Package org.deepsymmetry.beatlink.dbserver

Class Client

    • Field Detail

      • targetPlayer

        public final int targetPlayer
        The player number we are communicating with.

      • posingAsPlayer

        public final int posingAsPlayer
        The player we are pretending to be.

      • GREETING_FIELD

        public static final NumberField GREETING_FIELD
        The greeting message exchanged over a new connection consists of a 4-byte number field containing the value 1.

      • DEFAULT_MENU_BATCH_SIZE

        public static final long DEFAULT_MENU_BATCH_SIZE
        The default maximum number of menu items we will request at a single time. We are not sure what the largest safe value to use is, but 64 seems to work well for CDJ-2000 nexus players.
        See Also:
        Constant Field Values

    • Method Detail

      • isConnected

        public boolean isConnected()
        Check whether our connection is still available for use. We will close it if there is ever a problem communicating with the dbserver.
        Returns:
        true if this instance can still be used to query the connected dbserver

      • buildRMST

        public static NumberField buildRMST​(int requestingPlayer,
                                    Message.MenuIdentifier targetMenu,
                                    CdjStatus.TrackSourceSlot slot)

        Build the R:M:S:T parameter that begins many queries, when T=1.

        Many request messages take, as their first argument, a 4-byte value where each byte has a special meaning. The first byte is the player number of the requesting player. The second identifies the menu into which the response is being loaded, as described by Message.MenuIdentifier. The third specifies the media slot from which information is desired, as described by CdjStatus.TrackSourceSlot, and the fourth byte identifies the type of track about which information is being requested; in most requests this has the value 1, which corresponds to rekordbox tracks, and this version of the function assumes that.

        Parameters:
        requestingPlayer - the player number that is asking the question
        targetMenu - the destination for the response to this query
        slot - the media library of interest for this query
        Returns:
        the first argument to send with the query in order to obtain the desired information

      • buildRMST

        public static NumberField buildRMST​(int requestingPlayer,
                                    Message.MenuIdentifier targetMenu,
                                    CdjStatus.TrackSourceSlot slot,
                                    CdjStatus.TrackType trackType)

        Build the R:M:S:T parameter that begins many queries.

        Many request messages take, as their first argument, a 4-byte value where each byte has a special meaning. The first byte is the player number of the requesting player. The second identifies the menu into which the response is being loaded, as described by Message.MenuIdentifier. The third specifies the media slot from which information is desired, as described by CdjStatus.TrackSourceSlot, and the fourth byte identifies the type of track about which information is being requested; in most requests this has the value 1, which corresponds to rekordbox tracks.

        Parameters:
        requestingPlayer - the player number that is asking the question
        targetMenu - the destination for the response to this query
        slot - the media library of interest for this query
        trackType - the type of track about which information is being requested
        Returns:
        the first argument to send with the query in order to obtain the desired information

      • buildRMST

        public NumberField buildRMST​(Message.MenuIdentifier targetMenu,
                             CdjStatus.TrackSourceSlot slot)

        Build the R:M:S:T parameter that begins many queries.

        Many request messages take, as their first argument, a 4-byte value where each byte has a special meaning. The first byte is the player number of the requesting player. The second identifies the menu into which the response is being loaded, as described by Message.MenuIdentifier. The third specifies the media slot from which information is desired, as described by CdjStatus.TrackSourceSlot, and the fourth byte identifies the type of track about which information is being requested; in most requests this has the value 1, which corresponds to rekordbox tracks, and this version of the function assumes that.

        Parameters:
        targetMenu - the destination for the response to this query
        slot - the media library of interest for this query
        Returns:
        the first argument to send with the query in order to obtain the desired information

      • buildRMST

        public NumberField buildRMST​(Message.MenuIdentifier targetMenu,
                             CdjStatus.TrackSourceSlot slot,
                             CdjStatus.TrackType trackType)

        Build the R:M:S:T parameter that begins many queries.

