Reading files / data structures from other platforms into Elixir/Erlang

Hey @CharlesO, your file.io links do not work for me, I get a 404 for both.

To make sure I understand what you’re trying to do, you’re trying to read these files in Elixir and build maps out of them?

sorry, i’ve moved them to my personal server:
http://paperlesssolutionsltd.com.ng/sample1.zip
http://paperlesssolutionsltd.com.ng/sample2.zip

I want to read the content into elixir.
Looking @ the Java source, it’s clear how they are being constructed.

@CharlesO Unzipping those files turns into sample1.zip.cpgz, it does not unzip.

Sure, but it isn’t clear at all what the format of the files are. The java source has nothing to do with the structure of the file.

Oh, those zip files were encrypted.

Decrypting them is not the problem, it is reading the Java Hashmap that’s the issues.

The Java source shows how the file was constructed … if i can read back the parts, I can easily decrypt the files. I have the keys and all.

What does a java hashmap written to a file look like? What is its format?

Wouldn’t it be easier to read them back in a java application and save them as json or an other interop format?

There is no magical solution to read files from an internal java binary format. You could always try to understand and parse the java binary format but that sounds like something that will be a lot of work and possible error prone.

That’s my question exactly. See what the code is doing:

It reads the zipped file, encrypts it, and overwrites the same zipped file name with the encrypted content.

         byte[] arrayOfByte = getByteArray(this.compressedFile);
          arrayOfByte = SecurityService.performEnc(SecMgrConstants.ASYM_ALGORITHM, arrayOfByte);
          localFileOutputStream = new FileOutputStream(this.compressedFile);
          localFileOutputStream.write(arrayOfByte);
          localFileOutputStream.close();

basically this: https://paperlesssolutionsltd.com.ng/RSASecImpl.java.txt

But once Java has written the bits to a physical - binary file, shouldn’t any programing language be able to readback the binary content?

Sure, every language can read it the physical bits, but how do you know what these bits represent? But I guess (because you didn’t specify in your original question) that you need to do something with the files in Elixir, so how do you know what the contents of the file mean?

The information on how the bits are stored are defined by the ObjectOutputStream from java. If you want to read them, you can, and you will have to parse them yourself. Basically implementing an ObjectInputStream in elixir.

So, it would be a lot easier if instead of using the ObjectOutputStream you wrote the files to a json or xml format in java. Then you don’t have to implement the binary parsing yourself.