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We expose our underpinning technologies (at the Java API level, at least) for developers, so it is also helpful (and sometimes even necessary) to be familiar with the features and functions those technologies offer:

Modeshape

Modeshape is an implementation of the JSR-283 Java API for content repositories ("JCR"). Fedora wraps the Modeshape Java API with our own REST and Java APIs. 

ModeShape is a distributed, hierarchical, transactional, and consistent data store with support for events, versioning, references, and flexible schemas. It is very fast, highly available, extremely scalable, and it is 100% open source and written in Java.

ModeShape is perfect for data that is organized in a tree-like hierarchical structure where related data is stored close together, where navigation to related content is just as common and important as fast key-based lookups or queries. The hierarchical organization is similar to a file system, making ModeShape a natural for storing files annotated with metadata. ModeShape can even automatically extract the structured information within the files so that clients can navigate or use typed queries to find files satisfying complex, structurally-oriented criteria. ModeShape is an excellent store for data with a complex schema, since the schema can vary over the database and evolve over time. ModeShape is the perfect distributed data store for all kinds of applications, including repositories, content management systems, historical data services, provisioning and governance systems, and metadata management systems.

Modeshape stores object metadata in an Infinispan cache. Binary content MAY be stored on disk or in an alternative BinaryStore. Binary values are de-duplicated based on the SHA-1 hash of their content at the BinaryStore layer (meaning if you add 2 datastreams with identical content, it'll only store that 1 time in the storage system).Modeshape provides additional points of extensibility (e.g. Sequencers), and support for widely implemented APIs like CMIS, WebDAV, etc.  Modeshape also provides a "federation" feature, where:

• Clients (eg: such as Fedora) can access internal data (owned by ModeShape) and external data (owned by an external system) in exactly the same way, using the JCR API. ModeShape might cache this external data (for performance reasons), but it would never store any of this external data.

Fedora uses this feature to provide "instant ingest", where you can stage content on a filesystem, initiate an ingest into Fedora, and while that process occurs, Fedora can still serve up the content directly from the filesystem.

See also:

ModeShape

Introduction

 Introduction

First Steps

The Fedora object model

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