storage.md

#Storage

##Description Storage service is a core Cocaine service, it provides basic interface to storage operations. Storage just a lightweight proxy that directs user's requests to backends.

Storage provides interface for key-value processing. Data in storage organized into collections in manner of one level filesystem structure. Keys has additional attributes - tags. Tags are the strings that allows to flexible mark data keys inside each collection.

##Handles

Handle	Description
find	Find keys by tags. Returns list of keys.
read	Get data from the storage by the key.
remove	Remove data from storage by the key.
write	Put data into the storage by the key.

read(collection, key)
write(collection, key, blob, tags)
remove(collection, key)
find(collection, tags)

Parameters

Parameter	Description
collection	Name of collection.
key	Data identification string.
blob	Data.
tags	Set of attribute strings.

##Configuration

Service is configured in services section of the configuration file. Type of service is storage.

"storage": {
    "type": "storage",
    "args":{
        "backend": "storage_backend"
    }
}

As a backend (storage_backend) for this service any type of storages can be used, that support it internal interface. Nowdays it is a file storage and MongoDB plugin.

File storage is configured like:

"files_backend": {
    "type": "files",
    "args": {
        "path": "path to storage"
    }
}

path to storage should exists and user running Cocaine should have enough rights to read/write to that path.

Elliptics plugin can be used with storage also but it has more functions and if you want to use all of them you should configure it with the original storage service with elliptics type.

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