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  • The Manager Component

    Table of Contents

    Introduction

    新开户送体验金68 www.oneworldfilmnet.com The Manager element represents the session manager that will be used to create and maintain HTTP sessions as requested by the associated web application.

    A Manager element MAY be nested inside a Context component. If it is not included, a default Manager configuration will be created automatically, which is sufficient for most requirements, — see Standard Manager Implementation below for the details of this configuration.

    Attributes

    Common Attributes

    All implementations of Manager support the following attributes:

    Attribute Description
    className

    Java class name of the implementation to use. This class must implement the org.apache.catalina.Manager interface. If not specified, the standard value (defined below) will be used.

    maxActiveSessions

    The maximum number of active sessions that will be created by this Manager, or -1 (the default) for no limit.

    When the limit is reached, any attempt to create a new session (e.g. with HttpServletRequest.getSession() call) will fail with an IllegalStateException.

    Standard Implementation

    Tomcat provides two standard implementations of Manager for use — the default one stores active sessions, while the optional one stores active sessions that have been swapped out (in addition to saving sessions across a restart of Tomcat) in a storage location that is selected via the use of an appropriate Store nested element.

    Standard Manager Implementation

    The standard implementation of Manager is org.apache.catalina.session.StandardManager. It supports the following additional attributes (in addition to the common attributes listed above):

    Attribute Description
    pathname

    Absolute or relative (to the work directory for this Context) pathname of the file in which session state will be preserved across application restarts, if possible. The default is "SESSIONS.ser".
    See Persistence Across Restarts for more information. This persistence may be disabled by setting this attribute to an empty string.

    processExpiresFrequency

    Frequency of the session expiration, and related manager operations. Manager operations will be done once for the specified amount of backgroundProcess calls (i.e., the lower the amount, the more often the checks will occur). The minimum value is 1, and the default value is 6.

    secureRandomClass

    Name of the Java class that extends java.security.SecureRandom to use to generate session IDs. If not specified, the default value is java.security.SecureRandom.

    secureRandomProvider

    Name of the provider to use to create the java.security.SecureRandom instances that generate session IDs. If an invalid algorithm and/or provider is specified, the Manager will use the platform default provider and the default algorithm. If not specified, the platform default provider will be used.

    secureRandomAlgorithm

    Name of the algorithm to use to create the java.security.SecureRandom instances that generate session IDs. If an invalid algorithm and/or provider is specified, the Manager will use the platform default provider and the default algorithm. If not specified, the default algorithm of SHA1PRNG will be used. If the default algorithm is not supported, the platform default will be used. To specify that the platform default should be used, do not set the secureRandomProvider attribute and set this attribute to the empty string.

    sessionAttributeNameFilter

    A regular expression used to filter which session attributes will be distributed. An attribute will only be distributed if its name matches this pattern. If the pattern is zero length or null, all attributes are eligible for distribution. The pattern is anchored so the session attribute name must fully match the pattern. As an example, the value (userName|sessionHistory) will only distribute the two session attributes named userName and sessionHistory. If not specified, the default value of null will be used.

    sessionAttributeValueClassNameFilter

    A regular expression used to filter which session attributes will be distributed. An attribute will only be distributed if the implementation class name of the value matches this pattern. If the pattern is zero length or null, all attributes are eligible for distribution. The pattern is anchored so the fully qualified class name must fully match the pattern. If not specified, the default value of null will be used unless a SecurityManager is enabled in which case the default will be java\\.lang\\.(?:Boolean|Integer|Long|Number|String).

    warnOnSessionAttributeFilterFailure

    If sessionAttributeNameFilter or sessionAttributeValueClassNameFilter blocks an attribute, should this be logged at WARN level? If WARN level logging is disabled then it will be logged at DEBUG. The default value of this attribute is false unless a SecurityManager is enabled in which case the default will be true.

    Persistent Manager Implementation

    NOTE: You must set either the org.apache.catalina.session.StandardSession.ACTIVITY_CHECK or org.apache.catalina.STRICT_SERVLET_COMPLIANCE system properties to true for the persistent manager to work correctly.

    The persistent implementation of Manager is org.apache.catalina.session.PersistentManager. In addition to the usual operations of creating and deleting sessions, a PersistentManager has the capability to swap active (but idle) sessions out to a persistent storage mechanism, as well as to save all sessions across a normal restart of Tomcat. The actual persistent storage mechanism used is selected by your choice of a Store element nested inside the Manager element - this is required for use of PersistentManager.

