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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::Authorization - Catalyst Tutorial - Part 5: Authorization |
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4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
8 | This is B<Part 5 of 9> for the Catalyst tutorial. |
9 | |
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10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
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11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
16 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
17 | |
18 | =item 2 |
19 | |
20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
21 | |
22 | =item 3 |
23 | |
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24 | L<Basic CRUD|Catalyst::Manual::Tutorial_BasicCRUD> |
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25 | |
26 | =item 4 |
27 | |
28 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
29 | |
30 | =item 5 |
31 | |
32 | B<Authorization> |
33 | |
34 | =item 6 |
35 | |
36 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
37 | |
38 | =item 7 |
39 | |
40 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
41 | |
42 | =item 8 |
43 | |
44 | L<AdvancedCRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
45 | |
46 | =item 9 |
47 | |
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48 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
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49 | |
50 | =back |
51 | |
52 | |
53 | |
54 | =head1 DESCRIPTION |
55 | |
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56 | This part of the tutorial adds role-based authorization to the existing |
57 | authentication implemented in Part 4. It provides simple examples of |
58 | how to use roles in both TT templates and controller actions. The first |
59 | half looks at manually configured authorization. The second half looks |
60 | at how the ACL authorization plugin can simplify your code. |
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61 | |
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62 | You can checkout the source code for this example from the catalyst |
63 | subversion repository as per the instructions in |
64 | L<Catalyst::Manual::Tutorial::Intro> |
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65 | |
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66 | =head1 BASIC AUTHORIZATION |
67 | |
68 | In this section you learn how to manually configure authorization. |
69 | |
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70 | =head2 Update Plugins to Include Support for Authorization |
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71 | |
72 | Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list: |
73 | |
74 | use Catalyst qw/ |
75 | -Debug |
76 | ConfigLoader |
77 | Static::Simple |
78 | |
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79 | StackTrace |
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80 | |
81 | Authentication |
82 | Authentication::Store::DBIC |
83 | Authentication::Credential::Password |
84 | Authorization::Roles |
85 | |
86 | Session |
87 | Session::Store::FastMmap |
88 | Session::State::Cookie |
89 | /; |
90 | |
91 | |
92 | =head2 Add Config Information for Authorization |
93 | |
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94 | Edit C<myapp.yml> and update it to match (everything from the |
95 | "authorization:" line down is new): |
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96 | |
97 | --- |
98 | name: MyApp |
99 | authentication: |
100 | dbic: |
101 | # Note this first definition would be the same as setting |
102 | # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User' |
103 | # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file). |
104 | # |
105 | # This is the model object created by Catalyst::Model::DBIC from your |
106 | # schema (you created 'MyAppDB::User' but as the Catalyst startup |
107 | # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User'). |
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108 | # NOTE: Omit 'MyApp::Model' here just as you would when using |
109 | # '$c->model("MyAppDB::User)' |
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110 | user_class: MyAppDB::User |
111 | # This is the name of the field in your 'users' table that contains the user's name |
112 | user_field: username |
113 | # This is the name of the field in your 'users' table that contains the password |
114 | password_field: password |
115 | # Other options can go here for hashed passwords |
116 | # Enabled hashed passwords |
117 | password_type: hashed |
118 | # Use the SHA-1 hashing algorithm |
119 | password_hash_type: SHA-1 |
120 | authorization: |
121 | dbic: |
122 | # This is the model object created by Catalyst::Model::DBIC from your |
123 | # schema (you created 'MyAppDB::Role' but as the Catalyst startup |
124 | # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::Role'). |
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125 | # NOTE: Omit 'MyApp::Model' here just as you would when using |
126 | # '$c->model("MyAppDB::User)' |
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127 | role_class: MyAppDB::Role |
128 | # The name of the field in the 'roles' table that contains the role name |
