Table of Contents
Processing of large incoming SOAP requests can be made more efficient with some additional effort.
An implementation extension
Provider<Message> can be used to read an
incoming SOAP message by using XMLStreamReader (among
other things.) This allows you to read the SOAP message on-demand
lazily, without needing to buffer the whole message in
memory.
See the relevant Eclipse implementation of JAXB users guide section for how to combine Jakarta XML Binding with such streaming processing.
MTOM (and XOP) allows you to send and receive binary attachments (such as files and images) efficiently and in an interoperable manner.
Perhaps the best way to understand the pros and cons of MTOM is to see an actual on-the-wire message. See an example below:
Example 6.1. Sample MTOM message
Content-Type: Multipart/Related; start-info="text/xml"; type="application/xop+xml"; boundary="----=_Part_0_1744155.1118953559416"
Content-Length: 3453
SOAPAction: ""
------=_Part_1_4558657.1118953559446
Content-Type: application/xop+xml; type="text/xml"; charset=utf-8
<S:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/">
<S:Body>
<Detail xmlns="http://example.org/mtom/data">
<image>
<xop:Include xmlns:xop="http://www.w3.org/2004/08/xop/include" href="cid:5aeaa450-17f0-4484-b845-a8480c363444@example.org" />
</image>
</Detail>
</S:Body>
</S:Envelope>
------=_Part_1_4558657.1118953559446
Content-Type: image/jpeg
Content-ID: <5aeaa450-17f0-4484-b845-a8480c363444@example.org>
... binary data ...The noteworthy points are:
The binary attachment is packaged in a MIME multi-part message (the same mechanism used in e-mail to handle attachments.)
An <xop:Include> element is used to mark where the binary data is.
The actual binary data is kept in a different MIME part.
MTOM is efficient, in the sense that it doesn't have the
33% size increase penalty that xs:base64Binary
has. It is interoperable, in the sense that it is a W3C
standard. However, MIME multipart incurs a small cost
proportional to the number of attachments, so it is not
suitable for a large number of tiny attachments.
The schema that describes the above message is below.
The MTOM spec is designed to work below the XML infoset level,
so the schema describes the image as being of type
xs:base64Binary, even though it can be attached
as seen above. When using MTOM, any base64Binary can be
attached or inlined.
Example 6.2. Schema
<element name="Detail" type="types:DetailType"/>
<complexType name="DetailType">
<sequence>
<element name="image" type="base64Binary" />
</sequence>
</complexType>Schema elements of type xs:base64Binary or
xs:hexBinary can be annotated by using the xmime:expectedContentType
attribute to indicate the type of binary that is expected.
wsimport recognizes this annotation and will map
the binary data to its proper Java representation instead. The
table below is taken from Jakarta XML Binding spec Table 9-1, which shows the
mapping rules:
Table 6.1. JAXB Mapping Rules
| MIME Type | Java Type |
|---|---|
| image/* | java.awt.Image |
| text/plain | java.lang.String |
| application/xml, text/xml | javax.xml.transform.Source |
| (others) | javax.activation.DataHandler |
The schema can further use the xmime:contentType
attribute to designate the actual content type of the binary
data used in the message. (In contrast,
xmime:expectedContentTypes specifies what are
allowed. This combination allows you to say "image/* is
expected but this message contains image/jpeg".)
This attribute can be used with elements whose content
is either xs:base64Binary or
xs:hexBinary. Consider the following
example:
Example 6.3. Using xmime:contentType
<element name="TestMtomXmimeContentType" type="types:PictureType"/>
<complexType name="PictureType">
<simpleContent>
<restriction base="xmime:base64Binary">
<attribute ref="xmime:contentType" use="required" />
</restriction>
</simpleContent>
</complexType>Here xmime:base64Binary is defined by Describing
Media Content of Binary Data in XML. The following code
shows how your program can set the MIME type to the generated
beans:
Example 6.4. Setting content type
PictureType req = new PictureType();
req.setValue(name.getBytes());
req.setContentType("application/xml");On the wire this is how it looks:
Example 6.5. SOAP Message that uses xmime:contentType
<S:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:ns1="http://example.org/mtom/data"
xmlns:ns2="http://www.w3.org/2005/05/xmlmime">
<S:Body>
<ns1:TestMtomXmimeContentTypeResponse ns2:contentType="application/xml">
<xop:Include
xmlns:xop="http://www.w3.org/2004/08/xop/include"
href="cid:193ed174-d313-4325-8eed-16cc25595e4e@example.org"/>
</ns1:TestMtomXmimeContentTypeResponse>
</S:Body>
</S:Envelope>There are several ways to enable MTOM.
By using the @MTOM annotation on SEI. This is convenience and preferable for developers.
Example 6.6. Annotating SEI with @MTOM
@javax.xml.ws.soap.MTOM
@WebService
public class HelloImpl implements Hello {
....
}By using the enable-mtom attribute in
the sun-jaxws.xml configuration file. This
allows the MTOM setting to be changed at deployment time.
Example 6.7. Enabling MTOM in sun-jaxws.xml
<endpoints xmlns='http://java.sun.com/xml/ns/jax-ws/ri/runtime' version='2.0'>
<endpoint name="Mtom" implementation="mtom.server.HelloImpl"
url-pattern="/hello"
enable-mtom="true"/>
</endpoints>If you are using Eclipse Implementation of Jakarta XML Web Services via Spring, you can also enable MTOM from the bean definition file. See the JAX-WS spring extension for more.
There are several ways to enable MTOM.
By doing nothing. If the server WSDL advertises that it supports MTOM, the MTOM support in the client will be automatically enabled. This is the preferable way.
