2b:null 2c:["$","title",null,{"children":"Blog Catalog | datagenous | Observable"}] 31:T8b20,catalogA = html`

A: Blog articles ⤒

James Anderson, 2026/09/10 18:00:00 GMT+2

EXISTS via Lateral Join — Summary

As the W3C RDF 1.2 [Working group](https://www.w3.org/groups/wg/rdf-star/) works towards completion of the new SPARQL recommendation, it is [considering](https://github.com/w3c/sparql-query/issues/156) how to correct the definition of the EXISTS operator. This is a curated summary of the design analysis, the relational model, the lateralisability decision, the benchmark, and the scope theory behind an approach to evaluating the EXISTS operator as a lateral-join.
James Anderson, 2026/07/27 00:22:00 GMT+2

Teaching an Old Store New Triples: Implementing RDF 1.2 / SPARQL 1.2 in Dydra SPOCQ

RDF 1.2 and SPARQL 1.2 add a small number of features with an outsized reach into a triple store: triple terms (<<( s p o )>>, an unasserted value that is a triple), reified triples (<< s p o ~r >>, a triple given a named occurrence), annotation syntax (S P O {| … |}), base-direction language tags ("hello"@en--ltr), and the VERSION directive. None of them is large on paper and yet they touch the parser, the dictionary, the index, the query compiler, the evaluator, and every serializer. This is the story of bringing them into SPOCQ — a SPARQL 1.0/1.1 engine over LMDB — from a clean 1.1 baseline to a stable state against the W3C 1.2 test suite, and of decisions along the way.
Max-Gerd Retzlaff, 2026/05/26 2:29:20 PM GMT+2

ELS 2026 papers to conclude the series on using NDB interpreted code

May 26, 2026. Max-Gerd Retzlaff, Datagraph GmbH, Berlin.

This is the forth article in a series on using NDB interpreted code (IC) programs with RonDB and it contains the promised closer look at the NDB IC Compiler and how our graph database Dydra uses it.

To conclude the series I decided not to write more blog posts but rather two formal research papers, which I presented at The 19th European Lisp Symposium (ELS'26), Krakow, Poland, 11-12 May 2026.

… Read the whole article: ELS 2026 papers to conclude the series on using NDB interpreted code
Max-Gerd Retzlaff, 2025/11/07 11:11:27 AM GMT+1

A very short NDB interpreted program:
row counts and range estimations
November 17, 2025. Max-Gerd Retzlaff, Datagraph GmbH, Berlin.

This is the third article in a series on using NDB interpreted code (IC) programs with RonDB and discusses:
- an example of a very short but still very useful interpreted code program and
- I outline how it is used in RonDB to do quick row counts of entire tables, but
- the main part is how this is adapted to be useful to improve our graph database Dydra.
This is not just a theoretical discussion but a significant improvement and actually essential for Dydra.

I explain how triples can be stored in a very simply fashion in an SQL table and I show some simple SPARQL queries and how they translate to underlying RonDB index scans. All that combined with a simple interpreted program, bounded scans and retrieval of extra values. With the older RecAttr interface as well as the newer Record interface of the NDB API.

So this article contains a lot of source code for a change. C++. SQL, SPARQL and Common Lisp.

… Read the whole article: A very short NDB interpreted program: row counts and range estimations
Max-Gerd Retzlaff, 2025/10/07 13:22:16 PM GMT+2

A note on RonDB and MySQL NDB Cluster, their documentation, and RonDB's history

October 07, 2025. Max-Gerd Retzlaff, Datagraph GmbH, Berlin.

This is the second article in a series on using NDB interpreted code (IC) programs with RonDB and it just tries to work out how accurate the MySQL documentation still is for its fork RonDB. A question that I had for a long time, especially when I started to use RonDB and implemented code to access it. (The first article is "NDB interpreted code, cl-ndbapi, and the new NDB IC compiler".)

… Read the whole article: A note on RonDB and MySQL NDB Cluster, their documentation, and RonDB's history
Max-Gerd Retzlaff, 2025/09/29 12:39:38 PM GMT+2

NDB interpreted code, cl-ndbapi, and the new NDB IC compiler
September 29, 2025. Max-Gerd Retzlaff, Datagraph GmbH, Berlin.

