architecture.pot

hibernate-distribution-3.3.1.GA-dist.zip源码

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"POT-Creation-Date: 2008-08-14 15:28+0000\n"
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"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <[e-mail]>\n"
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"Content-Type: application/x-xml2pot; charset=UTF-8\n"
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#. Tag: title
#: architecture.xml:30
#, no-c-format
msgid "Architecture"
msgstr ""

#. Tag: title
#: architecture.xml:33
#, no-c-format
msgid "Overview"
msgstr ""

#. Tag: para
#: architecture.xml:35
#, no-c-format
msgid "A (very) high-level view of the Hibernate architecture:"
msgstr ""

#. Tag: para
#: architecture.xml:48
#, no-c-format
msgid "This diagram shows Hibernate using the database and configuration data to provide persistence services (and persistent objects) to the application."
msgstr ""

#. Tag: para
#: architecture.xml:53
#, no-c-format
msgid "We would like to show a more detailed view of the runtime architecture. Unfortunately, Hibernate is flexible and supports several approaches. We will show the two extremes. The \"lite\" architecture has the application provide its own JDBC connections and manage its own transactions. This approach uses a minimal subset of Hibernate's APIs:"
msgstr ""

#. Tag: para
#: architecture.xml:70
#, no-c-format
msgid "The \"full cream\" architecture abstracts the application away from the underlying JDBC/JTA APIs and lets Hibernate take care of the details."
msgstr ""

#. Tag: para
#: architecture.xml:84
#, no-c-format
msgid "Heres some definitions of the objects in the diagrams:"
msgstr ""

#. Tag: term
#: architecture.xml:89
#, no-c-format
msgid "SessionFactory (<literal>org.hibernate.SessionFactory</literal>)"
msgstr ""

#. Tag: para
#: architecture.xml:91
#, no-c-format
msgid "A threadsafe (immutable) cache of compiled mappings for a single database. A factory for <literal>Session</literal> and a client of <literal>ConnectionProvider</literal>. Might hold an optional (second-level) cache of data that is reusable between transactions, at a process- or cluster-level."
msgstr ""

#. Tag: term
#: architecture.xml:101
#, no-c-format
msgid "Session (<literal>org.hibernate.Session</literal>)"
msgstr ""

#. Tag: para
#: architecture.xml:103
#, no-c-format
msgid "A single-threaded, short-lived object representing a conversation between the application and the persistent store. Wraps a JDBC connection. Factory for <literal>Transaction</literal>. Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier."
msgstr ""

#. Tag: term
#: architecture.xml:113
#, no-c-format
msgid "Persistent objects and collections"
msgstr ""

#. Tag: para
#: architecture.xml:115
#, no-c-format
msgid "Short-lived, single threaded objects containing persistent state and business function. These might be ordinary JavaBeans/POJOs, the only special thing about them is that they are currently associated with (exactly one) <literal>Session</literal>. As soon as the <literal>Session</literal> is closed, they will be detached and free to use in any application layer (e.g. directly as data transfer objects to and from presentation)."
msgstr ""

#. Tag: term
#: architecture.xml:126
#, no-c-format
msgid "Transient and detached objects and collections"
msgstr ""

#. Tag: para
#: architecture.xml:128
#, no-c-format
msgid "Instances of persistent classes that are not currently associated with a <literal>Session</literal>. They may have been instantiated by the application and not (yet) persisted or they may have been instantiated by a closed <literal>Session</literal>."
msgstr ""

#. Tag: term
#: architecture.xml:137
#, no-c-format
msgid "Transaction (<literal>org.hibernate.Transaction</literal>)"
msgstr ""

#. Tag: para
#: architecture.xml:139
#, no-c-format
msgid "(Optional) A single-threaded, short-lived object used by the application to specify atomic units of work. Abstracts application from underlying JDBC, JTA or CORBA transaction. A <literal>Session</literal> might span several <literal>Transaction</literal>s in some cases. However, transaction demarcation, either using the underlying API or <literal>Transaction</literal>, is never optional!"
msgstr ""

#. Tag: term
#: architecture.xml:150
#, no-c-format
msgid "ConnectionProvider (<literal>org.hibernate.connection.ConnectionProvider</literal>)"
msgstr ""

#. Tag: para
#: architecture.xml:152
#, no-c-format
msgid "(Optional) A factory for (and pool of) JDBC connections. Abstracts application from underlying <literal>Datasource</literal> or <literal>DriverManager</literal>. Not exposed to application, but can be extended/implemented by the developer."
msgstr ""

#. Tag: term
#: architecture.xml:160
#, no-c-format
msgid "TransactionFactory (<literal>org.hibernate.TransactionFactory</literal>)"
msgstr ""

