1 Pithos v2 Developer Guide
2 =========================
7 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.
9 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.
11 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.
13 This document's goals are:
15 * Define the Pithos ReST API that allows the storage and retrieval of data and metadata via HTTP calls
16 * Specify metadata semantics and user interface guidelines for a common experience across client software implementations
18 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.
20 Whatever marked as to be determined (**TBD**), should not be considered by implementors.
25 ========================= ================================
27 ========================= ================================
28 0.7 (Nov 21, 2011) Suggest upload/download methods using hashmaps.
29 \ Propose syncing algorithm.
30 \ Support cross-account object copy and move.
31 \ Pass token as a request parameter when using ``POST`` via an HTML form.
32 \ Optionally use source account to update object from another object.
33 \ Use container ``POST`` to upload missing blocks of data.
34 \ Report policy in account headers.
35 \ Add insufficient quota reply.
36 \ Use special meta to always report Merkle hash.
37 0.6 (Sept 13, 2011) Reply with Merkle hash as the ETag when updating objects.
38 \ Include version id in object replace/change replies.
39 \ Change conflict (409) replies format to text.
40 \ Tags should be migrated to a meta value.
41 \ Container ``PUT`` updates metadata/policy.
42 \ Report allowed actions in shared object replies.
43 \ Provide ``https://hostname/login`` for Shibboleth authentication.
44 \ Use ``hashmap`` parameter in object ``GET``/``PUT`` to use hashmaps.
45 0.5 (July 22, 2011) Object update from another object's data.
46 \ Support object truncate.
47 \ Create object using a standard HTML form.
48 \ Purge container/object history.
49 \ List other accounts that share objects with a user.
50 \ List shared containers/objects.
51 \ Update implementation guidelines.
52 \ Check preconditions when creating/updating objects.
53 0.4 (July 01, 2011) Object permissions and account groups.
54 \ Control versioning behavior and container quotas with container policy directives.
55 \ Support updating/deleting individual metadata with ``POST``.
56 \ Create object using hashmap.
57 0.3 (June 14, 2011) Large object support with ``X-Object-Manifest``.
58 \ Allow for publicly available objects via ``https://hostname/public``.
59 \ Support time-variant account/container listings.
60 \ Add source version when duplicating with ``PUT``/``COPY``.
61 \ Request version in object ``HEAD``/``GET`` requests (list versions with ``GET``).
62 0.2 (May 31, 2011) Add object meta listing and filtering in containers.
63 \ Include underlying storage characteristics in container meta.
64 \ Support for partial object updates through ``POST``.
65 \ Expose object hashmaps through ``GET``.
66 \ Support for multi-range object ``GET`` requests.
67 0.1 (May 17, 2011) Initial release. Based on OpenStack Object Storage Developer Guide API v1 (Apr. 15, 2011).
68 ========================= ================================
70 Pithos Users and Authentication
71 -------------------------------
73 Pithos keeps separate databases for users and objects.
75 Each user is uniquely identified by the ``Uniq`` field. This should be used as the user's account in the API. The API uses the ``Token`` field to authenticate a user, thus allowing cross-account requests. All API requests require a token.
77 User entries can be modified/added via the management interface available at ``https://hostname/admin``.
79 Pithos is also compatible with Shibboleth (http://shibboleth.internet2.edu/). The connection between Shibboleth and Pithos is done by ``https://hostname/login``. An application that wishes to connect to Pithos, but does not have a token, should redirect the user to the login URI.
81 The login URI accepts the following parameters:
83 ====================== =========================
84 Request Parameter Name Value
85 ====================== =========================
86 next The URI to redirect to when the process is finished
87 renew Force token renewal (no value parameter)
88 ====================== =========================
90 The login process starts by redirecting the user to an external URI (controlled by Shibboleth), where the actual authentication credentials are entered. Then, the user is redirected back to the login URI from Shibboleth, with various identification information in the request headers.
92 If the user does not exist in the database, Pithos adds the user and creates a random token. If the user exists, the token has not expired and ``renew`` is not set, the existing token is reused. Finally, the login URI redirects to the URI provided with ``next``, adding the ``user`` and ``token`` parameters, which contain the ``Uniq`` and ``Token`` fields respectively.
97 The URI requests supported by the Pithos API follow one of the following forms:
99 * Top level: ``https://hostname/v1/``
100 * Account level: ``https://hostname/v1/<account>``
101 * Container level: ``https://hostname/v1/<account>/<container>``
102 * Object level: ``https://hostname/v1/<account>/<container>/<object>``
104 All requests must include an ``X-Auth-Token`` - as a header, or a parameter.
106 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.
108 ========================= ================================
109 Return Code Description
110 ========================= ================================
111 400 (Bad Request) The request is invalid
112 401 (Unauthorized) Missing or invalid token
113 403 (Forbidden) Request not allowed
114 404 (Not Found) The requested resource was not found
115 503 (Service Unavailable) The request cannot be completed because of an internal error
116 ========================= ================================
123 ========= ==================
124 Operation Description
125 ========= ==================
126 GET Authentication (for compatibility with the OOS API) or list allowed accounts
127 ========= ==================
132 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.