This is the first article in a series on using NDB interpreted code (IC) programs with RonDB. And how the compiler I wrote for it made the task much simpler (at least for me and probably for any other Lisp programmer), as it allows to:
- write the code with higher level constructs and
- compile not only to NDB interpreted code but also to a Lisp backend.
The last part means that a subset of the NDB interpreted code languages was also implemented in Lisp. NDB interpreted programs can also be compiled to this Lisp subset, so that new code can be tested in the Lisp image as ordinary Lisp code with full introspection instead of running it within RonDB data nodes which is quite opaque in comparison and often requires debugging crash logs instead when something goes wrong.

… Read the whole article: NDB interpreted code, cl-ndbapi, and the new NDB IC compiler
Max-Gerd Retzlaff, 2025/9/22, 1:18:02 PM

Scaling Dydra with RonDB: Toward a Trillion-Triple Store

September 22, 2025, Datagraph GmbH, Berlin, and Hopsworks AB, Stockholm.

What if your database could remember everything—every edit, every state, every version—across time, while scaling effortlessly beyond the limits of a single machine?

That’s exactly the kind of challenge we’ve been tackling with Dydra, a revisioned RDF graph store, and RonDB, a high-performance, clustered database built for scale.

… Read the whole article: Scaling Dydra with RonDB: Toward a Trillion-Triple Store
Max-Gerd Retzlaff, 2025/9/19, 1:16:52 PM

cl-ndbapi for RonDB 24.10

September 19, 2025. Release announcement.

Datagraph GmbH, Berlin. – After more than a year of work, we just released a much enhanced version of cl-ndbapi, the Common Lisp bindings to the C++ NDB API of RonDB. So, welcome cl-ndbapi for RonDB 24.10!

Since the version for RonDB 22.10.1, which was released in June 2024, cl-ndbapi evolved as new features of RonDB were developed in collaboration with us, changing its API often. Therefore we decided not to release it until RonDB 24.10 was released. Now that this has happened a short time ago in August 2025, it is time to release cl-ndbapi for RonDB 24.10 as well.

As a main feature it contains a neat little compiler which allows to write NDB API interpreted programs in a simplified Lisp and push computations from the query processor into the RonDB cluster, specifically the data nodes.

… Read the whole article: cl-ndbapi for RonDB 24.10
James Anderson, 2025/6/18, 0:34:30 AM

Dydra's SPARQL Query Processing Extensions: Entailed Paths

Dydra's SPARQL query processor enhances query processing by embedding predefined queries, views, within broader SPARQL queries. A notable recent extension allows these views to be embedded within SPARQL property paths, enabling advanced recursive entailment.

… Read the whole article: Dydra's SPARQL Query Processing Extensions: Entailed Paths
Max-Gerd Retzlaff, 2024/7/23, 3:22:38 PM

Pushing the logic to the data – Running Dydra's revisioning algorithm within RonDB's data nodes

July 23, 2024. News release.

We are working on ways to distribute not just data storage, but also query processing. A new capability of both Dydra and RonDB allows us to push the test to the data instead of having to pull all data to the test, greatly reducing the data that has to move.

Data that used to be opaque to RonDB and had needed to be retrieved from the data nodes and interpreted by the Dydra query processor, is now analyzed by hashtag#NDB interpreted code within the RonDB cluster already.

… Read the whole article: Pushing the logic to the data – Running Dydra's revisioning algorithm within RonDB's data nodes
John Walker, 2023/5/17, 4:26:52 PM

A Semaku perspective on RDF-star

[This is an early version of John Walker's post about RDF star. A revised version is to be found at https://semaku.com/post/why-im-worried-about-rdf-star/.]

In a recent post, Dean Allemang explained why he's not excited about RDF-star. In this post I want to expand on Dean's post with more concrete examples to illustrate why I'm worried about RDF-star.

In the flights example, Dean mentions that using RDF-star would encourage poor modeling practice. So how exactly would that manifest if we choose to model multiple flights with multiple triples:

… Read the whole article: A Semaku perspective on RDF-star
James Anderson, 2023/3/30, 5:27:00 PM

Correlated Subqueries in SPARQL

In the original 1.0 version, SPARQL provided means to express RDF graph patterns, apply them to an RDF dataset, arrange the terms matched from the given patterns into solutions, and return them as solution sequences or new RDF graphs. The language semantics described how to apply various algebra operators to combine the results from statement pattern matches to compute conjunctions and disjunctions, to constrain the results with filters, to modify their order, to apply a window to the solution sequence.