#. Tag: para
#: architecture.xml:162
#, no-c-format
msgid "(Optional) A factory for <literal>Transaction</literal> instances. Not exposed to the application, but can be extended/implemented by the developer."
msgstr ""

#. Tag: emphasis
#: architecture.xml:169
#, no-c-format
msgid "Extension Interfaces"
msgstr ""

#. Tag: para
#: architecture.xml:171
#, no-c-format
msgid "Hibernate offers many optional extension interfaces you can implement to customize the behavior of your persistence layer. See the API documentation for details."
msgstr ""

#. Tag: para
#: architecture.xml:180
#, no-c-format
msgid "Given a \"lite\" architecture, the application bypasses the <literal>Transaction</literal>/<literal>TransactionFactory</literal> and/or <literal>ConnectionProvider</literal> APIs to talk to JTA or JDBC directly."
msgstr ""

#. Tag: title
#: architecture.xml:188
#, no-c-format
msgid "Instance states"
msgstr ""

#. Tag: para
#: architecture.xml:189
#, no-c-format
msgid "An instance of a persistent classes may be in one of three different states, which are defined with respect to a <emphasis>persistence context</emphasis>. The Hibernate <literal>Session</literal> object is the persistence context:"
msgstr ""

#. Tag: term
#: architecture.xml:197
#, no-c-format
msgid "transient"
msgstr ""

#. Tag: para
#: architecture.xml:199
#, no-c-format
msgid "The instance is not, and has never been associated with any persistence context. It has no persistent identity (primary key value)."
msgstr ""

#. Tag: term
#: architecture.xml:207
#, no-c-format
msgid "persistent"
msgstr ""

#. Tag: para
#: architecture.xml:209
#, no-c-format
msgid "The instance is currently associated with a persistence context. It has a persistent identity (primary key value) and, perhaps, a corresponding row in the database. For a particular persistence context, Hibernate <emphasis>guarantees</emphasis> that persistent identity is equivalent to Java identity (in-memory location of the object)."
msgstr ""

#. Tag: term
#: architecture.xml:221
#, no-c-format
msgid "detached"
msgstr ""

#. Tag: para
#: architecture.xml:223
#, no-c-format
msgid "The instance was once associated with a persistence context, but that context was closed, or the instance was serialized to another process. It has a persistent identity and, perhaps, a corresponding row in the database. For detached instances, Hibernate makes no guarantees about the relationship between persistent identity and Java identity."
msgstr ""

#. Tag: title
#: architecture.xml:238
#, no-c-format
msgid "JMX Integration"
msgstr ""

#. Tag: para
#: architecture.xml:240
#, no-c-format
msgid "JMX is the J2EE standard for management of Java components. Hibernate may be managed via a JMX standard service. We provide an MBean implementation in the distribution, <literal>org.hibernate.jmx.HibernateService</literal>."
msgstr ""

#. Tag: para
#: architecture.xml:246
#, no-c-format
msgid "For an example how to deploy Hibernate as a JMX service on the JBoss Application Server, please see the JBoss User Guide. On JBoss AS, you also get these benefits if you deploy using JMX:"
msgstr ""

#. Tag: para
#: architecture.xml:254
#, no-c-format
msgid "<emphasis>Session Management:</emphasis> The Hibernate <literal>Session</literal>'s life cycle can be automatically bound to the scope of a JTA transaction. This means you no longer have to manually open and close the <literal>Session</literal>, this becomes the job of a JBoss EJB interceptor. You also don't have to worry about transaction demarcation in your code anymore (unless you'd like to write a portable persistence layer of course, use the optional Hibernate <literal>Transaction</literal> API for this). You call the <literal>HibernateContext</literal> to access a <literal>Session</literal>."
msgstr ""

#. Tag: para
#: architecture.xml:266
#, no-c-format
msgid "<emphasis>HAR deployment:</emphasis> Usually you deploy the Hibernate JMX service using a JBoss service deployment descriptor (in an EAR and/or SAR file), it supports all the usual configuration options of a Hibernate <literal>SessionFactory</literal>. However, you still have to name all your mapping files in the deployment descriptor. If you decide to use the optional HAR deployment, JBoss will automatically detect all mapping files in your HAR file."
msgstr ""

#. Tag: para
#: architecture.xml:277
#, no-c-format
msgid "Consult the JBoss AS user guide for more information about these options."
msgstr ""

#. Tag: para
#: architecture.xml:281
#, no-c-format
msgid "Another feature available as a JMX service are runtime Hibernate statistics. See <xref linkend=\"configuration-optional-statistics\"/>."
msgstr ""

#. Tag: title
#: architecture.xml:288
#, no-c-format
msgid "JCA Support"
msgstr ""

