1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.shiro.realm;
20
21 import org.apache.shiro.authc.AuthenticationException;
22 import org.apache.shiro.authc.AuthenticationInfo;
23 import org.apache.shiro.authc.AuthenticationToken;
24
25 /**
26 * A <tt>Realm</tt> is a security component that can access application-specific security entities
27 * such as users, roles, and permissions to determine authentication and authorization operations.
28 *
29 * <p><tt>Realm</tt>s usually have a 1-to-1 correspondance with a datasource such as a relational database,
30 * file sysetem, or other similar resource. As such, implementations of this interface use datasource-specific APIs to
31 * determine authorization data (roles, permissions, etc), such as JDBC, File IO, Hibernate or JPA, or any other
32 * Data Access API. They are essentially security-specific
33 * <a href="http://en.wikipedia.org/wiki/Data_Access_Object" target="_blank">DAO</a>s.
34 *
35 * <p>Because most of these datasources usually contain Subject (a.k.a. User) information such as usernames and
36 * passwords, a Realm can act as a pluggable authentication module in a
37 * <a href="http://en.wikipedia.org/wiki/Pluggable_Authentication_Modules">PAM</a> configuration. This allows a Realm to
38 * perform <i>both</i> authentication and authorization duties for a single datasource, which caters to the large
39 * majority of applications. If for some reason you don't want your Realm implementation to perform authentication
40 * duties, you should override the {@link #supports(org.apache.shiro.authc.AuthenticationToken)} method to always
41 * return <tt>false</tt>.
42 *
43 * <p>Because every application is different, security data such as users and roles can be
44 * represented in any number of ways. Shiro tries to maintain a non-intrusive development philosophy whenever
45 * possible - it does not require you to implement or extend any <tt>User</tt>, <tt>Group</tt> or <tt>Role</tt>
46 * interfaces or classes.
47 *
48 * <p>Instead, Shiro allows applications to implement this interface to access environment-specific datasources
49 * and data model objects. The implementation can then be plugged in to the application's Shiro configuration.
50 * This modular technique abstracts away any environment/modeling details and allows Shiro to be deployed in
51 * practically any application environment.
52 *
53 * <p>Most users will not implement the <tt>Realm</tt> interface directly, but will extend one of the subclasses,
54 * {@link org.apache.shiro.realm.AuthenticatingRealm AuthenticatingRealm} or {@link org.apache.shiro.realm.AuthorizingRealm}, greatly reducing the effort requird
55 * to implement a <tt>Realm</tt> from scratch.</p>
56 *
57 * @see org.apache.shiro.realm.CachingRealm CachingRealm
58 * @see org.apache.shiro.realm.AuthenticatingRealm AuthenticatingRealm
59 * @see org.apache.shiro.realm.AuthorizingRealm AuthorizingRealm
60 * @see org.apache.shiro.authc.pam.ModularRealmAuthenticator ModularRealmAuthenticator
61 * @since 0.1
62 */
63 public interface Realm {
64
65 /**
66 * Returns the (application-unique) name assigned to this <code>Realm</code>. All realms configured for a single
67 * application must have a unique name.
68 *
69 * @return the (application-unique) name assigned to this <code>Realm</code>.
70 */
71 String getName();
72
73 /**
74 * Returns <tt>true</tt> if this realm wishes to authenticate the Subject represented by the given
75 * {@link org.apache.shiro.authc.AuthenticationToken AuthenticationToken} instance, <tt>false</tt> otherwise.
76 *
77 * <p>If this method returns <tt>false</tt>, it will not be called to authenticate the Subject represented by
78 * the token - more specifically, a <tt>false</tt> return value means this Realm instance's
79 * {@link #getAuthenticationInfo} method will not be invoked for that token.
80 *
81 * @param token the AuthenticationToken submitted for the authentication attempt
82 * @return <tt>true</tt> if this realm can/will authenticate Subjects represented by specified token,
83 * <tt>false</tt> otherwise.
84 */
85 boolean supports(AuthenticationToken token);
86
87 /**
88 * Returns an account's authentication-specific information for the specified <tt>token</tt>,
89 * or <tt>null</tt> if no account could be found based on the <tt>token</tt>.
90 *
91 * <p>This method effectively represents a login attempt for the corresponding user with the underlying EIS datasource.
92 * Most implementations merely just need to lookup and return the account data only (as the method name implies)
93 * and let Shiro do the rest, but implementations may of course perform eis specific login operations if so
94 * desired.
95 *
96 * @param token the application-specific representation of an account principal and credentials.
97 * @return the authentication information for the account associated with the specified <tt>token</tt>,
98 * or <tt>null</tt> if no account could be found.
99 * @throws org.apache.shiro.authc.AuthenticationException
100 * if there is an error obtaining or constructing an AuthenticationInfo object based on the
101 * specified <tt>token</tt> or implementation-specifc login behavior fails.
102 */
103 AuthenticationInfo getAuthenticationInfo(AuthenticationToken token) throws AuthenticationException;
104
105 }