Cloudware Vendor Solutions - Guide to Cloud Computing for Business and Technology Managers - page 328

16.1.1.4 SimpleDB
SimpleDB is a nonrelational data store that allows developers to store and
query data items via Web Service requests. It supports store-and-query
functions traditionally provided only by relational databases. SimpleDB
creates multiple geographically distributed copies of each data item and
supports high-performance Web applications; at the same time, it automat-
ically manages infrastructure provisioning, hardware and software main-
tenance, replication and indexing of data items, and performance tuning.
Amazon SimpleDB is not designed for complex database schemes or
transactional properties but intended to provide simply structured, yet
highly reliable data storage, which is considered to be sufficient for a wide
range of applications. The database administration and optimization tasks
are thus reduced to a minimum. For applications that depend on the per-
formance and the comprehensive functionality of today's commercial rela-
tional database systems (RDBMS), Amazon RDS is the better choice (see
Section 16.2.1 below).
In line with the limited functionality of SimpleDB, its interface is also
restricted to a few simple Web Service calls. This should ensure both ease of
learning and a user-friendly behavior:
• CreateDomain, ListDomains, DeleteDomain : Create, list, or delete
domains. Domains correspond to the tables existing in relational
databases. Each command can only address one single domain at
a time.
• DomainMetadata : Reads metadata of a domain, such as the current
storage space requirements.
• PutAttributes : Adds or updates a record based on a record identifier
and attribute/value pairs.
• BatchPutAttributes : Simultaneously triggers multiple insert opera-
tions to increase the performance.
• DeleteAttributes : Deletes records, attributes, or values.
• GetAttributes : Reads an identified (partial) record.
• Select : Queries the database using an SQL-like syntax, but without
being applied to multiple domains (as with Join).
16.1.1.5 Simple Queue Service (SQS)
SQS is a hosted message queue. SQS is a system for supporting automated
workflows; it allows multiple Amazon EC2 instances to coordinate their
activities by sending and receiving SQS messages. Any computer connected
to the Internet can add or read messages without any installed software or
special firewall configurations.