        Many request messages take, as their first argument, a 4-byte value where each byte has a special meaning. The first byte is the player number of the requesting player. The second identifies the menu into which the response is being loaded, as described by Message.MenuIdentifier. The third specifies the media slot from which information is desired, as described by CdjStatus.TrackSourceSlot, and the fourth byte identifies the type of track about which information is being requested; in most requests this has the value 1, which corresponds to rekordbox tracks.

        Parameters:
        targetMenu - the destination for the response to this query
        slot - the media library of interest for this query
        trackType - the type of track about which information is being requested
        Returns:
        the first argument to send with the query in order to obtain the desired information

      • simpleRequest

        public Message simpleRequest​(Message.KnownType requestType,
                             Message.KnownType responseType,
                             Field... arguments)
                      throws IOException
        Send a request that expects a single message as its response, then read and return that response.
        Parameters:
        requestType - identifies what kind of request to send
        responseType - identifies the type of response we expect, or null if we’ll accept anything
        arguments - The argument fields to send in the request
        Returns:
        the response from the player
        Throws:
        IOException - if there is a communication problem, or if the response does not have the same transaction ID as the request.

      • menuRequestTyped

        public Message menuRequestTyped​(Message.KnownType requestType,
                                Message.MenuIdentifier targetMenu,
                                CdjStatus.TrackSourceSlot slot,
                                CdjStatus.TrackType trackType,
                                Field... arguments)
                         throws IOException
        Send a request for a menu that we will retrieve items from in subsequent requests, when the request must reflect the actual type of track being asked about.
        Parameters:
        requestType - identifies what kind of menu request to send
        targetMenu - the destination for the response to this query
        slot - the media library of interest for this query
        trackType - the type of track for which metadata is being requested, since this affects the request format
        arguments - the additional arguments needed, if any, to complete the request
        Returns:
        the Message.KnownType.MENU_AVAILABLE response reporting how many items are available in the menu
        Throws:
        IOException - if there is a problem communicating, or if the requested menu is not available
        IllegalStateException - if tryLockingForMenuOperations(long, TimeUnit) was not called successfully before attempting this call

      • tryLockingForMenuOperations

        public boolean tryLockingForMenuOperations​(long timeout,
                                           TimeUnit unit)
                                    throws InterruptedException
        Attempt to secure exclusive access to this player for performing a menu operation, which requires multiple request/response cycles. The caller must call unlockForMenuOperations() as soon as it is done (even if it is failing because of an exception), or no future menu operations will be possible by any other thread, unless false was returned, meaning the attempt failed.
        Parameters:
        timeout - the time to wait for the lock
        unit - the time unit of the timeout argument
        Returns:
        true if the lock was acquired within the specified time
        Throws:
        InterruptedException - if the thread is interrupted while waiting for the lock

      • unlockForMenuOperations

        public void unlockForMenuOperations()
        Allow other threads to perform menu operations. This must be called promptly, once for each time that tryLockingForMenuOperations(long, TimeUnit) was called with a true return value.

      • renderMenuItems

        public List<Message> renderMenuItems​(Message.MenuIdentifier targetMenu,
                                     CdjStatus.TrackSourceSlot slot,
                                     CdjStatus.TrackType trackType,
                                     Message availableResponse)
                              throws IOException
        Gather up all the responses that are available for a menu request. Will involve multiple requests if the number of responses available is larger than our maximum batch size (see getMenuBatchSize().
        Parameters:
        targetMenu - the destination for the response to this query
        slot - the media library of interest for this query
        trackType - the type of track about which information is being requested
        availableResponse - the response to the initial menu setup request, reporting how many responses are available, as well as the target menu we are working with
        Returns:
        all the response items, using as many queries as necessary to gather them safely, and omitting all the header and footer items
        Throws:
        IOException - if there is a problem reading the menu items
        IllegalStateException - if tryLockingForMenuOperations(long, TimeUnit) was not called successfully before attempting this call