Nodestream - Compress Transform

Zlib compression/decompression transform for Nodestream

Identity:: compress

API docs

Description

This transformer allows you to compress/decompress streams that you upload/download with Nodestream. Same functionality as with the built-in zlib module is supported.

You can use any combination of compressing/decompressing and downloading/uploading - you are not limited to ie. only compressing uploads and decompressing downloads.

Usage

Installation

npm install --save nodestream-transform-compress

Configuration

You need to register this tranform with Nodestream before you can use it:

// Assuming you already have a nodestream instance configured with an adapter
nodestream.registerTransform('compress')

Now you can create a pipeline which will use this transform:

const pipeline = nodestream.pipeline()
  .use('checksum', {
    algorithm: 'gzip',  // Either gzip or deflate, gzip is default
    raw: false  // For deflate, setting this to true will not prepend deflate header
  })

The following options are supported:

• algorithm: Either gzip or deflate - determines which compression algorithm should be used
• raw: true or false - Only available for deflate algorithm. If set to true, then no header will be added to the resulting stream.

The following per-file options are required:

• mode: Either compress or decompress - determines how the stream should be transformed

Pass this option via the last argument in .upload() or .download() methods on the pipeline via a compress key (this transform's identity) - see the examples below.

Results

This transform does not have any transformation results to publish, so it will publish the input configuration which was used for this transformation - it will be available on the compress property (this transform's identity) on the results response:

const file = fs.createReadStream('/users/me/profile-pic.png')
pipeline.upload(file, { name: 'avatar.png', compress: { mode: 'compress' } })
.then(results => {
  results.compress.algorithm  // gzip
  results.compress.raw  // false
})

// Downloads
const dest = fs.createWriteStream('/users/me/profile-pic.png')
pipeline.download('avatars/user-123.png', dest, { compress: { mode: 'decompress' } })
.then(results => {
  results.compress.algorithm  // gzip
  results.compress.raw  // false
})

License

This software is licensed under the BSD-3-Clause License. See the LICENSE file for more information.