+++ /dev/null
-Pithos v2 Developer Guide
-=========================
-
-Introduction
-------------
-
-Pithos is a storage service implemented by GRNET (http://www.grnet.gr). Data is stored as objects, organized in containers, belonging to an account. This hierarchy of storage layers has been inspired by the OpenStack Object Storage (OOS) API and similar CloudFiles API by Rackspace. The Pithos API follows the OOS API as closely as possible. One of the design requirements has been to be able to use Pithos with clients built for the OOS, without changes.
-
-However, to be able to take full advantage of the Pithos infrastructure, client software should be aware of the extensions that differentiate Pithos from OOS. Pithos objects can be updated, or appended to. Pithos will store sharing permissions per object and enforce corresponding authorization policies. Automatic version management, allows taking account and container listings back in time, as well as reading previous instances of objects.
-
-The storage backend of Pithos is block oriented, permitting efficient, deduplicated data placement. The block structure of objects is exposed at the API layer, in order to encourage external software to implement advanced data management operations.
-
-This document's goals are:
-
-* Define the Pithos ReST API that allows the storage and retrieval of data and metadata via HTTP calls
-* Specify metadata semantics and user interface guidelines for a common experience across client software implementations
-
-The present document is meant to be read alongside the OOS API documentation. Thus, it is suggested that the reader is familiar with associated technologies, the OOS API as well as the first version of the Pithos API. This document refers to the second version of Pithos. Information on the first version of the storage API can be found at http://code.google.com/p/gss.
-
-Whatever marked as to be determined (**TBD**), should not be considered by implementors.
-
-More info about Pithos can be found here: https://code.grnet.gr/projects/pithos
-
-Document Revisions
-^^^^^^^^^^^^^^^^^^
-
-========================= ================================
-Revision Description
-========================= ================================
-0.9 (Feb 17, 2012) Change permissions model.
-\ Do not include user-defined metadata in account/container/object listings.
-0.8 (Jan 24, 2012) Update allowed versioning values.
-\ Change policy/meta formatting in JSON/XML replies.
-\ Document that all non-ASCII characters in headers should be URL-encoded.
-\ Support metadata-based queries when listing objects at the container level.
-\ Note Content-Type issue when using the internal django web server.
-\ Add object UUID field.
-\ Always reply with the MD5 in the ETag.
-\ Note that ``/login`` will only work if an external authentication system is defined.
-\ Include option to ignore Content-Type on ``COPY``/``MOVE``.
-\ Use format parameter for conflict (409) and uploaded hash list (container level) replies.
-0.7 (Nov 21, 2011) Suggest upload/download methods using hashmaps.
-\ Propose syncing algorithm.
-\ Support cross-account object copy and move.
-\ Pass token as a request parameter when using ``POST`` via an HTML form.
-\ Optionally use source account to update object from another object.
-\ Use container ``POST`` to upload missing blocks of data.
-\ Report policy in account headers.
-\ Add insufficient quota reply.
-\ Use special meta to always report Merkle hash.
-0.6 (Sept 13, 2011) Reply with Merkle hash as the ETag when updating objects.
-\ Include version id in object replace/change replies.
-\ Change conflict (409) replies format to text.
-\ Tags should be migrated to a meta value.
-\ Container ``PUT`` updates metadata/policy.
-\ Report allowed actions in shared object replies.
-\ Provide ``https://hostname/login`` for Shibboleth authentication.
-\ Use ``hashmap`` parameter in object ``GET``/``PUT`` to use hashmaps.
-0.5 (July 22, 2011) Object update from another object's data.
-\ Support object truncate.
-\ Create object using a standard HTML form.
-\ Purge container/object history.
-\ List other accounts that share objects with a user.
-\ List shared containers/objects.
-\ Update implementation guidelines.
-\ Check preconditions when creating/updating objects.
-0.4 (July 01, 2011) Object permissions and account groups.
-\ Control versioning behavior and container quotas with container policy directives.
-\ Support updating/deleting individual metadata with ``POST``.
-\ Create object using hashmap.
-0.3 (June 14, 2011) Large object support with ``X-Object-Manifest``.
-\ Allow for publicly available objects via ``https://hostname/public``.
-\ Support time-variant account/container listings.
-\ Add source version when duplicating with ``PUT``/``COPY``.
-\ Request version in object ``HEAD``/``GET`` requests (list versions with ``GET``).
-0.2 (May 31, 2011) Add object meta listing and filtering in containers.
-\ Include underlying storage characteristics in container meta.
-\ Support for partial object updates through ``POST``.
-\ Expose object hashmaps through ``GET``.
-\ Support for multi-range object ``GET`` requests.
-0.1 (May 17, 2011) Initial release. Based on OpenStack Object Storage Developer Guide API v1 (Apr. 15, 2011).
-========================= ================================
-
-Pithos Users and Authentication
--------------------------------
-
-In Pithos, each user is uniquely identified by a token. All API requests require a token and each token is internally resolved to an account string. The API uses the account string to identify the user's own files, thus whether a request is local or cross-account.
-
-Pithos does not keep a user database. For development and testing purposes, user identifiers and their corresponding tokens can be defined in the settings file. However, Pithos is designed with an external authentication service in mind. This service must handle the details of validating user credentials and communicate with Pithos via a middleware software component that, given a token, fills in the internal request account variable.
-
-Client software using Pithos, if not already knowing a user's identifier and token, should forward to the ``/login`` URI. The Pithos server, depending on its configuration will redirect to the appropriate login page.
-
-The login URI accepts the following parameters:
-
-====================== =========================
-Request Parameter Name Value
-====================== =========================
-next The URI to redirect to when the process is finished
-renew Force token renewal (no value parameter)
-force Force logout current user (no value parameter)
-====================== =========================
-
-When done with logging in, the service's login URI should redirect to the URI provided with ``next``, adding ``user`` and ``token`` parameters, which contain the account and token fields respectively.
-
-A user management service that implements a login URI according to these conventions is Astakos (https://code.grnet.gr/projects/astakos), by GRNET.
-
-The Pithos API
---------------
-
-The URI requests supported by the Pithos API follow one of the following forms:
-
-* Top level: ``https://hostname/v1/``
-* Account level: ``https://hostname/v1/<account>``
-* Container level: ``https://hostname/v1/<account>/<container>``
-* Object level: ``https://hostname/v1/<account>/<container>/<object>``
-
-All requests must include an ``X-Auth-Token`` - as a header, or a parameter.
-
-The allowable request operations and respective return codes per level are presented in the remainder of this chapter. Common to all requests are the following return codes.
