The Java Binding, version 1.1a

WARNING: version 1.1a of the Java Binding is EXTREMELY OUTDATED, and is kept on this site for historical interest only. The work on the Java Binding changed approach radically with version 1.1b - you should be using the up to date version.

Specification Interfaces

Version 1.1a of the Java binding for ZOOM is specified as a set of .java files which specify interfaces representing the classes of the abtract API. These interfaces are all in the package org.z3950.zoom. Most of the interfaces include commented-out constructors.

The binding may be viewed in two forms:

• As a single file containing all the interfaces. This is convenient for humans to read, but no use to a Java compiler;

• As a set of ten separate, tiny, source files, each containing a single interface. This is the form in which Java compilers require them, due to the one-file, one-public-class rule.

  The ten files, in the order in which they should be read, are:

  • Global.java
  • Connection.java
  • Query.java
  • PrefixQuery.java
  • CCLQuery.java
  • ResultSet.java
  • Record.java
  • Error.java
  • SystemError.java
  • Bib1Error.java

Implementing the Binding

Implementations of this binding should define classes with the same names as these interfaces, but in a different package; it should be specified that each class implements its corresponding interface. For example, Knowledge Integration's putative implementation might specify:

	package com.k_int.zoom;
	class Connection implements org.z3950.zoom.Connection {
		// ...
	}
  

It turns out that this approach just plain does not work. More explanation of why to follow, but you might like to start with the commentaries on interface constructors, static methods in interfaces and abstract interfaces to get an idea of how Java's interfaces just don't do what we're trying to make them do here.