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Oracle Database 适配器中流式传输大型对象数据类型Streaming large object data types in Oracle Database adapter

06/08/2017

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用于 Oracle 数据库的 Microsoft BizTalk 适配器Microsoft BizTalk Adapter for Oracle Database支持 (LOB) 数据类型的 Oracle 大型对象的流式传输。The 用于 Oracle 数据库的 Microsoft BizTalk 适配器Microsoft BizTalk Adapter for Oracle Database supports streaming for Oracle large object (LOB) data types. Oracle 数据库适配器Oracle Database adapter调用时，将调用，并通过交换 SOAP 消息返回响应。With the Oracle 数据库适配器Oracle Database adapter operations are invoked and responses are returned by exchanging SOAP messages. SOAP 消息正文由 XML 节点组成。A SOAP message body is composed of XML nodes.

适配器支持两种类型的消息流：There are two kinds of message streaming that are supported by the adapter:

节点流式处理。Node streaming. 在节点流式处理中，每个节点在发送到 Oracle 数据库 (或返回给客户端) 之前由适配器进行缓冲。In node streaming each node is buffered by the adapter before it is sent to the Oracle database (or returned to the client). 这意味着，对于 LOB 数据类型，整个值都读入到缓冲区中。This means that, for an LOB data type, the entire value is read into a buffer.

节点-值流式处理。Node-value streaming. 在节点值流式处理中，可以在 Oracle 数据库和客户端之间以区块形式传输节点的实际值。In node-value streaming the actual value of the node can be streamed in chunks between the Oracle database and the client. 节点值流式处理支持适配器客户端和 Oracle 数据库之间的 LOB 数据类型的端到端流式处理。Node-value streaming supports end-to-end streaming of LOB data types between the adapter client and the Oracle database.

这两种流式处理模式都依赖于对 WCF 中消息的节点流和节点值流式处理的支持。Both of these streaming modes rely on support for node streaming and node-value streaming on messages in WCF. 出于此原因，LOB 类型的流式传输与适配器和客户端应用程序创建和使用消息的方式密切相关。For this reason, streaming for LOB types is tied closely to how messages are created and consumed both by the adapter and by a client application. 这样做的一个结果是，对流式处理 LOB 类型的支持在所有编程模型中都不相同。One result of this is that support for streaming LOB types is not the same across all programming models.

本主题中的部分提供：The sections in this topic provide:

有关如何在 WCF 中支持消息流以及如何通过适配器实现消息流的基本背景信息。Fundamental background information about how message streaming is supported in WCF and how it is implemented by the adapter.

在每个编程模型中使用适配器时，如何支持 LOB 数据类型的流。Information about how streaming for LOB data types is supported when you use the adapter in each programming model.

流式处理基础知识Streaming Fundamentals

实现的流式处理支持是的 Oracle 数据库适配器Oracle Database adapter 组合：The support for streaming implemented by the Oracle 数据库适配器Oracle Database adapter is a combination of:

WCF 中的消息流支持。Message streaming support in WCF.

Oracle 客户端库中的流支持 (ODP.NET) 。Streaming support in the Oracle client library (ODP.NET).

适配器在内部创建和使用消息的方式。The way messages are created and consumed internally by the adapter.

WCF 中的消息流支持Message Streaming Support in WCF

WCF 支持消息流式处理的方式取决于消息的创建方式和消息的使用方式。How WCF supports streaming on a message depends both on how the message is created and how the message is consumed.

WCF 消息是使用 system.servicemodel 的静态 Create 方法创建的。A WCF message is created by using the static Create method of System.ServiceModel.Channels.Message. 此方法有几个重载，它们支持不同的消息正文传递方式。This method has several overloads that support different ways of passing the message body. 可以通过使用传递消息正文来创建 WCF 消息：A WCF message can be created by passing the message body using:

System.Xml.Xml读取器，或A System.Xml.XmlReader, or

System.servicemodel. BodyWriter。A System.ServiceModel.Channels.BodyWriter.

WCF 消息可使用A WCF message can be consumed using

通过 调用 GetReaderAtBodyContents ( \# B1 或An XmlReader by calling Message.GetReaderAtBodyContents(), or

XmlDictionaryWriter 通过调用 WriteBodyContents (XmlDictionaryWriter)。An XmlDictionaryWriter by calling Message.WriteBodyContents(XmlDictionaryWriter).

下表显示了 WCF 对创建和使用消息的不同组合的行为。The following table shows how WCF behaves for different combinations of creating and consuming messages.

消息创建方式Message Created With

使用的消息Message Consumed With

WCF 行为WCF Behavior

XmlBodyWriterXmlBodyWriter

XmlDictionaryWriterXmlDictionaryWriter

支持 节点值流式处理。Node-value streaming is supported. WCF 将两个编写器管道一起用于启用流式传输。WCF pipes the two writers together to enable streaming. XmlBodyWriter 和 XmlDictionaryWriter 都必须支持节点-值流式处理才能进行。Both the XmlBodyWriter and the XmlDictionaryWriter must support node-value streaming for it to occur.