-
-========================= ================================
-Return Code Description
-========================= ================================
-400 (Bad Request) The request is invalid
-401 (Unauthorized) Missing or invalid token
-403 (Forbidden) Request not allowed
-404 (Not Found) The requested resource was not found
-503 (Service Unavailable) The request cannot be completed because of an internal error
-========================= ================================
-
-Top Level
-^^^^^^^^^
-
-List of operations:
-
-========= ==================
-Operation Description
-========= ==================
-GET Authentication (for compatibility with the OOS API) or list allowed accounts
-========= ==================
-
-GET
-"""
-
-If the ``X-Auth-User`` and ``X-Auth-Key`` headers are given, a dummy ``X-Auth-Token`` and ``X-Storage-Url`` will be replied, which can be used as a guest token/namespace for testing Pithos.
-
-================ =====================
-Return Code Description
-================ =====================
-204 (No Content) The request succeeded
-================ =====================
-
-If an ``X-Auth-Token`` is already present, the operation will be interpreted as a request to list other accounts that share objects to the user.
-
-====================== =========================
-Request Parameter Name Value
-====================== =========================
-limit The amount of results requested (default is 10000)
-marker Return containers with name lexicographically after marker
-format Optional extended reply type (can be ``json`` or ``xml``)
-====================== =========================
-
-The reply is a list of account names.
-If a ``format=xml`` or ``format=json`` argument is given, extended information on the accounts will be returned, serialized in the chosen format.
-For each account, the information will include the following (names will be in lower case and with hyphens replaced with underscores):
-
-=========================== ============================
-Name Description
-=========================== ============================
-name The name of the account
-last_modified The last account modification date (regardless of ``until``)
-=========================== ============================
-
-Example ``format=json`` reply:
-
-::
-
- [{"name": "user", "last_modified": "2011-12-02T08:10:41.565891+00:00"}, ...]
-
-Example ``format=xml`` reply:
-
-::
-
- <?xml version="1.0" encoding="UTF-8"?>
- <accounts>
- <account>
- <name>user</name>
- <last_modified>2011-12-02T08:10:41.565891+00:00</last_modified>
- </account>
- <account>...</account>
- </accounts>
-
-=========================== =====================
-Return Code Description
-=========================== =====================
-200 (OK) The request succeeded
-204 (No Content) The user has no access to other accounts (only for non-extended replies)
-=========================== =====================
-
-Will use a ``200`` return code if the reply is of type JSON/XML.
-
-Account Level
-^^^^^^^^^^^^^
-
-List of operations:
-
-========= ==================
-Operation Description
-========= ==================
-HEAD Retrieve account metadata
-GET List containers
-POST Update account metadata
-========= ==================
-
-HEAD
-""""
-
-==================== ===========================
-Request Header Name Value
-==================== ===========================
-If-Modified-Since Retrieve if account has changed since provided timestamp
-If-Unmodified-Since Retrieve if account has not changed since provided timestamp
-==================== ===========================
-
-|
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-until Optional timestamp
-====================== ===================================
-
-Cross-user requests are not allowed to use ``until`` and only include the account modification date in the reply.
-
-========================== =====================
-Reply Header Name Value
-========================== =====================
-X-Account-Container-Count The total number of containers
-X-Account-Bytes-Used The total number of bytes stored
-X-Account-Until-Timestamp The last account modification date until the timestamp provided
-X-Account-Group-* Optional user defined groups
-X-Account-Policy-* Account behavior and limits
-X-Account-Meta-* Optional user defined metadata
-Last-Modified The last account modification date (regardless of ``until``)
-========================== =====================
-
-|
-
-================ =====================
-Return Code Description
-================ =====================
-204 (No Content) The request succeeded
-================ =====================
-
-
-GET
-"""
-
-==================== ===========================
-Request Header Name Value
-==================== ===========================
-If-Modified-Since Retrieve if account has changed since provided timestamp
-If-Unmodified-Since Retrieve if account has not changed since provided timestamp
-==================== ===========================
-
-|
-
-====================== =========================
-Request Parameter Name Value
-====================== =========================
-limit The amount of results requested (default is 10000)
-marker Return containers with name lexicographically after marker
-format Optional extended reply type (can be ``json`` or ``xml``)
-shared Show only shared containers (no value parameter)
-until Optional timestamp
-====================== =========================
-
-The reply is a list of container names. Account headers (as in a ``HEAD`` request) will also be included.
-Cross-user requests are not allowed to use ``until`` and only include the account/container modification dates in the reply.
-
-If a ``format=xml`` or ``format=json`` argument is given, extended information on the containers will be returned, serialized in the chosen format.
-For each container, the information will include all container metadata, except user-defined (names will be in lower case and with hyphens replaced with underscores):
-
-=========================== ============================
-Name Description
-=========================== ============================
-name The name of the container
-count The number of objects inside the container
-bytes The total size of the objects inside the container
-last_modified The last container modification date (regardless of ``until``)
-x_container_until_timestamp The last container modification date until the timestamp provided
-x_container_policy Container behavior and limits
-=========================== ============================
-
-Example ``format=json`` reply:
-
-::
-
- [{"name": "pithos",
- "bytes": 62452,
- "count": 8374,
- "last_modified": "2011-12-02T08:10:41.565891+00:00",
- "x_container_policy": {"quota": "53687091200", "versioning": "auto"}}, ...]
-
-Example ``format=xml`` reply:
-
-::
-
- <?xml version="1.0" encoding="UTF-8"?>
- <account name="user">
- <container>
- <name>pithos</name>
- <bytes>62452</bytes>
- <count>8374</count>
- <last_modified>2011-12-02T08:10:41.565891+00:00</last_modified>
- <x_container_policy>
- <key>quota</key><value>53687091200</value>
- <key>versioning</key><value>auto</value>
- </x_container_policy>
- </container>
- <container>...</container>
- </account>
-
-For more examples of container details returned in JSON/XML formats refer to the OOS API documentation. In addition to the OOS API, Pithos returns policy fields, grouped as key-value pairs.
-
-=========================== =====================
-Return Code Description
-=========================== =====================
-200 (OK) The request succeeded
-204 (No Content) The account has no containers (only for non-extended replies)
-304 (Not Modified) The account has not been modified
-412 (Precondition Failed) The condition set can not be satisfied
-=========================== =====================
-
-Will use a ``200`` return code if the reply is of type JSON/XML.
-
-
-POST
-""""
-
-==================== ===========================
-Request Header Name Value
-==================== ===========================
-X-Account-Group-* Optional user defined groups
-X-Account-Meta-* Optional user defined metadata
-==================== ===========================
-
-|
-
-====================== ============================================
-Request Parameter Name Value
-====================== ============================================
-update Do not replace metadata/groups (no value parameter)
-====================== ============================================
-
-No reply content/headers.
