Packages

  • package root

    This is the documentation for the Apache Daffodil Scala API.

    This is the documentation for the Apache Daffodil Scala API.

    Package structure

    org.apache.daffodil.sapi - Provides the classes necessary to compile DFDL schemas, parse and unparse files using the compiled objects, and retrieve results and parsing diagnostics

    org.apache.daffodil.udf - Provides the classes necessary to create User Defined Functions to extend the DFDL expression language

    org.apache.daffodil.runtime1.layers.api - Provides the classes necessary to create custom Layer extensions to DFDL.

    Definition Classes
    root
  • package org
    Definition Classes
    root
  • package apache
    Definition Classes
    org
  • package daffodil
    Definition Classes
    apache
  • package sapi

    Provides the classes necessary to compile DFDL schemas, parse and unparse files using the compiled objects, and retrieve results and parsing diagnostics

    Provides the classes necessary to compile DFDL schemas, parse and unparse files using the compiled objects, and retrieve results and parsing diagnostics

    Overview

    The Daffodil object is a factory object to create a Compiler. The Compiler provides a method to compile a provided DFDL schema into a ProcessorFactory, which creates a DataProcessor:

    val c = Daffodil.compiler()
val pf = c.compileFile(file)
val dp = pf.onPath("/")

    The DataProcessor provides the necessary functions to parse and unparse data, returning a ParseResult or UnparseResult, respectively. These contain information about the parse/unparse, such as whether or not the processing succeeded with any diagnostic information.

    The DataProcessor also provides two functions that can be used to perform parsing/unparsing via the SAX API. The first creates a DaffodilParseXMLReader which is used for parsing, and the second creates a DaffodilUnparseContentHandler which is used for unparsing.

    val xmlReader = dp.newXMLReaderInstance
val unparseContentHandler = dp.newContentHandlerInstance(output)

    The DaffodilParseXMLReader has several methods that allow one to set properties and handlers (such as ContentHandlers or ErrorHandlers) for the reader. One can use any contentHandler/errorHandler as long as they extend the org.xml.sax.ContentHandler and org.xml.sax.ErrorHandler interfaces respectively. One can also set properties for the DaffodilParseXMLReader using DaffodilParseXMLReader.setProperty.

    The following properties can be set as follows:

    The constants below have literal values starting with "urn:ogf:dfdl:2013:imp:daffodil.apache.org:2018:sax:" and ending with "BlobDirectory", "BlobPrefix" and "BlobSuffix" respectively.

    xmlReader.setProperty(DaffodilParseXMLReader.DAFFODIL_SAX_URN_BLOBDIRECTORY,
 Paths.get(System.getProperty("java.io.tmpdir"))) // value type: java.nio.file.Paths
xmlReader.setProperty(DaffodilParseXMLReader.DAFFODIL_SAX_URN_BLOBPREFIX, "daffodil-sax-") // value type String
xmlReader.setProperty(DaffodilParseXMLReader.DAFFODIL_SAX_URN_BLOBSUFFIX, ".bin") // value type String

    The properties can be retrieved using the same variables with DaffodilParseXMLReader.getProperty and casting to the appropriate type as listed above.

    The following handlers can be set as follows:

    xmlReader.setContentHandler(contentHandler)
xmlReader.setErrorHandler(errorHandler)

    The handlers above must implement the following interfaces respectively:

    org.xml.sax.ContentHandler
org.xml.sax.ErrorHandler

    The ParseResult can be found as a property within the DaffodilParseXMLReader using this uri: "urn:ogf:dfdl:2013:imp:daffodil.apache.org:2018:sax:ParseResult" or DaffodilParseXMLReader.DAFFODIL_SAX_URN_PARSERESULT

    In order for a successful unparse to happen, the SAX API requires the unparse to be kicked off by a parse call to any org.xml.sax.XMLReader implementation that has the DaffodilUnparseContentHandler registered as its content handler. To retrieve the UnparseResult, one can use DaffodilUnparseContentHandler.getUnparseResult once the XMLReader.parse run is complete.

