transactions.po

hibernate 开源框架的代码 jar包希望大家能喜欢

msgid ""
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"POT-Creation-Date: 2007-10-25 07:47+0000\n"
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"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
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"Content-Transfer-Encoding: 8bit\n"

#. Tag: title
#: transactions.xml:5
#, no-c-format
msgid "Transactions And Concurrency"
msgstr "Transacciones y Concurrencia"

#. Tag: para
#: transactions.xml:7
#, no-c-format
msgid ""
"The most important point about Hibernate and concurrency control is that it "
"is very easy to understand. Hibernate directly uses JDBC connections and JTA "
"resources without adding any additional locking behavior. We highly "
"recommend you spend some time with the JDBC, ANSI, and transaction isolation "
"specification of your database management system."
msgstr ""
"El punto más importante sobre Hibernate y el control de concurrencia es que "
"muy fácil de comprender. Hibernate usa directamente conexiones JDBC y "
"recursos JTA sin agregar ningún comportamiento de bloqueo adicional. "
"Recomendamos altamente que gastes algo de tiempo con la especificación de "
"JDBC, ANSI, y el aislamiento de transacciones de tu sistema de gestión de "
"base de datos. Hibernate sólo añade versionado automático pero no bloquea "
"objetos en memoria ni cambia el nivel de aislamiento de tus transacciones de "
"base de datos. Básicamente, usa Hibernate como usarías JDBC directo (o JTA/"
"CMT) con tus recursos de base de datos."

#. Tag: para
#: transactions.xml:14
#, no-c-format
msgid ""
"Hibernate does not lock objects in memory. Your application can expect the "
"behavior as defined by the isolation level of your database transactions. "
"Note that thanks to the <literal>Session</literal>, which is also a "
"transaction-scoped cache, Hibernate provides repeatable reads for lookup by "
"identifier and entity queries (not reporting queries that return scalar "
"values)."
msgstr ""
"Hibernate does not lock objects in memory. Your application can expect the "
"behavior as defined by the isolation level of your database transactions. "
"Note that thanks to the <literal>Session</literal>, which is also a "
"transaction-scoped cache, Hibernate provides repeatable reads for lookup by "
"identifier and entity queries (not reporting queries that return scalar "
"values)."

#. Tag: para
#: transactions.xml:22
#, no-c-format
msgid ""
"In addition to versioning for automatic optimistic concurrency control, "
"Hibernate also offers a (minor) API for pessimistic locking of rows, using "
"the <literal>SELECT FOR UPDATE</literal> syntax. Optimistic concurrency "
"control and this API are discussed later in this chapter."
msgstr ""
"Sin embargo, además del versionado automático, Hibernate ofrece una API "
"(menor) para bloqueo pesimista de filas, usando la sintáxis <literal>SELECT "
"FOR UPDATE</literal>. Esta API se discute más adelante en este capítulo:"

#. Tag: para
#: transactions.xml:29
#, no-c-format
msgid ""
"We start the discussion of concurrency control in Hibernate with the "
"granularity of <literal>Configuration</literal>, <literal>SessionFactory</"
"literal>, and <literal>Session</literal>, as well as database transactions "
"and long conversations."
msgstr ""
"Comenzamos la discusión del control de concurrencia en Hibernate con la "
"granularidad de <literal>Configuration</literal>, <literal>SessionFactory</"
"literal>, y <literal>Session</literal>, así como la base de datos y las "
"transacciones de aplicación largas."

#. Tag: title
#: transactions.xml:36
#, no-c-format
msgid "Session and transaction scopes"
msgstr "Ámbitos de sesión y de transacción"

#. Tag: para
#: transactions.xml:38
#, no-c-format
msgid ""
"A <literal>SessionFactory</literal> is an expensive-to-create, threadsafe "
"object intended to be shared by all application threads. It is created once, "
"usually on application startup, from a <literal>Configuration</literal> "
"instance."
msgstr ""
"Una <literal>SessionFactory</literal> es un objeto seguro entre hebras caro-"
"de-crear pensado para ser compartido por todas las hebras de la aplicación. "
"Es creado una sola vez, usualmente en el arranque de la aplicación, a partir "
"de una instancia de <literal>Configuration</literal>."