-
-The operation will overwrite all user defined metadata, except if ``update`` is defined.
-To create a group, include an ``X-Account-Group-*`` header with the name in the key and a comma separated list of user names in the value. If no ``X-Account-Group-*`` header is present, no changes will be applied to groups. The ``update`` parameter also applies to groups. To delete a specific group, use ``update`` and an empty header value.
-
-================ ===============================
-Return Code Description
-================ ===============================
-202 (Accepted) The request has been accepted
-================ ===============================
-
-
-Container Level
-^^^^^^^^^^^^^^^
-
-List of operations:
-
-========= ============================
-Operation Description
-========= ============================
-HEAD Retrieve container metadata
-GET List objects
-PUT Create/update container
-POST Update container metadata
-DELETE Delete container
-========= ============================
-
-
-HEAD
-""""
-
-==================== ===========================
-Request Header Name Value
-==================== ===========================
-If-Modified-Since Retrieve if container has changed since provided timestamp
-If-Unmodified-Since Retrieve if container has not changed since provided timestamp
-==================== ===========================
-
-|
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-until Optional timestamp
-====================== ===================================
-
-Cross-user requests are not allowed to use ``until`` and only include the container modification date in the reply.
-
-=========================== ===============================
-Reply Header Name Value
-=========================== ===============================
-X-Container-Object-Count The total number of objects in the container
-X-Container-Bytes-Used The total number of bytes of all objects stored
-X-Container-Block-Size The block size used by the storage backend
-X-Container-Block-Hash The hash algorithm used for block identifiers in object hashmaps
-X-Container-Until-Timestamp The last container modification date until the timestamp provided
-X-Container-Object-Meta A list with all meta keys used by objects (**TBD**)
-X-Container-Policy-* Container behavior and limits
-X-Container-Meta-* Optional user defined metadata
-Last-Modified The last container modification date (regardless of ``until``)
-=========================== ===============================
-
-The keys returned in ``X-Container-Object-Meta`` are all the unique strings after the ``X-Object-Meta-`` prefix, formatted as a comma-separated list. See container ``PUT`` for a reference of policy directives. (**TBD**)
-
-================ ===============================
-Return Code Description
-================ ===============================
-204 (No Content) The request succeeded
-================ ===============================
-
-
-GET
-"""
-
-==================== ===========================
-Request Header Name Value
-==================== ===========================
-If-Modified-Since Retrieve if container has changed since provided timestamp
-If-Unmodified-Since Retrieve if container has not changed since provided timestamp
-==================== ===========================
-
-|
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-limit The amount of results requested (default is 10000)
-marker Return containers with name lexicographically after marker
-prefix Return objects starting with prefix
-delimiter Return objects up to the delimiter (discussion follows)
-path Assume ``prefix=path`` and ``delimiter=/``
-format Optional extended reply type (can be ``json`` or ``xml``)
-meta Return objects that satisfy the key queries in the specified comma separated list (use ``<key>``, ``!<key>`` for existence queries, ``<key><op><value>`` for value queries, where ``<op>`` can be one of ``=``, ``!=``, ``<=``, ``>=``, ``<``, ``>``)
-shared Show only shared objects (no value parameter)
-until Optional timestamp
-====================== ===================================
-
-The ``path`` parameter overrides ``prefix`` and ``delimiter``. When using ``path``, results will include objects ending in ``delimiter``.
-
-The keys given with ``meta`` will be matched with the strings after the ``X-Object-Meta-`` prefix.
-
-The reply is a list of object names. Container headers (as in a ``HEAD`` request) will also be included.
-Cross-user requests are not allowed to use ``until`` and include the following limited set of headers in the reply:
-
-=========================== ===============================
-Reply Header Name Value
-=========================== ===============================
-X-Container-Block-Size The block size used by the storage backend
-X-Container-Block-Hash The hash algorithm used for block identifiers in object hashmaps
-X-Container-Object-Meta A list with all meta keys used by allowed objects (**TBD**)
-Last-Modified The last container modification date
-=========================== ===============================
-
-If a ``format=xml`` or ``format=json`` argument is given, extended information on the objects will be returned, serialized in the chosen format.
-For each object, the information will include all object metadata, except user-defined (names will be in lower case and with hyphens replaced with underscores). User-defined metadata includes ``X-Object-Meta-*``, ``X-Object-Manifest``, ``Content-Disposition`` and ``Content-Encoding`` keys. Also, sharing directives will only be included with the actual shared objects (inherited permissions are not calculated):
-
-========================== ======================================
-Name Description
-========================== ======================================
-name The name of the object
-hash The ETag of the object
-bytes The size of the object
-content_type The MIME content type of the object
-last_modified The last object modification date (regardless of version)
-x_object_hash The Merkle hash
-x_object_uuid The object's UUID
-x_object_version The object's version identifier
-x_object_version_timestamp The object's version timestamp
-x_object_modified_by The user that committed the object's version
-x_object_sharing Object permissions (optional)
-x_object_allowed_to Allowed actions on object (optional)
-x_object_public Object's publicly accessible URI (optional)
-========================== ======================================
-
-Sharing metadata and last modification timestamp will only be returned if there is no ``until`` parameter defined.
-
-Extended replies may also include virtual directory markers in separate sections of the ``json`` or ``xml`` results.
-Virtual directory markers are only included when ``delimiter`` is explicitly set. They correspond to the substrings up to and including the first occurrence of the delimiter.
-In JSON results they appear as dictionaries with only a ``subdir`` key. In XML results they appear interleaved with ``<object>`` tags as ``<subdir name="..." />``.
-In case there is an object with the same name as a virtual directory marker, the object will be returned.
-
-Example ``format=json`` reply:
-
-::
-
- [{"name": "object",
- "bytes": 0,
- "hash": "d41d8cd98f00b204e9800998ecf8427e",
- "content_type": "application/octet-stream",
- "last_modified": "2011-12-02T08:10:41.565891+00:00",
- "x_object_hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
- "x_object_uuid": "8ed9af1b-c948-4bb6-82b0-48344f5c822c",
- "x_object_version": 98,
- "x_object_version_timestamp": "1322813441.565891",
- "x_object_modified_by": "user"}, ...]
-
-Example ``format=xml`` reply:
-
-::
-
- <?xml version="1.0" encoding="UTF-8"?>
- <container name="pithos">
- <object>
- <name>object</name>
- <bytes>0</bytes>
- <hash>d41d8cd98f00b204e9800998ecf8427e</hash>
- <content_type>application/octet-stream</content_type>
- <last_modified>2011-12-02T08:10:41.565891+00:00</last_modified>
- <x_object_hash>e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855</x_object_hash>
- <x_object_uuid>8ed9af1b-c948-4bb6-82b0-48344f5c822c</x_object_uuid>
- <x_object_version>98</x_object_version>
- <x_object_version_timestamp>1322813441.565891</x_object_version_timestamp>
- <x_object_modified_by>chazapis</x_object_modified_by>
- </object>
- <object>...</object>
- </container>
-
-For more examples of container details returned in JSON/XML formats refer to the OOS API documentation. In addition to the OOS API, Pithos returns more fields that should help with synchronization.
