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 0.5 (July 21, 2011) Object update from another object's data.
29 \ Support object truncate.
30 \ Create object using a standard HTML form.
31 \ Purge container/object history.
32 \ List other accounts that share objects with a user.
33 \ List shared containers/objects.
34 \ Update implementation guidelines.
35 0.4 (July 01, 2011) Object permissions and account groups.
36 \ Control versioning behavior and container quotas with container policy directives.
37 \ Support updating/deleting individual metadata with ``POST``.
38 \ Create object using hashmap.
39 0.3 (June 14, 2011) Large object support with ``X-Object-Manifest``.
40 \ Allow for publicly available objects via ``https://hostname/public``.
41 \ Support time-variant account/container listings.
42 \ Add source version when duplicating with ``PUT``/``COPY``.
43 \ Request version in object ``HEAD``/``GET`` requests (list versions with ``GET``).
44 0.2 (May 31, 2011) Add object meta listing and filtering in containers.
45 \ Include underlying storage characteristics in container meta.
46 \ Support for partial object updates through ``POST``.
47 \ Expose object hashmaps through ``GET``.
48 \ Support for multi-range object ``GET`` requests.
49 0.1 (May 17, 2011) Initial release. Based on OpenStack Object Storage Developer Guide API v1 (Apr. 15, 2011).
50 ========================= ================================
55 The URI requests supported by the Pithos API follow one of the following forms:
57 * Top level: ``https://hostname/v1/``
58 * Account level: ``https://hostname/v1/<account>``
59 * Container level: ``https://hostname/v1/<account>/<container>``
60 * Object level: ``https://hostname/v1/<account>/<container>/<object>``
62 All requests must include an ``X-Auth-Token`` - as a header, or a parameter. The process of obtaining the token is still to be determined (**TBD**).
64 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.
66 ========================= ================================
67 Return Code Description
68 ========================= ================================
69 400 (Bad Request) The request is invalid
70 401 (Unauthorized) Request not allowed
71 404 (Not Found) The requested resource was not found
72 503 (Service Unavailable) The request cannot be completed because of an internal error
73 ========================= ================================
80 ========= ==================
82 ========= ==================
83 GET Authentication (for compatibility with the OOS API) or list allowed accounts
84 ========= ==================
89 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.
91 ================ =====================
92 Return Code Description
93 ================ =====================
94 204 (No Content) The request succeeded
95 ================ =====================
97 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.
99 ====================== =========================
100 Request Parameter Name Value
101 ====================== =========================
102 limit The amount of results requested (default is 10000)
103 marker Return containers with name lexicographically after marker
104 format Optional extended reply type (can be ``json`` or ``xml``)
105 ====================== =========================
107 The reply is a list of account names.
108 If a ``format=xml`` or ``format=json`` argument is given, extended information on the containers will be returned, serialized in the chosen format.
109 For each account, the information will include the following (names will be in lower case and with hyphens replaced with underscores):
111 =========================== ============================
113 =========================== ============================
114 name The name of the account
115 last_modified The last container modification date (regardless of ``until``)
116 =========================== ============================
118 Example ``format=json`` reply:
122 [{"name": "user", "last_modified": "2011-07-19T10:48:16"}, ...]
124 Example ``format=xml`` reply:
128 <?xml version="1.0" encoding="UTF-8"?>
132 <last_modified>2011-07-19T10:48:16</last_modified>
134 <account>...</account>
137 =========================== =====================
138 Return Code Description
139 =========================== =====================
140 200 (OK) The request succeeded
141 204 (No Content) The account has no containers (only for non-extended replies)
