nova/api-guide/source/polling_changes-since_parameter.rst
Ken'ichi Ohmichi 7957b910dd Change api-site to v2.1 format
The endpoint of v2.1 API is CURRENT now.
On v2.1 API, a tenant-id is not necessary to be specified on the
URL, that is good for making API calls simple for users.
In addition, the endpoint is different from old v2.0 API.
Then this patch makes the api-site fit for v2.1 format.

Partially implements blueprint api-ref-in-rst

Change-Id: I99224dfa77d64f7800733c1af69a55b3b5c761ac
2016-08-16 16:17:03 -07:00

29 lines
1.6 KiB
ReStructuredText

==================================================
Efficient polling with the Changes-Since parameter
==================================================
The REST API allows you to poll for the status of certain operations by
performing a **GET** on various elements. Rather than re-downloading and
re-parsing the full status at each polling interval, your REST client
may use the *``changes-since``* parameter to check for changes since a
previous request. The *``changes-since``* time is specified as an `ISO
8601 <http://en.wikipedia.org/wiki/ISO_8601>`__ dateTime
(2011-01-24T17:08Z). The form for the timestamp is CCYY-MM-DDThh:mm:ss.
An optional time zone may be written in by appending the form ±hh:mm
which describes the timezone as an offset from UTC. When the timezone is
not specified (2011-01-24T17:08), the UTC timezone is assumed. If
nothing has changed since the *``changes-since``* time, an empty list is
returned. If data has changed, only the items changed since the
specified time are returned in the response. For example, performing a
**GET** against
https://api.servers.openstack.org/v2.1/servers?\ *``changes-since``*\ =2015-01-24T17:08Z
would list all servers that have changed since Mon, 24 Jan 2015 17:08:00
UTC.
To allow clients to keep track of changes, the changes-since filter
displays items that have been *recently* deleted. Both images and
servers contain a ``DELETED`` status that indicates that the resource
has been removed. Implementations are not required to keep track of
deleted resources indefinitely, so sending a changes since time in the
distant past may miss deletions.