RDF Server on SemSpect

Mon, 01 Jan 0001 00:00:00 +0000

Installation & Quickstart of the RDF Server #

System Requirements #

Java 17 or later (parsing is approx. 50% slower with Java >=19)
The RDF SemSpect server was tested under macOS, Linux, Windows
A recent web browser
WARNING: we do not recommend using Firefox under Windows, some versions have issues in the table view

Installation of the RDF SemSpect Server #

Download the RDF SemSpect server package from:

https://www.semspect.de/rdf-semspect-distribution-19.2.1.zip

Mon, 01 Jan 0001 00:00:00 +0000

Loading Data into RDF SemSpect #

SemSpect is a Snapshot Explorer #

SemSpect is an explorer and querying tool for RDF data snapshots. This means that SemSpect does not fetch data from a SPARQL endpoint on demand, but loads the specified list of RDF input data for which it generates special indices. If the input data changes, the index must be recalculated.

RDF SemSpect indices are managed by derivo SemStore, a proprietary in-memory RDF store. SemStore uses low-memory index structures that have been specially developed and optimized for the efficient processing of SemSpect front-end requests. Parts of these index structures are based on a variant of the Bitmap Triple (BT) indices, which extend the compact triple data structure of the RDF compression format HDT.

Mon, 01 Jan 0001 00:00:00 +0000

Configuration of the RDF Server #

Start scripts #

The start scripts are available as shell (*.sh) and batch (*.bat) variants for each of the 2 operation modes:

semspect-smart.* for the single-database “smart” mode described in the quickstart page.
semspect-server.* for the more complex but highly configurable multi-database “server” mode.

The batch and shell start scripts can be partially configured through environment variables:

Resource Considerations

Mon, 01 Jan 0001 00:00:00 +0000

Resource Considerations #

This section is intended to provide assistance in estimating the required memory and the resulting indexing speed of SemSpect on the basis of empirical values.

The following is a statistical evaluation of RDF SemSpect on the indexing speed and the memory requirements. For this, we considered altogether 26 datasets with up to 352M triples. The benchmark has been conducted for different JVM memory allocations in order to roughly estimate the memory requirements to support a desired amount of triples. Moreover, it compares our two indexing methods, namely the “one pass” and “two pass” approaches. In particular, we generate the index (compressed dictionary and triples) in a single parsing iteration (namely “one pass”: faster, higher memory consumption) or in two separate parsing iterations (“two pass”: slower, but less memory consumption).

Managed Mode - REST API

Mon, 01 Jan 0001 00:00:00 +0000

SemSpect Managed Mode #

RDF SemSpect can be started without any predefined databases. We provide a REST API to create/delete databases and replace their content while the server is running (hotswap). The UI not only monitors hotswaps but is also aware of the creation and deletion of new databases.

REST API Routes #

Create Database #

POST /api/database/{DATABASE_ID}
{
 "metadata": {
 "databaseCaption": "DB caption",
 "contentDescription": "",
 "exampleKey1": "test",
 "exampleKey2": 42
 },
 "config": {
 "indexing": {
 "disableDomainRangeEntailment": true,
 "rdfDataSources": [
 "file:///..." 
 ]
 },
 "exploration": {
 "showTopClassInTree": false,
 "showClassesAndPropertiesAsResources": false
 },
 "presentation": {
 "locales": ["en", "de", "fr"]
 }
 }
}

Notes #

Metadata

FAQ

Mon, 01 Jan 0001 00:00:00 +0000

Frequently Asked Questions #

Please also note the current limitations.

How are HTML tags in string values processed? #

SemSpect supports a predefined set of HTML tags in string values that are permitted for rendering within the user interface. These tags include a, b, i, em, and br. Any HTML tags not listed in this set will be automatically excluded from the rendered output.

How can I report bugs, request features, or provide general feedback? #

To report bugs, request features, or to provide general feedback, please open a new issue in our dedicated SemSpect Community GitHub repository.

Mon, 01 Jan 0001 00:00:00 +0000

Known Issues of RDF SemSpect Server #

This page contains information about all known issues of the latest release of RDF SemSpect. To report other bugs, request features, or just provide general feedback, you can use the dedicated SemSpect Community GitHub repository.

Some versions of Firefox under Windows have issues in the table view (e.g., opening the context menu of the columns in the table view selects the previous column). Try another version of Firefox or use another browser.

RDF Server on SemSpect

Installation & Quickstart of the RDF Server #

System Requirements #

Installation of the RDF SemSpect Server #

Loading Data into RDF SemSpect #

SemSpect is a Snapshot Explorer #

Configuration of the RDF Server #

Start scripts #

Resource Considerations

Resource Considerations #

Managed Mode - REST API

SemSpect Managed Mode #

REST API Routes #

Create Database #

Notes #

FAQ

Frequently Asked Questions #

How are HTML tags in string values processed? #

How can I report bugs, request features, or provide general feedback? #

Known Issues of RDF SemSpect Server #

The context menu of the column headers in the table view has an erratic behaviour #