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By introducing the IO concept, an insertable universal framework, ACDK distants itself even further from its model Java.

Content of this chapter:    The IO concept in Java    Character of frameworks      Streams as Pipes    Binary Reader and Writer classes in ACDK      Reader      Writer      Storage      Filter      FilterReader      FilterWriter    Formated Reader/Writer

 The IO concept in Java

In Java, there is not only one IO concept (Input/Output, appreviation IO), but several others as well.

 Character of frameworks

Frameworks with a good design are distinguished through:

• Their basic principles can be explained with only a few good interfaces
• are relative easy to be implemented
• are relative easy to be expanded
• can be universally inputted

 Streams as Pipes

When using input/output, there are several types of elements. Those, which read and write from a medium (like a file, console, TCP etc.)and those, which work as a filter with an existing stream. A well known example are the Unix command-line utilities, where pipes can be used for Standard-IN and Standard-OUT: cat address.dat | cut -d ';' -f 2 | grep 'Kassel' | wc -l > erg.dat
Unix-Tools can also be seen as the nucleus of classical component technologies.


These elements can now be put together, just like in a building set.

 Binary Reader and Writer classes in ACDK

In ACDK, Stream classes are divided like this:

 Reader

 acdk::io::Readerplaces the base interface for readable accesson a stream. A Reader reads bytes (octets) from the source.

 Writer

 acdk::io::Writer places the basis interface for writable access on a stream. A Writer writes bytes (octets) to a target.

 Storage

A  acdk::io::Storage represents the medium, from which one can read or write. Storage is usually a describer.

 Filter

Filters are again divided into readable and writable:

 FilterReader

A  acdk::io::FilterReader reads from a given reader. This can further be a  acdk::io::FilterReader or a  acdk::io::Storage which implementates a  acdk::io::Reader interface.

 FilterWriter

A  acdk::io::FilterWriter reads from a given reader. This can further be a  acdk::io::FilterWriter or a  acdk::io::Storage which implementates a  acdk::io::Writer interface.

 Formated Reader/Writer

On top of the Reader/Writer interface formated filter Reader/Writer provides an access to formated Data.

•  acdk::io::CharReader and  acdk::io::CharWriter reads/writes strings from/to a source/target.
  See also  Character Reader and Writer classes in ACDK.
  
•  acdk::io::DataReader and  acdk::io::DataWriter reads/writes basic types and Strings to/from a source/target.
  The format can be Binary ( acdk::io::BinaryDataReader) or XML ( acdk::xml::XMLObjectReader.
  
•  acdk::io::ObjectReader and  acdk::io::ObjectWriter is derived from DataReader/DataWriter and has the ability to read/write Object from/to a source/target. See also:  Serialization.