134 ================ =====================
135 Return Code Description
136 ================ =====================
137 204 (No Content) The request succeeded
138 ================ =====================
140 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.
142 ====================== =========================
143 Request Parameter Name Value
144 ====================== =========================
145 limit The amount of results requested (default is 10000)
146 marker Return containers with name lexicographically after marker
147 format Optional extended reply type (can be ``json`` or ``xml``)
148 ====================== =========================
150 The reply is a list of account names.
151 If a ``format=xml`` or ``format=json`` argument is given, extended information on the accounts will be returned, serialized in the chosen format.
152 For each account, the information will include the following (names will be in lower case and with hyphens replaced with underscores):
154 =========================== ============================
156 =========================== ============================
157 name The name of the account
158 last_modified The last account modification date (regardless of ``until``)
159 =========================== ============================
161 Example ``format=json`` reply:
165 [{"name": "user", "last_modified": "2011-07-19T10:48:16"}, ...]
167 Example ``format=xml`` reply:
171 <?xml version="1.0" encoding="UTF-8"?>
175 <last_modified>2011-07-19T10:48:16</last_modified>
177 <account>...</account>
180 =========================== =====================
181 Return Code Description
182 =========================== =====================
183 200 (OK) The request succeeded
184 204 (No Content) The user has no access to other accounts (only for non-extended replies)
185 =========================== =====================
187 Will use a ``200`` return code if the reply is of type json/xml.
194 ========= ==================
195 Operation Description
196 ========= ==================
197 HEAD Retrieve account metadata
199 POST Update account metadata
200 ========= ==================
205 ==================== ===========================
206 Request Header Name Value
207 ==================== ===========================
208 If-Modified-Since Retrieve if account has changed since provided timestamp
209 If-Unmodified-Since Retrieve if account has not changed since provided timestamp
210 ==================== ===========================
214 ====================== ===================================
215 Request Parameter Name Value
216 ====================== ===================================
217 until Optional timestamp
218 ====================== ===================================
220 Cross-user requests are not allowed to use ``until`` and only include the account modification date in the reply.
222 ========================== =====================
223 Reply Header Name Value
224 ========================== =====================
225 X-Account-Container-Count The total number of containers
226 X-Account-Bytes-Used The total number of bytes stored
227 X-Account-Until-Timestamp The last account modification date until the timestamp provided
228 X-Account-Group-* Optional user defined groups
229 X-Account-Policy-* Account behavior and limits
230 X-Account-Meta-* Optional user defined metadata
231 Last-Modified The last account modification date (regardless of ``until``)
232 ========================== =====================
236 ================ =====================
237 Return Code Description
238 ================ =====================
239 204 (No Content) The request succeeded
240 ================ =====================
246 ==================== ===========================
247 Request Header Name Value
248 ==================== ===========================
249 If-Modified-Since Retrieve if account has changed since provided timestamp
250 If-Unmodified-Since Retrieve if account has not changed since provided timestamp
251 ==================== ===========================
255 ====================== =========================
256 Request Parameter Name Value
257 ====================== =========================
258 limit The amount of results requested (default is 10000)
259 marker Return containers with name lexicographically after marker
260 format Optional extended reply type (can be ``json`` or ``xml``)
261 shared Show only shared containers (no value parameter)
262 until Optional timestamp
263 ====================== =========================
265 The reply is a list of container names. Account headers (as in a ``HEAD`` request) will also be included.
266 Cross-user requests are not allowed to use ``until`` and only include the account/container modification dates in the reply.
268 If a ``format=xml`` or ``format=json`` argument is given, extended information on the containers will be returned, serialized in the chosen format.
269 For each container, the information will include all container metadata (names will be in lower case and with hyphens replaced with underscores):
271 =========================== ============================
273 =========================== ============================
274 name The name of the container
275 count The number of objects inside the container
276 bytes The total size of the objects inside the container
277 last_modified The last container modification date (regardless of ``until``)
278 x_container_until_timestamp The last container modification date until the timestamp provided
279 x_container_policy_* Container behavior and limits
280 x_container_meta_* Optional user defined metadata
281 =========================== ============================
283 For examples of container details returned in JSON/XML formats refer to the OOS API documentation.
285 =========================== =====================
286 Return Code Description
287 =========================== =====================
288 200 (OK) The request succeeded
289 204 (No Content) The account has no containers (only for non-extended replies)
290 304 (Not Modified) The account has not been modified
291 412 (Precondition Failed) The condition set can not be satisfied
292 =========================== =====================
294 Will use a ``200`` return code if the reply is of type json/xml.
300 ==================== ===========================
301 Request Header Name Value
302 ==================== ===========================
303 X-Account-Group-* Optional user defined groups
304 X-Account-Meta-* Optional user defined metadata
305 ==================== ===========================
309 ====================== ============================================
310 Request Parameter Name Value
311 ====================== ============================================
312 update Do not replace metadata/groups (no value parameter)
313 ====================== ============================================
315 No reply content/headers.
317 The operation will overwrite all user defined metadata, except if ``update`` is defined.
318 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.