142 =========================== =====================
144 Will use a ``200`` return code if the reply is of type json/xml.
151 ========= ==================
152 Operation Description
153 ========= ==================
154 HEAD Retrieve account metadata
156 POST Update account metadata
157 ========= ==================
162 ====================== ===================================
163 Request Parameter Name Value
164 ====================== ===================================
165 until Optional timestamp
166 ====================== ===================================
168 Cross-user requests are not allowed to use ``until`` and only include the account modification date in the reply.
170 ========================== =====================
171 Reply Header Name Value
172 ========================== =====================
173 X-Account-Container-Count The total number of containers
174 X-Account-Object-Count The total number of objects (**TBD**)
175 X-Account-Bytes-Used The total number of bytes stored
176 X-Account-Bytes-Remaining The total number of bytes remaining (**TBD**)
177 X-Account-Last-Login The last login (**TBD**)
178 X-Account-Until-Timestamp The last account modification date until the timestamp provided
179 X-Account-Group-* Optional user defined groups
180 X-Account-Meta-* Optional user defined metadata
181 Last-Modified The last account modification date (regardless of ``until``)
182 ========================== =====================
186 ================ =====================
187 Return Code Description
188 ================ =====================
189 204 (No Content) The request succeeded
190 ================ =====================
196 ==================== ===========================
197 Request Header Name Value
198 ==================== ===========================
199 If-Modified-Since Retrieve if account has changed since provided timestamp
200 If-Unmodified-Since Retrieve if account has not changed since provided timestamp
201 ==================== ===========================
205 ====================== =========================
206 Request Parameter Name Value
207 ====================== =========================
208 limit The amount of results requested (default is 10000)
209 marker Return containers with name lexicographically after marker
210 format Optional extended reply type (can be ``json`` or ``xml``)
211 shared Show only shared containers (no value parameter)
212 until Optional timestamp
213 ====================== =========================
215 The reply is a list of container names. Account headers (as in a ``HEAD`` request) will also be included.
216 Cross-user requests are not allowed to use ``until`` and only include the account/container modification dates in the reply.
218 If a ``format=xml`` or ``format=json`` argument is given, extended information on the containers will be returned, serialized in the chosen format.
219 For each container, the information will include all container metadata (names will be in lower case and with hyphens replaced with underscores):
221 =========================== ============================
223 =========================== ============================
224 name The name of the container
225 count The number of objects inside the container
226 bytes The total size of the objects inside the container
227 last_modified The last container modification date (regardless of ``until``)
228 x_container_until_timestamp The last container modification date until the timestamp provided
229 x_container_policy_* Container behavior and limits
230 x_container_meta_* Optional user defined metadata
231 =========================== ============================
233 For examples of container details returned in JSON/XML formats refer to the OOS API documentation.
235 =========================== =====================
236 Return Code Description
237 =========================== =====================
238 200 (OK) The request succeeded
239 204 (No Content) The account has no containers (only for non-extended replies)
240 304 (Not Modified) The account has not been modified
241 412 (Precondition Failed) The condition set can not be satisfied
242 =========================== =====================
244 Will use a ``200`` return code if the reply is of type json/xml.
250 ====================== ============================================
251 Request Parameter Name Value
252 ====================== ============================================
253 update Do not replace metadata/groups (no value parameter)
254 ====================== ============================================
258 ==================== ===========================
259 Request Header Name Value
260 ==================== ===========================
261 X-Account-Group-* Optional user defined groups
262 X-Account-Meta-* Optional user defined metadata
263 ==================== ===========================
265 No reply content/headers.
267 The operation will overwrite all user defined metadata, except if ``update`` is defined.
268 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.
270 ================ ===============================
271 Return Code Description
272 ================ ===============================
273 202 (Accepted) The request has been accepted
274 ================ ===============================
282 ========= ============================
283 Operation Description
284 ========= ============================
285 HEAD Retrieve container metadata
287 PUT Create/update container
288 POST Update container metadata
289 DELETE Delete container
290 ========= ============================
296 ====================== ===================================
297 Request Parameter Name Value
298 ====================== ===================================
299 until Optional timestamp
300 ====================== ===================================
302 Cross-user requests are not allowed to use ``until`` and only include the container modification date in the reply.
304 =========================== ===============================
305 Reply Header Name Value
306 =========================== ===============================
307 X-Container-Object-Count The total number of objects in the container
308 X-Container-Bytes-Used The total number of bytes of all objects stored
309 X-Container-Block-Size The block size used by the storage backend
310 X-Container-Block-Hash The hash algorithm used for block identifiers in object hashmaps
311 X-Container-Until-Timestamp The last container modification date until the timestamp provided
312 X-Container-Object-Meta A list with all meta keys used by objects
313 X-Container-Policy-* Container behavior and limits
314 X-Container-Meta-* Optional user defined metadata
315 Last-Modified The last container modification date (regardless of ``until``)
316 =========================== ===============================
318 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.
