

        The store will ensure that the new content URL will be valid for all subsequent read attempts.

        By supplying a reader to existing content, the store implementation may enable random access. The store implementation can enable this by copying the existing content into the new location before supplying a writer onto the new content.

        Parameters:
        context - the context of content.
        Returns:
        Returns a write-only content accessor
        Throws:
        java.lang.UnsupportedOperationException - if the store is unable to provide the information
        UnsupportedContentUrlException - if the content URL supplied is not supported by the store
        ContentExistsException - if the content URL is already in use
        ContentIOException - if an IO error occurs
        See Also:
        ContentAccessor.addListener(ContentStreamListener), ContentAccessor.getContentUrl()
      • delete

        boolean delete​(java.lang.String contentUrl)
        Deletes the content at the given URL.

        A delete cannot be forced since it is much better to have the file remain longer than desired rather than deleted prematurely.

        Parameters:
        contentUrl - the URL of the content to delete
        Returns:
        Returns true if the content was deleted (either by this or another operation), otherwise false. If the content no longer exists, then true is returned.
        Throws:
        java.lang.UnsupportedOperationException - if the store is unable to perform the action
        UnsupportedContentUrlException - if the content URL supplied is not supported by the store
        ContentIOException - if an error occurs if an IO error occurs
      • getDirectAccessUrl

        default java.lang.String getDirectAccessUrl​(java.lang.String contentUrl,
                                                    int expiryTime)
        Gets a presigned URL to directly access a binary content. It is up to the actual store implementation if it can fulfil this request with an expiry time or not.
        Parameters:
        contentUrl - A content store URL
        expiryTime - Expiration time in milliseconds
        Returns:
        A direct access URL for a binary content
        Throws:
        java.lang.UnsupportedOperationException - if the store is unable to provide the information
      • isDirectAccessSupported

        default boolean isDirectAccessSupported()
        Checks if the store supports the retrieving of direct access URLs.
        Returns:
        true if direct access URLs retrieving is supported, false otherwise