[Reading CXF message content] What is CachedOutputStream's primary purpose and how its different than DelegatingInputStream ?

[Varun Singhal]

Hi all,

Greetings !

I have designed a interceptor that runs in RECEIVE phase and takes a decision 
whether to modify the header of an incoming SOAP request OR not.
It does so by reading the message's contents and parsing it into a XML document 
instance.

Here is the code:

      //get message as stream
      InputStream ipStream = message.getContent(InputStream.class);
      CachedOutputStream cos = new CachedOutputStream();
      //create a re-readable inputstream
      IOUtils.copy(ipStream, cos);
      ipStream.close();
      cos.flush();
      //set the new inputstream
      message.setContent(InputStream.class, cos.getInputStream());
     //XML document instance
      DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
      doc = dBuilder.parse(cos.getInputStream());
      cos.close();
      if (doc != null) {
          takeDecisionOnHeaderModification(doc);
        }
      }

The code works fine.
As you can make out i needed a re-readable `inputStream` otherwise successive 
application code/interceptors would have empty input stream.
so i used CachedOutputStream because cos.getInputStream() is re-readable.

Here are my queries about this approach :

Query#1 :
 If CachedOutputStream  is used for creating a re-readable inputStream why the 
name is so misleading ? (It doesn't even have input word in it)

Query#2 :
For the requirement of re-readable inputStream, is CachedOutputStream  the best 
candidate, why not 
DelegatingInputStream<https://cxf.apache.org/javadoc/latest/org/apache/cxf/io/DelegatingInputStream.html>,
 if yes would you be kind enough to provide a working code snippet of same ?

I will be very grateful if anyone could shed light on these queries ?

Many Thanks !

Warm Regards,

Varun SINGHAL