1 $Id: README,v 1.22 2002-12-09 16:29:44 mike Exp $
3 CQL-Java - a free CQL compiler, and other CQL tools, for Java
9 CQL-Java is a Free Software project that provides:
11 * A set of classes for representing a CQL parse tree (a base CQLNode
12 class, CQLBooleanNode and its subclasses, CQLTermNode, etc.)
13 * A CQLCompiler class (and its lexer) which builds a parse tree given
15 * A selection of compiler back-ends to render out the parse tree as:
16 * XCQL (the standard XML representation)
17 * CQL (i.e. decompiling the parse-tree)
18 * PQF (Yaz-style Prefix Query Format)
19 * A random query generator, useful for testing.
21 CQL is "Common Query Language", a new query language designed under
22 the umbrella of the ZING initiative (Z39.59-International Next
23 Generation). The official specification is at
24 http://www.loc.gov/z3950/agency/zing/cql/cql-syntax.html
25 and there's more (and friendlier) information at
26 http://zing.z3950.org/cql/index.html
28 XCQL is "XML CQL", a representation of CQL-equivalent queries in XML
29 which is supposed to be easier to parse. The specification is at
30 http://www.loc.gov/z3950/agency/zing/cql/xcql.html
31 and includes an XML Schema.
33 But if you didn't know that, why are you even reading this? :-)
36 What's what in this distribution?
39 VERSION The version-number of this distribution
40 src Source-code for the CQL-Java library
41 lib The compiled library file, "cql-java.jar"
42 bin Simple shell-scripts to invoke the test-harnesses
43 docs Documentation automatically generated by "javadoc"
44 test Various testing and sanity-checking frameworks
45 etc Other files: CQL Grammar, generator properties, etc.
47 "Installation" of this package would consist of putting the bin
48 directory on your PATH and lib/cql-java.jar on your CLASSPATH.
54 Using the test-harnesses:
56 $ CQLParser 'title=foo and author=(bar or baz)'
57 $ CQLParser -c 'title=foo and author=(bar or baz)'
58 $ CQLParser -p /etc/pqf.properties 'title=foo and author=(bar or baz)'
59 $ CQLLexer 'title=foo and author=(bar or baz)'
60 (not very interesting unless you're debugging)
61 $ CQLGenerator etc/generate.properties seed 18
63 Using the library in your own applications:
65 import org.z3950.zing.cql.*
67 // Building a parse-tree by hand
68 CQLNode n1 = new CQLTermNode("dc.author", new CQLRelation("="),
70 CQLNode n2 = new CQLTermNode("dc.title", new CQLRelation("all"),
72 CQLNode root = new CQLAndNode(n1, n2);
73 System.out.println(root.toXCQL(0));
75 // Parsing a CQL query
76 CQLParser parser = new CQLParser();
77 CQLNode root = parser.parse("title=dinosaur");
78 System.out.print(root.toXCQL(0));
79 System.out.println(root.toCQL());
80 System.out.println(root.toPQF(config));
81 // ... where `config' specifies CQL-qualfier => Z-attr mapping
87 See the automatically generated class documentation in the "doc"
94 All code and documentation by Mike Taylor <mike@z3950.org>
95 http://www.miketaylor.org.uk
96 Please email me with bug-reports, wishlist items, patches, deployment
97 stories and, of course, large cash donations.
103 The CQL-Java suite is Free Software, which is pretty much legally
104 equivalent -- though not morally equivalent -- to Open Source. See
105 http://www.gnu.org/philosophy/free-software-for-freedom.html
106 for a detailed if somewhat one-sided discussion of the differences,
107 and particularly of why Free Software is an important idea.
109 CQL-Java is distributed under version 2.1 of the LGPL (GNU LESSER
110 GENERAL PUBLIC LICENSE). A copy of the licence is included in this
111 distribution, as the file LGPL-2.1. This licence does not allow you
112 to restrict the freedom of others to use derived versions of CQL-Java
113 (i.e. you must share your enhancements), but does let you deploy
114 CQL-Java as a part of a non-free larger work.
120 Adam Dickmeiss's CQL compiler, written in C.
121 Rob Sanderson's CQL compiler, written in Python.
122 All the other free CQL compilers everyone's going to write :-)
123 The "Changes" file, including the "Still to do" section.