XmlBodyWriterXmlBodyWriter

XmlReaderXmlReader

支持 节点流式处理。Node streaming is supported. WCF 在内部缓冲 XmlReader。WCF internally buffers the XmlReader.

XmlReaderXmlReader

XmlDictionaryWriterXmlDictionaryWriter

支持 节点流式处理。Node streaming is supported. WCF 在内部缓冲 XmlReader 并回调到 XmlDictionaryWriter 中。WCF internally buffers the XmlReader and calls back into the XmlDictionaryWriter.

XmlReaderXmlReader

支持 节点流式处理。Node streaming is supported. WCF 在内部缓冲 XmlReader。WCF internally buffers the XmlReader.

Oracle 客户端库中的流支持 (ODP.NET)Streaming Support in the Oracle Client Library (ODP.NET)

ODP.NET 支持通过以下方式进行流式传输：ODP.NET supports streaming in the following manner:

仅 Oracle LOB 数据类型支持流式处理。Streaming is supported only on Oracle LOB data types.

对于某些表 (和查看) 操作，会缓冲 LOB 数据类型。For some table (and view) operations, LOB data types are buffered. 因此，不支持流式处理。Therefore, no streaming is supported.

适配器内部消息处理Internal Message Handling by the Adapter

适配器支持通过以下方式进行流式传输：The adapter supports streaming in the following manner:

适配器对 消息 进行扩展，以实现自定义邮件类 AdapterUtilities. AdapterMessage。The adapter extends Message to implement a custom message class, Microsoft.Adapters.AdapterUtilities.AdapterMessage. 它为它提供给适配器客户端的所有 WCF 消息创建 AdapterMessage ;这包括所有出站操作的响应消息和 POLLINGSTMT 操作的请求消息。It creates an AdapterMessage for all WCF messages that it provides to the adapter client; this includes the response messages for all outbound operations and the request message for the POLLINGSTMT operation. 这使适配器能够为 ReadLOB 操作支持节点值流式处理，方法是提供支持 ReadValueChunk 到适配器客户端的 XmlReader 。This enables the adapter to support node-value streaming for the ReadLOB operation by providing an XmlReader that supports ReadValueChunk to adapter clients.

适配器使用 XmlDictionaryWriter 的自定义实现来使用从客户端接收的所有消息。The adapter consumes all messages received from the client by using a custom implementation of XmlDictionaryWriter.

适配器通过使用 XmlBodyWriter 的自定义实现(ReadLOB 响应消息除外)来创建它发送到客户端的所有消息。The adapter creates all messages that it sends to the client by using a custom implementation of XmlBodyWriter, except for the ReadLOB response message. (包括所有出站操作的响应消息和 POLLINGSTMT 操作的请求消息。 )(This includes response messages for all outbound operations and the request message for the POLLINGSTMT operation.)

WCF 通道模型中的流支持Streaming Support in the WCF Channel Model

下表提供有关 WCF 通道模型中如何支持流式处理的详细信息。The following table provides detailed information about how streaming is supported in the WCF channel model.

OperationOperation

节点流式处理Node Streaming

Node-Value 流式处理Node-Value Streaming

描述Description

表插入操作Table Insert operation

支持\*Supported\*

在适配器和 Oracle 数据库之间不受支持。Not supported between the adapter and the Oracle database. 在客户端和适配器之间受支持。\*Supported between the client and adapter.\*

不支持端到端节点值流式处理，因为 LOB 列的值由 ODP.NET 缓冲，然后执行插入。End-to-end node-value streaming is not supported because the values of LOB columns are buffered by ODP.NET, and then the insert is performed. 但是，如果客户端使用 BodyWriter 创建消息，则可能会在客户端与适配器之间进行节点值流式处理。However, node-value streaming between the client and the adapter is possible for LOB columns, if the client creates the message with a BodyWriter.

表选择操作Table Select operation

支持Supported

适配器使用 BodyWriter 来创建响应消息。The adapter uses a BodyWriter to create the response message. 如果客户端使用 XmlDictionaryWriter 的消息，则会发生 LOB 列的节点-值流式处理。If the client consumes the message using an XmlDictionaryWriter, node-value streaming for LOB columns occurs.

表更新操作Table Update operation

支持Supported

在适配器和 Oracle 数据库之间不受支持。Not supported between the adapter and the Oracle database. 在客户端和适配器之间受支持。Supported between the client and adapter.