    This implementation of Manager supports the following attributes in addition to the Common Attributes described earlier.

    Attribute Description
    className

    It has the same meaning as described in the Common Attributes above. You must specify org.apache.catalina.session.PersistentManager to use this manager implementation.

    maxIdleBackup

    The time interval (in seconds) since the last access to a session before it is eligible for being persisted to the session store, or -1 to disable this feature. By default, this feature is disabled.

    maxIdleSwap

    The maximum time a session may be idle before it is eligible to be swapped to disk due to inactivity. Setting this to -1 means sessions should not be swapped out just because of inactivity. If this feature is enabled, the time interval specified here should be equal to or longer than the value specified for maxIdleBackup. By default, this feature is disabled.

    minIdleSwap

    The minimum time in seconds a session must be idle before it is eligible to be swapped to disk to keep the active session count below maxActiveSessions. Setting to -1 means sessions will not be swapped out to keep the active session count down. If specified, this value should be less than that specified by maxIdleSwap. By default, this value is set to -1.

    processExpiresFrequency

    It is the same as described above for the org.apache.catalina.session.StandardManager class.

    saveOnRestart

    Should all sessions be persisted and reloaded when Tomcat is shut down and restarted (or when this application is reloaded)? By default, this attribute is set to true.

    secureRandomClass

    It is the same as described above for the org.apache.catalina.session.StandardManager class.

    secureRandomProvider

    It is the same as described above for the org.apache.catalina.session.StandardManager class.

    secureRandomAlgorithm

    It is the same as described above for the org.apache.catalina.session.StandardManager class.

    sessionAttributeNameFilter

    A regular expression used to filter which session attributes will be distributed. An attribute will only be distributed if its name matches this pattern. If the pattern is zero length or null, all attributes are eligible for distribution. The pattern is anchored so the session attribute name must fully match the pattern. As an example, the value (userName|sessionHistory) will only distribute the two session attributes named userName and sessionHistory. If not specified, the default value of null will be used.

    sessionAttributeValueClassNameFilter

    A regular expression used to filter which session attributes will be distributed. An attribute will only be distributed if the implementation class name of the value matches this pattern. If the pattern is zero length or null, all attributes are eligible for distribution. The pattern is anchored so the fully qualified class name must fully match the pattern. If not specified, the default value of null will be used unless a SecurityManager is enabled in which case the default will be java\\.lang\\.(?:Boolean|Integer|Long|Number|String).

    warnOnSessionAttributeFilterFailure

    If sessionAttributeNameFilter or sessionAttributeValueClassNameFilter blocks an attribute, should this be logged at WARN level? If WARN level logging is disabled then it will be logged at DEBUG. The default value of this attribute is false unless a SecurityManager is enabled in which case the default will be true.

    In order to successfully use a PersistentManager, you must nest inside it a <Store> element, as described below.

    Nested Components

    All Manager Implementations

    All Manager implementations allow nesting of a <SessionIdGenerator> element. It defines the behavior of session id generation. All implementations of the SessionIdGenerator allow the following attributes:

    Attribute Description
    sessionIdLength

    The length of the session ID may be changed with the sessionIdLength attribute.

    Persistent Manager Implementation

    If you are using the Persistent Manager Implementation as described above, you MUST nest a <Store> element inside, which defines the characteristics of the persistent data storage. Two implementations of the <Store> element are currently available, with different characteristics, as described below.

    File Based Store

    The File Based Store implementation saves swapped out sessions in individual files (named based on the session identifier) in a configurable directory. Therefore, you are likely to encounter scalability problems as the number of active sessions increases, and this should primarily be considered a means to easily experiment.

    To configure this, add a <Store> nested inside your <Manager> element with the following attributes:

    Attribute Description
    className

    Java class name of the implementation to use. This class must implement the org.apache.catalina.Store interface. You must specify org.apache.catalina.session.FileStore to use this implementation.

    directory

    Absolute or relative (to the temporary work directory for this web application) pathname of the directory into which individual session files are written. If not specified, the temporary work directory assigned by the container is utilized.

    JDBC Based Store

    The JDBC Based Store implementation saves swapped out sessions in individual rows of a preconfigured table in a database that is accessed via a JDBC driver. With large numbers of swapped out sessions, this implementation will exhibit improved performance over the File Based Store described above.