-
-=========================== ===============================
-Return Code Description
-=========================== ===============================
-200 (OK) The request succeeded
-204 (No Content) The account has no containers (only for non-extended replies)
-304 (Not Modified) The container has not been modified
-412 (Precondition Failed) The condition set can not be satisfied
-=========================== ===============================
-
-Will use a ``200`` return code if the reply is of type JSON/XML.
-
-
-PUT
-"""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-X-Container-Policy-* Container behavior and limits
-X-Container-Meta-* Optional user defined metadata
-==================== ================================
-
-No reply content/headers.
-
-If no policy is defined, the container will be created with the default values.
-Available policy directives:
-
-* ``versioning``: Set to ``auto`` or ``none`` (default is ``auto``)
-* ``quota``: Size limit in KB (default is ``0`` - unlimited)
-
-If the container already exists, the operation is equal to a ``POST`` with ``update`` defined.
-
-================ ===============================
-Return Code Description
-================ ===============================
-201 (Created) The container has been created
-202 (Accepted) The request has been accepted
-================ ===============================
-
-
-POST
-""""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-Content-Length The size of the supplied data (optional, to upload)
-Content-Type The MIME content type of the supplied data (optional, to upload)
-Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
-X-Container-Policy-* Container behavior and limits
-X-Container-Meta-* Optional user defined metadata
-==================== ================================
-
-|
-
-====================== ============================================
-Request Parameter Name Value
-====================== ============================================
-format Optional hash list reply type (can be ``json`` or ``xml``)
-update Do not replace metadata/policy (no value parameter)
-====================== ============================================
-
-No reply content/headers, except when uploading data, where the reply consists of a list of hashes for the blocks received (in the format specified).
-
-The operation will overwrite all user defined metadata, except if ``update`` is defined.
-To change policy, include an ``X-Container-Policy-*`` header with the name in the key. If no ``X-Container-Policy-*`` header is present, no changes will be applied to policy. The ``update`` parameter also applies to policy - deleted values will revert to defaults. To delete/revert a specific policy directive, use ``update`` and an empty header value. See container ``PUT`` for a reference of policy directives.
-
-To upload blocks of data to the container, set ``Content-Type`` to ``application/octet-stream`` and ``Content-Length`` to a valid value (except if using ``chunked`` as the ``Transfer-Encoding``).
-
-================ ===============================
-Return Code Description
-================ ===============================
-202 (Accepted) The request has been accepted
-================ ===============================
-
-
-DELETE
-""""""
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-until Optional timestamp
-====================== ===================================
-
-If ``until`` is defined, the container is "purged" up to that time (the history of all objects up to then is deleted).
-
-No reply content/headers.
-
-================ ===============================
-Return Code Description
-================ ===============================
-204 (No Content) The request succeeded
-409 (Conflict) The container is not empty
-================ ===============================
-
-
-Object Level
-^^^^^^^^^^^^
-
-List of operations:
-
-========= =================================
-Operation Description
-========= =================================
-HEAD Retrieve object metadata
-GET Read object data
-PUT Write object data or copy/move object
-COPY Copy object
-MOVE Move object
-POST Update object metadata/data
-DELETE Delete object
-========= =================================
-
-
-HEAD
-""""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-If-Match Retrieve if ETags match
-If-None-Match Retrieve if ETags don't match
-If-Modified-Since Retrieve if object has changed since provided timestamp
-If-Unmodified-Since Retrieve if object has not changed since provided timestamp
-==================== ================================
-
-|
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-version Optional version identifier
-====================== ===================================
-
-|
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-ETag The ETag of the object
-Content-Length The size of the object
-Content-Type The MIME content type of the object
-Last-Modified The last object modification date (regardless of version)
-Content-Encoding The encoding of the object (optional)
-Content-Disposition The presentation style of the object (optional)
-X-Object-Hash The Merkle hash
-X-Object-UUID The object's UUID
-X-Object-Version The object's version identifier
-X-Object-Version-Timestamp The object's version timestamp
-X-Object-Modified-By The user that comitted the object's version
-X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
-X-Object-Sharing Object permissions (optional)
-X-Object-Shared-By Object inheriting permissions (optional)
-X-Object-Allowed-To Allowed actions on object (optional)
-X-Object-Public Object's publicly accessible URI (optional)
-X-Object-Meta-* Optional user defined metadata
-========================== ===============================
-
-|
-
-================ ===============================
-Return Code Description
-================ ===============================
-200 (No Content) The request succeeded
-================ ===============================
-
-
-GET
-"""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-Range Optional range of data to retrieve
-If-Range Retrieve the missing part if entity is unchanged; otherwise, retrieve the entire new entity (used together with Range header)
-If-Match Retrieve if ETags match
-If-None-Match Retrieve if ETags don't match
-If-Modified-Since Retrieve if object has changed since provided timestamp
-If-Unmodified-Since Retrieve if object has not changed since provided timestamp
-==================== ================================
-
-|
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-format Optional extended reply type (can be ``json`` or ``xml``)
-hashmap Optional request for hashmap (no value parameter)
-version Optional version identifier or ``list`` (specify a format if requesting a list)
-====================== ===================================
-
-The reply is the object's data (or part of it), except if a hashmap is requested with ``hashmap``, or a version list with ``version=list`` (in both cases an extended reply format must be specified). Object headers (as in a ``HEAD`` request) are always included.
-
-Hashmaps expose the underlying storage format of the object. Note that each hash is computed after trimming trailing null bytes of the corresponding block. The ``X-Object-Hash`` header reports the single Merkle hash of the object's hashmap (refer to http://bittorrent.org/beps/bep_0030.html for more information).
-
-Example ``format=json`` reply:
-
-::
-
- {"block_hash": "sha1", "hashes": ["7295c41da03d7f916440b98e32c4a2a39351546c", ...], "block_size": 131072, "bytes": 242}
-
-Example ``format=xml`` reply:
-
-::
-
- <?xml version="1.0" encoding="UTF-8"?>
- <object name="file" bytes="24223726" block_size="131072" block_hash="sha1">
- <hash>7295c41da03d7f916440b98e32c4a2a39351546c</hash>
- <hash>...</hash>
- </object>
-
-Version lists include the version identifier and timestamp for each available object version. Version identifiers can be arbitrary strings, so use the timestamp to find newer versions.
