GraphDB-SE Introduction

This chapter briefly explains the purpose and the scope of this document, its place in the GraphDB user documentation set, and provides some suggestions for efficient use. It starts with an introduction on the differences between the two editions of GraphDB, which facilitates the understanding of the GraphDB product family, the design objectives behind each of the versions and the rationale behind the structuring of the documentation.

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h2. GraphDB Editions

GraphDB comes in four editions: GraphDB-Lite, GraphDB-SE (standard edition), GraphDB-Enterprise and GraphDB Cloud via the AWS Marketplace.

h3. GraphDB-Lite
GraphDB-Lite is designed for medium data volumes (below 100 million statements) and for prototyping. Its key characteristics are as follows:
* reasoning and query evaluation are performed in main memory;
* it employs a persistence strategy that ensures data preservation and consistency;
* the loading of data, including reasoning, is extremely fast;
* easy configuration.

h3. GraphDB-SE
GraphDB-SE is suitable for handling massive volumes of data and very intensive querying activities. It is designed as an enterprise-grade database management system. This has been made possible through:
* file-based indices, which enable it to scale to billions of statements even on desktop machines;
* special-purpose index and query optimisation techniques, ensuring fast query evaluation against very large volumes of data;
* optimized handling of owl:sameAs (identifier equality) to boost efficiency for data integration tasks;
* efficient retraction of explicit statements and their inferences, which allows for efficient delete operations.


{info}GraphDB-Lite and GraphDB-SE are identical in terms of usage and integration. Apart from a few differences in the configuration parameters, these editions have the same functionality and implement the same Sesame APIs. However, they use different indexing, inference and query evaluation implementations, which results in different performance, memory requirements, and scalability.
{info}

h3. GraphDB-Enterprise
GraphDB-Enterprise is a component that can manage and synchronise multiple GraphDB instances in a resilient and scalable cluster configuration.

This document is designed for software engineers, system integrators and system administrators who wish to integrate the GraphDB-SE semantic repository in to their applications or who wish to use GraphDB-SE and Sesame as a stand-alone server for storing and processing structured data. It is also useful for system administrators who need to support and maintain a GraphDB-SE repository.
The reader is assumed to be familiar with databases, but not an expert in semantic database systems, semantic information retrieval,
Semantic Web, or GraphDB itself. Less experienced readers are recommended to read the GraphDB Primer where the required minimum of Semantic Web and related concepts is covered, as well as GraphDB basics.
This document has multiple uses:
* To provide the information necessary to use GraphDB-SE repositories via the Sesame APIs;
* To give instructions on managing repositories through the Sesame web front-end;
* For familiarisation with GraphDB-SE's reasoning capabilities and rule language;
* To enable the creation of custom installations and configurations of GraphDB-SE;
* To introduce the most important factors that affect the efficiency of GraphDB-SE and to provide some productivity tips.

h1. How to Use This Document

Readers new to GraphDB should read the GraphDB Primer first and then this document in its entirety. This will guarantee that the necessary basic information has been covered in sufficient depth. After some experience using GraphDB, this guide can be used as a reference for carrying out specific tasks.
The following conventions are used in this document:
* Code examples are listed in a {{typewriter-like font}}
* Other important terms, when first introduced, will be written in _italics_
* Formulas are always in _italics_
* References are given in square brackets, e.g. \[3\] means "Refer to publication #3 in the References section"
* GraphDB-Lite, GraphDB-SE and GraphDB-Enterprise are referred to collectively as "GraphDB" in those cases where it is not necessary to distinguish between the editions, i.e. the specifications, features, and/or settings described are common for all editions.

h1. Copyrights and Licensing

This document and the products discussed in it are copyrighted and subject to licensing as follows:
* *GraphDB-SE, © Copyright Ontotext AD.* 135 Tsarigradsko Shosse, Sofia 1784, Bulgaria, [http://www.ontotext.com].
* *Sesame, © Copyright Aduna b.v*. Stadsring 181, 3817 BA Amersfoort, The Netherlands Sesame is an open-source library, available under the GNU Lesser GPL ([http://www.gnu.org/copyleft/lesser.html])
** All other trademarks mentioned in this document, belong to their respective owners.

Full licensing information is available at [http://www.ontotext.com/products/ontotext-graphdb/|http://www.ontotext.com/products/ontotext-graphdb/], as well as in the license files located in the main folder of the distribution package.