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# In Rails 3.2.13 using accepts_nested_attributes_for, a scoped 
# validates_uniqueness_of validator will incorrectly reject unique values.

# Below are two models, Question and AnswerChoice. The validates_uniqueness_of
# validator in AnswerChoice says that AnswerChoice label must be unique within a
# Question. This validator incorrectly rejects unique labels when they are 
# reordered. Follow these steps to see the bug.
#
# This occurs when using nested resources and allowing users to edit the 
# Question and AnswerChoices in a single form. The form looks like this:

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# Given an S3 URL, this returns a signed S3 url that will force the browser
# to download the file rather than opening it in the browser window. The key
# is to add response-content-disposition to the query string, which tells S3
# to send the content-disposition header you specify. S3 will respect this
# parameter only if the URL is signed. You can override other S3 headers such
# as content-type using this same method. See:
#
# http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectGET.html
#
def s3_download_url(url)

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curl "https://storage.googleapis.com/golang/go1.4.linux-amd64.tar.gz" > go1.4.linux-amd64.tar.gz
sudo tar -C /usr/local -xzf go1.4.linux-amd64.tar.gz
rm go1.4.linux-amd64.tar.gz
rm -rf go1.4.linux-amd64

curl "https://s3.amazonaws.com/bitly-downloads/nsq/nsq-0.3.0.linux-amd64.go1.3.3.tar.gz" > nsq-0.3.0.linux-amd64.go1.3.3.tar.gz
tar -xzf nsq-0.3.0.linux-amd64.go1.3.3.tar.gz
cd nsq-0.3.0.linux-amd64.go1.3.3/bin
cp * ~/go/bin
rm nsq-0.3.0.linux-amd64.go1.3.3.tar.gz

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After copying a bag (via rsync) from the ingest node, I send this to the node that asked me to replicate:

PUT http://localhost:3003/api-v1/replicate/30000000-0000-4000-a000-000000000001/
{
	"from_node": "hathi",
	"to_node": "aptrust",
	"uuid": "00000000-0000-4000-a000-000000000003",
	"replication_id": "30000000-0000-4000-a000-000000000001",
	"fixity_algorithm": "sha256",
	"fixity_nonce": null,

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I sync replication requests from remote nodes to my own node. Any requests in which I'm the to_node go into my processing queue. For each replication request in the queue, I do this:

1. Copy the bag from the remote node, via rsync/ssh.
2. Calculate the sha256 digest of the bag's tag manifest.
3. Send that fixity value back to the ingest node. If I get back a record in which StoreRequested == false, I delete the bag from my staging area and consider the job done.
4. If StoreRequested == true, I validate the bag by making sure all required files and tags are present, and all checksums in the manifest-sha256.txt match. If the bag is invalid, I cancel the transfer on the remote node with a cancel reason indicating that the bag did not pass validation. I delete the bag from staging, and am done. 
5. If the bag is valid, I copy it to long-term storage and delete it from my staging area.
6. I update the transfer record on the ingest node to say Stored = true.

My own node does not know the bag is stored until the n

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// In the code below, extract is a tar-stream extract object. 
// See https://github.com/mafintosh/tar-stream/blob/master/extract.js
//
// This 'entry' handler does not care about the contents of the entry,
// it just has to restructure the tar header data into a format that
// the caller understands. It then passes 'stream' to a PassThrough
// which discards the contents and allows tar-stream to move on to 
// the next entry.
//
// The problem with the initial pipe to PassThrough on line 35 is that

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// This code shows how to stop a JavaScript async.queue after 
// the first error.

const async = require('async');

// Create a queue that calls the write function (defined below).
// Concurrency is set to 1 to guarantee sequential operation.
let q = async.queue(write, 1);

// The drain function is called when all tasks in the queue are complete.

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Pharos Code vs. Registry Code

Defining routes for a few basic controllers

Pharos Routes

Be sure to scroll sideways, so you can take it all in.

  # INSTITUTION ROUTES
  institution_ptrn = /(?:[a-zA-Z0-9\-_]+)(?:\.[a-zA-Z]+)+/