Package ucar.nc2.iosp

Interface IOServiceProvider

  • All Known Subinterfaces:
    IOServiceProviderWriter
    All Known Implementing Classes:
    AbstractIOServiceProvider, H4iosp, H4iosp, H5iosp, H5iospNew, N3iosp, N3iospNew, N3iospWriter, N3raf, NcStreamIosp
    public interface IOServiceProvider
    This is the service provider interface for the low-level I/O access classes (read only). This is only used by service implementors. An implementation must have a no-argument constructor. The NetcdfFile class manages all registered IOServiceProvider classes. When NetcdfFiles.open() is called:
    1. the file is opened as a ucar.unidata.io.RandomAccessFile;
    2. the file is handed to the isValidFile() method of each registered IOServiceProvider class (until one returns true, which means it can read the file).
    3. the open() method on the resulting IOServiceProvider class is handed the file.

    • Method Detail

      • isValidFile

        boolean isValidFile​(RandomAccessFile raf)
             throws IOException
        Check if this is a valid file for this IOServiceProvider. You must make this method thread safe, ie dont keep any state.
        Parameters:
        raf - RandomAccessFile
        Returns:
        true if valid.
        Throws:
        IOException - if read error

      • open

        @Deprecated
void open​(RandomAccessFile raf,
          NetcdfFile ncfile,
          CancelTask cancelTask)
   throws IOException
        Deprecated.
        Use build(RandomAccessFile raf, Group.Builder rootGroup, CancelTask cancelTask)
        Open existing file, and populate ncfile with it. This method is only called by the NetcdfFile constructor on itself. The provided NetcdfFile object will be empty except for the location String and the IOServiceProvider associated with this NetcdfFile object.
        Parameters:
        raf - the file to work on, it has already passed the isValidFile() test.
        ncfile - add objects to this empty NetcdfFile
        cancelTask - used to monitor user cancellation; may be null.
        Throws:
        IOException - if read error

      • isBuilder

        boolean isBuilder()
        If this iosp implements build().

      • build

        void build​(RandomAccessFile raf,
           Group.Builder rootGroup,
           CancelTask cancelTask)
    throws IOException
        Open existing file, and populate it. Note that you cannot reference the NetcdfFile within this routine. This is the bridge to immutable objects that will be used exclusively in version 6.
        Parameters:
        raf - the file to work on, it has already passed the isValidFile() test.
        rootGroup - add objects to the root group.
        cancelTask - used to monitor user cancellation; may be null.
        Throws:
        IOException - if read error

      • buildFinish

        void buildFinish​(NetcdfFile ncfile)
        Sometimes the builder needs access to the finished objects. This is called after ncfile.build()

      • readData

        Array readData​(Variable v2,
               Section section)
        throws IOException,
               InvalidRangeException
        Read data from a top level Variable and return a memory resident Array. This Array has the same element type as the Variable, and the requested shape.
        Parameters:
        v2 - a top-level Variable
        section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.
        Returns:
        the requested data in a memory-resident Array
        Throws:
        IOException - if read error
        InvalidRangeException - if invalid section
        See Also:
        Range

      • readToByteChannel

        @Deprecated
long readToByteChannel​(Variable v2,
                       Section section,
                       WritableByteChannel channel)
                throws IOException,
                       InvalidRangeException
        Deprecated.
        do not use
        Read data from a top level Variable and send data to a WritableByteChannel. Must be in big-endian order.
        Parameters:
        v2 - a top-level Variable
        section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.
        channel - write data to this WritableByteChannel
        Returns:
        the number of bytes written to the channel
        Throws:
        IOException - if read error
        InvalidRangeException - if invalid section

      • readToOutputStream

        long readToOutputStream​(Variable v2,
                        Section section,
                        OutputStream out)
                 throws IOException,
                        InvalidRangeException
        Read data from a top level Variable and send data to a OutputStream. Must be in big-endian order, following ncstream conventions. Default implementation just reads to memory and writes to stream. Allow override for possible performance improvements.
        Parameters:
        v2 - a top-level Variable
        section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.
        out - write data to this OutputStream
        Returns:
        the number of bytes written to the channel
        Throws:
        IOException - if read error
        InvalidRangeException - if invalid section

      • getStructureIterator

        StructureDataIterator getStructureIterator​(Structure s,
                                           int bufferSize)
                                    throws IOException
        Get the structure iterator. iosps with top level sequences must override. Not threadsafe; do not use multiple StructureDataIterator for the same iosp.
        Parameters:
        s - the Structure
        bufferSize - the buffersize
        Returns:
        the data iterator
        Throws:
        IOException - if problem reading data

      • close

        void close()
    throws IOException
        Close the file. It is the IOServiceProvider's job to close the file (even though it didnt open it), and to free any other resources it has used.
        Throws:
        IOException - if read error

      • syncExtend

        @Deprecated
boolean syncExtend()
            throws IOException
        Deprecated.
        Do not use.
        Extend the NetcdfFile if the underlying dataset has changed in a way that is compatible with the current metadata. For example, if the unlimited dimension has grown.
        Returns:
        true if the NetcdfFile was extended.
        Throws:
        IOException - if a read error occured when accessing the underlying dataset.

      • release

        void release()
      throws IOException
        Release any system resources like file handles. Optional, implement only if you are able to reacquire. Used when object is made inactive in cache.
        Throws:
        IOException

      • reacquire

        void reacquire()
        throws IOException
        Reacquire any resources like file handles Used when reactivating in cache.
        Throws:
        IOException

      • sendIospMessage

        @Nullable
Object sendIospMessage​(@Nullable
                       Object message)
        A way to communicate arbitrary information to and from an iosp.
        Parameters:
        message - opaque message sent to the IOSP object when its opened (not when isValidFile() is called)
        Returns:
        opaque Object, may be null.

      • toStringDebug

        String toStringDebug​(Object o)
        Debug info for this object.
        Parameters:
        o - which object
        Returns:
        debug info for this object

      • getDetailInfo

        String getDetailInfo()
        Show debug / underlying implementation details
        Returns:
        debug info

      • getFileTypeId

        String getFileTypeId()
        Get a unique id for this file type.
        Returns:
        registered id of the file type
        See Also:
        "https://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"

      • getFileTypeVersion

        String getFileTypeVersion()
        Get the version of this file type.
        Returns:
        version of the file type
        See Also:
        "https://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"

      • getFileTypeDescription

        String getFileTypeDescription()
        Get a human-readable description for this file type.
        Returns:
        description of the file type
        See Also:
        "https://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"