129 | role_field: role |
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130 | # The name of the accessor used to map a role to the users who have this role |
131 | # See the has_many() in MyAppDB/Role.pm |
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132 | role_rel: map_user_role |
133 | # The name of the field in the user_role table that references the user |
134 | user_role_user_field: user_id |
135 | |
136 | |
137 | =head2 Add Role-Specific Logic to the "Book List" Template |
138 | |
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139 | Open C<root/src/books/list.tt2> in your editor and add the following |
140 | lines to the bottom of the file: |
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141 | |
142 | <p>Hello [% Catalyst.user.username %], you have the following roles:</p> |
143 | |
144 | <ul> |
145 | [% # Dump list of roles -%] |
146 | [% FOR role = Catalyst.user.roles %]<li>[% role %]</li>[% END %] |
147 | </ul> |
148 | |
149 | <p> |
150 | [% # Add some simple role-specific logic to template %] |
151 | [% # Use $c->check_user_roles() to check authz -%] |
152 | [% IF Catalyst.check_user_roles('user') %] |
153 | [% # Give normal users a link for 'logout' %] |
154 | <a href="[% Catalyst.uri_for('/logout') %]">Logout</a> |
155 | [% END %] |
156 | |
157 | [% # Can also use $c->user->check_roles() to check authz -%] |
158 | [% IF Catalyst.check_user_roles('admin') %] |
159 | [% # Give admin users a link for 'create' %] |
160 | <a href="[% Catalyst.uri_for('form_create') %]">Create</a> |
161 | [% END %] |
162 | </p> |
163 | |
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164 | This code displays a different combination of links depending on the |
165 | roles assigned to the user. |
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166 | |
167 | =head2 Limit C<Books::add> to C<admin> Users |
168 | |
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169 | C<IF> statements in TT templates simply control the output that is sent |
170 | to the user's browser; it provides no real enforcement (if users know or |
171 | guess the appropriate URLs, they are still perfectly free to hit any |
172 | action within your application). We need to enhance the controller |
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173 | logic to wrap restricted actions with role-validation logic. |
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174 | |
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175 | For example, we might want to restrict the "formless create" action to |
176 | admin-level users by editing C<lib/MyApp/Controller/Books.pm> and |
177 | updating C<url_create> to match the following code: |
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178 | |
179 | =head2 url_create |
180 | |
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181 | Create a book with the supplied title and rating, |
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182 | with manual authorization |
183 | |
184 | =cut |
185 | |
186 | sub url_create : Local { |
187 | # In addition to self & context, get the title, rating & author_id args |
188 | # from the URL. Note that Catalyst automatically puts extra information |
189 | # after the "/<controller_name>/<action_name/" into @_ |
190 | my ($self, $c, $title, $rating, $author_id) = @_; |
191 | |
192 | # Check the user's roles |
193 | if ($c->check_user_roles('admin')) { |
194 | # Call create() on the book model object. Pass the table |
195 | # columns/field values we want to set as hash values |
196 | my $book = $c->model('MyAppDB::Book')->create({ |
197 | title => $title, |
198 | rating => $rating |
199 | }); |
200 | |
201 | # Add a record to the join table for this book, mapping to |
202 | # appropriate author |
203 | $book->add_to_book_authors({author_id => $author_id}); |
204 | # Note: Above is a shortcut for this: |
205 | # $book->create_related('book_authors', {author_id => $author_id}); |
206 | |
207 | # Assign the Book object to the stash for display in the view |
208 | $c->stash->{book} = $book; |
209 | |
210 | # This is a hack to disable XSUB processing in Data::Dumper |
211 | # (it's used in the view). This is a work-around for a bug in |
212 | # the interaction of some versions or Perl, Data::Dumper & DBIC. |
213 | # You won't need this if you aren't using Data::Dumper (or if |
214 | # you are running DBIC 0.06001 or greater), but adding it doesn't |
215 | # hurt anything either. |
216 | $Data::Dumper::Useperl = 1; |
217 | |
218 | # Set the TT template to use |
219 | $c->stash->{template} = 'books/create_done.tt2'; |
220 | } else { |
221 | # Provide very simple feedback to the user |
222 | $c->response->body('Unauthorized!'); |
223 | } |
224 | } |
225 | |
226 | |
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227 | To add authorization, we simply wrap the main code of this method in an |
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228 | C<if> statement that calls C<check_user_roles>. If the user does not |
229 | have the appropriate permissions, they receive an "Unauthorized!" |
230 | message. Note that we intentionally chose to display the message this |
231 | way to demonstrate that TT templates will not be used if the response |
232 | body has already been set. In reality you would probably want to use a |
