-
Notifications
You must be signed in to change notification settings - Fork 7
/
basics---getting-things.html
311 lines (260 loc) · 14.7 KB
/
basics---getting-things.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Basics - Getting Things</title>
<meta name="description" content="Apache TomEE">
<meta name="author" content="Apache TomEE">
<meta name="google-translate-customization" content="f36a520c08f4c9-0a04e86a9c075ce9-g265f3196f697cf8f-10">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Expires" content="0">
<meta http-equiv="Cache-Control" content="no-store, no-cache, must-revalidate, max-age=0">
<!-- Le HTML5 shim, for IE6-8 support of HTML elements -->
<!--[if lt IE 9]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<!-- Le styles -->
<link href="./resources/css/bootstrap.css" rel="stylesheet">
<link href="./resources/css/prettify.css" rel="stylesheet">
<!--link href="./resources/css/bootstrap-mods.css" rel="stylesheet"-->
<link href="./resources/css/main.css" rel="stylesheet">
<link href="./resources/font-awesome-4.6.3/css/font-awesome.min.css" rel="stylesheet">
<script type="text/javascript">
var t = encodeURIComponent(document.title.replace(/^\s+|\s+$/g,""));
var u = encodeURIComponent(""+document.URL);
function fbshare () {
window.open(
"http://www.facebook.com/sharer/sharer.php?u="+u,
'Share on Facebook',
'width=640,height=426');
};
function gpshare () {
window.open(
"https://plus.google.com/share?url="+u,
'Share on Google+',
'width=584,height=385');
};
function twshare () {
window.open(
"https://twitter.com/intent/tweet?url="+u+"&text="+t,
'Share on Twitter',
'width=800,height=526');
};
function pinshare () {
window.open("//www.pinterest.com/pin/create/button/?url="+u+"&media=http%3A%2F%2Ftomee.apache.org%2Fresources%2Fimages%2Ffeather-logo.png&description="+t,
'Share on Pinterest',
'width=800,height=526');
};
</script>
<!-- Le fav and touch icons -->
<link rel="shortcut icon" href="./favicon.ico">
<link rel="apple-touch-icon" href="./resources/images/apple-touch-icon.png">
<link rel="apple-touch-icon" sizes="72x72" href="./resources/images/apple-touch-icon-72x72.png">
<link rel="apple-touch-icon" sizes="114x114" href="./resources/images/apple-touch-icon-114x114.png">
<script src="./resources/js/prettify.js" type="text/javascript"></script>
<script src="./resources/js/jquery-latest.js"></script>
<script src="http://platform.twitter.com/widgets.js" type="text/javascript"></script>
<script src="./resources/js/common.js"></script>
<script src="./resources/js/prettyprint.js"></script>
<!--script src="//assets.pinterest.com/js/pinit.js" type="text/javascript" async></script//-->
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-2717626-1']);
_gaq.push(['_setDomainName', 'apache.org']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
</script>
</head>
<body>
<div class="topbar" data-dropdown="dropdown">
<div class="fill">
<div class="container">
<a class="brand" href="./index.html">Apache TomEE</a>
<ul class="nav">
<li class="dropdown">
<a class="dropdown-toggle" data-toggle="dropdown" href="#">
Apache
<b class="caret"></b>
</a>
<ul class="dropdown-menu">
<!-- <li><a href="./misc/whoweare.html">Who we are?</a></li> -->
<!-- <li><a href="./misc/heritage.html">Heritage</a></li> -->
<li><a href="http://www.apache.org">Apache Home</a></li>
<!-- <li><a href="./misc/resources.html">Resources</a></li> -->
<li><a href="./misc/contact.html">Contact</a></li>
<li><a href="./misc/legal.html">Legal</a></li>
<li><a href="http://www.apache.org/foundation/sponsorship.html">Sponsorship</a></li>
<li><a href="http://www.apache.org/foundation/thanks.html">Thanks</a></li>
<li class="divider"/>
<li><a href="http://www.apache.org/security">Security</a></li>
</ul>
</li>
<li><a href="./index.html">Home</a></li>
<li><a href="./downloads.html">Downloads</a></li>
<li><a href="./documentation.html">Documentation</a></li>
<li><a href="./examples-trunk/index.html">Examples</a></li>
<li><a href="./support.html">Support</a></li>
<li><a href="./contribute.html">Contribute</a></li>
<li><a href="./security/index.html">Security</a></li>
</ul>
<!-- Google CSE Search Box Begins -->
<FORM class="pull-right" id="searchbox_010475492895890475512:_t4iqjrgx90" action="http://www.google.com/cse">
<INPUT type="hidden" name="cx" value="010475492895890475512:_t4iqjrgx90">
<INPUT type="hidden" name="cof" value="FORID:0">
<INPUT size="18" width="130" style="width:130px" name="q" type="text" placeholder="Search">
</FORM>
<!--<SCRIPT type="text/javascript" src="http://www.google.com/coop/cse/brand?form=searchbox_010475492895890475512:_t4iqjrgx90"></SCRIPT>-->
<!-- Google CSE Search Box Ends -->
</div>
</div>
</div>
<div class="container">
<div class="page-header">