320 ================ ===============================
321 Return Code Description
322 ================ ===============================
323 202 (Accepted) The request has been accepted
324 ================ ===============================
332 ========= ============================
333 Operation Description
334 ========= ============================
335 HEAD Retrieve container metadata
337 PUT Create/update container
338 POST Update container metadata
339 DELETE Delete container
340 ========= ============================
346 ==================== ===========================
347 Request Header Name Value
348 ==================== ===========================
349 If-Modified-Since Retrieve if container has changed since provided timestamp
350 If-Unmodified-Since Retrieve if container has not changed since provided timestamp
351 ==================== ===========================
355 ====================== ===================================
356 Request Parameter Name Value
357 ====================== ===================================
358 until Optional timestamp
359 ====================== ===================================
361 Cross-user requests are not allowed to use ``until`` and only include the container modification date in the reply.
363 =========================== ===============================
364 Reply Header Name Value
365 =========================== ===============================
366 X-Container-Object-Count The total number of objects in the container
367 X-Container-Bytes-Used The total number of bytes of all objects stored
368 X-Container-Block-Size The block size used by the storage backend
369 X-Container-Block-Hash The hash algorithm used for block identifiers in object hashmaps
370 X-Container-Until-Timestamp The last container modification date until the timestamp provided
371 X-Container-Object-Meta A list with all meta keys used by objects (**TBD**)
372 X-Container-Policy-* Container behavior and limits
373 X-Container-Meta-* Optional user defined metadata
374 Last-Modified The last container modification date (regardless of ``until``)
375 =========================== ===============================
377 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**)
379 ================ ===============================
380 Return Code Description
381 ================ ===============================
382 204 (No Content) The request succeeded
383 ================ ===============================
389 ==================== ===========================
390 Request Header Name Value
391 ==================== ===========================
392 If-Modified-Since Retrieve if container has changed since provided timestamp
393 If-Unmodified-Since Retrieve if container has not changed since provided timestamp
394 ==================== ===========================
398 ====================== ===================================
399 Request Parameter Name Value
400 ====================== ===================================
401 limit The amount of results requested (default is 10000)
402 marker Return containers with name lexicographically after marker
403 prefix Return objects starting with prefix
404 delimiter Return objects up to the delimiter (discussion follows)
405 path Assume ``prefix=path`` and ``delimiter=/``
406 format Optional extended reply type (can be ``json`` or ``xml``)
407 meta Return objects having the specified meta keys (can be a comma separated list)
408 shared Show only shared objects (no value parameter)
409 until Optional timestamp
410 ====================== ===================================
412 The ``path`` parameter overrides ``prefix`` and ``delimiter``. When using ``path``, results will include objects ending in ``delimiter``.
414 The keys given with ``meta`` will be matched with the strings after the ``X-Object-Meta-`` prefix.
416 The reply is a list of object names. Container headers (as in a ``HEAD`` request) will also be included.
417 Cross-user requests are not allowed to use ``until`` and include the following limited set of headers in the reply:
419 =========================== ===============================
420 Reply Header Name Value
421 =========================== ===============================
422 X-Container-Block-Size The block size used by the storage backend
423 X-Container-Block-Hash The hash algorithm used for block identifiers in object hashmaps
424 X-Container-Object-Meta A list with all meta keys used by allowed objects (**TBD**)
425 Last-Modified The last container modification date
426 =========================== ===============================
428 If a ``format=xml`` or ``format=json`` argument is given, extended information on the objects will be returned, serialized in the chosen format.
429 For each object, the information will include all object metadata (names will be in lower case and with hyphens replaced with underscores):
431 ========================== ======================================
433 ========================== ======================================
434 name The name of the object
435 hash The ETag of the object
436 bytes The size of the object
437 content_type The MIME content type of the object
438 content_encoding The encoding of the object (optional)
439 content-disposition The presentation style of the object (optional)
440 last_modified The last object modification date (regardless of version)
441 x_object_hash The Merkle hash
442 x_object_version The object's version identifier
443 x_object_version_timestamp The object's version timestamp
444 x_object_modified_by The user that committed the object's version
445 x_object_manifest Object parts prefix in ``<container>/<object>`` form (optional)
446 x_object_sharing Object permissions (optional)
447 x_object_shared_by Object inheriting permissions (optional)
448 x_object_allowed_to Allowed actions on object (optional)
449 x_object_public Object's publicly accessible URI (optional)
450 x_object_meta_* Optional user defined metadata
451 ========================== ======================================
453 Extended replies may also include virtual directory markers in separate sections of the ``json`` or ``xml`` results.
454 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.
455 In JSON results they appear as dictionaries with only a ``"subdir"`` key. In XML results they appear interleaved with ``<object>`` tags as ``<subdir name="..." />``.