In all combinations, however, an algebra expression is interpreted "from the bottom up". This means that each branch of an expression is interpreted independent of others, with the respective results combined within the operators only. Variables are bound by basic graph statement patterns, SELECT, BIND, and VALUES clauses and a binding's scope is those operators in the algebra tree to which it is supplied in solution arguments.

… Read the whole article: Correlated Subqueries in SPARQL
James Anderson, Edited 4/30/2023, 3:15:33 AM

Smithsonian AAM Probes

This exploration concerns the Smithsonian American Art Museum dataset available through their endpoint.

20230430: the endpoint is no longer available.

Note, there appears to be no service description. The dataset is difficult to explore, as it integrates no metadata to support introspective exploration. It is not as daunting as Wikidata, but all is relative.

… Read the whole article: Smithsonian AAM Probes
James Anderson, 2022/8/24, 12:05:20 AM

Autonomous Entailment

The problem is to derive specific values for some relationship when the only stored data pertains to relationships which should be similar but are not identical. In the context of SPARQL processing, this is known as entailment. A simple SPARQL evaluation involves interpreting the triples in both the RDF data and the query as designators for node graphs and matching the query graph against the data graph to yield bindings for any variables. Entailment adds meaning to the data by incorporating into the interpretation relationships which the processor derives from rules or infers from data statistics. Rule-based entailment involves definitions independent of the data. These may be fixed collections, such as RDFS- or D-entailment, or them may involve a meta-language, such as OWL which permits to define the rules. Autonomous entailment is based on rules extracted from the data itself, based on "a joint probability distribution of input (measurements) and output (say class labels) variables."[^shashua2008]

… Read the whole article: Autonomous Entailment
Max-Gerd Retzlaff, 2022/07/11 18:00

Almost 600,000 entries per secondfrom Lisp to Accumulo

This is a condensed graph taken from the Accumulo Monitor when writing 120M entries to six tables in parallel, or 20M entries per table:

It was acchieved by using six Apache Accumulo Proxy servers talking to six tablet servers of a single-node Apache Accumulo cluster, and using one connection to the proxy per thread.

… Read the whole article: Almost 600,000 entries per secondfrom Lisp to Accumulo
James Anderson, 2021/11/17

About RDF Annotation (4)

for Internal Attributes

Dydra records several internal attributes for each quad. When a repository is configured to retain revisions, each quad associates a record ^[0] of the transactions which determined its visibility. For a simple revisioned repository, these are the ordinals of the transaction ordinals which added and removed. For a replicable repository, these would be the respective uuid revision operations.

The external interface^[1] to query those repositories which enable this capability permits a temporal constraint to designate a single revision, an interval or a sliding window, which is interpreted to apply the query to one or more snapshots of the repository. The snapshot serves as the source to constitute the dataset to which to apply the SPARQL query as if it were static. The SPARQL 1.1 language, unfortunately, offers no facility with which to address the internal data.

… Read the whole article: About RDF Annotation (4)
James Anderson, 2021/11/16

About RDF annotation (3)

non-Standard Reification
The recent "GraphDB Users Ask" blog post^[0] is yet another occasion to reflect about RDF annotation. In the beginning, there was the triple:
```
  <http:ex.org/subject>  <http:ex.org/predicate> "object" .
        
```
… Read the whole article: About RDF annotation (3)
James Anderson, 2021/10/8

About RDF annotation (2)

Annotating single statements

Using property lists

Continuing the discussion from "About RDF Annotation", how might one use SPARQL to annotate statements?

The simplest change is to use the existing syntax for a statement property list to do exactly that

… Read the whole article: About RDF annotation (2)
James Anderson, 2021/9/21, 1:12:01 AM

About Interleaved Update Queries

Support for constraints notification in SPARQL update clauses

SPARQL queries include expressions which modify the content of the target dataset. These appear in a Update clause:

… Read the whole article: About Interleaved Update Queries
James Anderson, 2021/07/10

Collated Reification

reasons for rdf-star

One reason given for the RDF-star imperative is the difficulty presented by reified statements. It is proposed that the extra storage space and the increased processing time required by a representation which involves a triple for each statement term justifies introducing a data type to represent statements more compactly and permit more efficient processing.

