MATLAB: Do I get a larger array when I try to read a ‘byte-array’ from the web service using the ‘createClassFromWsdl’ interface in MATLAB 7.12 (R2011a)

arraybase64bytedatadecodeencodeimportMATLABwebservice

I have a webservice that returns some data in the form of a byte-array in both my Java and C# client interfaces. However, if I read that same data into MATLAB using the 'createClassFromWsdl' interface, I get data whose size is larger than the expected array. Moreover, it consists of different data.

Best Answer

MATLAB returns the base64 encoded byte stream for any data that is sent over the SOAP message. Unlike C# or Java clients which interface to the webservice, MATLAB does not convert this data back to a binary byte array.

Base64 encoding takes every 3 bytes (24 bits) and encodes them into 4 bytes with 6 bits of data per byte. Each of these 4 bytes comes from a 64-byte dictionary of regular characters (e.g. A-Z,a-z, 0-9, / etc).

To get the raw byte data, manually decode this Base64 encoded data.

A small example of how to do this within MATLAB is shown below:

%Import Java
import java.lang.String;
%Import the base64 encoder object
encoder = org.apache.commons.codec.binary.Base64;
% Create a sample Base64 encoded string
bs64data = '7tyg546bf0a2316dhvber345' ; 
% Create Java String 
JavaString = String(bs64data);
% Extract the Bytes from this String
ByteFromString = JavaString.getBytes();
% Perform the Base64 Decoding - Output is int8 data format
DecodedBytes = encoder.decodeBase64(ByteFromString);

Related Solutions

MATLAB: Matlab GZIP http postrequest

This example of outrageous hackery does appear to do the job. A bit stinky though...

   myJson = jsonencode(toSend);
    outStream= java.io.ByteArrayOutputStream();
    gzipped = java.util.zip.GZIPOutputStream(outStream);
    gzipped.write( uint8(myJson));
    gzipped.close();
   closedBytes = outStream.toByteArray();
   messageBody.Payload = typecast (closedBytes, 'uint8');
request.Header.addFields(...
        matlab.net.http.field.GenericField('Content-Encoding', 'gzip'), ...
        matlab.net.http.field.ContentTypeField('application/json'))
response = send(request, uri, opts);
% To decode the stream to check ... 
% someStream = java.io.ByteArrayInputStream(typecast( messageBody.Payload , 'int8'));   
%    gzipInStream = java.util.zip.GZIPInputStream( someStream );
%    inReader = java.io.InputStreamReader(gzipInStream, 'UTF-8');
%    

%    aTest = char();
%    
%    data=inReader.read;
%    while data ~=-1
%         aTest = [aTest, char(data)];    
%        data = inReader.read;       
%    end

MATLAB: How can export the MATLAB figure encoding it in base64 format in MATLAB 7.7 (R2008b)

This feature is not available in MATLAB 7.7 (R2008b).

As a alternative, you might want to refer to the following external sources:

 Data type and data conversion utilities
 <http://home.online.no/~pjacklam/matlab/software/util/datautil/index.html>
 base64decode  -   Perform base64 decoding on a string
 base64encode  -   Perform base64 encoding on a string

Please understand that we can not guarantee or support third party products or functions, however customers have reported to successfully work with the above functions before. You also might be interested in the following source:

 <http://www.wikihow.com/Encode-a-String-to-Base64-With-Java>

To convert the figure to a string you can print it to the desired image format (using the menu or PRINT command) and afterwards read it to a string using low level I/O functions (FOPEN, FREAD, FCLOSE). Note the following example:

function str64 = encodeFigure( h )
filename = 'encodeFigure.png';
if exist('h','var')
      print(['-f' num2str(h)], '-r300','-dpng', filename );
else
      print( '-r300','-dpng', filename );
end
fid = fopen( filename, 'r' );
im = fread( fid );
fclose(fid);
str64 = base64encode( im, [] );
delete(filename);
end

Best Answer

Related Solutions

MATLAB: Matlab GZIP http postrequest

MATLAB: How can export the MATLAB figure encoding it in base64 format in MATLAB 7.7 (R2008b)

Related Question