456 In case there is an object with the same name as a virtual directory marker, the object will be returned.
458 For examples of object details returned in JSON/XML formats refer to the OOS API documentation.
460 =========================== ===============================
461 Return Code Description
462 =========================== ===============================
463 200 (OK) The request succeeded
464 204 (No Content) The account has no containers (only for non-extended replies)
465 304 (Not Modified) The container has not been modified
466 412 (Precondition Failed) The condition set can not be satisfied
467 =========================== ===============================
469 Will use a ``200`` return code if the reply is of type json/xml.
475 ==================== ================================
476 Request Header Name Value
477 ==================== ================================
478 X-Container-Policy-* Container behavior and limits
479 X-Container-Meta-* Optional user defined metadata
480 ==================== ================================
482 No reply content/headers.
484 If no policy is defined, the container will be created with the default values.
485 Available policy directives:
487 * ``versioning``: Set to ``auto``, ``manual`` or ``none`` (default is ``manual``)
488 * ``quota``: Size limit in KB (default is ``0`` - unlimited)
490 If the container already exists, the operation is equal to a ``POST`` with ``update`` defined.
492 ================ ===============================
493 Return Code Description
494 ================ ===============================
495 201 (Created) The container has been created
496 202 (Accepted) The request has been accepted
497 ================ ===============================
503 ==================== ================================
504 Request Header Name Value
505 ==================== ================================
506 Content-Length The size of the supplied data (optional, to upload)
507 Content-Type The MIME content type of the supplied data (optional, to upload)
508 Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
509 X-Container-Policy-* Container behavior and limits
510 X-Container-Meta-* Optional user defined metadata
511 ==================== ================================
515 ====================== ============================================
516 Request Parameter Name Value
517 ====================== ============================================
518 update Do not replace metadata/policy (no value parameter)
519 ====================== ============================================
521 No reply content/headers, except when uploading data, where the reply consists of a list of hashes for the blocks received (in a simple text format, with one hash per line).
523 The operation will overwrite all user defined metadata, except if ``update`` is defined.
524 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.
526 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``).
528 ================ ===============================
529 Return Code Description
530 ================ ===============================
531 202 (Accepted) The request has been accepted
532 ================ ===============================
538 ====================== ===================================
539 Request Parameter Name Value
540 ====================== ===================================
541 until Optional timestamp
542 ====================== ===================================
544 If ``until`` is defined, the container is "purged" up to that time (the history of all objects up to then is deleted).
546 No reply content/headers.
548 ================ ===============================
549 Return Code Description
550 ================ ===============================
551 204 (No Content) The request succeeded
552 409 (Conflict) The container is not empty
553 ================ ===============================
561 ========= =================================
562 Operation Description
563 ========= =================================
564 HEAD Retrieve object metadata
566 PUT Write object data or copy/move object
569 POST Update object metadata/data
571 ========= =================================
577 ==================== ================================
578 Request Header Name Value
579 ==================== ================================
580 If-Match Retrieve if ETags match
581 If-None-Match Retrieve if ETags don't match
582 If-Modified-Since Retrieve if object has changed since provided timestamp
583 If-Unmodified-Since Retrieve if object has not changed since provided timestamp
584 ==================== ================================
588 ====================== ===================================
589 Request Parameter Name Value
590 ====================== ===================================
591 version Optional version identifier
592 ====================== ===================================
596 ========================== ===============================
597 Reply Header Name Value
598 ========================== ===============================
599 ETag The ETag of the object
600 Content-Length The size of the object
601 Content-Type The MIME content type of the object
602 Last-Modified The last object modification date (regardless of version)
603 Content-Encoding The encoding of the object (optional)
604 Content-Disposition The presentation style of the object (optional)
605 X-Object-Hash The Merkle hash
606 X-Object-Version The object's version identifier
607 X-Object-Version-Timestamp The object's version timestamp
608 X-Object-Modified-By The user that comitted the object's version
609 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
610 X-Object-Sharing Object permissions (optional)
611 X-Object-Shared-By Object inheriting permissions (optional)
612 X-Object-Allowed-To Allowed actions on object (optional)
613 X-Object-Public Object's publicly accessible URI (optional)
614 X-Object-Meta-* Optional user defined metadata
615 ========================== ===============================
619 ================ ===============================
620 Return Code Description
621 ================ ===============================
622 200 (No Content) The request succeeded
623 ================ ===============================
629 ==================== ================================
630 Request Header Name Value
631 ==================== ================================
632 Range Optional range of data to retrieve
633 If-Range Retrieve the missing part if entity is unchanged; otherwise, retrieve the entire new entity (used together with Range header)
634 If-Match Retrieve if ETags match
635 If-None-Match Retrieve if ETags don't match
636 If-Modified-Since Retrieve if object has changed since provided timestamp
637 If-Unmodified-Since Retrieve if object has not changed since provided timestamp
638 ==================== ================================
642 ====================== ===================================
643 Request Parameter Name Value
644 ====================== ===================================
645 format Optional extended reply type (can be ``json`` or ``xml``)
646 hashmap Optional request for hashmap (no value parameter)
647 version Optional version identifier or ``list`` (specify a format if requesting a list)
648 ====================== ===================================
650 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.