This document looks at the processsing required for term reification.

… Read the whole article: Collated Reification
James Anderson, 2021/7/7, 10:45:21 AM

About Materialized Text Views

Support for free-text in materialized views in Dydra

Dydra provides two text index forms. One approach recognizes an active predicate (a magic property) as an operator in a BGP. The other supports free text arguments to parameterized SPARQL view requests. The BGP variant accepts the pattern plus optional constraints and yields matched results to the BGP evaluation process. The SPARQL view variant accepts pattern arguments to constrain the solutions returned from a materialzed view cache.

Both rely on PostgreSQL full text index support to extend materialized views.

This document describes materialized text views. These combine the text index with the additional terms projected for a materialized view. The alternative, free text indexes, provides a mechanism to match patterns to literal strings and their rank.

… Read the whole article: About Materialized Text Views
James Anderson, 2021/7/4, 1:59:50 AM

About Simple Free-Text Queries

Support for free-text in Dydra

Dydra provides two text index forms. One approach recognizes an active predicate (a magic property) as an operator in a BGP. The other supports free text arguments to parameterized SPARQL view requests. The BGP variant accepts the pattern plus optional constraints and yields matched results to the BGP evaluation process. The SPARQL view variant accepts arguments for pattern parameters to constrain the solutions returned from the materialized cache.

Both rely on PostgreSQL full text index support to extend materialized views.

This document describes the simple text index forms. This mechanism matches patterns to literal strings and their rank. The alternative, the materialized text view, combines the text index with the additional terms projected for a materialized view.

… Read the whole article: About Simple Free-Text Queries
James Anderson, 2021/3/24 9:11:47 PM

Javascript Presentation Library
The service interface (SOW-20210305) requires both renders the service definition and uses that rendering mediate interaction with the service state.

interaction lacks native support

Browsers offers alternative graphics iterfaces :
- SVG : document.createElementNS("http://www.w3.org/2000/svg", 'svg');
- canvas : canvas.getContext('2d');
- WebGL : canvas.getContext('webgl');
… Read the whole article: Javascript Presentation Library
James Anderson, 2021/3/5

SOW-20210305 : Visible Workflows
The service can reify SPARQL queries and associate them with URL among an account's resources in the HTTP interface and to be referenced internally in other SPARQL queries. They mediate between various sources and destinations, they can
- act as schema to define data entry interfaces,
- operate as internal transformation instructions between repositories,
- govern data import into a repository,
- afford access to local and remote virtual sources,
- fulfill the standard role as queries against repositories.
… Read the whole article: SOW-20210305 : Visible Workflows
James Anderson, 2020/10/19

About RDF annotation

Formulae and RDF*

There is interest to emulate the expressive capabilities of property graphs in RDF forms. Attention focuses on an approach called "RDF *", which extends RDF forms with triple forms as subject and object terms in order to express RDF statement annotations that are equivalent to link attributes in property graphs.

Somehow, the discussion neglects the aspects of N3 to which it closely relates. . Hayes did mention that in passing, but the thread was inexplicably neglected. He also called attention to issues from treating "entailed assertion (PG) and "separate assertion" (SA) semantics as representations associated with syntax (variants) rather than as independent interpretations and reiterated the insight, that PG interpretations are possible based on an abstract syntax which permits SA interpretations, while the opposite is not.

… Read the whole article: About RDF annotation
James Anderson, 2020/8/24, 6:29:55 PM

Opinions on a LISP API for LMDB

what benefits and risks does a lisp binding for lmdb embody?

the principal matter is how well the binding mediates the capabilities of the lmdb library. this is to be weighed against ways a binding might constrain or modulate those capabilities to bring access to them in line with best - or even just customary, practice, to mitigate dangers a foreign library introduces or to facilitate access patterns prevalent in a given application.

… Read the whole article: Opinions on a LISP API for LMDB
James Anderson, 2016/07/14 23:00

A Linked Data Fragments Service

Linked data fragments propose to facilitate more robust remote access to linked data sources by limiting the resources required to afford access. One way proposed to achieve this goal is to provide access to this data through the triple pattern fragments interface.[0]

This document discusses a TPF server implemented on the basis of a SPARQL runtime.