320 ================ ===============================
321 Return Code Description
322 ================ ===============================
323 204 (No Content) The request succeeded
324 ================ ===============================
330 ==================== ===========================
331 Request Header Name Value
332 ==================== ===========================
333 If-Modified-Since Retrieve if container has changed since provided timestamp
334 If-Unmodified-Since Retrieve if container has not changed since provided timestamp
335 ==================== ===========================
339 ====================== ===================================
340 Request Parameter Name Value
341 ====================== ===================================
342 limit The amount of results requested (default is 10000)
343 marker Return containers with name lexicographically after marker
344 prefix Return objects starting with prefix
345 delimiter Return objects up to the delimiter (discussion follows)
346 path Assume ``prefix=path`` and ``delimiter=/``
347 format Optional extended reply type (can be ``json`` or ``xml``)
348 meta Return objects having the specified meta keys (can be a comma separated list)
349 shared Show only shared objects (no value parameter)
350 until Optional timestamp
351 ====================== ===================================
353 The ``path`` parameter overrides ``prefix`` and ``delimiter``. When using ``path``, results will include objects ending in ``delimiter``.
355 The keys given with ``meta`` will be matched with the strings after the ``X-Object-Meta-`` prefix.
357 The reply is a list of object names. Container headers (as in a ``HEAD`` request) will also be included.
358 Cross-user requests are not allowed to use ``until`` and include the following limited set of headers in the reply:
360 =========================== ===============================
361 Reply Header Name Value
362 =========================== ===============================
363 X-Container-Block-Size The block size used by the storage backend
364 X-Container-Block-Hash The hash algorithm used for block identifiers in object hashmaps
365 X-Container-Object-Meta A list with all meta keys used by allowed objects (**TBD**)
366 Last-Modified The last container modification date
367 =========================== ===============================
369 If a ``format=xml`` or ``format=json`` argument is given, extended information on the objects will be returned, serialized in the chosen format.
370 For each object, the information will include all object metadata (names will be in lower case and with hyphens replaced with underscores):
372 ========================== ======================================
374 ========================== ======================================
375 name The name of the object
376 hash The ETag of the object
377 bytes The size of the object
378 content_type The MIME content type of the object
379 content_encoding The encoding of the object (optional)
380 content-disposition The presentation style of the object (optional)
381 last_modified The last object modification date (regardless of version)
382 x_object_version The object's version identifier
383 x_object_version_timestamp The object's version timestamp
384 x_object_modified_by The user that committed the object's version
385 x_object_manifest Object parts prefix in ``<container>/<object>`` form (optional)
386 x_object_sharing Object permissions (optional)
387 x_object_shared_by Object inheriting permissions (optional)
388 x_object_public Object's publicly accessible URI (optional)
389 x_object_meta_* Optional user defined metadata
390 ========================== ======================================
392 Extended replies may also include virtual directory markers in separate sections of the ``json`` or ``xml`` results.
393 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.
394 In JSON results they appear as dictionaries with only a ``"subdir"`` key. In XML results they appear interleaved with ``<object>`` tags as ``<subdir name="..." />``.
395 In case there is an object with the same name as a virtual directory marker, the object will be returned.
397 For examples of object details returned in JSON/XML formats refer to the OOS API documentation.
399 =========================== ===============================
400 Return Code Description
401 =========================== ===============================
402 200 (OK) The request succeeded
403 204 (No Content) The account has no containers (only for non-extended replies)
404 304 (Not Modified) The container has not been modified
405 412 (Precondition Failed) The condition set can not be satisfied
406 =========================== ===============================
408 Will use a ``200`` return code if the reply is of type json/xml.
414 ==================== ================================
415 Request Header Name Value
416 ==================== ================================
417 X-Container-Policy-* Container behavior and limits
418 X-Container-Meta-* Optional user defined metadata
419 ==================== ================================
421 No reply content/headers.
423 If no policy is defined, the container will be created with the default values.
424 Available policy directives:
426 * ``versioning``: Set to ``auto``, ``manual`` or ``none`` (default is ``manual``)
427 * ``quota``: Size limit in KB (default is ``0`` - unlimited)
429 ================ ===============================
430 Return Code Description
431 ================ ===============================
432 201 (Created) The container has been created
433 202 (Accepted) The request has been accepted
434 ================ ===============================
440 ====================== ============================================
441 Request Parameter Name Value
442 ====================== ============================================
443 update Do not replace metadata/policy (no value parameter)
444 ====================== ============================================
448 ==================== ================================
449 Request Header Name Value
450 ==================== ================================
451 X-Container-Policy-* Container behavior and limits
452 X-Container-Meta-* Optional user defined metadata
453 ==================== ================================
455 No reply content/headers.
457 The operation will overwrite all user defined metadata, except if ``update`` is defined.
458 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.