不支持端到端节点值流式处理，因为 LOB 列的值由 ODP.NET 缓冲，然后执行更新。End-to-end node-value streaming is not supported because the values of LOB columns are buffered by ODP.NET, and then the update is performed. 但是，如果客户端使用 BodyWriter 创建消息，则可能会在客户端和适配器之间进行节点值流式处理。However, node-value streaming between the client and the adapter is possible for LOB columns if the client creates the message with a BodyWriter.

表删除操作Table Delete operation

支持Supported

在适配器和 Oracle 数据库之间不受支持。Not supported between the adapter and the Oracle database. 在客户端和适配器之间受支持。Supported between the client and adapter.

不支持端到端节点值流式处理，因为 LOB 列的值由 ODP.NET 缓冲，然后执行删除。End-to-end node-value streaming is not supported because the values of LOB columns are buffered by ODP.NET and then the delete is performed. 但是，如果客户端使用 BodyWriter 创建消息，则可能会在客户端和适配器之间进行节点值流式处理。However, node-value streaming between the client and the adapter is possible for LOB columns if the client creates the message with a BodyWriter.

表 ReadLOB 操作Table ReadLOB operation

支持Supported

ReadLOB 操作主要用于对 WCF 服务模型中的 LOB 数据列进行流式处理。The ReadLOB operation is primarily designed to stream LOB data columns in the WCF service model. 在 WCF 信道模型中，如果客户端使用 XmlReader (通过对响应消息调用 GetReaderAtBodyContents 方法来使用消息) ，则会进行端到端节点值流式处理。In the WCF channel model, if the client consumes the message using an XmlReader (by invoking the GetReaderAtBodyContents method on the response message), end-to-end node-value streaming occurs. 这是因为适配器返回支持 ReadLOB 响应消息的 ReadValueChunk 调用的 XmlReader 。This is because the adapter returns an XmlReader that supports ReadValueChunk calls for the ReadLOB response message. 但建议您不要使用 WCF 通道模型中的 ReadLOB 操作。However, it is recommended that you do not use the ReadLOB operation from the WCF channel model. 可以改为使用 Select 操作或 SQLEXECUTE 操作。You can use a Select operation or a SQLEXECUTE operation instead.

表 UpdateLOB 操作Table UpdateLOB operation

支持Supported

适配器使用 XmlDictionaryWriter 来使用请求消息。The adapter uses an XmlDictionaryWriter to consume the request message. 如果客户端使用 BodyWriter 来创建请求消息，则会发生 LOB 数据的端到端节点-值流式处理。If the client uses a BodyWriter to create the request message, end-to-end node-value streaming for LOB data occurs.

SQLEXECUTE 操作SQLEXECUTE operation

支持Supported

适配器使用 BodyWriter 来创建响应消息。The adapter uses a BodyWriter to create the response message.

请求消息不支持端到端节点值流式处理，因为适配器必须先缓冲所有操作数，然后才能在 Oracle 数据库上调用该操作。End-to-end node-value streaming is not supported for the request message because the adapter must buffer all operands before it can invoke the operation on the Oracle database.

存储过程和函数操作Stored procedure and function operation

支持Supported

适配器使用 BodyWriter 来创建响应消息。The adapter uses a BodyWriter to create the response message.

如果客户端使用 XmlDictionaryWriter 来使用响应消息，则会发生 LOB 数据的端到端节点-值流式处理。If the client uses an XmlDictionaryWriter to consume the response message, end-to-end node-value streaming for the LOB data occurs. (这意味着响应消息中的输出和输出过程和函数参数支持流式处理。 )(This means that streaming is supported for OUT and IN OUT procedure and function parameters in the response message.)

POLLINGSTMT 操作POLLINGSTMT operation

支持Supported

适配器使用 BodyWriter 创建 POLLINGSTMT 请求消息。The adapter uses a BodyWriter to create the POLLINGSTMT request message. 如果客户端使用 XmlDictionaryWriter 来使用消息，则会发生 LOB 列的节点-值流式处理。If the client consumes the message using an XmlDictionaryWriter, then node-value streaming for LOB columns occurs.

For information about how to implement LOB data streaming in your code when you use the WCF channel model, see Streaming Oracle Database LOB Data Types Using the WCF Channel Model.

WCF 服务模型中的流支持Streaming Support in the WCF Service Model

在消息的 XML 表示形式和该消息的托管代码对象表示形式之间进行序列化和反序列化需要在内存中写入和读取整个消息。Serializing and deserializing between the XML representation of a message and the managed code object representation of that message requires writing and reading the entire message into memory. 出于此原因，大多数操作都不支持节点流式处理和节点值流式处理。For this reason, neither node streaming nor node-value streaming is supported for most operations.

唯一的例外是 ReadLOB 操作。The only exception to this is the ReadLOB operation. 此操作的实现专门用于支持在 WCF 服务模型中读取表和查看 LOB 列的端到端流式处理。This operation is implemented specifically to support end-to-end streaming for reading table and view LOB columns in the WCF service model.

