Writing an IOSP - Overview

public class MyIosp extends AbstractIOServiceProvider {

  /**
   * Methods that must be implemented
   */
  public boolean isValidFile(RandomAccessFile raf) throws IOException {
    // You must examine the file that is passed to you, and quickly and accurately determine if it can be opened
    // by this IOSP. You may not keep any state (i.e. store any information) in this call,
    // and it must be thread-safe.
  }

  public Array readData(Variable v2, Section section)
      throws IOException, InvalidRangeException {
    // Data will be read from Variable through this call. The Section defines the requested data subset.
  }

  public String getFileTypeId() {
    // See below for details on File Types.
  }

  public String getFileTypeDescription() {
    // See below for details on File Types.
  }

  public boolean isBuilder() {
    // This method should return true.
    // See notes below regarding the Builder pattern and API changes.
  }

  public void build(RandomAccessFile raf, Group.Builder rootGroup, CancelTask cancelTask)
      throws IOException {
    // If isValidFile returns true, the build method will be called.
    // This method should populate a CDM object from the RandomAccessFile, using the Group.Builder object.
    // If you need to do a lot of I/O, you should periodically check cancelTask.isCancel(), and if its true,
    // return immediately. This allows users to cancel the opening of a dataset if its taking too long.
  }

  /**
   * Methods with a default implementation, that can optionally be overriden
   */
  public void buildFinish(NetcdfFile ncfile) {
    // Implement any clean-up or finish actions for your file type.
  }

  public String getFileTypeVersion() {
    // See below for details on File Types.
  }

  public ucar.ma2.Array readSection(ParsedSectionSpec cer)
      throws IOException, InvalidRangeException {
    // If you use Structures, data for Variables that are members of Structures are read through this method.
    // If you dont override, the default implementation in AbstractIOServiceProvider is used.
    // Override in order to improve performance.
  }

  public StructureDataIterator getStructureIterator(Structure s, int bufferSize)
      throws java.io.IOException {
    // If any of your top-level variables (not inside of a Structure) are Sequences,
    // this is how the data in them will be accessed, and you must implement it.
  }

  public boolean syncExtend() throws IOException {
    // If the file may change since it was opened, you may optionally implement this routine.
    // The changes must not affect any of the structural metadata.
    // For example, in the NetCDF-3 IOSP, we check to see if the record dimension has grown.
  }

  public Object sendIospMessage(Object message) {
    // This allows applications to pass an arbitrary object to the IOSP,
    // through the NetcdfFiles.open( location, buffer_size, cancelTask, spiObject) method.
    // As a rule, you should not count on having such special information available,
    // unless you are controlling all data access in an application.
  }

  public String getDetailInfo() {
    // Here you can pass any information that is useful to debugging.
    // It can be viewed through the ToolsUI application.
  }
}