460 ================ ===============================
461 Return Code Description
462 ================ ===============================
463 202 (Accepted) The request has been accepted
464 ================ ===============================
470 ====================== ===================================
471 Request Parameter Name Value
472 ====================== ===================================
473 until Optional timestamp
474 ====================== ===================================
476 If ``until`` is defined, the container is "purged" up to that time (the history of all objects up to then is deleted).
478 No reply content/headers.
480 ================ ===============================
481 Return Code Description
482 ================ ===============================
483 204 (No Content) The request succeeded
484 409 (Conflict) The container is not empty
485 ================ ===============================
493 ========= =================================
494 Operation Description
495 ========= =================================
496 HEAD Retrieve object metadata
498 PUT Write object data or copy/move object
501 POST Update object metadata/data
503 ========= =================================
509 ====================== ===================================
510 Request Parameter Name Value
511 ====================== ===================================
512 version Optional version identifier
513 ====================== ===================================
517 ========================== ===============================
518 Reply Header Name Value
519 ========================== ===============================
520 ETag The ETag of the object
521 Content-Length The size of the object
522 Content-Type The MIME content type of the object
523 Last-Modified The last object modification date (regardless of version)
524 Content-Encoding The encoding of the object (optional)
525 Content-Disposition The presentation style of the object (optional)
526 X-Object-Version The object's version identifier
527 X-Object-Version-Timestamp The object's version timestamp
528 X-Object-Modified-By The user that comitted the object's version
529 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
530 X-Object-Sharing Object permissions (optional)
531 X-Object-Shared-By Object inheriting permissions (optional)
532 X-Object-Public Object's publicly accessible URI (optional)
533 X-Object-Meta-* Optional user defined metadata
534 ========================== ===============================
538 ================ ===============================
539 Return Code Description
540 ================ ===============================
541 200 (No Content) The request succeeded
542 ================ ===============================
548 ==================== ================================
549 Request Header Name Value
550 ==================== ================================
551 Range Optional range of data to retrieve
552 If-Range Retrieve the missing part if entity is unchanged; otherwise, retrieve the entire new entity (used together with Range header)
553 If-Match Retrieve if ETags match
554 If-None-Match Retrieve if ETags don't match
555 If-Modified-Since Retrieve if object has changed since provided timestamp
556 If-Unmodified-Since Retrieve if object has not changed since provided timestamp
557 ==================== ================================
561 ====================== ===================================
562 Request Parameter Name Value
563 ====================== ===================================
564 format Optional extended reply type (can be ``json`` or ``xml``)
565 version Optional version identifier or ``list`` (specify a format if requesting a list)
566 ====================== ===================================
568 The reply is the object's data (or part of it), except if a hashmap is requested with the ``format`` parameter, or a version list with ``version=list`` (in which case an extended reply format must be specified). Object headers (as in a ``HEAD`` request) are always included.
570 Hashmaps expose the underlying storage format of the object. Note that each hash is computed after trimming trailing null bytes of the corresponding block.
572 Example ``format=json`` reply:
576 {"block_hash": "sha1", "hashes": ["7295c41da03d7f916440b98e32c4a2a39351546c", ...], "block_size": 131072, "bytes": 242}
578 Example ``format=xml`` reply:
582 <?xml version="1.0" encoding="UTF-8"?>
583 <object name="file" bytes="24223726" block_size="131072" block_hash="sha1">
584 <hash>7295c41da03d7f916440b98e32c4a2a39351546c</hash>
588 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.
590 Example ``format=json`` reply:
594 {"versions": [[23, 1307700892], [28, 1307700898], ...]}
596 Example ``format=xml`` reply:
600 <?xml version="1.0" encoding="UTF-8"?>
602 <version timestamp="1307700892">23</version>
603 <version timestamp="1307700898">28</version>
604 <version timestamp="...">...</version>
607 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.