    Parse
    Dataprocessor Parse

    The DataProcessor.parse method accepts input data to parse in the form of a InputSourceDataInputStream and an InfosetOutputter to determine the output representation of the infoset (e.g. Scala XML Nodes, JDOM2 Documents, etc.):

    val scalaOutputter = new ScalaXMLInfosetOutputter()
val is = new InputSourceDataInputStream(data)
val pr = dp.parse(is, scalaOutputter)
val node = scalaOutputter.getResult

    The DataProcessor.parse method is thread-safe and may be called multiple times without the need to create other data processors. However, InfosetOutputter's are not thread safe, requiring a unique instance per thread. An InfosetOutputter should call InfosetOutputter.reset before reuse (or a new one should be allocated). For example:

    val scalaOutputter = new ScalaXMLInfosetOutputter()
files.foreach { f => {
  outputter.reset
  val is = new InputSourceDataInputStream(new FileInputStream(f))
  val pr = dp.parse(is, scalaOutputter)
  val node = scalaOutputter.getResult
}

    One can repeat calls to parse() using the same InputSourceDataInputStream to continue parsing where the previous parse ended. For example:

    val is = new InputSourceDataInputStream(dataStream)
val scalaOutputter = new ScalaXMLInfosetOutputter()
val keepParsing = true
while (keepParsing && is.hasData()) {
  scalaOutputter.reset()
  val pr = dp.parse(is, jdomOutputter)
  ...
  keepParsing = !pr.isError()
}
    SAX Parse

    The DaffodilParseXMLReader.parse method accepts input data to parse in the form of a InputSourceDataInputStream. The output representation of the infoset, as well as how parse errors are handled, are dependent on the content handler and the error handler provided to the DaffodilParseXMLReader. For example, the org.jdom2.input.sax.SAXHandler provides a JDOM representation, whereas other ContentHandlers may output directly to a java.io.OutputStream or java.io.Writer.

    val contentHandler = new SAXHandler()
xmlReader.setContentHandler(contentHandler)
val is = new InputSourceDataInputStream(data)
xmlReader.parse(is)
val pr = xmlReader.getProperty(DaffodilParseXMLReader.DAFFODIL_SAX_URN_PARSERESULT)
val doc = saxHandler.getDocument

    The DaffodilParseXMLReader.parse method is not thread-safe and may only be called again/reused once a parse operation is completed. This can be done multiple times without the need to create new DaffodilParseXMLReaders, ContentHandlers or ErrorHandlers. It might be necessary to reset whatever ContentHandler is used (or allocate a new one). A thread-safe implementation would require unique instances of the DaffodilParseXMLReader and its components. For example:

    val contentHandler = new SAXHandler()
xmlReader.setContentHandler(contentHandler)
files.foreach { f => {
  contentHandler.reset
  val is = new InputSourceDataInputStream(new FileInputStream(f))
  xmlReader.parse(is)
  val pr = xmlReader.getProperty(DaffodilParseXMLReader.DAFFODIL_SAX_URN_PARSERESULT)
  val doc = saxHandler.getDocument
}

    The value of the supported features cannot be changed during a parse, and the parse will run with the value of the features as they were when the parse was kicked off. To run a parse with different feature values, one must wait until the running parse finishes, set the feature values using the XMLReader's setFeature and run the parse again.

    One can repeat calls to parse() using the same InputSourceDataInputStream to continue parsing where the previous parse ended. For example:

    val is = new InputSourceDataInputStream(dataStream)
val contentHandler = new SAXHandler()
xmlReader.setContentHandler(contentHandler)
val keepParsing = true
while (keepParsing && is.hasData()) {
  contentHandler.reset()
  xmlReader.parse(is)
  val pr = xmlReader.getProperty(DaffodilParseXMLReader.DAFFODIL_SAX_URN_PARSERESULT)
  ...
  keepParsing = !pr.isError()
}
    Unparse
    Dataprocessor Unparse

    The same DataProcessor used for parse can be used to unparse an infoset via the DataProcessor.unparse method. An InfosetInputter provides the infoset to unparse, with the unparsed data written to the provided java.nio.channels.WritableByteChannel. For example:

    val inputter = new ScalaXMLInfosetInputter(node)
val ur = dp.unparse(inputter, wbc)
    SAX Unparse

    In order to kick off an unparse via the SAX API, one must register the DaffodilUnparseContentHandler as the contentHandler for an XMLReader implementation. The call to the DataProcessor.newContentHandlerInstance method must be provided with the java.nio.channels.WritableByteChannel, where the unparsed data ought to be written to. Any XMLReader implementation is permissible, as long as they have XML Namespace support.

    val is = new ByteArrayInputStream(data)
val os = new ByteArrayOutputStream()
val wbc = java.nio.channels.Channels.newChannel(os)
val unparseContentHandler = dp.newContentHandlerInstance(wbc)
val xmlReader = SAXParserFactory.newInstance.newSAXParser.getXMLReader
xmlReader.setContentHandler(unparseContentHandler)
try {
 xmlReader.parse(is)
} catch {
 case _: DaffodilUnparseErrorSAXException => ...
 case _: DaffodilUnhandledSAXException => ...
}

    The call to the XMLReader.parse method must be wrapped in a try/catch, as DaffodilUnparseContentHandler relies on throwing an exception to end processing in the case of anyerrors/failures. There are two kinds of errors to expect: DaffodilUnparseErrorSAXException, for the case when the UnparseResult.isError, and DaffodilUnhandledSAXException, for any other errors.