#. Tag: para
#: transactions.xml:44
#, no-c-format
msgid ""
"A <literal>Session</literal> is an inexpensive, non-threadsafe object that "
"should be used once, for a single request, a conversation, single unit of "
"work, and then discarded. A <literal>Session</literal> will not obtain a "
"JDBC <literal>Connection</literal> (or a <literal>Datasource</literal>) "
"unless it is needed, hence consume no resources until used."
msgstr ""
"Una <literal>Session</literal> es un objeto barato, inseguro entre hebras "
"que debe ser usado una sola vez, para un solo proceso de negocio, una sola "
"unidad de trabajo, y luego descartado. Una <literal>Session</literal> no "
"obtendrá una <literal>Connection</literal> JDBC (o un <literal>Datasource</"
"literal>) a menos que sea necesario, de modo que puedas abrir y cerrar "
"seguramente una <literal>Session</literal> incluso si no estás seguro que se "
"necesitará acceso a los datos para servir una petición en particular. (Esto "
"se vuelve importante en cuanto estés implementando alguno de los siguientes "
"patrones usando intercepción de peticiones)."

#. Tag: para
#: transactions.xml:52
#, no-c-format
msgid ""
"To complete this picture you also have to think about database transactions. "
"A database transaction has to be as short as possible, to reduce lock "
"contention in the database. Long database transactions will prevent your "
"application from scaling to highly concurrent load. Hence, it is almost "
"never good design to hold a database transaction open during user think "
"time, until the unit of work is complete."
msgstr ""
"Para completar este cuadro tienes que pensar también en las transacciones de "
"base de datos. Una transacción de base de datos tiene que ser tan corta como "
"sea posible, para reducir la contención de bloqueos en la base de datos. Las "
"transacciones largas de base de datos prevendrán a tu aplicación de escalar "
"a una carga altamente concurrente."

#. Tag: para
#: transactions.xml:61
#, no-c-format
msgid ""
"What is the scope of a unit of work? Can a single Hibernate "
"<literal>Session</literal> span several database transactions or is this a "
"one-to-one relationship of scopes? When should you open and close a "
"<literal>Session</literal> and how do you demarcate the database transaction "
"boundaries?"
msgstr ""
"¿Qué es el ámbito de una unidad de trabajo? ¿Puede una sola "
"<literal>Session</literal> de Hibernate extenderse a través de varias "
"transacciones de base de datos o es ésta una relación uno-a-uno de ámbitos? "
"¿Cuándo debes abrir y cerrar una <literal>Session</literal> y cómo demarcas "
"los límites de la transacción de base de datos?"

#. Tag: title
#: transactions.xml:69
#, no-c-format
msgid "Unit of work"
msgstr "Unidad de trabajo"

#. Tag: para
#: transactions.xml:71
#, no-c-format
msgid ""
"First, don't use the <emphasis>session-per-operation</emphasis> antipattern, "
"that is, don't open and close a <literal>Session</literal> for every simple "
"database call in a single thread! Of course, the same is true for database "
"transactions. Database calls in an application are made using a planned "
"sequence, they are grouped into atomic units of work. (Note that this also "
"means that auto-commit after every single SQL statement is useless in an "
"application, this mode is intended for ad-hoc SQL console work. Hibernate "
"disables, or expects the application server to do so, auto-commit mode "
"immediately.) Database transactions are never optional, all communication "
"with a database has to occur inside a transaction, no matter if you read or "
"write data. As explained, auto-commit behavior for reading data should be "
"avoided, as many small transactions are unlikely to perform better than one "
"clearly defined unit of work. The latter is also much more maintainable and "
"extensible."
msgstr ""
"Primero, no uses el antipatrón <emphasis>sesión-por-operación</emphasis>, "
"esto es, ¡no abras y cierres una <literal>Session</literal> para cada simple "
"llamada a la base de datos en una sola hebra! Por supuesto, lo mismo es "
"verdad para transacciones de base de datos. Las llamadas a base de datos en "
"una aplicación se hacen usando una secuencia prevista, que están agrupadas "
"dentro de unidades de trabajo atómicas. (Nota que esto también significa que "
"el auto-commit después de cada una de las sentencias SQL es inútil en una "
"aplicación, este modo está pensado para trabajo ad-hoc de consola SQL. "
"Hibernate deshabilita, o espera que el servidor de aplicaciones lo haga, el "
"modo auto-commit inmediatamente.)"

