Remote Storage Resource Management in WS-PGRADE/gUSE - Science Gateways for Distributed Computing Infrastructures - page 71

available to query what types of storage resources are supported by the Blacktop,
what credentials are needed to authenticate to a given storage resource, and what
sort of operations are available on the selected storage (e.g., read, write, directory
creation, etc.).
The Blacktop was designed as an extendable plugin architecture, where plugins
are aware of communicating with the particular storage resources using the
appropriate storage-speci c protocols. These adaptors are connected to the Black-

top through an Adaptor interface as shown in Fig. 5.3 .
At the time of this writing, two adaptors have been implemented and connected
to the Blacktop: JSAGA Generic Adaptor and S3 Adaptor . JSAGA Generic Adaptor
is based on JSAGA API ([JSAGA]), which is a Java implementation of the Simple
API for Grid Applications (SAGA) speci cation from the Open Grid Forum. This

adaptor is used by the Blacktop to connect to HTTP(s), SFTP, GSIFTP, and SRM
storage resources. S3 Adaptor uses Amazon

s AWS SDK to connect to Simple
Storage Services (Amazon, Ceph Object Gateways) over the S3 protocol, by which
Data Avenue can connect to cloud storage resources as well.
An adaptor implementation must be developed according to the Data Avenue
Adaptor interface to be able to be attached by the Blacktop, which consists of a set of
low-level storage operations such as list , mkdir , delete , rename , read resource
stream , write resource stream , etc. It should be noted that not all operations can be
performed on every storage, e.g., writing is not possible on HTTP storages; therefore
adaptor implementations are limited to the relevant operations only. The Blacktop

'

Fig. 5.3 Blacktop architecture