Arvados

The PullHandler should be called for any "PUT /pull" request.

It expects the request body to be a JSON object encoding a list of block pull requests. Each request is an object that specifies the locator of the block to be pulled, and an ordered list of servers to pull from. Example pull list:

[
    {
        "locator":"e4d909c290d0fb1ca068ffaddf22cbd0+4985",
        "servers":["keep0.qr1hi.arvadosapi.com:25107","keep1.qr1hi.arvadosapi.com:25108"]
    },
    {
        "locator":"55ae4d45d2db0793d53f03e805f656e5+658395",
        "servers":["10.0.1.5:25107","10.0.1.6:25107","10.0.1.7:25108"]
    },
    ...
}

The pull list should be stored in memory. Any previously sent pull list is discarded and replaced with the new one.