#. Tag: para
#: transactions.xml:87
#, no-c-format
msgid ""
"The most common pattern in a multi-user client/server application is "
"<emphasis>session-per-request</emphasis>. In this model, a request from the "
"client is send to the server (where the Hibernate persistence layer runs), a "
"new Hibernate <literal>Session</literal> is opened, and all database "
"operations are executed in this unit of work. Once the work has been "
"completed (and the response for the client has been prepared), the session "
"is flushed and closed. You would also use a single database transaction to "
"serve the clients request, starting and committing it when you open and "
"close the <literal>Session</literal>. The relationship between the two is "
"one-to-one and this model is a perfect fit for many applications."
msgstr ""
"El patrón más común en una aplicación mutiusuario cliente/servidor es "
"<emphasis>sesión-por-petición</emphasis>. En este modelo, una petición del "
"cliente es enviada al servidor (en donde se ejecuta la capa de persistencia "
"de Hibernate), se abre una nueva <literal>Session</literal> de Hibernate, y "
"todas las operaciones de base de datos se ejecutan en esta unidad de "
"trabajo. Una vez completado el trabajo (y se ha preparado la respuesta para "
"el cliente) la sesión es limpiada y cerrada. Podrías usar una sola "
"transacción de base de datos para servir a petición del cliente, "
"comenzándola y comprometiéndola cuando abres y cierras la <literal>Session</"
"literal>. La relación entre las dos es uno-a-uno y este modelo es a la "
"medida perfecta de muchas aplicaciones."

#. Tag: para
#: transactions.xml:99
#, no-c-format
msgid ""
"The challenge lies in the implementation. Hibernate provides built-in "
"management of the \"current session\" to simplify this pattern. All you have "
"to do is start a transaction when a server request has to be processed, and "
"end the transaction before the response is send to the client. You can do "
"this in any way you like, common solutions are <literal>ServletFilter</"
"literal>, AOP interceptor with a pointcut on the service methods, or a proxy/"
"interception container. An EJB container is a standardized way to implement "
"cross-cutting aspects such as transaction demarcation on EJB session beans, "
"declaratively with CMT. If you decide to use programmatic transaction "
"demarcation, prefer the Hibernate <literal>Transaction</literal> API shown "
"later in this chapter, for ease of use and code portability."
msgstr ""
"The challenge lies in the implementation. Hibernate provides built-in "
"management of the \"current session\" to simplify this pattern. All you have "
"to do is start a transaction when a server request has to be processed, and "
"end the transaction before the response is send to the client. You can do "
"this in any way you like, common solutions are <literal>ServletFilter</"
"literal>, AOP interceptor with a pointcut on the service methods, or a proxy/"
"interception container. An EJB container is a standardized way to implement "
"cross-cutting aspects such as transaction demarcation on EJB session beans, "
"declaratively with CMT. If you decide to use programmatic transaction "
"demarcation, prefer the Hibernate <literal>Transaction</literal> API shown "
"later in this chapter, for ease of use and code portability."

#. Tag: para
#: transactions.xml:112
#, no-c-format
msgid ""
"Your application code can access a \"current session\" to process the "
"request by simply calling <literal>sessionFactory.getCurrentSession()</"
"literal> anywhere and as often as needed. You will always get a "
"<literal>Session</literal> scoped to the current database transaction. This "
"has to be configured for either resource-local or JTA environments, see "
"<xref linkend=\"architecture-current-session\"/>."
msgstr ""
"Your application code can access a \"current session\" to process the "
"request by simply calling <literal>sessionFactory.getCurrentSession()</"
"literal> anywhere and as often as needed. You will always get a "
"<literal>Session</literal> scoped to the current database transaction. This "
"has to be configured for either resource-local or JTA environments, see "
"<xref linkend=\"architecture-current-session\"/>."

#. Tag: para
#: transactions.xml:120
#, no-c-format
msgid ""
"Sometimes it is convenient to extend the scope of a <literal>Session</"
"literal> and database transaction until the \"view has been rendered\". This "
"is especially useful in servlet applications that utilize a separate "
"rendering phase after the request has been processed. Extending the database "
"transaction until view rendering is complete is easy to do if you implement "
"your own interceptor. However, it is not easily doable if you rely on EJBs "
"with container-managed transactions, as a transaction will be completed when "
"an EJB method returns, before rendering of any view can start. See the "
"Hibernate website and forum for tips and examples around this <emphasis>Open "
"Session in View</emphasis> pattern."
msgstr ""
"Sometimes it is convenient to extend the scope of a <literal>Session</"