609 ========================== ===============================
610 Reply Header Name Value
611 ========================== ===============================
612 ETag The ETag of the object
613 Content-Length The size of the data returned
614 Content-Type The MIME content type of the object
615 Content-Range The range of data included (only on a single range request)
616 Last-Modified The last object modification date (regardless of version)
617 Content-Encoding The encoding of the object (optional)
618 Content-Disposition The presentation style of the object (optional)
619 X-Object-Version The object's version identifier
620 X-Object-Version-Timestamp The object's version timestamp
621 X-Object-Modified-By The user that comitted the object's version
622 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
623 X-Object-Sharing Object permissions (optional)
624 X-Object-Shared-By Object inheriting permissions (optional)
625 X-Object-Public Object's publicly accessible URI (optional)
626 X-Object-Meta-* Optional user defined metadata
627 ========================== ===============================
631 =========================== ==============================
632 Return Code Description
633 =========================== ==============================
634 200 (OK) The request succeeded
635 206 (Partial Content) The range request succeeded
636 304 (Not Modified) The object has not been modified
637 412 (Precondition Failed) The condition set can not be satisfied
638 416 (Range Not Satisfiable) The requested range is out of limits
639 =========================== ==============================
645 ==================== ================================
646 Request Header Name Value
647 ==================== ================================
648 ETag The MD5 hash of the object (optional to check written data)
649 Content-Length The size of the data written
650 Content-Type The MIME content type of the object
651 Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
652 X-Copy-From The source path in the form ``/<container>/<object>``
653 X-Move-From The source path in the form ``/<container>/<object>``
654 X-Source-Version The source version to copy from
655 Content-Encoding The encoding of the object (optional)
656 Content-Disposition The presentation style of the object (optional)
657 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
658 X-Object-Sharing Object permissions (optional)
659 X-Object-Public Object is publicly accessible (optional)
660 X-Object-Meta-* Optional user defined metadata
661 ==================== ================================
665 ====================== ===================================
666 Request Parameter Name Value
667 ====================== ===================================
668 format Optional extended request type (can be ``json``) to create the object by suppling its hashmap instead
669 ====================== ===================================
671 The request is the object's data (or part of it), except if a hashmap is provided with the ``format`` parameter. If format is used 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.
673 Hashmaps expose the underlying storage format of the object.
675 Example ``format=json`` request:
679 {"block_hash": "sha1", "hashes": ["7295c41da03d7f916440b98e32c4a2a39351546c", ...], "block_size": 131072, "bytes": 242}
681 Example ``format=xml`` request:
685 <?xml version="1.0" encoding="UTF-8"?>
686 <object name="file" bytes="24223726" block_size="131072" block_hash="sha1">
687 <hash>7295c41da03d7f916440b98e32c4a2a39351546c</hash>
691 ========================== ===============================
692 Reply Header Name Value
693 ========================== ===============================
694 ETag The MD5 hash of the object (on create)
695 ========================== ===============================
697 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.
699 =========================== ==============================
700 Return Code Description
701 =========================== ==============================
702 201 (Created) The object has been created
703 409 (Conflict) The object can not be created from the provided hashmap, or there are conflicting permissions (a list of missing hashes, or a conflicting sharing path will be included in the reply - in JSON format)
704 411 (Length Required) Missing ``Content-Length`` or ``Content-Type`` in the request
705 422 (Unprocessable Entity) The MD5 checksum of the data written to the storage system does not match the (optionally) supplied ETag value
706 =========================== ==============================
712 ==================== ================================
713 Request Header Name Value
714 ==================== ================================
715 Destination The destination path in the form ``/<container>/<object>``
716 Content-Type The MIME content type of the object (optional)
717 Content-Encoding The encoding of the object (optional)
718 Content-Disposition The presentation style of the object (optional)
719 X-Source-Version The source version to copy from
720 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
721 X-Object-Sharing Object permissions (optional)
722 X-Object-Public Object is publicly accessible (optional)
723 X-Object-Meta-* Optional user defined metadata
724 ==================== ================================
726 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.
728 No reply content/headers.
730 =========================== ==============================
731 Return Code Description
732 =========================== ==============================
733 201 (Created) The object has been created
734 409 (Conflict) There are conflicting permissions (a conflicting sharing path will be included in the reply - in JSON format)
735 =========================== ==============================
741 Same as ``COPY``, without the ``X-Source-Version`` request header. The ``MOVE`` operation is always applied on the latest version.
