Adrian Cole created JCLOUDS-299:
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Summary: Multi-Region Support for BlobStore
Key: JCLOUDS-299
URL: https://issues.apache.org/jira/browse/JCLOUDS-299
Project: jclouds
Issue Type: Improvement
Components: jclouds-blobstore
Reporter: Adrian Cole
Assignee: Adrian Cole
Fix For: 1.7.0
Currently, the BlobStoreContext api is only effective for a specific region.
This has some benefits, such as knowing failure cases only apply to one region.
The way to achieve this is in swift-keystone is to provide a context property
of a well-known region id. This was introduced in
https://issues.apache.org/jira/browse/JCLOUDS-126
For effective multi-region apps, we need to both expose which regions are
available, and also continue isolating a BlobStore to a specific one. Using
this model, users can have predictable performance (ex. one BlobStore command
won't cross regions), and isolation (one down region won't affect the BlobStore
in use).
The style of exposing an api scoped to region is also something we've practiced
for well over a year, at the provider api level.
ex. SwiftApi.getObjectApiForRegion("foo") style is commonplace now, even if not
yet in the "View" interfaces such as BlobStore.
During the last planning meeting, Maginatics (via andrew gaul) raised
supporting multiple regions in BlobStore is becoming a must have. Users need to
interact with multiple regions within Rackspace and OpenStack, for example, and
these users may not know the magic region ids, nor desire maintaining a
separate context for each.
This issue introduces a design that takes directly from the 'provider api"
practice of get*ApiForRegion("foo"), applied it to BlobStore, specifically the
word "region" as that has a fairly common understanding across BlobStore
providers.
Ex. BlobStoreContext ctx = ...
// new command
// note we aren't propagating the rarely useful Location object, and instead
dealing w/ Strings
// also note this is *before* you get a blobstore instance, hinting that this
is a discovery command Set<String> regionIds = ctx.configuredRegions();
// maintain current behaviour, which defers to defaults.
BlobStore defaultBS = ctx.getBlobStore();
// new command
// isolated to a specific region and will not make calls across multiple
endpoints
BlobStore defaultBS = ctx.blobStoreInRegion("foo");
Note the style above is opinionated a bit. For example, we aren't following the
javabeans practice of putting "get" in front of everything. See "how to write a
method" http://vimeo.com/74316116
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