… Read the whole article: A Linked Data Fragments Service

`32:T56e6,catalogB = html`

B: Blog articles from older blog ⤒

These are all static articles. For newer articles we switched to Observable notebooks, that allow us to integrate interactive elements.

James Anderson, 2016/05/12

Inferring Quicklisp System Descriptions

We presented, at the recent ELS 2016[0], the speculative results from using SPARQL to analyse implicit dependancy relations in the LISP ecosystem, as embodied in a recent Quicklisp[1] release.

The slides are now up and available at the link from the programme page. The repository is available[2] -- together with several illustrative queries and the ontology is online as well[3].

… Read the whole article: Inferring Quicklisp System Descriptions
Arto Bendiken, 2015/10/08

NXP Wins the EU Linked Data Award

We are pleased to be able to report that the Product Marketing group at NXP Semiconductors has been awarded first prize in both the Dutch Best Linked Data Application of 2015 contest and the 2015 1st European Linked Data Award contest. Both

… Read the whole article: NXP Wins the EU Linked Data Award
James Anderson, 2015/09/15

An RDF Patch Format

As we move towards "Linked Data Platform"[0] support, we need to provide a mechanism to modify selectively repository content which represents containers and collections. Yes, in principle, the SPARQL and Graph Store protocols provide such facilities, but there is a wide-spread reluctance to admit their suitability due to one common issue: the restrictions placed on blank node designators. Any sorts of models which involve blank nodes require special procssing in order to specify the statements to modify.

… Read the whole article: An RDF Patch Format
Arto Bendiken, 2015/09/02

Repository Revision History

We have now enabled repository revisioning for all Dydra evaluation users on the dydra.com cloud service. Customers with dedicated and on-site servers will receive this feature in their next scheduled system upgrade.

… Read the whole article: Repository Revision History
James Anderson, 2015/08/30 00:00

Variable SPARQL Service Locations

The SPARQL grammar--in particular the ServiceGraphPattern production, indicates that it should be possible to specify either an IRI or a variable as a service location.[1] The W3C's "SPARQL 1.1 Federated Query" recommendation[2] does not, however, define an evaluation semantics for a service variable.

… Read the whole article: Variable SPARQL Service Locations
James Anderson, 2015/05/06

Collation Sequences in SPARQL

The SPARQL query language is relatively silent about how to order strings. When the question was posed to us a while back, what to expect as the order of a solution sequence which contained string literals with language tags, we had just the conservative answer that the relation among simple or string literals and plain literals was undefined. This was not a nice situation.

… Read the whole article: Collation Sequences in SPARQL
James Anderson, 2015/04/28

Extended Temporal Datatype Support
Dydra recently extended its native support to cover the full XSD temporal data type complement. This means not only that our platform continues to provide compact native representations for the core data types:
- xsd:date
- xsd:dateTime
- xsd:time
where each term requires one cell - that is, eight bytes, but, in addition, SPOCQ, Dydra's SPARQL processor, implements internal data classes for the remaining types:
- xsd:dayTimeDuration
- xsd:yearMonthDuration
- xsd:gDay
- xsd:gMonth
- xsd:gMonthDay
- xsd:gYear
- xsd:gYearMonth
… Read the whole article: Extended Temporal Datatype Support
James Anderson, 2015/04/21

Quads with a View

One may have noticed recently, that the controls in our query editor have changed ever so slightly. In particular, the entries in the query list have an additional icon: a link.

… Read the whole article: Quads with a View
James Anderson, 2015/04/14

BGP Statement Pattern Counts

A recent developer mailing list inquiry caught our attention a few days ago. The author was wondering, _"[can] anyone ... give me a recommendation for 'how big a sane query can get'?"_ His use case was to apply a SPARQL query against the LOD dataset in order to test for the presence of "patterns for human associations". There was mention of subgraph sizes in excess of 400K triples, but as it were, his efforts appeared thwarted by much lower limits which his query processor set for the number of statement patterns in a BGP.