<small><a href="./index.html">Home</a></small><br>
<h1>Basics - Getting Things
<div style="float: right; position: relative; bottom: -10px; ">
<a onclick="javascript:gpshare()" class="gp-share sprite" title="Share on Google+">share [gp]</a>
<a onclick="javascript:fbshare()" class="fb-share sprite" title="Share on Facebook">share [fb]</a>
<a onclick="javascript:twshare()" class="tw-share sprite" title="Share on Twitter">share [tw]</a>
<a onclick="javascript:pinshare()" class="pin-share sprite" title="Share on Pinterest">share [pin]</a>
<a data-toggle="modal" href="#edit" class="edit-page" title="Contribute to this Page">contribute</a>
</div>
</h1>
</div>
<p><a name="Basics-GettingThings-GettingStufffromtheContainer"></a></p>
<h1>Getting Stuff from the Container</h1>
<p>Generally speaking the only way to get a <a href="container-managed-resource.html">Container-Managed Resource</a>
is via <em>dependency injection</em> or <em>lookup</em> from within a [Container-Managed Component]
.</p>
<p>The <em>unbreakable rules</em>. Read these over and over again when things don't
work.</p>
<ol>
<li>java:comp/env is the spec defined namespace for lookup of any <a href="container-managed-resource.html">Container-Managed Resource</a></li>
<li>java:comp/env is <em>empty</em> by default</li>
<li>java:comp/env is <em>read-only</em> at runtime</li>
<li>java:comp/env is populated by <a href="declaring-references.html">Declaring References</a>
to [Container-Managed Resource]
via xml or annotation</li>
<li>only <a href="container-managed-component.html">Container-Managed Component</a>
s, <em>not</em> their libraries, can [Declare References|Declaring References]
via xml or annotation</li>
<li>only <a href="container-managed-component.html">Container-Managed Component</a>
s, <em>not</em> their libraries, can get dependency injection of [Container-Managed Resource]
s</li>
<li>only <a href="container-managed-component.html">Container-Managed Component</a>
s, <em>and</em> their libraries, may lookup from java:comp/env</li>
<li>you <em>must</em> use the <em>no-arg</em> 'new InitialContext()' constructor to
lookup something from java:comp/env</li>
<li>the annotations and xml for <a href="declaring-references.html">Declaring References</a>
are <em>identical</em> in functionality, both <em>always</em> configure lookup with
<em>optional</em> dependency injection</li>
</ol>
<p><a name="Basics-GettingThings-Commonmistakes,misunderstandings,andmyths"></a></p>
<h2>Common mistakes, misunderstandings, and myths</h2>
<ul>
<li><em><em>"I tried it via annotation and it didn't work, so I used xml and then
it did work"</em></em></li>
</ul>
<p>See rule 9. If one form worked and the other didn't, it means you simply
made a mistake in using one versus the other. Use what works for you, but
understand both annotations or xml will work for either lookup or injection
if used correctly.</p>
<ul>
<li><em><em>"I need to use lookups, so I can't use the annotation"</em></em></li>
</ul>
<p>See rule 9. Annotations are not just for injection, that is just how they
are typically used. Know that when you use an annotation for injection, it
will <em>always</em> create an entry in java:comp/env. As well you can use the
annotation at the <em>class level</em> and it will cause no dependency injection
and only the entry creation in java:comp/env.</p>
<ul>
<li><em><em>"I don't want injection, so I can't use the annotation"</em></em></li>
</ul>
<p>See rule 9 and the above. You can use the annotation at the <em>class level</em>
and it will cause no dependency injection and only the entry creation in
java:comp/env.</p>
<ul>
<li><em><em>"I tried to list java:comp/env but it's empty?!"</em></em></li>
</ul>
<p>See rule 2 and rule 4. There will be nothing in java:comp/env unless you <a href="declaring-references.html">Declare a Reference</a>
to it. It does not matter if is a DataSource configured at the server
level, etc. Nothing is bound into java:comp/env unless you explicitly
declare a reference to it. The Java EE 5 TCK (Technology Compatibility
Kit) tests for this extensively and is a rule we cannot break. Java EE 6
does finally offer some new namesaces (java:global, java:app, and
java:module) which will offer some great new options for more global-style
lookups.</p>
<ul>
<li><em><em>"I deployed the EJB but can't look it up, it's name is Foo"</em></em></li>
</ul>
<p>See rule 2 and the above. Just creating an EJB doesn't cause it to be
added to java:comp/env. If a <a href="container-managed-component.html">Container-Managed Component</a>
wants to lookup the EJB they must [Declare a Reference|Declaring References]
to it via the @EJB annotionation or <ejb-local-ref> or <ejb-ref> in xml.