747 ====================== ============================================
748 Request Parameter Name Value
749 ====================== ============================================
750 update Do not replace metadata (no value parameter)
751 ====================== ============================================
755 ==================== ================================
756 Request Header Name Value
757 ==================== ================================
758 Content-Length The size of the data written (optional, to update)
759 Content-Type The MIME content type of the object (optional, to update)
760 Content-Range The range of data supplied (optional, to update)
761 Transfer-Encoding Set to ``chunked`` to specify incremental uploading (if used, ``Content-Length`` is ignored)
762 Content-Encoding The encoding of the object (optional)
763 Content-Disposition The presentation style of the object (optional)
764 X-Source-Object Update with data from the object at path ``/<container>/<object>`` (optional, to update)
765 X-Source-Version The source version to update from (optional, to update)
766 X-Object-Bytes The updated object's final size (optional, when updating)
767 X-Object-Manifest Object parts prefix in ``<container>/<object>`` form (optional)
768 X-Object-Sharing Object permissions (optional)
769 X-Object-Public Object is publicly accessible (optional)
770 X-Object-Meta-* Optional user defined metadata
771 ==================== ================================
773 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.
775 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.
777 To update an object's data:
779 * 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.
780 * 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``).
781 * Set ``Content-Range`` as specified in RFC2616, with the following differences:
783 * Client software MAY omit ``last-byte-pos`` of if the length of the range being transferred is unknown or difficult to determine.
784 * Client software SHOULD not specify the ``instance-length`` (use a ``*``), unless there is a reason for performing a size check at the server.
785 * If ``Content-Range`` used has a ``byte-range-resp-spec = *``, data will be appended to the object.
787 Optionally, truncate the updated object to the desired length with the ``X-Object-Bytes`` header.
789 A data update will trigger an ETag change. The new ETag will not correspond to the object's MD5 sum (**TBD**) and will be included in reply headers.
791 No reply content. No reply headers if only metadata is updated.
793 ========================== ===============================
794 Reply Header Name Value
795 ========================== ===============================
796 ETag The new ETag of the object (data updated)
797 ========================== ===============================
801 =========================== ==============================
802 Return Code Description
803 =========================== ==============================
804 202 (Accepted) The request has been accepted (not a data update)
805 204 (No Content) The request succeeded (data updated)
806 409 (Conflict) There are conflicting permissions (a conflicting sharing path will be included in the reply - in JSON format)
807 411 (Length Required) Missing ``Content-Length`` in the request
808 416 (Range Not Satisfiable) The supplied range is invalid
809 =========================== ==============================
811 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 exactly two fields, as in the following example. ::
813 <form method="post" action="https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt" enctype="multipart/form-data">
814 <input type="hidden" name="X-Auth-Token" value="0000">
815 <input type="file" name="X-Object-Data">
816 <input type="submit">
819 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. Metadata, sharing and other object attributes can not be set this way.
821 ========================== ===============================
822 Reply Header Name Value
823 ========================== ===============================
824 ETag The MD5 hash of the object
825 ========================== ===============================
829 =========================== ==============================
830 Return Code Description
831 =========================== ==============================
832 201 (Created) The object has been created
833 =========================== ==============================
839 ====================== ===================================
840 Request Parameter Name Value
841 ====================== ===================================
842 until Optional timestamp
843 ====================== ===================================
845 If ``until`` is defined, the object is "purged" up to that time (the history up to then is deleted).
847 No reply content/headers.
849 =========================== ==============================
850 Return Code Description
851 =========================== ==============================
852 204 (No Content) The request succeeded
853 =========================== ==============================
855 Sharing and Public Objects
856 ^^^^^^^^^^^^^^^^^^^^^^^^^^
858 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.
860 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.
862 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):
864 ========================== ===============================
865 Reply Header Name Value
866 ========================== ===============================
867 ETag The ETag of the object
868 Content-Length The size of the data returned
869 Content-Type The MIME content type of the object
870 Content-Range The range of data included (only on a single range request)
871 Last-Modified The last object modification date (regardless of version)
872 Content-Encoding The encoding of the object (optional)
873 Content-Disposition The presentation style of the object (optional)
874 ========================== ===============================
876 Public objects are not included and do not influence cross-user listings. They are, however, readable by all users.
881 List of differences from the OOS API:
883 * Support for ``X-Account-Meta-*`` style headers at the account level. Use ``POST`` to update.