… Read the whole article: BGP Statement Pattern Counts
James Anderson, 2015/04/04

Support Issue Workflow

Where Dydra appears, in public, as a strictly remote service, the question occurs --
"If one cannot walk down the hall and knock on a door - or pound on a table, how does one get issues resolved in a timely manner?"
Any claims notwithstanding, that our availability statistics are well over three nines, a better answer describes how we resolve those issues which do appear in a manner which ensures that 24/7 customer operations remain in service.

… Read the whole article: Support Issue Workflow
Arto Bendiken, 2011/09/17 18:00

Simplified SPARQL Aggregates
We have observed that SPARQL 1.1's syntax for aggregates tends to surprise many, if not most, people. According to the standard SPARQL 1.1 grammar, to write a COUNT() query you have to be somewhat verbose:
```
   SELECT (COUNT(*) AS ?count) WHERE {?s ?p ?o}
        
```
Note the required explicit variable name, ?count, as well as the required parentheses surrounding the projected expression. With a strictly standards-compliant SPARQL query processor, omitting either the parentheses or the variable binding will result in a syntax error. This was also the case with Dydra until recently.

… Read the whole article: Simplified SPARQL Aggregates
James Anderson, 2011/09/08 22:00

DAWG Test Suite for SPOCQ

ARQ proposed a standard textual notation for abstract SPARQL algebra expressions, which it calls 'symbolic SPARQL expressions' (SSEs). The documentation describes expressions which are compatible with Lisp's S-expressions and, given appropriate reader and printer support, can serve as the externalization for a model of abstract SPARQL algebra expressions represented as simple lists.

… Read the whole article: DAWG Test Suite for SPOCQ
Arto Bendiken, 2011/09/07 12:30

SPARQL 1.1 Support

The top feature request we've heard from our users and customers lately has been support for SPARQL 1.1. We've listened, and are pleased to announce that Dydra now implements SPARQL 1.1 Query and Update in full.

… Read the whole article: SPARQL 1.1 Support
Arto Bendiken, 2011/07/20 17:30

Hosting Heltnormalt's CMS Store

There are several ways to approach RDF with the goal, to generate site content from the a triple-store. The evolutionary approaches were to adapt LAMP mechanisms from MySQL to RDF by translating SQL[1] queries into SPARQL[2] and replacing one object-relational mapping layer with an object-triple mapping layer. Alternative to that aproach, several more projective approaches are finding adoption and convincing by rendering much of the mediating processing superfluous. In one of them, Graphity, combined with Dydra to realize an RDF-bsed CMS which described page content and structure as a graph and relied just on SPARQL and XSLT to generate page content on demand.

… Read the whole article: Hosting Heltnormalt's CMS Store
Arto Bendiken, 2011/05/27

SP2B Benchmark Results

SP²Bench (hereafter referred to as SP2B) is a challenging and comprehensive SPARQL performance benchmark suite designed to cover the most important SPARQL constructs and operator constellations using a broad range of RDF data access patterns. While there exist other benchmark suites for RDF data access--BSBM and LUBM are two other benchmarks--we've found SP2B to overall be the most helpful metric by which to track and evaluate performance gains in Dydra's query processing. Not coincidentally, SP2B's main author also wrote one of the definitive works on SPARQL query optimization--exactly the kind of light reading we like to enjoy in our copious free time...

… Read the whole article: SP2B Benchmark Results
Arto Bendiken, 2011/05/13

Tuning SPARQL Queries

Here follows an excerpt from our upcoming Dydra Developer Guide, from a section that provides some simple tips on how to tune your queries for better application performance.

SPARQL is a powerful query language, and as such it is easy to write complex queries that require a great deal of computing power to execute. As both query execution time and billing directly depend on how much processing a query requires, it is useful to understand some of Dydra's key performance characteristics. With larger datasets, simple changes to a query can result in a significant performance improvement.

… Read the whole article: Tuning SPARQL Queries
Ben Lavender, 2011/04/13

Default Prefixes

Going over our failed and slow query log last week (another administrative task that we do so you don't have to), we noticed that for many of our testers, the first query attempted fails, as it will be copied from an existing application which has \`PREFIX\` defaults associated with the repository. That's no fun.

… Read the whole article: Default Prefixes
Ben Lavender, 2011/04/06

Using the Dydra CLI

One of the best things about using Dydra's dirt-simple interface is that we made it dirt-simpler with our CLI client. If you're comfortable on the command line, you can store, publish, and query any RDF data without opening a browser.