In Java EE 6, however, EJBs will be automatically bound to
"java:global[/<app-name>]/<module-name>/<bean-name>[!<fully-qualified-interface-name>]"
and can be looked up without declaring a reference first.</p>
<ul>
<li><em><em>"Which InitialContextFactory do I use for java:comp/env?"</em></em></li>
</ul>
<p>See rule 8. You are not allowed to use an InitialContextFactory for
java:comp/env lookups. Setting an InitialContextFactory via
'java.naming.factory.initial' in either System properties, InitialContext
properties, or a jndi.properties file is illegal and will cause
java:comp/env lookups to fail.</p>
<ul>
<li><em><em>"My Client can't lookup the EJB from java:comp/env"</em></em></li>
</ul>
<p>See rule 7. A plain, standalone, Java application cannot use
java:comp/env. There is the official concept of a Java EE Application
Client which can be packaged in an ear and deployed into the Container. In
practice, most people find them restrictive, cumbersome, and hard to use
and are therefore rarely employed in "real world" projects. Most people
opt to use the non-standard, vendor-specific, approach to looking up EJBs
from their plain java clients. In OpenEJB this can be done via either the
RemoteInitialContextFactory (for remote clients) or the
LocalInitialContextFactory (for local clients of an embedded container).
The JNDI names can be configured as <a href="jndi-names.html">shown here</a>
.</p>
<ul>
<li><em><em>"I declared the reference, but still can't look it up"</em></em></li>
</ul>
<p>See all of the above and reread the rules a few times. Always check the
log output as well.</p>
<div id="edit" class="modal hide fade in" style="display: none; ">
<div class="modal-header">
<a class="close" data-dismiss="modal">x</a>
<h3>Thank you for contributing to the documentation!</h3>
</div>
<div class="modal-body">
<h4>Any help with the documentation is greatly appreciated.</h4>
<p>All edits are reviewed before going live, so feel free to do much more than fix typos or links. If you see a page that could benefit from an entire rewrite, we'd be thrilled to review it. Don't be surprised if we like it so much we ask you for help with other pages :)</p>
<small>NOTICE: unless indicated otherwise on the pages in question, all editable content available from apache.org is presumed to be licensed under the Apache License (AL) version 2.0 and hence all submissions to apache.org treated as formal Contributions under the license terms.</small>
<!--[if gt IE 6]>
<h4>Internet Explorer Users</h4>
<p>If you are not an Apache committer, click the Yes link and enter a <i>anonymous</i> for the username and leave the password empty</p>
<![endif]-->
</div>
<div class="modal-footer">
Do you have an Apache ID?
<a href="javascript:void(location.href='https://cms.apache.org/redirect?uri='+escape(location.href))" class="btn">Yes</a>
<a href="javascript:void(location.href='https://anonymous:@cms.apache.org/redirect?uri='+escape(location.href))" class="btn">No</a>
</div>
</div>
<script src="./resources/js/bootstrap-modal.js"></script>
<footer>
<p>Copyright © 1999-2016 The Apache Software Foundation, Licensed under the Apache License, Version 2.0.
Apache TomEE, TomEE, Apache, the Apache feather logo, and the Apache TomEE project logo are trademarks of The Apache Software Foundation.
All other marks mentioned may be trademarks or registered trademarks of their respective owners.</p>
</footer>
</div> <!-- /container -->
<!-- Javascript
================================================== -->
<!-- Placed at the end of the document so the pages load faster -->
<script src="./resources/js/bootstrap-dropdown.js"></script>
</body>
</html>