884 * Support for ``X-Container-Meta-*`` style headers at the container level. Can be set when creating via ``PUT``. Use ``POST`` to update.
885 * Header ``X-Container-Object-Meta`` at the container level and parameter ``meta`` in container listings.
886 * Container policies to manage behavior and limits.
887 * Headers ``X-Container-Block-*`` at the container level, exposing the underlying storage characteristics.
888 * All metadata replies, at all levels, include latest modification information.
889 * At all levels, a ``GET`` request may use ``If-Modified-Since`` and ``If-Unmodified-Since`` headers.
890 * 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.
891 * Option to include only shared containers/objects in listings.
892 * 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.
893 * Multi-range object ``GET`` support as outlined in RFC2616.
894 * Object hashmap retrieval through ``GET`` and the ``format`` parameter.
895 * Object create via hashmap through ``PUT`` and the ``format`` parameter.
896 * Object create using ``POST`` to support standard HTML forms.
897 * 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``.
898 * Object ``MOVE`` support.
899 * Time-variant account/container listings via the ``until`` parameter.
900 * Object versions - parameter ``version`` in ``HEAD``/``GET`` (list versions with ``GET``), ``X-Object-Version-*`` meta in replies, ``X-Source-Version`` in ``PUT``/``COPY``.
901 * Sharing/publishing with ``X-Object-Sharing``, ``X-Object-Public`` at the object level. Cross-user operations are allowed - controlled by sharing directives. Permissions may include groups defined with ``X-Account-Group-*`` at the account level. These apply to the object - not its versions.
902 * Support for prefix-based inheritance when enforcing permissions. Parent object carrying the authorization directives is reported in ``X-Object-Shared-By``.
903 * Large object support with ``X-Object-Manifest``.
904 * Trace the user that created/modified an object with ``X-Object-Modified-By``.
905 * Purge container/object history with the ``until`` parameter in ``DELETE``.
907 Clarifications/suggestions:
909 * 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.
910 * 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.
911 * A ``GET`` reply for a level will include all headers of the corresponding ``HEAD`` request.
912 * 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.
913 * The ``Accept`` header may be used in requests instead of the ``format`` parameter to specify the desired reply format. The parameter overrides the header (**TBD**).
914 * Container/object lists use a ``200`` return code if the reply is of type json/xml. The reply will include an empty json/xml.
915 * In headers, dates are formatted according to RFC 1123. In extended information listings, dates are formatted according to ISO 8601.
916 * 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.
917 * A copy/move using ``PUT``/``COPY``/``MOVE`` will always update metadata, keeping all old values except the ones redefined in the request headers.
918 * 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.
926 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.
928 Upon entrance to the service, a user is presented with the following elements - which can be represented as folders or with other related icons:
930 * 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.
931 * The ``trash`` element, which contains files that have been marked for deletion, but can still be recovered.
932 * The ``shared`` element, which contains all objects shared by the user to other users of the system.
933 * The ``others`` element, which contains all objects that other users share with the user.
934 * The ``tags`` element, which lists the names of tags the user has defined. This can be an entry point to list all files that have been assigned a specific tag or manage tags in general (remove a tag completely, rename a tag etc.).
935 * 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.
936 * The ``history`` element, which allows browsing past instances of ``home`` and - optionally - ``trash``.
938 Objects in Pithos can be:
940 * Assigned custom tags.
941 * Moved to trash and then deleted.
942 * Shared with specific permissions.
943 * Made public (shared with non-Pithos users).
944 * Restored from previous versions.
946 Some of these functions are performed by the client software and some by the Pithos server.
948 Implementation Guidelines
949 ^^^^^^^^^^^^^^^^^^^^^^^^^
951 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 (**TBD**). Such conflicts should be resolved by the user.
953 Object names should use the ``/`` delimiter to impose a hierarchy of folders and files.
955 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.
957 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).
959 At the object level, tags are implemented by managing metadata keys. The client software should allow the user to use any string as a tag and set the corresponding ``X-Object-Meta-<tag>`` key at the server. The API extensions provided, allow for listing all tags in a container and filtering object listings based on one or more tags. The tag list is sufficient for implementing the ``tags`` element, either as a special, virtual folder (as done in the first version of Pithos), or as an application menu.
