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Java > Open Source Codes > com > sun > enterprise > config > serverbeans > validation > FrameHolderBuilder


1 /*
2  * The contents of this file are subject to the terms
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4  * (the License). You may not use this file except in
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9  * glassfish/bootstrap/legal/CDDLv1.0.txt.
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21  * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
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23
24 package com.sun.enterprise.config.serverbeans.validation;
25
26 import java.util.Stack JavaDoc;
27 import org.xml.sax.Attributes JavaDoc;
28 import org.xml.sax.ContentHandler JavaDoc;
29 import org.xml.sax.ContentHandler JavaDoc;
30 import org.xml.sax.Locator JavaDoc;
31 import org.xml.sax.SAXException JavaDoc;
32 import org.xml.sax.XMLFilter JavaDoc;
33 import org.xml.sax.helpers.DefaultHandler JavaDoc;
34 import org.xml.sax.helpers.XMLFilterImpl JavaDoc;
35
36
37
38 /**
39  * FrameHolderBuilder.java
40  * Instances of the class are responsible for handling a SAX input
41  * stream to build a series of connected Frames to hold the
42  * system-property definitions found inside the XML.
43  *
44  * The Frames are connected by an inheritance pattern - it is this
45  * class that knows what that inheritance pattern is. As of the time
46  * of writing the pattern is:
47  * <verbatim>
48  * server [-> cluster] -> config -> domain
49  * </verbatim>
50  * With the cluster inheritance being optional, and only occuring when
51  * a cluster refers to a server. (So, a server might look as if its
52  * inheriting from one config, but a cluster can override the
53  * server's own settings and cause the server to inherit from the
54  * cluster and thus from some other config).
55  *
56  * The inheritance hierarchy between configs and domains is
57  * implicit. Between the other elements it is explicit, and is
58  * achieved through the XML attributes "config-ref", "server-ref".
59  *
60  * This system will function even if the XML is quite poorly formed,
61  * but the results will be peculiar, to say the least! The best
62  * debugging method is to extract each frame from the resulting
63  * FrameHolder and print it out - that gives you a pretty good picture
64  * of what the inheritance tree looks like (at least in terms of
65  * properties!).
66  *
67  * @author <a HREF="mailto:toby.h.ferguson@sun.com">Toby H Ferguson</a>
68  * @version $Revision: 1.3 $
69  */
70
71 // Upon revisiting this code I can't help but believe that this class
72 // should be called something slightly different. It appears to be an
73 // inheritance manager, and tightly tied into the Framer concept. I'm
74 // unsure why I built it this way!
75 public class FrameHolderBuilder extends Framer
76 {
77     protected final Frame getClusterFrame(Attributes JavaDoc atts){
78         final Frame f = super.getClusterFrame(atts);
79         inheritFromConfigPerhaps(f, atts);
80 // final String sr = atts.getValue(NAMESPACE, SERVER_REF);
81 // if (sr != null){
82 // frameHolder.getServerFrame(sr).inheritFrom(f);
83 // }
84 return f;
85     }
86
87     protected final void handleStartServerRefEvent(Attributes JavaDoc atts){
88         final String JavaDoc sr = atts.getValue(NAMESPACE, NAME);
89         if (sr != null){
90             frameHolder.getServerFrame(sr).inheritFrom(currentFrame());
91         }
92     }
93     
94     protected final Frame getConfigFrame(Attributes JavaDoc atts){
95         final Frame f = super.getConfigFrame(atts);
96         f.inheritFrom(frameHolder.getDomainFrame());
97         return f;
98     }
99     
100     protected final Frame getServerFrame(Attributes JavaDoc atts){
101         final Frame f = super.getServerFrame(atts);
102         return inheritFromConfigPerhaps(f, atts);
103     }
104
105     private final Frame inheritFromConfigPerhaps(Frame f, Attributes JavaDoc atts){
106         final String JavaDoc cr = atts.getValue(NAMESPACE, CONFIG_REF);
107         if (cr != null){
108             f.inheritFrom(frameHolder.getConfigFrame(cr));
109         }
110         return f;
111     }
112
113 }
114
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