#. Tag: para
#: architecture.xml:289
#, no-c-format
msgid "Hibernate may also be configured as a JCA connector. Please see the website for more details. Please note that Hibernate JCA support is still considered experimental."
msgstr ""

#. Tag: title
#: architecture.xml:296
#, no-c-format
msgid "Contextual Sessions"
msgstr ""

#. Tag: para
#: architecture.xml:297
#, no-c-format
msgid "Most applications using Hibernate need some form of \"contextual\" sessions, where a given session is in effect throughout the scope of a given context. However, across applications the definition of what constitutes a context is typically different; and different contexts define different scopes to the notion of current. Applications using Hibernate prior to version 3.0 tended to utilize either home-grown <literal>ThreadLocal</literal>-based contextual sessions, helper classes such as <literal>HibernateUtil</literal>, or utilized third-party frameworks (such as Spring or Pico) which provided proxy/interception-based contextual sessions."
msgstr ""

#. Tag: para
#: architecture.xml:306
#, no-c-format
msgid "Starting with version 3.0.1, Hibernate added the <literal>SessionFactory.getCurrentSession()</literal> method. Initially, this assumed usage of <literal>JTA</literal> transactions, where the <literal>JTA</literal> transaction defined both the scope and context of a current session. The Hibernate team maintains that, given the maturity of the numerous stand-alone <literal>JTA TransactionManager</literal> implementations out there, most (if not all) applications should be using <literal>JTA</literal> transaction management whether or not they are deployed into a <literal>J2EE</literal> container. Based on that, the <literal>JTA</literal>-based contextual sessions is all you should ever need to use."
msgstr ""

#. Tag: para
#: architecture.xml:316
#, no-c-format
msgid "However, as of version 3.1, the processing behind <literal>SessionFactory.getCurrentSession()</literal> is now pluggable. To that end, a new extension interface (<literal>org.hibernate.context.CurrentSessionContext</literal>) and a new configuration parameter (<literal>hibernate.current_session_context_class</literal>) have been added to allow pluggability of the scope and context of defining current sessions."
msgstr ""

#. Tag: para
#: architecture.xml:323
#, no-c-format
msgid "See the Javadocs for the <literal>org.hibernate.context.CurrentSessionContext</literal> interface for a detailed discussion of its contract. It defines a single method, <literal>currentSession()</literal>, by which the implementation is responsible for tracking the current contextual session. Out-of-the-box, Hibernate comes with three implementations of this interface."
msgstr ""

#. Tag: para
#: architecture.xml:333
#, no-c-format
msgid "<literal>org.hibernate.context.JTASessionContext</literal> - current sessions are tracked and scoped by a <literal>JTA</literal> transaction. The processing here is exactly the same as in the older JTA-only approach. See the Javadocs for details."
msgstr ""

#. Tag: para
#: architecture.xml:341
#, no-c-format
msgid "<literal>org.hibernate.context.ThreadLocalSessionContext</literal> - current sessions are tracked by thread of execution. Again, see the Javadocs for details."
msgstr ""

#. Tag: para
#: architecture.xml:347
#, no-c-format
msgid "<literal>org.hibernate.context.ManagedSessionContext</literal> - current sessions are tracked by thread of execution. However, you are responsible to bind and unbind a <literal>Session</literal> instance with static methods on this class, it does never open, flush, or close a <literal>Session</literal>."
msgstr ""

#. Tag: para
#: architecture.xml:356
#, no-c-format
msgid "The first two implementations provide a \"one session - one database transaction\" programming model, also known and used as <emphasis>session-per-request</emphasis>. The beginning and end of a Hibernate session is defined by the duration of a database transaction. If you use programmatic transaction demarcation in plain JSE without JTA, you are advised to use the Hibernate <literal>Transaction</literal> API to hide the underlying transaction system from your code. If you use JTA, use the JTA interfaces to demarcate transactions. If you execute in an EJB container that supports CMT, transaction boundaries are defined declaratively and you don't need any transaction or session demarcation operations in your code. Refer to <xref linkend=\"transactions\"/> for more information and code examples."
msgstr ""

#. Tag: para
#: architecture.xml:368
#, no-c-format
msgid "The <literal>hibernate.current_session_context_class</literal> configuration parameter defines which <literal>org.hibernate.context.CurrentSessionContext</literal> implementation should be used. Note that for backwards compatibility, if this config param is not set but a <literal>org.hibernate.transaction.TransactionManagerLookup</literal> is configured, Hibernate will use the <literal>org.hibernate.context.JTASessionContext</literal>. Typically, the value of this parameter would just name the implementation class to use; for the three out-of-the-box implementations, however, there are three corresponding short names, \"jta\", \"thread\", and \"managed\"."
msgstr ""