ucar.nc2.iosp

Interface IOServiceProvider

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

AbstractIOServiceProvider, H4iosp, H5iosp, H5iospArrays, N3iosp, N3iospWriter, NcStreamIosp

public interface IOServiceProvider
extends Closeable

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 Summary

Modifier and Type	Method and Description
void	build(RandomAccessFile raf, Group.Builder rootGroup, CancelTask cancelTask) Read an existing RandomAccessFile, and populate rootGroup.
void	buildFinish(NetcdfFile ncfile) Sometimes the builder needs access to the finished objects.
void	close() Close the file.
String	getDetailInfo() Show debug / underlying implementation details
String	getFileTypeDescription() Get a human-readable description for this file type.
String	getFileTypeId() Get a unique id for this file type.
String	getFileTypeVersion() Get the version of this file type.
long	getLastModified() Get last time the file was modified.
Iterator<StructureData>	getStructureDataArrayIterator(Sequence s, int bufferSize) Get the structure iterator.
StructureDataIterator	getStructureIterator(Structure s, int bufferSize) Deprecated. use getStructureDataArrayIterator
boolean	isValidFile(RandomAccessFile raf) Check if this is a valid file for this IOServiceProvider.
void	reacquire() Reacquire any resources like file handles Used when reactivating in cache.
Array<?>	readArrayData(Variable v2, Section section) Read data from a top level Variable and return a memory resident Array.
default Array	readData(Variable v2, Section section) Deprecated. use readArrayData
Array	readSection(ParsedSectionSpec cer) Deprecated. do not use.
long	readToOutputStream(Variable v2, Section section, OutputStream out) Deprecated. do not use.
void	release() Release any system resources like file handles.
Object	sendIospMessage(Object message) A way to communicate arbitrary information to and from an iosp.
String	toStringDebug(Object o) Debug info for this object.

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

build

void build(RandomAccessFile raf,
           Group.Builder rootGroup,
           CancelTask cancelTask)
    throws IOException

Read an existing RandomAccessFile, and populate rootGroup. Note that you cannot reference the NetcdfFile within this routine, since it hasnt been created yet.

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 when ncfile is finished being built.

readData

@Deprecated
default Array readData(Variable v2,
                                    Section section)
                             throws IOException,
                                    InvalidRangeException

Deprecated. use readArrayData

Throws:

IOException

InvalidRangeException

readArrayData

Array<?> readArrayData(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

InvalidRangeException

readToOutputStream

@Deprecated
long readToOutputStream(Variable v2,
                                     Section section,
                                     OutputStream out)
                              throws IOException,
                                     InvalidRangeException

Deprecated. do not use.

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

readSection

@Deprecated
Array readSection(ParsedSectionSpec cer)
                        throws IOException,
                               InvalidRangeException

Deprecated. do not use.

Throws:

IOException

InvalidRangeException

getStructureIterator

@Deprecated
StructureDataIterator getStructureIterator(Structure s,
                                                        int bufferSize)
                                                 throws IOException

Deprecated. use getStructureDataArrayIterator

Throws:

IOException

getStructureDataArrayIterator

Iterator<StructureData> getStructureDataArrayIterator(Sequence s,
                                                      int bufferSize)

Get the structure iterator. Iosps with top level sequences must override.

Parameters:

s - the Structure

bufferSize - the buffersize, may be -1 for default.

Returns:

an iterator over the StructureData

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.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException - if read error

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

getLastModified

long getLastModified()

Get last time the file was modified.

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"