    To configure this, add a <Store> nested inside your <Manager> element with the following attributes:

    Attribute Description
    className

    Java class name of the implementation to use. This class must implement the org.apache.catalina.Store interface. You must specify org.apache.catalina.session.JDBCStore to use this implementation.

    connectionName

    The user name that will be handed to the configured JDBC driver to establish a connection to the database containing the session table.

    connectionPassword

    The password that will be handed to the configured JDBC driver to establish a connection to the database containing the session table.

    connectionURL

    The connection URL that will be handed to the configured JDBC driver to establish a connection to the database containing our session table.

    dataSourceName

    Name of the JNDI resource for a JDBC DataSource-factory. If this option is given and a valid JDBC resource can be found, it will be used and any direct configuration of a JDBC connection via connectionURL, connectionName, connectionPassword and driverName will be ignored. Since this code uses prepared statements, you might want to configure pooled prepared statements as shown in the JNDI resources HOW-TO.

    driverName

    Java class name of the JDBC driver to be used.

    localDataSource

    This allows the Store to use a DataSource defined for the Context rather than a global DataSource. If not specified, the default is false: use a global DataSource.

    sessionAppCol

    Name of the database column, contained in the specified session table, that contains the Engine, Host, and Web Application Context name in the format /Engine/Host/Context. If not specified the default value of app will be used.

    sessionDataCol

    Name of the database column, contained in the specified session table, that contains the serialized form of all session attributes for a swapped out session. The column type must accept a binary object (typically called a BLOB). If not specified the default value of data will be used.

    sessionIdCol

    Name of the database column, contained in the specified session table, that contains the session identifier of the swapped out session. The column type must accept character string data of at least as many characters as are contained in session identifiers created by Tomcat (typically 32). If not specified the default value of id will be used.

    sessionLastAccessedCol

    Name of the database column, contained in the specified session table, that contains the lastAccessedTime property of this session. The column type must accept a Java long (64 bits). If not specified the default value of maxinactive will be used.

    sessionMaxInactiveCol

    Name of the database column, contained in the specified session table, that contains the maxInactiveInterval property of this session. The column type must accept a Java integer (32 bits). If not specified, the default value of maxinactive will be used.

    sessionTable

    Name of the database table to be used for storing swapped out sessions. This table must contain (at least) the database columns that are configured by the other attributes of this element. If not specified the default value of tomcat$sessions will be used.

    sessionValidCol

    Name of the database column, contained in the specified session table, that contains a flag indicating whether this swapped out session is still valid or not. The column type must accept a single character. If not specified the default value of valid will be used.

    Before attempting to use the JDBC Based Store for the first time, you must create the table that will be used to store swapped out sessions. Detailed SQL commands vary depending on the database you are using, but a script like this will generally be required:

    create table tomcat_sessions (
      session_id     varchar(100) not null primary key,
      valid_session  char(1) not null,
      max_inactive   int not null,
      last_access    bigint not null,
      app_name       varchar(255),
      session_data   mediumblob,
      KEY kapp_name(app_name)
    );

    Note: The SQL command above does not use the default names for either the table or the columns so the JDBC Store would need to be configured to reflect this.

    In order for the JDBC Based Store to successfully connect to your database, the JDBC driver you configure must be visible to Tomcat's internal class loader. Generally, that means you must place the JAR file containing this driver into the $CATALINA_HOME/lib directory.

    Special Features

    Persistence Across Restarts

    Whenever Apache Tomcat is shut down normally and restarted, or when an application reload is triggered, the standard Manager implementation will attempt to serialize all currently active sessions to a disk file located via the pathname attribute. All such saved sessions will then be deserialized and activated (assuming they have not expired in the mean time) when the application reload is completed.

    In order to successfully restore the state of session attributes, all such attributes MUST implement the java.io.Serializable interface. You MAY cause the Manager to enforce this restriction by including the <distributable> element in your web application deployment descriptor (/WEB-INF/web.xml).

    The persistence across restarts provided by the StandardManager is a simpler implementation than that provided by the PersistentManager. If robust, production quality persistence across restarts is required then the PersistentManager should be used with an appropriate configuration.

    Disable Session Persistence

    As documented above, every web application by default has standard manager implementation configured, and it performs session persistence across restarts. To disable this persistence feature, create a Context configuration file for your web application and add the following element there:

    <Manager pathname="" />

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