-
-Example ``format=json`` reply:
-
-::
-
- {"versions": [[85, "1322734861.248469"], [86, "1322734905.009272"], ...]}
-
-Example ``format=xml`` reply:
-
-::
-
- <?xml version="1.0" encoding="UTF-8"?>
- <object name="file">
- <version timestamp="1322734861.248469">85</version>
- <version timestamp="1322734905.009272">86</version>
- <version timestamp="...">...</version>
- </object>
-
-The ``Range`` header may include multiple ranges, as outlined in RFC2616. Then the ``Content-Type`` of the reply will be ``multipart/byteranges`` and each part will include a ``Content-Range`` header.
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-ETag The ETag of the object
-Content-Length The size of the data returned
-Content-Type The MIME content type of the object
-Content-Range The range of data included (only on a single range request)
-Last-Modified The last object modification date (regardless of version)
-Content-Encoding The encoding of the object (optional)
-Content-Disposition The presentation style of the object (optional)
-X-Object-Hash The Merkle hash
-X-Object-UUID The object's UUID
-X-Object-Version The object's version identifier
-X-Object-Version-Timestamp The object's version timestamp
-X-Object-Modified-By The user that comitted the object's version
-X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
-X-Object-Sharing Object permissions (optional)
-X-Object-Shared-By Object inheriting permissions (optional)
-X-Object-Allowed-To Allowed actions on object (optional)
-X-Object-Public Object's publicly accessible URI (optional)
-X-Object-Meta-* Optional user defined metadata
-========================== ===============================
-
-Sharing headers (``X-Object-Sharing``, ``X-Object-Shared-By`` and ``X-Object-Allowed-To``) are only included if the request is for the object's latest version (no specific ``version`` parameter is set).
-
-=========================== ==============================
-Return Code Description
-=========================== ==============================
-200 (OK) The request succeeded
-206 (Partial Content) The range request succeeded
-304 (Not Modified) The object has not been modified
-412 (Precondition Failed) The condition set can not be satisfied
-416 (Range Not Satisfiable) The requested range is out of limits
-=========================== ==============================
-
-
-PUT
-"""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-If-Match Put if ETags match with current object
-If-None-Match Put if ETags don't match with current object
-ETag The MD5 hash of the object (optional to check written data)
-Content-Length The size of the data written
-Content-Type The MIME content type of the object
-Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
-X-Copy-From The source path in the form ``/<container>/<object>``
-X-Move-From The source path in the form ``/<container>/<object>``
-X-Source-Account The source account to copy/move from
-X-Source-Version The source version to copy from
-Content-Encoding The encoding of the object (optional)
-Content-Disposition The presentation style of the object (optional)
-X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
-X-Object-Sharing Object permissions (optional)
-X-Object-Public Object is publicly accessible (optional)
-X-Object-Meta-* Optional user defined metadata
-==================== ================================
-
-|
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-format Optional extended request/conflict response type (can be ``json`` or ``xml``)
-hashmap Optional hashmap provided instead of data (no value parameter)
-====================== ===================================
-
-The request is the object's data (or part of it), except if a hashmap is provided (using ``hashmap`` and ``format`` parameters). If using a hashmap and all different parts are stored in the server, the object is created. Otherwise the server returns Conflict (409) with the list of the missing parts (in simple text format, with one hash per line, or in JSON/XML - depending on the ``format`` parameter).
-
-Hashmaps should be formatted as outlined in ``GET``.
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-ETag The MD5 hash of the object
-X-Object-Version The object's new version
-========================== ===============================
-
-The ``X-Object-Sharing`` header may include either a ``read=...`` comma-separated user/group list, or a ``write=...`` comma-separated user/group list, or both separated by a semicolon (``;``). Groups are specified as ``<account>:<group>``. To publish the object, set ``X-Object-Public`` to ``true``. To unpublish, set to ``false``, or use an empty header value.
-
-============================== ==============================
-Return Code Description
-============================== ==============================
-201 (Created) The object has been created
-409 (Conflict) The object can not be created from the provided hashmap (a list of missing hashes will be included in the reply)
-411 (Length Required) Missing ``Content-Length`` or ``Content-Type`` in the request
-413 (Request Entity Too Large) Insufficient quota to complete the request
-422 (Unprocessable Entity) The MD5 checksum of the data written to the storage system does not match the (optionally) supplied ETag value
-============================== ==============================
-
-
-COPY
-""""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-If-Match Proceed if ETags match with object
-If-None-Match Proceed if ETags don't match with object
-Destination The destination path in the form ``/<container>/<object>``
-Destination-Account The destination account to copy to
-Content-Type The MIME content type of the object (optional :sup:`*`)
-Content-Encoding The encoding of the object (optional)
-Content-Disposition The presentation style of the object (optional)
-X-Source-Version The source version to copy from
-X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
-X-Object-Sharing Object permissions (optional)
-X-Object-Public Object is publicly accessible (optional)
-X-Object-Meta-* Optional user defined metadata
-==================== ================================
-
-:sup:`*` *When using django locally with the supplied web server, use the ignore_content_type parameter, or do provide a valid Content-Type, as a type of text/plain is applied by default to all requests. Client software should always state ignore_content_type, except when a Content-Type is explicitly defined by the user.*
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-format Optional conflict response type (can be ``json`` or ``xml``)
-ignore_content_type Ignore the supplied Content-Type
-====================== ===================================
-
-Refer to ``PUT``/``POST`` for a description of request headers. Metadata is also copied, updated with any values defined. Sharing/publishing options are not copied.
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-X-Object-Version The object's new version
-========================== ===============================
-
-|
-
-============================== ==============================
-Return Code Description
-============================== ==============================
-201 (Created) The object has been created
-413 (Request Entity Too Large) Insufficient quota to complete the request
-============================== ==============================
-
-
-MOVE
-""""
-
-Same as ``COPY``, without the ``X-Source-Version`` request header. The ``MOVE`` operation is always applied on the latest version.
-
-
-POST
-""""
-
-==================== ================================
-Request Header Name Value
-==================== ================================
-If-Match Proceed if ETags match with object
-If-None-Match Proceed if ETags don't match with object
-Content-Length The size of the data written (optional, to update)
-Content-Type The MIME content type of the object (optional, to update)
-Content-Range The range of data supplied (optional, to update)
-Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
-Content-Encoding The encoding of the object (optional)
-Content-Disposition The presentation style of the object (optional)
-X-Source-Object Update with data from the object at path ``/<container>/<object>`` (optional, to update)
-X-Source-Account The source account to update from
-X-Source-Version The source version to update from (optional, to update)
-X-Object-Bytes The updated object's final size (optional, when updating)
-X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
-X-Object-Sharing Object permissions (optional)
-X-Object-Public Object is publicly accessible (optional)
-X-Object-Meta-* Optional user defined metadata
-==================== ================================
-
-|
-
-====================== ============================================
-Request Parameter Name Value
-====================== ============================================
-format Optional conflict response type (can be ``json`` or ``xml``)
-update Do not replace metadata (no value parameter)
-====================== ============================================
-
-The ``Content-Encoding``, ``Content-Disposition``, ``X-Object-Manifest`` and ``X-Object-Meta-*`` headers are considered to be user defined metadata. An operation without the ``update`` parameter will overwrite all previous values and remove any keys not supplied. When using ``update`` any metadata with an empty value will be deleted.