After you've installed the program, you can create, load, and query databases simply and easily:

… Read the whole article: Using the Dydra CLI
Ben Lavender, 2011/04/05

New Privacy Options

More new features!

Some of our testers were having trouble using existing tools to access their repositories, as not every tool out there supports one of our authentication methods.

So today we've given you the ability to make your repositories, both public and private, accessible to a range of IP addresses without any authentication. The options are available to you on your repository's administration page, and the settings are per-repository.

… Read the whole article: New Privacy Options
Ben Lavender, 2011/03/18 12:00

Get Your Named Graphs!

We're back from a bit of radio silence. Not that we wanted to go silent, you see, but your initial response to our announcement made a mockery of our capacity planning. We got an order of magnitude more beta invite requests than we expected to need for our entire beta period, let alone for a first round. We've adjusted our capacity planning accordingly.

… Read the whole article: Get Your Named Graphs!
Ben Lavender, 2011/02/07 12:00

Dydra Lifts Off

Today is the first day that Dydra has landed into the hands of people we haven't met in person. It feels like a big day, but while it's a big step in this 14-month journey, it's a road with a lot longer to go. In either case, we're celebrating.

… Read the whole article: Dydra Lifts Off

`33:Td03,catalogC = html`

C: Release notes ⤒

Release notes of our products.

James Anderson, 2022/7/4, 10:45:03 PM

dydra-2022-Q2 Release Notes
This release includes numerous improvements to SPARQL processing capabilities and to site administration:
- inotify integration
- bgp compilation changes
… Read the whole article: dydra-2022-Q2 Release Notes
James Anderson, 2022/2/14, 8:53:31 PM

dydra-2022-Q1 Release Notes
This release includes numerous improvements to SPARQL processing capabilities and to site administration:
… Read the whole article: dydra-2022-Q1 Release Notes
James Anderson, 2020/8/26, 12:03:32 PM

dydra-2020-Q3 Release Notes
This release includes numerous improvements to SPARQL processing capabilities and to site administration:
… Read the whole article: dydra-2020-Q3 Release Notes

`34:T21e9,catalogD = html`

D: Documentation of our Observable facilities ⤒

These notebooks mainly explain our additions to Observable and document our libraries. They allow to directly access data stored in Dydra and also new visualizations and presentation.

Access to Dydra is facilitated by our resource protocol library, which in turn uses our JavaScript web client library.

datagenous, Published 8/18/2021, 5:49:47 PM

Arquero with SPARQL

This notebook adds an operator the Arquero library to retrieve the data from a SPARQL endpoint.

Note that, where the query returns no result rows, the Arquero CSV parser fails.

… Read the whole article: Arquero with SPARQL
James Anderson, Published 6/19/2021, 2:17:02 AM

Performance Donut Chart
The makeGauge function constructs a visual gauge for a dataset. It accepts an element, data and options to describe nested donuts. It permits an array of object, each of which comrpises
- level
- maximum
- samples
- label
… Read the whole article: Performance Donut Chart
James Anderson, Published 5/4/2021, 10:28:54 AM

Examples: Repository Pattern Diagram
The repositoryPatternDiagram function renders a pattern reference diagram for a given host/account/repository.

API

Each invocation accepts
- hostName
- accountName
- repositoryName
- profile : 'construct" | 'select'
… Read the whole article: Examples: Repository Pattern Diagram
James Anderson, Published 5/4/2021, 10:19:16 AM

Library: Repository Diagrams

repositoryPatternDiagram returns a view which depicts the relations which basic graph patterns create among views and between views and repository content.

… Read the whole article: Library: Repository Diagrams
James Anderson, Published 5/3/2021, 1:05:02 AM

Library: ListElement cell

The ListElement cell accepts value and label arrays, presents them in a table. It is instantiated given a single options object to specify parameters. Given a selectAction, changes are provided immediately. Give a saveAction, an 'update' button is aded to the presentation. Where selections are managed, an additional check box checks/unchecks all entries. A click in the header collapses and expands the presentation.

The presentation is provided as the value of the html attribute.

