Stream Protocol Negotiation at Stream Creation Time

Following are some statements regarding stream protocol negotiation.

• The following flags are set to On in the negotiated SPCB for the stream handler that should perform the action specified by the flag. Either the source or the target negotiated SPCB will contain these bit flags.

  SPCBHAND_GENSYNC

  SPCBHAND_RCVSYNC
  SPCBHAND_GENTIME
  SPCBHAND_PHYS_SEEK
  
  The DATATYPE_GENERIC will match any other data type during negotiation. This is useful for stream handlers like the File System Stream Handler that can be a source for almost any data type.
  
  If neither of the SPCB key data types are generic, then both the data type and subtype fields must match or an error will occur. The internal key field is not used during negotiation. The internal key of 0 is returned from negotiation.
  
  The block size will default to 1 byte if not specified. The source and target block size must match or the negotiation will fail.
  
  The Data Buffer Size must be a multiple of block size.
  
  The negotiation will fail if one stream handler has a fixed buffer size (SPCBBUF_FIXEDBUF) greater than the maximum buffer size (SPCBBUF_MAXSIZE) of the other.
  
  Both handlers must not have fixed buffer sizes (SPCBBUF_FIXEDBUF) of different lengths.
  
  Both handlers must not have maximum buffer sizes (SPCBBUF_MAXSIZE) of different lengths.
  
  Negotiation will default to a fixed buffer size (SPCBBUF_FIXEDBUF). Otherwise, the buffer size is set the greater of the two SPCB buffer sizes, but not greater than the maximum buffer size (SPCBBUF_MAXSIZE), if one is specified.
  
  If no special conditions (SPCBBUF_FIXEDBUF,SPCBBUF_MAXSIZE,SPCBBUF_USERPROVIDED) were specified, the largest buffer size is the one that will be used for the stream creation.
  
  For user-provided buffers (SPCBBUF_USERPROVIDED), the buffer size is set to the maximum buffer size (SPCBBUF_MAXSIZE), or to the largest buffers possible rounded to a multiple of the block size.
  
  Split streams (SPCBBUF_INTERLEAVED) must have a maximum number of records per buffer greater than 0. The target stream handler must set this field to 0, since only the source stream handler can set this value.
  
  The Minimum and Maximum number of buffers must be greater than zero.
  
  The largest Minimum number of buffers value is used.
  
  The largest Maximum number of buffers value is used.
  
  The Sync/Stream Manager attempts to allocate the maximum number of stream buffers requested. If it is unable to allocate this amount of space, but is able to allocate the minimum needed, the stream is created. Otherwise, the stream creation fails for lack of resources.
  
  The number of EMPTY buffers required to start the source is always taken from the source SPCB.
  
  The number of FULL buffers required to start the target is always taken from the target SPCB.
  
  For SpiGetTime requests, each handler must specify whether it can receive these requests and return real-time information. It can do this by specifying the SPCBHAND_GENTIME flag. For negotiation, the target stream handler is the default provider of this information unless only the source can provide this information.
  
  The Bytes Per Unit and MMTIME Per Unit are set from the stream handler that handles the real-time requests per the previous statement.
  
  For sync pulses, each handler must specify whether it can send or receive sync pulses. It can do this by specifying the SPCBHAND_GENSYNC or SPCBHAND_RCVSYNC flag. For negotiation, the target stream handler is the default generator and receiver of sync pulses unless only the source can generate and receive sync pulses.
  
  The sync tolerance is only valid for handlers that set the SPCBHAND_RCVSYNC.
  
  The sync pulse granularity is only valid for handlers that set the SPCBHAND_GENSYNC.
  
  The SPCBHAND_PHYS_SEEK flag is used to specify if a stream handler does a physical device seek when called on an SHC_SEEK call. The Sync/Stream Manager uses this information to determine which stream handler should be called first on an SpiSeekStream call. The handler that does a physical device seek will be called first, otherwise, the stream handler that specified SPCBHAND_GENTIME will be called last.
  
  Any reserved fields must be set to NULL.
  
  Any undefined bit in any bit flag of the stream protocol must be set to 0.

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