-
-To change permissions, include an ``X-Object-Sharing`` header (as defined in ``PUT``). To publish, include an ``X-Object-Public`` header, with a value of ``true``. If no such headers are defined, no changes will be applied to sharing/public. Use empty values to remove permissions/unpublish (unpublishing also works with ``false`` as a header value). Sharing options are applied to the object - not its versions.
-
-To update an object's data:
-
-* Either set ``Content-Type`` to ``application/octet-stream``, or provide an object with ``X-Source-Object``. If ``Content-Type`` has some other value, it will be ignored and only the metadata will be updated.
-* If the data is supplied in the request (using ``Content-Type`` instead of ``X-Source-Object``), a valid ``Content-Length`` header is required - except if using chunked transfers (set ``Transfer-Encoding`` to ``chunked``).
-* Set ``Content-Range`` as specified in RFC2616, with the following differences:
-
- * Client software MAY omit ``last-byte-pos`` of if the length of the range being transferred is unknown or difficult to determine.
- * Client software SHOULD not specify the ``instance-length`` (use a ``*``), unless there is a reason for performing a size check at the server.
-* If ``Content-Range`` used has a ``byte-range-resp-spec = *``, data will be appended to the object.
-
-Optionally, truncate the updated object to the desired length with the ``X-Object-Bytes`` header.
-
-A data update will trigger an ETag change. Updated ETags may happen asynchronously and appear at the server with a delay.
-
-No reply content. No reply headers if only metadata is updated.
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-ETag The new ETag of the object (data updated)
-X-Object-Version The object's new version
-========================== ===============================
-
-|
-
-============================== ==============================
-Return Code Description
-============================== ==============================
-202 (Accepted) The request has been accepted (not a data update)
-204 (No Content) The request succeeded (data updated)
-411 (Length Required) Missing ``Content-Length`` in the request
-413 (Request Entity Too Large) Insufficient quota to complete the request
-416 (Range Not Satisfiable) The supplied range is invalid
-============================== ==============================
-
-The ``POST`` method can also be used for creating an object via a standard HTML form. If the request ``Content-Type`` is ``multipart/form-data``, none of the above headers will be processed. The form should have an ``X-Object-Data`` field, as in the following example. The token is passed as a request parameter. ::
-
- <form method="post" action="https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt?X-Auth-Token=0000" enctype="multipart/form-data">
- <input type="file" name="X-Object-Data">
- <input type="submit">
- </form>
-
-This will create/override the object with the given name, as if using ``PUT``. The ``Content-Type`` of the object will be set to the value of the corresponding header sent in the part of the request containing the data (usually, automatically handled by the browser). Metadata, sharing and other object attributes can not be set this way. The response will contain the object's ETag.
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-ETag The MD5 hash of the object
-X-Object-Version The object's new version
-========================== ===============================
-
-|
-
-============================== ==============================
-Return Code Description
-============================== ==============================
-201 (Created) The object has been created
-413 (Request Entity Too Large) Insufficient quota to complete the request
-============================== ==============================
-
-
-DELETE
-""""""
-
-====================== ===================================
-Request Parameter Name Value
-====================== ===================================
-until Optional timestamp
-====================== ===================================
-
-If ``until`` is defined, the object is "purged" up to that time (the history up to then is deleted).
-
-No reply content/headers.
-
-=========================== ==============================
-Return Code Description
-=========================== ==============================
-204 (No Content) The request succeeded
-=========================== ==============================
-
-Sharing and Public Objects
-^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Read and write control in Pithos is managed by setting appropriate permissions with the ``X-Object-Sharing`` header. The permissions are applied using directory-based inheritance. A directory is an object with the corresponding content type. The default delimiter is ``/``. Thus, each set of authorization directives is applied to all objects in the directory object where the corresponding ``X-Object-Sharing`` header is defined. If there are nested/overlapping permissions, the closest to the object is applied. When retrieving an object, the ``X-Object-Shared-By`` header reports where it gets its permissions from. If not present, the object is the actual source of authorization directives.
-
-A user may ``GET`` another account or container. The result will include a limited reply, containing only the allowed containers or objects respectively. A top-level request with an authentication token, will return a list of allowed accounts, so the user can easily find out which other users share objects. The ``X-Object-Allowed-To`` header lists the actions allowed on an object, if it does not belong to the requesting user.
-
-Objects that are marked as public, via the ``X-Object-Public`` meta, are also available at the corresponding URI returned for ``HEAD`` or ``GET``. Requests for public objects do not need to include an ``X-Auth-Token``. Pithos will ignore request parameters and only include the following headers in the reply (all ``X-Object-*`` meta is hidden):
-
-========================== ===============================
-Reply Header Name Value
-========================== ===============================
-ETag The ETag of the object
-Content-Length The size of the data returned
-Content-Type The MIME content type of the object
-Content-Range The range of data included (only on a single range request)
-Last-Modified The last object modification date (regardless of version)
-Content-Encoding The encoding of the object (optional)
-Content-Disposition The presentation style of the object (optional)
-========================== ===============================
-
-Public objects are not included and do not influence cross-user listings. They are, however, readable by all users.
-
-Summary
-^^^^^^^
-
-List of differences from the OOS API:
-
-* Support for ``X-Account-Meta-*`` style headers at the account level. Use ``POST`` to update.
-* Support for ``X-Container-Meta-*`` style headers at the container level. Can be set when creating via ``PUT``. Use ``POST`` to update.
-* Header ``X-Container-Object-Meta`` at the container level and parameter ``meta`` in container listings. (**TBD**)
-* Account and container policies to manage behavior and limits. Container behavior overrides account settings. Account quota sets the maximum bytes limit, regardless of container values.
-* Headers ``X-Container-Block-*`` at the container level, exposing the underlying storage characteristics.
-* All metadata replies, at all levels, include latest modification information.
-* At all levels, a ``HEAD`` or ``GET`` request may use ``If-Modified-Since`` and ``If-Unmodified-Since`` headers.