652 Hashmaps expose the underlying storage format of the object. Note that each hash is computed after trimming trailing null bytes of the corresponding block.
654 Example ``format=json`` reply:
658 {"block_hash": "sha1", "hashes": ["7295c41da03d7f916440b98e32c4a2a39351546c", ...], "block_size": 131072, "bytes": 242}
660 Example ``format=xml`` reply:
664 <?xml version="1.0" encoding="UTF-8"?>
665 <object name="file" bytes="24223726" block_size="131072" block_hash="sha1">
666 <hash>7295c41da03d7f916440b98e32c4a2a39351546c</hash>
670 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.
672 Example ``format=json`` reply:
676 {"versions": [[23, 1307700892], [28, 1307700898], ...]}
678 Example ``format=xml`` reply:
682 <?xml version="1.0" encoding="UTF-8"?>
684 <version timestamp="1307700892">23</version>
685 <version timestamp="1307700898">28</version>
686 <version timestamp="...">...</version>
689 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.
691 ========================== ===============================
692 Reply Header Name Value
693 ========================== ===============================
694 ETag The ETag of the object
695 Content-Length The size of the data returned
696 Content-Type The MIME content type of the object
697 Content-Range The range of data included (only on a single range request)
698 Last-Modified The last object modification date (regardless of version)
699 Content-Encoding The encoding of the object (optional)
700 Content-Disposition The presentation style of the object (optional)
701 X-Object-Hash The Merkle hash
702 X-Object-Version The object's version identifier
703 X-Object-Version-Timestamp The object's version timestamp
704 X-Object-Modified-By The user that comitted the object's version
705 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
706 X-Object-Sharing Object permissions (optional)
707 X-Object-Shared-By Object inheriting permissions (optional)
708 X-Object-Allowed-To Allowed actions on object (optional)
709 X-Object-Public Object's publicly accessible URI (optional)
710 X-Object-Meta-* Optional user defined metadata
711 ========================== ===============================
715 =========================== ==============================
716 Return Code Description
717 =========================== ==============================
718 200 (OK) The request succeeded
719 206 (Partial Content) The range request succeeded
720 304 (Not Modified) The object has not been modified
721 412 (Precondition Failed) The condition set can not be satisfied
722 416 (Range Not Satisfiable) The requested range is out of limits
723 =========================== ==============================
729 ==================== ================================
730 Request Header Name Value
731 ==================== ================================
732 If-Match Put if ETags match with current object
733 If-None-Match Put if ETags don't match with current object
734 ETag The MD5 hash of the object (optional to check written data)
735 Content-Length The size of the data written
736 Content-Type The MIME content type of the object
737 Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
738 X-Copy-From The source path in the form ``/<container>/<object>``
739 X-Move-From The source path in the form ``/<container>/<object>``
740 X-Source-Account The source account to copy/move from
741 X-Source-Version The source version to copy from
742 Content-Encoding The encoding of the object (optional)
743 Content-Disposition The presentation style of the object (optional)
744 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
745 X-Object-Sharing Object permissions (optional)
746 X-Object-Public Object is publicly accessible (optional)
747 X-Object-Meta-* Optional user defined metadata
748 ==================== ================================
752 ====================== ===================================
753 Request Parameter Name Value
754 ====================== ===================================
755 format Optional extended request type (can be ``json`` or ``xml``)
756 hashmap Optional hashmap provided instead of data (no value parameter)
757 ====================== ===================================
759 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 a simple text format, with one hash per line).
761 Hashmaps should be formatted as outlined in ``GET``.
763 ========================== ===============================
764 Reply Header Name Value
765 ========================== ===============================
766 ETag The MD5 hash of the object (on create)
767 X-Object-Version The object's new version
768 ========================== ===============================
770 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.
772 ============================== ==============================
773 Return Code Description
774 ============================== ==============================
775 201 (Created) The object has been created
776 409 (Conflict) The object can not be created from the provided hashmap, or there are conflicting permissions (a list of missing hashes, or a list of conflicting sharing paths will be included in the reply - in simple text format)
777 411 (Length Required) Missing ``Content-Length`` or ``Content-Type`` in the request
778 413 (Request Entity Too Large) Insufficient quota to complete the request
779 422 (Unprocessable Entity) The MD5 checksum of the data written to the storage system does not match the (optionally) supplied ETag value
780 ============================== ==============================
786 ==================== ================================
787 Request Header Name Value
788 ==================== ================================
789 If-Match Proceed if ETags match with object
790 If-None-Match Proceed if ETags don't match with object
791 Destination The destination path in the form ``/<container>/<object>``
792 Destination-Account The destination account to copy to
793 Content-Type The MIME content type of the object (optional)
794 Content-Encoding The encoding of the object (optional)
795 Content-Disposition The presentation style of the object (optional)
796 X-Source-Version The source version to copy from
797 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
798 X-Object-Sharing Object permissions (optional)
799 X-Object-Public Object is publicly accessible (optional)
800 X-Object-Meta-* Optional user defined metadata
801 ==================== ================================
803 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.