233 | technique that maintains the visual continuity of your template layout |
234 | (for example, using the "status" or "error" message feature added in |
235 | Part 2). |
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236 | |
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237 | B<TIP>: If you want to keep your existing C<url_create> method, you can |
238 | create a new copy and comment out the original by making it look like a |
239 | Pod comment. For example, put something like C<=begin> before C<sub add |
240 | : Local {> and C<=end> after the closing C<}>. |
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241 | |
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242 | =head2 Try Out Authentication And Authorization |
243 | |
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244 | Press C<Ctrl-C> to kill the previous server instance (if it's still |
245 | running) and restart it: |
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246 | |
247 | $ script/myapp_server.pl |
248 | |
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249 | Now trying going to L<http://localhost:3000/books/list> and you should |
250 | be taken to the login page (you might have to C<Shift+Reload> your |
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251 | browser and/or click the "Logout" link on the book list page). Try |
252 | logging in with both C<test01> and C<test02> (both use a password |
253 | of C<mypass>) and notice how the roles information updates at the |
254 | bottom of the "Book List" page. Also try the C<Logout> link on the |
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255 | book list page. |
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256 | |
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257 | Now the "url_create" URL will work if you are already logged in as user |
258 | C<test01>, but receive an authorization failure if you are logged in as |
259 | C<test02>. Try: |
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260 | |
261 | http://localhost:3000/books/url_create/test/1/6 |
262 | |
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263 | while logged in as each user. Use one of the 'Logout' links (or go to |
264 | L<http://localhost:3000/logout> in you browser directly) when you are |
265 | done. |
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266 | |
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267 | |
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268 | =head1 ENABLE ACL-BASED AUTHORIZATION |
269 | |
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270 | This section takes a brief look at how the |
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271 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
272 | plugin can automate much of the work required to perform role-based |
273 | authorization in a Catalyst application. |
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274 | |
275 | =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin |
276 | |
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277 | Open C<lib/MyApp.pm> in your editor and add the following plugin to the |
278 | C<use Catalyst> statement: |
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279 | |
280 | Authorization::ACL |
281 | |
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282 | Note that the remaining C<use Catalyst> plugins from earlier sections |
283 | are not shown here, but they should still be included. |
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284 | |
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285 | =head2 Add ACL Rules to the Application Class |
286 | |
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287 | Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the |
288 | C<__PACKAGE__-E<gt>setup;> statement: |
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289 | |
290 | # Authorization::ACL Rules |
291 | __PACKAGE__->deny_access_unless( |
292 | "/books/form_create", |
293 | [qw/admin/], |
294 | ); |
295 | __PACKAGE__->deny_access_unless( |
296 | "/books/form_create_do", |
297 | [qw/admin/], |
298 | ); |
299 | __PACKAGE__->deny_access_unless( |
300 | "/books/delete", |
301 | [qw/user admin/], |
302 | ); |
303 | |
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304 | Each of the three statements above comprises an ACL plugin "rule". The |
305 | first two rules only allow admin-level users to create new books using |
306 | the form (both the form itself and the data submission logic are |
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307 | protected). The third statement allows both users and admins to delete |
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308 | books. The C</books/url_create> action will continue to be protected by |
309 | the "manually configured" authorization created earlier in this part of |
310 | the tutorial. |
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311 | |
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312 | The ACL plugin permits you to apply allow/deny logic in a variety of |
313 | ways. The following provides a basic overview of the capabilities: |
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314 | |
315 | =over 4 |
316 | |
317 | =item * |
318 | |