BizTalk Server 中的流式处理支持Streaming Support in BizTalk Server

下表提供了有关如何在 BizTalk Server 中支持流式处理的详细信息。The following table provides detailed information about how streaming is supported in BizTalk Server. (对 "适配器" 的所有引用，请参阅 Oracle 数据库适配器Oracle Database adapter ; 在此表中，WCF-Custom 适配器的全名始终由其全名引用。 )(All references to the "adapter" refer to the Oracle 数据库适配器Oracle Database adapter; the WCF-Custom adapter is always referred to by its full name in this table.)

OperationOperation

节点流式处理Node Streaming

Node-Value 流式处理Node-Value Streaming

描述Description

表插入操作Table Insert operation

支持\*Supported\*

在适配器和 Oracle 数据库之间不受支持;但是，在 BizTalk Server 和适配器之间传输数据。Not supported between the adapter and the Oracle database; however, data is streamed between BizTalk Server and the adapter.

不支持端到端节点值流式处理，因为 LOB 列的值由 ODP.NET 缓冲，然后执行插入。End-to-end node-value streaming is not supported because the values of LOB columns are buffered by ODP.NET and then the insert is performed. 但是，LOB 数据类型支持 BizTalk Server 和适配器之间的节点值流式处理，因为 WCF-Custom 适配器使用 BodyWriter 创建消息。However, node-value streaming between BizTalk Server and the adapter is supported for LOB data types because the WCF-Custom adapter creates the message with a BodyWriter.

表选择操作Table Select operation

支持Supported

WCF-Custom 适配器使用 XmlDictionaryWriter 来使用响应消息，因此支持 LOB 类型的端到端节点-值流。The WCF-Custom adapter uses an XmlDictionaryWriter to consume the response message, so end-to-end node-value streaming for LOB types is supported.

表更新操作Table Update operation

支持Supported

不支持端到端节点值流式处理，因为 LOB 列的值由 ODP.NET 缓冲，然后执行更新。End-to-end node-value streaming is not supported because the values of LOB columns are buffered by ODP.NET and then the update is performed. 但是，LOB 数据类型支持 BizTalk Server 和适配器之间的节点值流式处理，因为 WCF-Custom 适配器使用 BodyWriter 创建消息。However, node-value streaming between BizTalk Server and the adapter is supported for LOB data types because the WCF-Custom adapter creates the message with a BodyWriter.

表删除操作Table Delete operation

支持Supported

不支持端到端节点值流式处理，因为 LOB 列的值由 ODP.NET 缓冲，然后执行删除。End-to-end node-value streaming is not supported because the values of LOB columns are buffered by ODP.NET and then the delete is performed. 但是，LOB 数据类型支持 BizTalk Server 和适配器之间的节点值流式处理，因为 WCF-Custom 适配器使用 BodyWriter 创建消息。However, node-value streaming between BizTalk Server and the adapter is supported for LOB data types because the WCF-Custom adapter creates the message with a BodyWriter.

表 ReadLOB 操作Table ReadLOB operation

BizTalk Server 不支持 ReadLOB 操作。The ReadLOB operation is not supported for BizTalk Server.

BizTalk Server 不支持 ReadLOB 操作。The ReadLOB operation is not supported for BizTalk Server. 请改用 Select 操作或 SQLEXECUTE 操作。Use the Select operation or a SQLEXECUTE operation instead.

表 UpdateLOB 操作Table UpdateLOB operation

支持Supported

WCF-Custom 适配器使用 BodyWriter 创建请求消息，因此支持 LOB 数据类型的端到端节点-值流。The WCF-Custom adapter uses a BodyWriter to create the request message, so end-to-end node-value streaming for LOB data types is supported.

SQLEXECUTE 操作SQLEXECUTE operation

支持Supported

存储过程和函数操作Stored procedure and function operation

支持Supported

WCF-Custom 适配器使用 XmlDictionaryWriter 来使用响应消息，因此支持响应消息中 LOB 数据类型的端到端节点值流式处理。The WCF-Custom adapter uses an XmlDictionaryWriter to consume the response message, so end-to-end node-value streaming for LOB data types in the response message is supported. (这意味着响应消息中的输出和输出过程和函数参数支持流式处理。 )(This means that streaming is supported for OUT and IN OUT procedure and function parameters in the response message.)

POLLINGSTMT 操作POLLINGSTMT operation

支持Supported

WCF-Custom 适配器使用 XmlDictionaryWriter 来使用 (入站) 请求消息，因此支持 LOB 数据类型的端到端节点-值流。The WCF-Custom adapter uses an XmlDictionaryWriter to consume the (inbound) request message, so end-to-end node-value streaming for LOB data types is supported.

另请参阅See Also