Please refer to relevant product page for more up-to-date product information and resources. The sample use case which we are going to implement is a Download Statistics Service. This service provides data relating to monthly download statistics of a set of software products. These statistics includes a graph image of the distribution of downloads over a period of one month together with some other data. The objective of the SOAP with Attachments note is to describe a standard way to associate one or more binary attachments with a SOAP message in their original formats. The service implementation class returns the download statistics data specific to a software product.
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Web services users may want to transmit binary attachments of various sorts like images, drawings, XML docs, etc. Such data is often in a particular binary format.
Traditionally, two techniques have been used in dealing with opaque data in XML; "By value" Sending binary data by value is achieved by embedding opaque data of course after some form of encoding as an element or attribute content of the XML component of data. The main advantage of this technique is that it gives applications the ability to process and describe data, based only on the XML component of the data. XML supports opaque data as content through the use of either base64 or hexadecimal text encoding.
Both techniques bloat the size of the data. For UTF-8 underlying text encoding, base64 encoding increases the size of the binary data by a factor of 1. The above factors will be doubled if UTF text encoding is used. Also of concern is the overhead in processing costs both real and perceived for these formats, especially when decoding back into raw binary.
This prevents the unnecessary bloating of data and wasting of processing power. The primary obstacle for using these unparsed entities is their heavy reliance on DTDs, which impedes modularity as well as the use of XML namespaces.
There were several specifications introduced in the Web services world to deal with this binary attachment problem using the "by reference" technique.
SOAP with Attachments is one such example. Since SOAP prohibits document type declarations DTD in messages, this leads to the problem of not representing data as part of the message infoset, therefore creating two data models. This scenario is like sending attachments with an e-mail message. Even though those attachments are related to the message content they are not inside the message.
This causes the technologies that process and describe the data based on the XML component of the data to malfunction. One example is WS-Security. MTOM tries to leverage the advantages of the above two techniques by trying to merge the two techniques. MTOM is actually a "by reference" method. With the use of this exclusive element, the attached binary content logically becomes inline by value with the SOAP document even though it is actually attached separately.
This merges the two realms by making it possible to work only with one data model. This allows the applications to process and describe by only looking at the XML part, making the reliance on DTDs obsolete.
The following is an extract from the XOP specification. At the conceptual level, this binary data can be thought of as being baseencoded in the XML Document. As this conceptual form might be needed during some processing of the XML document e. In the reverse direction, XOP is capable of optimizing only baseencoded Infoset data that is in the canonical lexical form.
It has this ability as OMText can hold raw binary content in the form of javax. OMText has been chosen for this purpose with two reasons.
Other one is to preserve the infoset in both the sender and receiver. To store the binary content in the same kind of object regardless of whether it is optimized or not. MTOM allows to selectively encode portions of the message, which allows us to send base64encoded data as well as externally attached raw binary data referenced by the "XOP" element optimized content to be sent in a SOAP message.
You can specify whether an OMText node that contains raw binary data or base64encoded binary data is qualified to be optimized at the time of construction of that node or later. For optimum efficiency of MTOM, a user is advised to send smaller binary attachments using base64encoding non-optimized and larger attachments as optimized content. DataSource interface can fit here. DataHandler to handle the binary data.
You can also create binary content nodes, which will not be optimized at any case. They will be serialized and sent as Base64 Strings. Axis2 serializes all binary content nodes as Base64 encoded strings regardless of whether they are qualified to be optimized or not if the "enableMTOM" property is set to False. XOP Infosets Constructs. Axis2 will automatically identify and de-serialize accordingly, as and when an MTOM message arrives.
If it is not set, all the binary data in the binary content nodes will be serialized as Base64 encoded strings. This configuration can be overriden in services. Do whatever you need with the DataHandler Having an element with the type "xsd:base64Binary" is enough for the Axis2 code generators to identify possible MTOM attachments, and to generate code accordingly.
With the xmime schema, you can indicate the type of content in the element at runtime using an MTOM attribute extension xmime:contentType. Furthermore, you can identify what type of data might be expected in the element using the xmime:expectedContentType.
Here is an example: public org. AttachmentResponse attachment org. It returns a message once it is successful. FileDataSource from the input file. Axis2 preserves the order of the received attachments when storing them in the MessageContext. Users can access binary attachments using the attachement API given in the Message Context using the content-id of the mime part as the key. Care needs be taken to rip off the "cid" prefix when content-id is taken from the "Href" attributes.
Users can access the message context from whithin a service implementation class using the "setOperationContext " method as shown in the following example. Note: Axis2 supports content-id based referencing only. This can be set using the axis2.
Client side SwA capability can be used only with the OperationClient api, since the user needs the ability to access the MessageContext. Even though the representation is different, both technologies have the same wire format. Note : Above backword compatibility was succesfully tested against Axis 1.
Also, a user can specify a size threshold for the File caching in bytes. When this threshold value is specified, only the attachments whose size is bigger than the threshold value will get cached in the files. Smaller attachments will remain in the memory.
Note : It is a must to specify a directory to temporarily store the attachments. Also care should be taken to clean that directory from time to time. The following parameters need to be set in Axis2.
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