-* Container/object lists include more fields if the reply is of type JSON/XML. Some names are kept to their OOS API equivalents for compatibility.
-* Option to include only shared containers/objects in listings.
-* Object metadata allowed, in addition to ``X-Object-Meta-*``: ``Content-Encoding``, ``Content-Disposition``, ``X-Object-Manifest``. These are all replaced with every update operation, except if using the ``update`` parameter (in which case individual keys can also be deleted). Deleting meta by providing empty values also works when copying/moving an object.
-* Multi-range object ``GET`` support as outlined in RFC2616.
-* Object hashmap retrieval through ``GET`` and the ``format`` parameter.
-* Object create via hashmap through ``PUT`` and the ``format`` parameter.
-* The object's Merkle hash is always returned in the ``X-Object-Hash`` header.
-* The object's UUID is always returned in the ``X-Object-UUID`` header. The UUID remains unchanged, even when the object's data or metadata changes, or the object is moved to another path (is renamed). A new UUID is assigned when creating or copying an object.
-* Object create using ``POST`` to support standard HTML forms.
-* Partial object updates through ``POST``, using the ``Content-Length``, ``Content-Type``, ``Content-Range`` and ``Transfer-Encoding`` headers. Use another object's data to update with ``X-Source-Object`` and ``X-Source-Version``. Truncate with ``X-Object-Bytes``.
-* Include new version identifier in replies for object replace/change requests.
-* Object ``MOVE`` support and ``ignore_content_type`` parameter in both ``COPY`` and ``MOVE``.
-* Conditional object create/update operations, using ``If-Match`` and ``If-None-Match`` headers.
-* Time-variant account/container listings via the ``until`` parameter.
-* Object versions - parameter ``version`` in ``HEAD``/``GET`` (list versions with ``GET``), ``X-Object-Version-*`` meta in replies, ``X-Source-Version`` in ``PUT``/``COPY``.
-* Sharing/publishing with ``X-Object-Sharing``, ``X-Object-Public`` at the object level. Cross-user operations are allowed - controlled by sharing directives. Available actions in cross-user requests are reported with ``X-Object-Allowed-To``. Permissions may include groups defined with ``X-Account-Group-*`` at the account level. These apply to the object - not its versions.
-* Support for directory-based inheritance when enforcing permissions. Parent object carrying the authorization directives is reported in ``X-Object-Shared-By``.
-* Copy and move between accounts with ``X-Source-Account`` and ``Destination-Account`` headers.
-* Large object support with ``X-Object-Manifest``.
-* Trace the user that created/modified an object with ``X-Object-Modified-By``.
-* Purge container/object history with the ``until`` parameter in ``DELETE``.
-
-Clarifications/suggestions:
-
-* All non-ASCII characters in headers should be URL-encoded.
-* Authentication is done by another system. The token is used in the same way, but it is obtained differently. The top level ``GET`` request is kept compatible with the OOS API and allows for guest/testing operations.
-* Some processing is done in the variable part of all ``X-*-Meta-*`` headers. If it includes underscores, they will be converted to dashes and the first letter of all intra-dash strings will be capitalized.
-* A ``GET`` reply for a level will include all headers of the corresponding ``HEAD`` request.
-* To avoid conflicts between objects and virtual directory markers in container listings, it is recommended that object names do not end with the delimiter used.
-* The ``Accept`` header may be used in requests instead of the ``format`` parameter to specify the desired request/reply format. The parameter overrides the header.
-* Container/object lists use a ``200`` return code if the reply is of type JSON/XML. The reply will include an empty JSON/XML.
-* In headers, dates are formatted according to RFC 1123. In extended information listings, the ``last_modified`` field is formatted according to ISO 8601 (for OOS API compatibility). All other fields (Pithos extensions) use integer tiemstamps.
-* The ``Last-Modified`` header value always reflects the actual latest change timestamp, regardless of time control parameters and version requests. Time precondition checks with ``If-Modified-Since`` and ``If-Unmodified-Since`` headers are applied to this value.
-* A copy/move using ``PUT``/``COPY``/``MOVE`` will always update metadata, keeping all old values except the ones redefined in the request headers.
-* A ``HEAD`` or ``GET`` for an ``X-Object-Manifest`` object, will include modified ``Content-Length`` and ``ETag`` headers, according to the characteristics of the objects under the specified prefix. The ``Etag`` will be the MD5 hash of the corresponding ETags concatenated. In extended container listings there is no metadata processing.
-
-The Pithos Client
------------------
-
-User Experience
-^^^^^^^^^^^^^^^
-
-Hopefully this API will allow for a multitude of client implementations, each supporting a different device or operating system. All clients will be able to manipulate containers and objects - even software only designed for OOS API compatibility. But a Pithos interface should not be only about showing containers and folders. There are some extra user interface elements and functionalities that should be common to all implementations.
-
-Upon entrance to the service, a user is presented with the following elements - which can be represented as folders or with other related icons:
-
-* The ``home`` element, which is used as the default entry point to the user's "files". Objects under ``home`` are represented in the usual hierarchical organization of folders and files.
-* The ``trash`` element, which contains files that have been marked for deletion, but can still be recovered.
-* The ``shared`` element, which contains all objects shared by the user to other users of the system.
-* The ``others`` element, which contains all objects that other users share with the user.
-* The ``groups`` element, which contains the names of groups the user has defined. Each group consists of a user list. Group creation, deletion, and manipulation is carried out by actions originating here.
-* The ``history`` element, which allows browsing past instances of ``home`` and - optionally - ``trash``.
-
-Objects in Pithos can be:
-
-* Moved to trash and then deleted.
-* Shared with specific permissions.
-* Made public (shared with non-Pithos users).
-* Restored from previous versions.
-
-Some of these functions are performed by the client software and some by the Pithos server.
-
-In the first version of Pithos, objects could also be assigned custom tags. This is no longer supported. Existing deployments can migrate tags into a specific metadata value, i.e. ``X-Object-Meta-Tags``.
-
-Implementation Guidelines
-^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Pithos clients should use the ``pithos`` and ``trash`` containers for active and inactive objects respectively. If any of these containers is not found, the client software should create it, without interrupting the user's workflow. The ``home`` element corresponds to ``pithos`` and the ``trash`` element to ``trash``. Use ``PUT`` with the ``X-Move-From`` header, or ``MOVE`` to transfer objects from one container to the other. Use ``DELETE`` to remove from ``pithos`` without trashing, or to remove from ``trash``. When moving objects, detect naming conflicts with the ``If-Match`` or ``If-None-Match`` headers. Such conflicts should be resolved by the user.
-
-Object names should use the ``/`` delimiter to impose a hierarchy of folders and files.