805 ========================== ===============================
806 Reply Header Name Value
807 ========================== ===============================
808 X-Object-Version The object's new version
809 ========================== ===============================
813 ============================== ==============================
814 Return Code Description
815 ============================== ==============================
816 201 (Created) The object has been created
817 409 (Conflict) There are conflicting permissions (a list of conflicting sharing paths will be included in the reply - in simple text format)
818 413 (Request Entity Too Large) Insufficient quota to complete the request
819 ============================== ==============================
825 Same as ``COPY``, without the ``X-Source-Version`` request header. The ``MOVE`` operation is always applied on the latest version.
831 ==================== ================================
832 Request Header Name Value
833 ==================== ================================
834 If-Match Proceed if ETags match with object
835 If-None-Match Proceed if ETags don't match with object
836 Content-Length The size of the data written (optional, to update)
837 Content-Type The MIME content type of the object (optional, to update)
838 Content-Range The range of data supplied (optional, to update)
839 Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
840 Content-Encoding The encoding of the object (optional)
841 Content-Disposition The presentation style of the object (optional)
842 X-Source-Object Update with data from the object at path ``/<container>/<object>`` (optional, to update)
843 X-Source-Account The source account to update from
844 X-Source-Version The source version to update from (optional, to update)
845 X-Object-Bytes The updated object's final size (optional, when updating)
846 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
847 X-Object-Sharing Object permissions (optional)
848 X-Object-Public Object is publicly accessible (optional)
849 X-Object-Meta-* Optional user defined metadata
850 ==================== ================================
854 ====================== ============================================
855 Request Parameter Name Value
856 ====================== ============================================
857 update Do not replace metadata (no value parameter)
858 ====================== ============================================
860 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.
862 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.
864 To update an object's data:
866 * 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.
867 * 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``).
868 * Set ``Content-Range`` as specified in RFC2616, with the following differences:
870 * Client software MAY omit ``last-byte-pos`` of if the length of the range being transferred is unknown or difficult to determine.
871 * Client software SHOULD not specify the ``instance-length`` (use a ``*``), unless there is a reason for performing a size check at the server.
872 * If ``Content-Range`` used has a ``byte-range-resp-spec = *``, data will be appended to the object.
874 Optionally, truncate the updated object to the desired length with the ``X-Object-Bytes`` header.
876 A data update will trigger an ETag change. Updated ETags correspond to the single Merkle hash of the object's hashmap (refer to http://bittorrent.org/beps/bep_0030.html for more information).
878 No reply content. No reply headers if only metadata is updated.
880 ========================== ===============================
881 Reply Header Name Value
882 ========================== ===============================
883 ETag The new ETag of the object (data updated)
884 X-Object-Version The object's new version
885 ========================== ===============================
889 ============================== ==============================
890 Return Code Description
891 ============================== ==============================
892 202 (Accepted) The request has been accepted (not a data update)
893 204 (No Content) The request succeeded (data updated)
894 409 (Conflict) There are conflicting permissions (a list of conflicting sharing paths will be included in the reply - in simple text format)
895 411 (Length Required) Missing ``Content-Length`` in the request
896 413 (Request Entity Too Large) Insufficient quota to complete the request
897 416 (Range Not Satisfiable) The supplied range is invalid
898 ============================== ==============================
900 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. ::
902 <form method="post" action="https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt?X-Auth-Token=0000" enctype="multipart/form-data">
903 <input type="file" name="X-Object-Data">
904 <input type="submit">
907 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.
909 ========================== ===============================
910 Reply Header Name Value
911 ========================== ===============================
912 ETag The MD5 hash of the object
913 X-Object-Version The object's new version
914 ========================== ===============================
918 ============================== ==============================
919 Return Code Description
920 ============================== ==============================
921 201 (Created) The object has been created
922 413 (Request Entity Too Large) Insufficient quota to complete the request
923 ============================== ==============================
929 ====================== ===================================
930 Request Parameter Name Value
931 ====================== ===================================
932 until Optional timestamp
933 ====================== ===================================
935 If ``until`` is defined, the object is "purged" up to that time (the history up to then is deleted).
937 No reply content/headers.
939 =========================== ==============================
940 Return Code Description
941 =========================== ==============================
942 204 (No Content) The request succeeded
943 =========================== ==============================
945 Sharing and Public Objects
946 ^^^^^^^^^^^^^^^^^^^^^^^^^^
948 Read and write control in Pithos is managed by setting appropriate permissions with the ``X-Object-Sharing`` header. The permissions are applied using prefix-based inheritance. Thus, each set of authorization directives is applied to all objects sharing the same prefix with the object where the corresponding ``X-Object-Sharing`` header is defined. For simplicity, nested/overlapping permissions are not allowed. Setting ``X-Object-Sharing`` will fail, if the object is already "covered", or another object with a longer common-prefix name already has permissions. 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.
950 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.
