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Package java.util.concurrent.atomic Description A small toolkit of classes that support lock-free thread-safe programming on single variables. In essence, the classes in this package extend the notion of volatile values, fields, and array elements to those that also provide an atomic conditional update operation of the form: boolean compareAndSet(expectedValue, updateValue);

"AtomServer is a generic data store implemented as a RESTful web service. It is designed as a GData-style Atom Store. It is based on the following concepts and protocols; REST. REST is a design pattern. It's not a technology like SOAP or HTTP. REST is a proven design pattern for building loosely-coupled, highly-scalable applications. There are important benefits to sticking to the REST design pattern; Simple. REST is incredibly simple to define. There are just a handful of principles and well defined semantics associated with it. Scalable. REST leads to a very scalable solution by promoting a stateless protocol and allowing state to be distributed across the web. Layered. REST allows any number of intermediaries, such as proxies, gateways, and firewalls. Ultimately REST is just a web site, albeit one that adheres to a design pattern, so one can easily layer aspects such as Security, Compression, etc. on an as needed basis. Atom. Fundamentally, Atom is an XML vocabulary for describing lists of timestamped entries. These entries can be anything, although because Atom was originally conceived to replace RSS, Atom lists are Feeds, and the items in the lists are Entries. Atom is a RESTful protocol. AtomServer stands on the shoulders of giants. It is built on top of several open source projects - most notably, Apache Abdera (a Java-based Atom Publishing framework) and Spring. AtomServer is an Atom Store. Thus, it requires a relational database to run. AtomServer currently supports; PostgresSQL, SQLServer, and HSQLDB. Using HSQLDB, AtomServer requires zero configuration and can run out-of-the-box. While this configuration is suitable for many applications, those that see significant load will likely require a database with better transactional semantics, such as PostgreSQL. AtomServer is easy to use. It deploys as a simple WAR file into any Servlet container. Or alternately, can be used out-of-the-box as a standalone server, running with

" The primary purpose of the JcrCollectionAdapter class is to equip a stand-alone Atom server with a JCR repository for storage. However, with a bit of tweaking the class can also be used to provide an Atom interface to an existing CRX repository: a simple way to get things running is to leave the existing CRX Quickstart untouched and connect to the repository through RMI. RMI is disabled by default, but on CRX's Knowledge Base is an article how to enable it. "

"The goal of the Apache Abdera project is to build a functionally-complete, high-performance implementation of the IETF Atom Syndication Format (RFC 4287) and Atom Publishing Protocol (RFC 5023) specifications."

"http://www.atompub.org/ defines a simple interface over HTTP to publish and subscribe to artifacts (files) and collections of artifacts (services/packages). AtomPub interface serves following purposes: 1: provide "feeds" for people/systems to monitor for changes: For example, user subscribes to a feed which lists contents of package or user subscribes to feed which lists changed contents in a package 2. provide the default remote api to push/pull content and meta data from the repository. This allows other applications to integrate with Guvnor by accessing repository content via atom pub programmatically."

"Unfortunately, in a distributed world, SOA or otherwise, it is rarely a good idea to use atomic short lived transactions (see the Cross-Service Transactions anti-pattern in chapter 10 for more details). Indeed, the fact that cross service transactions are discourages is one of the main reasons we would to consider using the Saga pattern in the first place. One of the obvious shortcomings of Sagas is that you cannot perform rollbacks. The two conditions mentioned above, locking and isolation do not hold anymore so you cannot provide the needed guarantee. Still, since interactions, and especially long running ones, can fail or be canceled Sagas offer the notion of Compensations. Compensations are cool; we can't have rollbacks so instead we will reverse the interaction's operation and have a pseudo rollback. If we added one hundred (dollars/units/whatnot) during the original activity we'll just subtract the same 100 in the compensation. Easy, right?"

This project will mainly contain utility stuff for diverse purpose. Initially it will primarily comprise of Spring Utilities which will perform the following purposes: Load a single resource properties file from pre-configured locations with priority based override. Application context registrar to make the context available to other interested components. Use Cacheable Jersey Client Use a generic RESTful WS Client OpenSearchDescriptor JAX-RS Provider based on XOM based DOM I/O Useful utilities for Atom Syndication Feed, such as pagination over entities, retrieval of resource to certain depth, etc.

" Further talk about the overall approach to REST access in the Guvnor project expanded from the JIRA issue, ad hoc discussions on the dev list to Jevis Liu's "AtomPub Interface for Guvnor" proposal on the Drools community wikI. Taking off from where Michael Neale's original "Guvnor AtomPub Interface" started in 2008 and expanding into categories, metadata and other return types, this page became a rough, but working implementation specification. "