-
-The ``shared`` element should be implemented as a read-only view of the ``pithos`` container, using the ``shared`` parameter when listing objects. The ``others`` element, should start with a top-level ``GET`` to retrieve the list of accounts accessible to the user. It is suggested that the client software hides the next step of navigation - the container - if it only includes ``pithos`` and forwards the user directly to the objects.
-
-Public objects are not included in ``shared`` and ``others`` listings. It is suggested that they are marked in a visually distinctive way in ``pithos`` listings (for example using an icon overlay).
-
-A special application menu, or a section in application preferences, should be devoted to managing groups (the ``groups`` element). All group-related actions are implemented at the account level.
-
-Browsing past versions of objects should be available both at the object and the container level. At the object level, a list of past versions can be included in the screen showing details or more information on the object (metadata, permissions, etc.). At the container level, it is suggested that clients use a ``history`` element, which presents to the user a read-only, time-variable view of ``pithos`` contents. This can be accomplished via the ``until`` parameter in listings. Optionally, ``history`` may include ``trash``.
-
-Uploading and downloading data
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-By using hashmaps to upload and download objects the corresponding operations can complete much faster.
-
-In the case of an upload, only the missing blocks will be submitted to the server:
-
-* Calculate the hash value for each block of the object to be uploaded. Use the hash algorithm and block size of the destination container.
-* Send a hashmap ``PUT`` request for the object.
-
- * Server responds with status ``201`` (Created):
-
- * Blocks are already on the server. The object has been created. Done.
-
- * Server responds with status ``409`` (Conflict):
-
- * Server's response body contains the hashes of the blocks that do not exist on the server.
- * For each hash value in the server's response (or all hashes together):
-
- * Send a ``POST`` request to the destination container with the corresponding data.
-
-* Repeat hashmap ``PUT``. Fail if the server's response is not ``201``.
-
-Consulting hashmaps when downloading allows for resuming partially transferred objects. The client should retrieve the hashmap from the server and compare it with the hashmap computed from the respective local file. Any missing parts can be downloaded with ``GET`` requests with the additional ``Range`` header.
-
-Syncing
-^^^^^^^
-
-Consider the following algorithm for synchronizing a local folder with the server. The "state" is the complete object listing, with the corresponding attributes.
-
-::
-
- L: local state (stored state from last sync with the server)
- C: current state (state computed right before sync)
- S: server state
-
- if C == L:
- # No local changes
- if S == L:
- # No remote changes, nothing to do
- else:
- # Update local state to match that of the server
- L = S
- else:
- # We have local changes
- if S == L:
- # No remote changes, update the server
- S = C
- L = S
- else:
- # Both we and server have changes
- if C == S:
- # We were lucky, we did the same change
- L = S
- else:
- # We have conflicting changes
- resolve conflict
-
-Notes:
-
-* States represent file hashes (it is suggested to use Merkle). Deleted or non-existing files are assumed to have a magic hash (e.g. empty string).
-* Updating a state (either local or remote) implies downloading, uploading or deleting the appropriate file.
-
-Recommended Practices and Examples
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Assuming an authentication token is obtained, the following high-level operations are available - shown with ``curl``:
-
-* Get account information ::
-
- curl -X HEAD -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user
-
-* List available containers ::
-
- curl -X GET -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user
-
-* Get container information ::
-
- curl -X HEAD -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/pithos
-
-* Add a new container ::
-
- curl -X PUT -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/test
-
-* Delete a container ::
-
- curl -X DELETE -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/test
-
-* List objects in a container ::
-
- curl -X GET -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/pithos
-
-* List objects in a container (extended reply) ::
-
- curl -X GET -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/pithos?format=json
-
- It is recommended that extended replies are cached and subsequent requests utilize the ``If-Modified-Since`` header.
-
-* List metadata keys used by objects in a container
-
- Will be in the ``X-Container-Object-Meta`` reply header, included in container information or object list (``HEAD`` or ``GET``). (**TBD**)
-
-* List objects in a container having a specific meta defined ::
-
- curl -X GET -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/pithos?meta=favorites
-
-* Retrieve an object ::
-
- curl -X GET -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/pithos/README.txt
-
-* Retrieve an object (specific ranges of data) ::
-
- curl -X GET -D - \
- -H "X-Auth-Token: 0000" \
- -H "Range: bytes=0-9" \
- https://pithos.dev.grnet.gr/v1/user/pithos/README.txt
-
- This will return the first 10 bytes. To get the first 10, bytes 30-39 and the last 100 use ``Range: bytes=0-9,30-39,-100``.
-
-* Add a new object (folder type) (**TBD**) ::
-
- curl -X PUT -D - \
- -H "X-Auth-Token: 0000" \
- -H "Content-Type: application/directory" \
- https://pithos.dev.grnet.gr/v1/user/pithos/folder
-
-* Add a new object ::
-
- curl -X PUT -D - \
- -H "X-Auth-Token: 0000" \
- -H "Content-Type: text/plain" \
- -T EXAMPLE.txt
- https://pithos.dev.grnet.gr/v1/user/pithos/folder/EXAMPLE.txt
-
-* Update an object ::
-
- curl -X POST -D - \
- -H "X-Auth-Token: 0000" \
- -H "Content-Length: 10" \
- -H "Content-Type: application/octet-stream" \
- -H "Content-Range: bytes 10-19/*" \
- -d "0123456789" \
- https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
-
- This will update bytes 10-19 with the data specified.
-
-* Update an object (append) ::
-
- curl -X POST -D - \
- -H "X-Auth-Token: 0000" \
- -H "Content-Length: 10" \
- -H "Content-Type: application/octet-stream" \
- -H "Content-Range: bytes */*" \
- -d "0123456789" \
- https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
-
-* Update an object (truncate) ::
-
- curl -X POST -D - \
- -H "X-Auth-Token: 0000" \
- -H "X-Source-Object: /folder/EXAMPLE.txt" \
- -H "Content-Range: bytes 0-0/*" \
- -H "X-Object-Bytes: 0" \
- https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
-
- This will truncate the object to 0 bytes.
-
-* Add object metadata ::
-
- curl -X POST -D - \
- -H "X-Auth-Token: 0000" \
- -H "X-Object-Meta-First: first_meta_value" \
- -H "X-Object-Meta-Second: second_meta_value" \
- https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
-
-* Delete object metadata ::
-
- curl -X POST -D - \
- -H "X-Auth-Token: 0000" \
- -H "X-Object-Meta-First: first_meta_value" \
- https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
-
- Metadata can only be "set". To delete ``X-Object-Meta-Second``, reset all metadata.
-
-* Delete an object ::
-
- curl -X DELETE -D - \
- -H "X-Auth-Token: 0000" \
- https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
projects / pithos / commitdiff