952 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):
954 ========================== ===============================
955 Reply Header Name Value
956 ========================== ===============================
957 ETag The ETag of the object
958 Content-Length The size of the data returned
959 Content-Type The MIME content type of the object
960 Content-Range The range of data included (only on a single range request)
961 Last-Modified The last object modification date (regardless of version)
962 Content-Encoding The encoding of the object (optional)
963 Content-Disposition The presentation style of the object (optional)
964 ========================== ===============================
966 Public objects are not included and do not influence cross-user listings. They are, however, readable by all users.
971 List of differences from the OOS API:
973 * Support for ``X-Account-Meta-*`` style headers at the account level. Use ``POST`` to update.
974 * Support for ``X-Container-Meta-*`` style headers at the container level. Can be set when creating via ``PUT``. Use ``POST`` to update.
975 * Header ``X-Container-Object-Meta`` at the container level and parameter ``meta`` in container listings. (**TBD**)
976 * 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.
977 * Headers ``X-Container-Block-*`` at the container level, exposing the underlying storage characteristics.
978 * All metadata replies, at all levels, include latest modification information.
979 * At all levels, a ``HEAD`` or ``GET`` request may use ``If-Modified-Since`` and ``If-Unmodified-Since`` headers.
980 * Container/object lists include all associated metadata if the reply is of type json/xml. Some names are kept to their OOS API equivalents for compatibility.
981 * Option to include only shared containers/objects in listings.
982 * 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.
983 * Multi-range object ``GET`` support as outlined in RFC2616.
984 * Object hashmap retrieval through ``GET`` and the ``format`` parameter.
985 * Object create via hashmap through ``PUT`` and the ``format`` parameter.
986 * The object's Merkle hash is always returned in the ``X-Object-Hash`` header.
987 * Object create using ``POST`` to support standard HTML forms.
988 * 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``. New ETag corresponds to the Merkle hash of the object's hashmap.
989 * Include new version identifier in replies for object replace/change requests.
990 * Object ``MOVE`` support.
991 * Conditional object create/update operations, using ``If-Match`` and ``If-None-Match`` headers.
992 * Time-variant account/container listings via the ``until`` parameter.
993 * Object versions - parameter ``version`` in ``HEAD``/``GET`` (list versions with ``GET``), ``X-Object-Version-*`` meta in replies, ``X-Source-Version`` in ``PUT``/``COPY``.
994 * 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.
995 * Support for prefix-based inheritance when enforcing permissions. Parent object carrying the authorization directives is reported in ``X-Object-Shared-By``.
996 * Copy and move between accounts with ``X-Source-Account`` and ``Destination-Account`` headers.
997 * Large object support with ``X-Object-Manifest``.
998 * Trace the user that created/modified an object with ``X-Object-Modified-By``.
999 * Purge container/object history with the ``until`` parameter in ``DELETE``.
1001 Clarifications/suggestions:
1003 * 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.
1004 * 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.
1005 * A ``GET`` reply for a level will include all headers of the corresponding ``HEAD`` request.
1006 * 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.
1007 * 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.
1008 * Container/object lists use a ``200`` return code if the reply is of type json/xml. The reply will include an empty json/xml.
1009 * 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.
1010 * 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.
1011 * A copy/move using ``PUT``/``COPY``/``MOVE`` will always update metadata, keeping all old values except the ones redefined in the request headers.
1012 * 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.
1020 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.
1022 Upon entrance to the service, a user is presented with the following elements - which can be represented as folders or with other related icons:
1024 * 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.
1025 * The ``trash`` element, which contains files that have been marked for deletion, but can still be recovered.
1026 * The ``shared`` element, which contains all objects shared by the user to other users of the system.
1027 * The ``others`` element, which contains all objects that other users share with the user.
1028 * 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.
1029 * The ``history`` element, which allows browsing past instances of ``home`` and - optionally - ``trash``.
1031 Objects in Pithos can be:
1033 * Moved to trash and then deleted.
1034 * Shared with specific permissions.
1035 * Made public (shared with non-Pithos users).
1036 * Restored from previous versions.
1038 Some of these functions are performed by the client software and some by the Pithos server.
1040 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``.
1042 Implementation Guidelines
1043 ^^^^^^^^^^^^^^^^^^^^^^^^^
1045 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.
1047 Object names should use the ``/`` delimiter to impose a hierarchy of folders and files.
1049 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.
1051 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).
1053 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.
1055 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``.
1057 Uploading and downloading data
1058 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1060 By using hashmaps to upload and download objects the corresponding operations can complete much faster.
1062 In the case of an upload, only the missing blocks will be submitted to the server:
1064 * Calculate the hash value for each block of the object to be uploaded. Use the hash algorithm and block size of the destination container.
1065 * Send a hashmap ``PUT`` request for the object.
1067 * Server responds with status ``201`` (Created):
1069 * Blocks are already on the server. The object has been created. Done.
1071 * Server responds with status ``409`` (Conflict):
1073 * Server's response body contains the hashes of the blocks that do not exist on the server.
1074 * For each hash value in the server's response (or all hashes together):
1076 * Send a ``POST`` request to the destination container with the corresponding data.