961 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.
963 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, tags, 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``.
965 Recommended Practices and Examples
966 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
968 Assuming an authentication token is obtained (**TBD**), the following high-level operations are available - shown with ``curl``:
970 * Get account information ::
973 -H "X-Auth-Token: 0000" \
974 https://pithos.dev.grnet.gr/v1/user
976 * List available containers ::
979 -H "X-Auth-Token: 0000" \
980 https://pithos.dev.grnet.gr/v1/user
982 * Get container information ::
985 -H "X-Auth-Token: 0000" \
986 https://pithos.dev.grnet.gr/v1/user/pithos
988 * Add a new container ::
991 -H "X-Auth-Token: 0000" \
992 https://pithos.dev.grnet.gr/v1/user/test
994 * Delete a container ::
996 curl -X DELETE -D - \
997 -H "X-Auth-Token: 0000" \
998 https://pithos.dev.grnet.gr/v1/user/test
1000 * List objects in a container ::
1003 -H "X-Auth-Token: 0000" \
1004 https://pithos.dev.grnet.gr/v1/user/pithos
1006 * List objects in a container (extended reply) ::
1009 -H "X-Auth-Token: 0000" \
1010 https://pithos.dev.grnet.gr/v1/user/pithos?format=json
1012 It is recommended that extended replies are cached and subsequent requests utilize the ``If-Modified-Since`` header.
1014 * List metadata keys used by objects in a container
1016 Will be in the ``X-Container-Object-Meta`` reply header, included in container information or object list (``HEAD`` or ``GET``).
1018 * List objects in a container having a specific meta defined ::
1021 -H "X-Auth-Token: 0000" \
1022 https://pithos.dev.grnet.gr/v1/user/pithos?meta=favorites
1024 * Retrieve an object ::
1027 -H "X-Auth-Token: 0000" \
1028 https://pithos.dev.grnet.gr/v1/user/pithos/README.txt
1030 * Retrieve an object (specific ranges of data) ::
1033 -H "X-Auth-Token: 0000" \
1034 -H "Range: bytes=0-9" \
1035 https://pithos.dev.grnet.gr/v1/user/pithos/README.txt
1037 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``.
1039 * Add a new object (folder type) (**TBD**) ::
1042 -H "X-Auth-Token: 0000" \
1043 -H "Content-Type: application/folder" \
1044 https://pithos.dev.grnet.gr/v1/user/pithos/folder
1046 * Add a new object ::
1049 -H "X-Auth-Token: 0000" \
1050 -H "Content-Type: text/plain" \
1052 https://pithos.dev.grnet.gr/v1/user/pithos/folder/EXAMPLE.txt
1054 * Update an object ::
1057 -H "X-Auth-Token: 0000" \
1058 -H "Content-Length: 10" \
1059 -H "Content-Type: application/octet-stream" \
1060 -H "Content-Range: bytes 10-19/*" \
1062 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1064 This will update bytes 10-19 with the data specified.
1066 * Update an object (append) ::
1069 -H "X-Auth-Token: 0000" \
1070 -H "Content-Length: 10" \
1071 -H "Content-Type: application/octet-stream" \
1072 -H "Content-Range: bytes */*" \
1074 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1076 * Update an object (truncate) ::
1079 -H "X-Auth-Token: 0000" \
1080 -H "X-Source-Object: /folder/EXAMPLE.txt" \
1081 -H "Content-Range: bytes 0-0/*" \
1082 -H "X-Object-Bytes: 0" \
1083 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1085 This will truncate the object to 0 bytes.
1087 * Add object metadata ::
1090 -H "X-Auth-Token: 0000" \
1091 -H "X-Object-Meta-First: first_meta_value" \
1092 -H "X-Object-Meta-Second: second_meta_value" \
1093 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1095 * Delete object metadata ::
1098 -H "X-Auth-Token: 0000" \
1099 -H "X-Object-Meta-First: first_meta_value" \
1100 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
1102 Metadata can only be "set". To delete ``X-Object-Meta-Second``, reset all metadata.
1104 * Delete an object ::
1106 curl -X DELETE -D - \
1107 -H "X-Auth-Token: 0000" \
1108 https://pithos.dev.grnet.gr/v1/user/folder/EXAMPLE.txt
projects / pithos / blob