By passing MTOMFeature as
WebServiceFeature parameter while creating a
proxy or a Dispatch. See the
example below:
Example 6.8. Passing MTOMFeature
Hello port = new HelloService().getHelloPort(new MTOMFeature()); Dispatch d = new HelloService().createDispatch(....,new MTOMFeature());
As discussed above, in rare situations where you have a lot of tiny attachments, the overhead of MTOM may outweigh the benefit of binary transfer. To cope with this situation, the Eclipse Implementation of Jakarta XML Web Services supports the notion of "threshold" --- if an attachment is smaller than the size specified in threshold, it will simply inline the binary data as base64 binary instead of making it an attachment. Because of the way MTOM spec is designed, such inline vs attachment decision is handled by the toolkits of both ends and will not harm the application running on both sides.
There are two ways to control the threshold:
By using the
com.sun.xml.ws.developer.JAXWSProperties.MTOM_THRESHOLD_VALUE
property in the RequestContext on the client
side and in the MessageContext on the server
side.
By adding parameter to the @MTOM
annotation, such as
@MTOM(threshold=3000)
By adding parameter to the MTOMFeature
object, such as new MTOM(3000)
MTOM support is fully interoperable with .NET clients and servers. If you are working with Metro then your MTOM solution as a endpoint or as client will work out of the box.
If you are using Eclipse Implementation of Jakarta XML Web Services distribution, MTOM interop with .NET client or server will not work out of the box. The reason behind this is that Eclipse Implementation of Jakarta XML Web Services does not have built in support for WS-Policy and .NET 3.0/.NET 3.5 looks for an MTOM policy assertion in the WSDL before turning on MTOM encoding. So, you will need to turn it on explicitly on your .NET 3.0/3.5 or Eclipse Implementation of Jakarta XML Web Services client.
The MTOM policy assertion that .NET 3.0/.NET 3.5 understands is: <wsoma:OptimizedMimeSerialization/>
Turn on MTOM explicitly on your .NET client using the WCF editor available with Visual Studio 2005.
Turn on MTOM on Eclipse Implementation of Jakarta XML Web Services client as defined above.
Here is a sample Metro MTOM endpoint and a .NET 3.0 client.
Eclipse Implementation of Jakarta XML Web Services provides support for sending and receiving large attachments in a streaming fashion. Often times, large attachments need to be stored on the file system since they cannot be kept in memory(limited by heap size). But in certain cases, streaming of attachments is possible without ever storing the content on the file system. RI will try to stream the attachments whenever it is possible. Otherwise, it would store the large attachments on the file system.
The programming model is based on MTOM and DataHandler. You want
to send large data as a SOAP attachment, see this section for
more details. Also you want to bind large data to
DataHandler instead of byte[]. RI provides a
StreamingDataHandler, a DataHandler implementation that
can be used to access the data efficiently in a streaming
fashion.
RI uses Java SE's HttpURLConnection
for web service invocations. HttpURLConnection
buffers the request data by default. So the client applications
need to enable streaming explicitly, see http client
streaming. The following sample show how to send and
receive large data.
Example 6.9. Sample client for large attachments
import com.sun.xml.ws.developer.JAXWSProperties; import com.sun.xml.ws.developer.StreamingDataHandler; MTOMFeature feature = new MTOMFeature(); MyService service = new MyService(); MyProxy proxy = service.getProxyPort(feature); Map<String, Object> ctxt = ((BindingProvider)proxy).getRequestContext(); // Enable HTTP chunking mode, otherwise HttpURLConnection buffers ctxt.put(JAXWSProperties.HTTP_CLIENT_STREAMING_CHUNK_SIZE, 8192); DataHandler dh = proxy.fileUpload(...); StreamingDataHandler sdh = (StreamingDataHandler)dh; InputStream in = sdh.readOnce(); ... in.close(); sdh.close();
Use @MTOM feature for a service and DataHandler
parameter for large data. If the WSDL contains
xmime:expectedContentTypes="application/octet-stream", it would be
mapped to DataHandler in the generated SEI. If the service is
starting from java, @XmlMimeType("application/octet-stream") can
be used to generate an appropriate schema type in the generated
WSDL.
The following sample shows how to upload files. It uses
StreamingDataHandler.moveTo(File) convenient method
to store the contents of the attachment to a file.
Example 6.10. Sample service for large attachments
import com.sun.xml.ws.developer.StreamingDataHandler;
...
@MTOM
@WebService
public class UploadImpl {
// Use @XmlMimeType to map to DataHandler on the client side
public void fileUpload(String name,
@XmlMimeType("application/octet-stream")
DataHandler data) {
try {
StreamingDataHandler dh = (StreamingDataHandler) data;
File file = File.createTempFile(name, "");
dh.moveTo(file);
dh.close();
} catch (Exception e) {
throw new WebServiceException(e);
}
}
}You can configure streaming attachments behaviour using
@StreamingAttachment on the server side, and using
StreamingAttachmentFeature on the client side. Using
this feature, you can configure only certain sized attachments are
written to a file.
Example 6.11. Sample Service Configuration
import com.sun.xml.ws.developer.StreamingAttachment;
// Configure such that whole MIME message is parsed eagerly,
// Attachments under 4MB are kept in memory
@MTOM
@StreamingAttachment(parseEagerly=true, memoryThreshold=4000000L)
@WebService
public class UploadImpl {
}Example 6.12. Sample client configuration
import com.sun.xml.ws.developer.StreamingAttachmentFeature;
MTOMFeature mtom = new MTOMFeature();
// Configure such that whole MIME message is parsed eagerly,
// Attachments under 4MB are kept in memory
StreamingAttachmentFeature stf =
new StreamingAttachmentFeature(null, true, 4000000L);
MyService service = new MyService();
MyProxy proxy = service.getProxyPort(feature, stf);