… Read the whole article: Library: ListElement cell
James Anderson, Published 3/7/2021, 11:16:02 PM

resource presentation examples
These operators add presentation capabilities to the resource protocol library to retrieve data models in the form of SPARL qqueries and transform them into HTML editing components.

usage

Generate data presentations with
```
   import { sparqlObjectPresenter } from "@datagenous/resource-protocol-library";
          
```
… Read the whole article: resource presentation examples
James Anderson, Published 8/14/2020, 5:27:02 PM
Linked markdown-style footnotes with tooltips

[verbatim from the original] This plugin allows you to quickly and easily write markdown-style footnotes in Observable notebooks and have them linked properly without having to keep track of all the wiring. It also displays a tooltip for each footnote reference, so viewers don't have to jump back and forth to read footnotes.

I was dissatisfied with other footnote approaches for Observable and I wanted to create a convenient and reader-friendly way to add footnotes to my own notebooks. But I am happy if other people also find this useful.[^1]

… Read the whole article: Linked markdown-style footnotes with tooltips
James Anderson, Published 6/29/2020, 10:23:56 PM

RDF Path Diagram

Chord diagrams show directed relationships among a group of entities. This example is adapted from Chord Diagram. It indicates the path relation for a given predicate within a single RDF dataset.

… Read the whole article: RDF Path Diagram
James Anderson, 2020/6/13 9:19:48 PM

resource protocol library

This is a collection of operators which interact with remote SPARQL and Graph Store resources over HTTP. The interfaces accept service location urls, content and response media types and yield results either through a continuation or as promise.

… Read the whole article: resource protocol library

`35:T15bc,catalogE = html`

E: Interactive notebooks and Observable demos ⤒

These are interactive notebooks that might work better if you open them on Observable. Just click on the link that appears on top of each page: "Open on this page on observablehq.com."

Note that some or even most require an authentication token for them to work.

James Anderson, Published 6/23/2021, 10:02:25 PM

NEXPERIA Services

These are also available from the respective host as /admin/status.html. For example from dev.datahub.

… Read the whole article: NEXPERIA Services
James Anderson, Published 6/23/2021, 5:42:50 PM

Service Status Panel

This notebook exposes an operator which accepts a host name and returns a status display panel which contains service indicators for that host. In addition to the host name it accepts general style information and information specific to ech indicator.

The resources follow the patterns

… Read the whole article: Service Status Panel
James Anderson, Published 6/19/2021, 2:43:33 AM

Service Indicators

A running service provides several resources in its HTTP api which serve as probes into its activites. These act as read-only information sources separate from the resource curation API.

The resources follow the patterns

… Read the whole article: Service Indicators
James Anderson, Published 6/11/2021, 12:42:51 AM

SPARQL execution graphs

… Read the whole article: SPARQL execution graphs
James Anderson, Published 6/8/2021, 12:04:16 PM

Repository Request Overview

This uses Observable to display the requests to a repository over time. The data comes from a repository metadata request for the "service statistics".

… Read the whole article: Repository Request Overview
James Anderson, 2021/6/7, 2:17:34 PM

SOW-20210305 : Visible Workflows (nexperia/plm)

This is the version of the "Visible Workflows" notebook which draws on the content of the qa.datahub nexperia/plm repository. It requires authentication and may fail to yield the diagrams if the metadata extraction process fails to complete before the connection times out or the respective server cycles.

… Read the whole article: SOW-20210305 : Visible Workflows (nexperia/plm)
James Anderson, Published 5/21/2021, 3:56:11 AM

SPARQL View Inspector

This instrument accepts a view location and presents selected introspective analyses

… Read the whole article: SPARQL View Inspector

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A: Blog articles
B: Blog articles from older blog
C: Release notes
D: Documentation of our Observable facilities
E: Interactive notebooks and Observable demos

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A: Blog articles ⤒

for Internal Attributes

non-Standard Reification

Annotating single statements

Support for constraints notification in SPARQL update clauses

reasons for rdf-star

Support for free-text in materialized views in Dydra

Support for free-text in Dydra

interaction lacks native support

Formulae and RDF*

what benefits and risks does a lisp binding for lmdb embody?

B: Blog articles from older blog ⤒

More new features!

C: Release notes ⤒

D: Documentation of our Observable facilities ⤒

API

usage

E: Interactive notebooks and Observable demos ⤒