Apache Axis2 supports Base64 encoding, SOAP with Attachments & MTOM // create an OMText node with the above DataHandler and set “optimized” to false. Axis 2 source code file: (datahandler, datahandler, exception, package ; import ; import. The details of the solution are in the original message above. The issues were resolved using the following two sites: DataHandler issue.
|Published (Last):||1 June 2014|
|PDF File Size:||17.99 Mb|
|ePub File Size:||7.98 Mb|
|Price:||Free* [*Free Regsitration Required]|
Despite the flexibility, interoperability and global acceptance of XML, there are times when serializing data into XML does not make sense. Web services users may need to transmit binary attachments of various darahandler like images, drawings, xml docs, etc together with SOAP message. Such data are often in a particular binary format. Sending binary data by value is achieved by embedding opaque data of course after some form of encoding datahanddler 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 and looking only on XML component of the data. XML supports opaque data as content through the use of either base64 or hexadecimal text encoding. Both these techniques bloat axs2 size of the data. For UTF-8 underlying text encoding, base64 encoding increases the size of the binary data by a factor of 1.
Above factors will be doubled if UTF text encoding is used.
Also of concern is the overhead in processing costs both real and perceived aaxis2 these formats, especially when decoding back into raw binary. Sending binary data by reference is achieved by attaching pure binary data as external unparsed general entities outside of the XML document and then embedding reference URI’s to those entities as elements or attribute values.
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 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, 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 for processing and description of data based on 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.
Include element, which is defined in XML Binary Optimized Packaging XOP specification to reference the binary attachments external unparsed general entities of the message. With the use of this exclusive element the attached binary content logically become inline by value with the SOAP document even though actually it is attached separately. This merges the two realms by making it possible to work only with one data model.
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. Therefore, the conceptual representation of such binary data is as if it were baseencoded, using the canonical lexical form of XML Schema base64Binary datatype see [XML Schema Part 2: Datatypes Second Edition] 3.
In the reverse direction, XOP is capable of optimizing only baseencoded Infoset data that is in the canonical lexical form. It has been given this ability by allowing OMText to 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 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 “XOP” element optimized content to be send in a SOAP message. User can specify whether an OMText node which contains raw binary data or base64encoded binary data is qualified to be optimized or not at the construction time of that node or later.
To take the optimum efficiency of MTOM a user is advised to send smaller binary attachments using base64encoding None optimized and larger attachments as optimized content. Also a user can create an optimizable binary content node using a base64 encoded string, which contains encoded binary content, given with the mime type of the actual binary representation.
DataHandler to handle the binary data. One can also create binary content nodes which will not be optimized at any case. They will be serialized and send as Base64 Strings.
Axis2 serializes all binary content nodes as Base64 encoded strings regardless of they are qualified to be optimize or not, if. Axis2 will automatically identify and de-serialize accordingly as and when a MTOM message arrives. Axis 2 server automatically identifies incoming MTOM optimized messages based on the content-type and de-serializes accordingly. User can enableMTOM in the server side for outgoing messages.
If it is not set all the binary data in binary content nodes will be serialized as Base64 encoded strings.
MTOM with Axis2
This configuration can be overriden in services. Having an element with the type “xsd: Going a little bit further you can use the xmime schema http: With xmime schema you can indicate the type of content in the element at runtime using an MTOM attribute extension, xmime: Furthermore, you can identify what type of data might be expected in the element using the xmime: Putting it all together, our example element becomes:.
You can also use the xmime: The important point here is we import http: Axi2 the ‘Code Generator Tool’ guide datahqndler more info. Our ant task for this example is:. Now we are ready to code. Following is an example:. The code above receives a file and writes it to disk using the given file name. It returns a message on success. Now lets define the client:. The last step is to create an AAR with our Skeleton and the services. Here, we define an ant task that chooses XMLBeans as the databinding implementation.
Handling Binary Data with Axis2 (MTOM/SwA)
We also choose to axjs2 an interface which our Skeleton will implement. The end result becomes:. The code above receives a jpeg file and writes it to disk.
It returns zero on success and in the case of an error, returns -1 along with a stacktrace. The last step is to create an AAR with our Skeleton and the generated interface and services.
MTOM with Axis2
See the user guide for more info. Axis2 automatically identifies SwA messages based on the content type. Axis2 preserves the order of datahandker received attachments when storing them in the MessageContext. Users can access binary attachments using the attachement API given in the Message Context using 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 the message context from whithin a service implementation class using the “setOperationContext ” method as shown in the following example.
Axis2 supports content-id based referencing only. User need to set the “enableSwA” property daatahandler true in order to be able to send SwA messages. Users are expected to use the attachment API provided in the MessageContext to specify the binary attachments needed to be attached to the outgoing message as SwA type attachments. Client side SwA capability can be used only with the OperationClient api, since the user datahnadler the ability to access the MessageContext.
Even though the representation is different, both technologies have the same wire format. Axis2 comes handy with a file caching mechanism for incoming attachments, which gives Axis2 the ability to handle very large attachments without buffering them in memory at any time.
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 files. Smaller attachments will remain in Memory. It is a must to specify a directory to temporary store the attachments.
Also care should be taken to clean that directory from time to time. Enabling file caching for client side receiving can be done for the by setting the Options as follows.