Handling Large Messages with Content Streaming in OSB

Handling Large Messages with Content Streaming

OSB supports the streaming of content through the service bus and also supports streaming transformations. Content streaming is enabled by simply selecting the Enabled check box during proxy service definition

The following are some of the best practices related to streaming content:

Enable streaming for pure content-based routing scenarios. Read-only scenarios such as content-based routing can gain significantly from enabling streaming. OSB leverages the partial parsing capabilities of the XQuery engine when streaming is used in conjunction with indexed XPaths. Thus, the payload is parsed and processed only to the field referred to in the XPath. Other than partial parsing, an additional benefit for read-only scenarios is that streaming eliminates the overhead associated with parsing and serialization of XMLBeans.

Enable streaming if there is an out-of-memory error when transforming large messages.

The output of a transformation is stored in a compressed buffer format either in memory or on disk. Using a compressed buffer format has a significant CPU penalty. Hence, when running out of memory is not a concern, streaming with compressed buffering should beavoided.

Use a hybrid approach for multiple reads with streaming.

The gains from streaming can be negated if the payload is accessed a large number of times for reading multiple fields. If all fields read are located in a single subsection of the XML document, a hybrid approach provides the best performance. The hybrid approach includes enabling streaming at the proxy level and assigning the relevant subsection to a context variable

For example, the fields Total and Status from the Below XML can be retrieved from a fully materialized subsection Summary:

****************************************************************

<soap-env:Body>

    <Order>

<CtrlArea>

<CustName>Mary</CustName>

</CtrlArea>

<ItemList>

<Item name="ACE_Car" >20000 </Item>

<Item name=" Ext_Warranty" >1500</Item>

.... a large number of items

</ItemList>

<Summary>

<Total>70000</Total>

<Status>Shipped</Status>

<Shipping>My Shipping Firm </Shipping>

</Summary>

</Order>

</soap-env:Body>

****************************************************************

Assign "$body/Order[1]/Summary[1]" to "summary"

Assign "$summary/Total" to "total"

Assign "$summary /Status" to "status"