    In the case of an DaffodilUnhandledSAXException,DaffodilUnparseContentHandler.getUnparseResult will return null.

    try {
  xmlReader.parse(new InputSource(is))
} catch {
  case _: DaffodilUnhandledSAXException => ...
  case _: DaffodilUnparseErrorSAXException => ...
}
val ur = unparseContentHandler.getUnparseResult
    Failures and Diagnostics

    It is possible that failures could occur during the creation of the ProcessorFactory, DataProcessor, or ParseResult. However, rather than throwing an exception on error (e.g. invalid DFDL schema, parse error, etc), these classes extend WithDiagnostics, which is used to determine if an error occurred, and any diagnostic information (see Diagnostic) related to the step. Thus, before continuing, one must check WithDiagnostics.isError. For example:

    val pf = c.compile(file)
if (pf.isError()) {
  val diags = pf.getDiagnostics()
  diags.foreach { d =>
    System.out.println(d.toString())
  }
  return -1;
}
    Saving and Reloading Parsers

    In some cases, it may be beneficial to save a parser and reload it. For example, when starting up, it may be quicker to reload an already compiled parser than to compile it from scratch. To save a DataProcessor:

    val dp = pf.onPath("/")
dp.save(saveFile);

    And to restore a saved DataProcessor:

    val dp = Daffodil.reload(saveFile);

    And use like below:

    val pr = dp.parse(data);

    or

    val xmlReader = dp.newXMLReaderInstance
... // setting appropriate handlers
xmlReader.parse(data)
val pr = xmlReader.getProperty("...ParseResult")
    Definition Classes
    daffodil
  • package debugger

    Provides the classes necessary to perform parse tracing or create a custom debugger

    Provides the classes necessary to perform parse tracing or create a custom debugger

    Overview

    Daffodil comes with one prebuilt debugger, the TraceDebuggerRunner, which outputs verbose information during the parsing processes, which can be used to aid in debugging a DFDL schema. For example, the TraceDebuggerRunner can be use like so:

    val tdr = new TraceDebuggerRunner()
Daffodil.setDebugger(tdr)

    Additionally, one may create their own debugger runner by implementing the methods in the DebuggerRunner.

    Once the debugger is set, it must then be turned on, like so:

    Daffodil.setDebugging(true);
    Definition Classes
    sapi
  • package infoset

    Defines various classes used control the representation of the infoset for parse and unparse.

    Defines various classes used control the representation of the infoset for parse and unparse. Classes that extend InfosetOutputter are provided to the DataProcessor.parse method to deteremine how to output an infoset. These classes are not guaranteed to be thread-safe. Classes that extend InfosetInputter are provided to the DataProcessor.unparse method to determine how to read in an infoset. A new InfosetOutputter is required for each call to unparse().

    Definition Classes
    sapi
  • package io
    Definition Classes
    sapi
  • InputSourceDataInputStream

package io

Type Members

  1. class InputSourceDataInputStream extends Closeable

    Provides Daffodil with byte data from an InputStream, ByteBuffer, or byte Array.

    Provides Daffodil with byte data from an InputStream, ByteBuffer, or byte Array.

    Note that the InputStream variant has potential overhead due to streaming capabilities and support for files greater than 2GB. In some cases, better performance might come from using the byte array or ByteBuffer variants instead. For example, if your data is already in a byte array, one should use the Array[Byte] or ByteBuffer variants instead of wrapping it in a ByteArrayInputStream. As another example, instead of using a FileInputStream like this:

    val path = Paths.get(file)
val fis = Files.newInputStream(path)
val input = InputSourceDataInputStream(fis)

    You might consider mapping the file to a MappedByteBuffer like below, keeping in mind that MappedByteBuffers have size limitations and potentially different performance characteristics depending on the file size and system--it maybe not always be faster than above.

    val path = Paths.get(file)
val size = Files.size(path)
val fc = FileChannel.open(path, StandardOpenOption.READ)
val bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, size)
fc.close()
val input = InputSourceDataInputStream(bb)

Ungrouped