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319 | The ACL plugin only operates on the Catalyst "private namespace". You |
320 | are using the private namespace when you use C<Local> actions. C<Path>, |
321 | C<Regex>, and C<Global> allow you to specify actions where the path and |
322 | the namespace differ -- the ACL plugin will not work in these cases. |
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323 | |
324 | =item * |
325 | |
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326 | Each rule is expressed in a separate |
327 | C<__PACKAGE__-E<gt>deny_access_unless()> or |
328 | C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other |
329 | methods that can be used for more complex policies, see the C<METHODS> |
330 | portion of the |
331 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
332 | documentation for more details). |
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333 | |
334 | =item * |
335 | |
336 | Each rule can contain multiple roles but only a single path. |
337 | |
338 | =item * |
339 | |
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340 | The rules are tried in order (with the "most specific" rules tested |
341 | first), and processing stops at the first "match" where an allow or deny |
342 | is specified. Rules "fall through" if there is not a "match" (where a |
343 | "match" means the user has the specified role). If a "match" is found, |
344 | then processing stops there and the appropriate allow/deny action is |
345 | taken. |
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346 | |
347 | =item * |
348 | |
349 | If none of the rules match, then access is allowed. |
350 | |
351 | =item * |
352 | |
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353 | The rules currently need to be specific in the application class |
354 | C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line. |
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355 | |
356 | =back |
357 | |
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358 | =head2 Add a Method to Handle Access Violations |
359 | |
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360 | By default, |
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361 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
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362 | throws an exception when authorization fails. This will take the user |
363 | to the Catalyst debug screen, or a "Please come back later" message if |
364 | you are not using the C<-Debug> flag. This step uses the |
365 | C<access_denied> method in order to provide more appropriate feedback to |
366 | the user. |
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367 | |
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368 | Open C<lib/MyApp/Controller/Books.pm> in your editor and add the |
369 | following method: |
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370 | |
371 | =head2 access_denied |
372 | |
373 | Handle Catalyst::Plugin::Authorization::ACL access denied exceptions |
374 | |
375 | =cut |
376 | |
377 | sub access_denied : Private { |
378 | my ($self, $c) = @_; |
379 | |
380 | # Set the error message |
381 | $c->stash->{error_msg} = 'Unauthorized!'; |
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382 | |
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383 | # Display the list |
384 | $c->forward('list'); |
385 | } |
386 | |
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387 | Then run the Catalyst development server script: |
388 | |
389 | $ script/myapp_server.pl |
390 | |
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391 | Log in as C<test02>. Once at the book list, click the "Create" link to |
392 | try the C<form_create> action. You should receive a red "Unauthorized!" |
393 | error message at the top of the list. (Note that in reality you would |
394 | probably want to place the "Create" link code in |
395 | C<root/src/books/list.tt2> inside an C<IF> statement that only displays |
396 | the list to admin-level users.) If you log in as C<test01> you should |
397 | be able to view the C<form_create> form and add a new book. |
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398 | |
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399 | When you are done, use one of the 'Logout' links (or go to the |
400 | L<http://localhost:3000/logout> URL directly) when you are done. |
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401 | |
402 | |
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403 | =head1 AUTHOR |
404 | |
405 | Kennedy Clark, C<hkclark@gmail.com> |
406 | |
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407 | Please report any errors, issues or suggestions to the author. The |
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408 | most recent version of the Catalyst Tutorial can be found at |
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409 | L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Runtime/lib/Catalyst/Manual/Tutorial/>. |
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410 | |
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411 | Copyright 2006, Kennedy Clark, under Creative Commons License |
412 | (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>). |
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413 | |