ofs 0.1

OFS - provides plugin-orientated low-level blobstore.

OFS is a bucket/object storage library.

It provides a common API for doing storing bitstreams (+ a bit of related metadata) in ‘bucket/object’ stores such as:

• Filesystem (+ pairtree)

• S3-compatible: S3, Google Storage, Eucalytus, Archive.org

• Riak (buggy)

• ‘REST’ Store (see remote/reststore.py - implementation at http://bitbucket.org/pudo/repod/)

• add a backend here

Why use the library:

• Abstraction: write common code but use different storage backends

• More than a filesystem, less than a database - support for metadata as well bitstreams

• Extra features:

  • Sharding - automatic sharding of files to support distributed file-system like structure (planned)

Example Usage

(local version - depends on ‘pairtree’, and ‘simplejson’):

 >>> from ofs.local import OFS

 >>> o = OFS()
 (Equivalent to 'o = OFS(storage_dir = "data", uri_base="urn:uuid:", hashing_type="md5")')

 # Claim a bucket - this will add the bucket to the list of existing ones
 >>> uuid_id = o.claim_a_bucket()
 >>> uuid_id
 '4aaa43cdf5ba44e2ad25acdbd1cf2f70'

 # Choose a bucket name - if it exists, a new UUID one will be formed instead and returned
 >>> bucket_id = o.claim_a_bucket("foo")
 >>> bucket_id
 'foo'
 >>> bucket_id = o.claim_a_bucket("foo")
 >>> bucket_id
 '1bf93208521545879e79c13614cd12f0'

 # Store a file:
 >>> o.put_stream(bucket_id, "foo.txt", open("foo....))
 {'_label': 'foo.txt', '_content_length': 10, '_checksum': 'md5:10feda25f8da2e2ebfbe646eea351224', '_last_modified': '2010-08-02T11:37:21', '_creation_date': '2010-08-02T11:37:21'}

 # or:
 >>> o.put_stream(bucket_id, "foo.txt", "asidaisdiasjdiajsidjasidji")
 {'_label': 'foo.txt', '_content_length': 10, '_checksum': 'md5:10feda25f8da2e2ebfbe646eea351224', '_last_modified': '2010-08-02T11:37:21', '_creation_date': '2010-08-02T11:37:21'}

 # adding a file with some parameters:
 >>> o.put_stream(bucket_id, "foooo", "asidaisdiasjdiajsidjasidji", params={"original_uri":"http://...."})
 {'_label': 'foooo', 'original_uri': 'http://....', '_last_modified': '2010-08-02T11:39:11', '_checksum': 'md5:3d690d7e0f4479c5a7038b8a4572d0fe', '_creation_date': '2010-08-02T11:39:11', '_content_length': 26}

 # Get the underlying URL pointing to a resource
 >>> o.get_url(bucket_id, "foo")
   [typical local pairtree response:]
"file:///opt/ofs_store/pairtree_root/1b/f9/32/......./obj/foo"
   [typical remote response]
"http://..."
"ftp://..."

 # adding to existing metadata:
 >>> o.update_metadata(bucket_id, "foooo", {'foo':'bar'})
 {'_label': 'foooo', 'original_uri': 'http://....', '_last_modified': '2010-08-02T11:39:11', '_checksum': 'md5:3d690d7e0f4479c5a7038b8a4572d0fe', '_creation_date': '2010-08-02T11:39:11', '_content_length': 26, 'foo': 'bar'}

 # Remove keys
 >>> o.remove_metadata_keys(bucket_id, "foooo", ['foo'])
 {'_label': 'foooo', 'original_uri': 'http://....', '_last_modified': '2010-08-02T11:39:11', '_checksum': 'md5:3d690d7e0f4479c5a7038b8a4572d0fe', '_creation_date': '2010-08-02T11:39:11', '_content_length': 26}

 # Delete blob
 >>> o.exists(bucket_id, "foooo")
 True
 >>> o.del_stream(bucket_id, "foooo")
 >>> o.exists(bucket_id, "foooo")
 False

 # Iterate through ids for buckets held:
 >>> for item in o.list_buckets():
 ...   print item
 ...
 447536aa0f1b411089d12399738ede8e
 4a726b0a33974480a2a26d34fa0d494d
 4aaa43cdf5ba44e2ad25acdbd1cf2f70
 .... etc