1078 * Repeat hashmap ``PUT``. Fail if the server's response is not ``201``.
1080 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.
1085 Consider the following algorithm for synchronizing a local folder with the server. The "state" is the complete object listing, with the corresponding attributes.
1089 L: local state (stored state from last sync with the server)
1090 C: current state (state computed right before sync)
1096 # No remote changes, nothing to do
1098 # Update local state to match that of the server
1101 # We have local changes
1103 # No remote changes, update the server
1107 # Both we and server have changes
1109 # We were lucky, we did the same change
1112 # We have conflicting changes
1117 * States represent file hashes (either MD5 or Merkle). Deleted or non-existing files are assumed to have a magic hash (e.g. empty string).
1118 * Updating a state (either local or remote) implies downloading, uploading or deleting the appropriate file.
1120 Recommended Practices and Examples
1121 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1123 Assuming an authentication token is obtained, the following high-level operations are available - shown with ``curl``:
1125 * Get account information ::
1128 -H "X-Auth-Token: 0000" \
1129 https://pithos.dev.grnet.gr/v1/user
1131 * List available containers ::
1134 -H "X-Auth-Token: 0000" \
1135 https://pithos.dev.grnet.gr/v1/user
1137 * Get container information ::
1140 -H "X-Auth-Token: 0000" \
1141 https://pithos.dev.grnet.gr/v1/user/pithos
1143 * Add a new container ::
1146 -H "X-Auth-Token: 0000" \
1147 https://pithos.dev.grnet.gr/v1/user/test
1149 * Delete a container ::
1151 curl -X DELETE -D - \
1152 -H "X-Auth-Token: 0000" \
1153 https://pithos.dev.grnet.gr/v1/user/test
1155 * List objects in a container ::
1158 -H "X-Auth-Token: 0000" \
1159 https://pithos.dev.grnet.gr/v1/user/pithos
1161 * List objects in a container (extended reply) ::
1164 -H "X-Auth-Token: 0000" \
1165 https://pithos.dev.grnet.gr/v1/user/pithos?format=json
1167 It is recommended that extended replies are cached and subsequent requests utilize the ``If-Modified-Since`` header.
1169 * List metadata keys used by objects in a container
1171 Will be in the ``X-Container-Object-Meta`` reply header, included in container information or object list (``HEAD`` or ``GET``). (**TBD**)
1173 * List objects in a container having a specific meta defined ::
1176 -H "X-Auth-Token: 0000" \
1177 https://pithos.dev.grnet.gr/v1/user/pithos?meta=favorites
1179 * Retrieve an object ::
1182 -H "X-Auth-Token: 0000" \
1183 https://pithos.dev.grnet.gr/v1/user/pithos/README.txt
1185 * Retrieve an object (specific ranges of data) ::
1188 -H "X-Auth-Token: 0000" \
1189 -H "Range: bytes=0-9" \
1190 https://pithos.dev.grnet.gr/v1/user/pithos/README.txt
1192 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``.
1194 * Add a new object (folder type) (**TBD**) ::
1197 -H "X-Auth-Token: 0000" \
1198 -H "Content-Type: application/directory" \
1199 https://pithos.dev.grnet.gr/v1/user/pithos/folder
1201 * Add a new object ::
1204 -H "X-Auth-Token: 0000" \
1205 -H "Content-Type: text/plain" \
1207 https://pithos.dev.grnet.gr/v1/user/pithos/folder/EXAMPLE.txt
1209 * Update an object ::
1212 -H "X-Auth-Token: 0000" \
1213 -H "Content-Length: 10" \
1214 -H "Content-Type: application/octet-stream" \
1215 -H "Content-Range: bytes 10-19/*" \
1217 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1219 This will update bytes 10-19 with the data specified.
1221 * Update an object (append) ::
1224 -H "X-Auth-Token: 0000" \
1225 -H "Content-Length: 10" \
1226 -H "Content-Type: application/octet-stream" \
1227 -H "Content-Range: bytes */*" \
1229 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1231 * Update an object (truncate) ::
1234 -H "X-Auth-Token: 0000" \
1235 -H "X-Source-Object: /folder/EXAMPLE.txt" \
1236 -H "Content-Range: bytes 0-0/*" \
1237 -H "X-Object-Bytes: 0" \
1238 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1240 This will truncate the object to 0 bytes.
1242 * Add object metadata ::
1245 -H "X-Auth-Token: 0000" \
1246 -H "X-Object-Meta-First: first_meta_value" \
1247 -H "X-Object-Meta-Second: second_meta_value" \
1248 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1250 * Delete object metadata ::
1253 -H "X-Auth-Token: 0000" \
1254 -H "X-Object-Meta-First: first_meta_value" \
1255 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1257 Metadata can only be "set". To delete ``X-Object-Meta-Second``, reset all metadata.
1259 * Delete an object ::
1261 curl -X DELETE -D - \
1262 -H "X-Auth-Token: 0000" \
1263 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
projects / pithos / blob