atomgraph/linkeddatahub

The low-code Knowledge Graph application platform. Apache license.

linkeddatahub's Issues

"Get started / Setup guide" incomplete in Documentation

When i launched with docker, linkeddatahub container crashes with error Admin base URI and/or admin quad store could not be extracted from /WEB-INF/classes/com/atomgraph/linkeddatahub/system.trig for root app. remaining other containers started properly.

Support RDFa output

The XSLT stylesheets could be augmented with RDFa attributes

Signup - 500 error on create context link

After signing up, Email says:

When you're ready, proceed to create a context for your Linked Data applications by following this link: https://linkeddatahub.com/docs/create?forClass=https%3A%2F%2Flinkeddatahub.com%2Fdocs%2Fns%23Context
Read more about LinkedDataHub contexts here: https://linkeddatahub.com/docs/manage-apps#contexts

But this fails with:

HTTP Status 500 - com.sun.jersey.api.container.ContainerException: Unable to create resource class com.atomgraph.platform.server.impl.ResourceBase

root cause
...
com.atomgraph.processor.exception.ParameterException: Parameter 'forClass' not supported by Template '[<http://atomgraph.com/ns/platform/templates#Item>: "(.*)", 0.0]'
    com.atomgraph.processor.util.TemplateCall.applyArguments(TemplateCall.java:90)

Correct link should probably be https://linkeddatahub.com/create?forClass=https%3A%2F%2Flinkeddatahub.com%2Fns%23Context

Layout tabs should be visible in item view

Right now layout mode controls are only shown in the Container view. There's no reason why some of them (at least ac:MapMode and ac:GraphMode couldn't also be shown in Item view.

HTTP test for dct:created/dct:modified metadata in PUT

There's some new logic in ResourceBase.put() that retains the original dct:created value and adds a dct:modified value. This needs an HTTP test.

Move Varnish cache invalidation to response filter?

Right now non-safe ResourceBase and graph.Item methods are littered with ban() calls. Ideally it should be possible to separate them into a separate layer, most likely a Jersey response filter.

HTTP test for creating Restrictions

Right now creating a Restriction instance such as TopicOfConceptItem results in a 500 Internal Server Error cause by an exception in the SkolemizingDatasetProvider:

org.glassfish.jersey.server.internal.process.MappableException: org.apache.jena.ontology.ConversionException: Cannot convert node http://www.w3.org/2002/07/owl#Restriction to OntClass: it does not have rdf:type owl:Class or equivalent

Can be reproduce using the SKOS demo app.

url format question

Using https://linkeddatahub.com/proxml/test/?filterRegex=label&uri=http://topbraid.org/examples/kennedys#AlfredTucker
I get the full kennedys dataset as result.
Using https://linkeddatahub.com/demo/iswc-2017/?filterRegex=label&uri=https%3A%2F%2Fw3id.org%2Fscholarlydata%2Fperson%2Fmartin-voigt
I get only info on martin-voight.
Is this different behaviour due to the difference in # versus / url's. Or are different templates triggered? If yes, how can I find this out in the most efficient way?

Insufficient Java memory

During installation of https://linkeddatahub.com:4443/demo/city-graph/:

There is insufficient memory for the Java Runtime Environment to continue.
Native memory allocation (mmap) failed to map 39321600 bytes for committing reserved memory.
An error report file with more information is saved as:
/usr/local/tomcat/hs_err_pid39.log

Bad Accept-Language header value

Bad Accept-Language header value: en-GB,en;q=0.9,en-US;q=0.8,nl;q=0.7,es-419;q=0.6,es;q=0.5,de;q=0.4

Browser: Chrome on MacOS
Reported by @warpr

Add copy buttons for URIs

Next to each URI, add a small button that copies its value into the clipboard. As seen on AWS etc.
This kind of icon could be used: https://freeicons.io/free-mobile-app-icons/copy-icon-icon

Replace WebID delegation property

Replace cert:secretary with acl:delegates, as that seems to be the convention now

CLI scripts for updating resources

Currently we only provide create CLI scripts for resources such as services, queries, charts etc. That results in duplicate resources with different URIs being created with each app install run, and means that resource metadata cannot be updated.

We do have update-document script for documents which updates them using a PUT request. We should use this approach for resources as well, and provide update-* scripts in addition to create-*.

Xerces hangs when parsing non-XML Source

XSLT processor hangs when parsing StreamSource read from https://www.w3.org/1999/xhtml/vocab.

Looks like it's not a Saxon bug but a Xerces bug in XMLConfiguration, probably something like:
https://issues.apache.org/jira/browse/NUTCH-2223

Handle 403 during form POST

Currently, if the agent is authenticated but not authorized, it can still see "Create", "Edit" buttons etc. and can see the forms.
When "Save" is clicked, the server returns 403 Not Authorized, but the UI silently swallows it.
Fix by showing an error popup.
Alternatively, don't show the form controls in the first place?

Container responses get cached

After creating a child document, container view is not updated. Varnish returns a stale cached response.

There used to be code that BANs (removes from Varnish cache) all objects with container URL after a child document is created?

Check that certificate password is ASCII

Apparently keytool (which we use during signup to generate WebID cert) does not accept non-ASCII characters:

stage.linkeddatahub-prod_1       | keytool error: java.security.KeyStoreException: Key protection  
algorithm not found: java.security.UnrecoverableKeyException: Encrypt Private Key failed: getSecretKey failed: Password is not ASCII

Container ordering

We need a mechanism to specify children ordering in containers. Currently it is controlled using ORDER BY in the container's SELECT query, and while that works correctly, the ordering is generally lost after we wrap the query into DESCRIBE and retrieve a graph, which is unordered. Therefore a secondary sort in XSLT needs to be done, and to be able to sort by properties and their values, we need to know the URI of the property used as the sort key.

Document $LETSENCRYPT_CERT_DIR

Currently the non-self-signed service certificate (e.g. from LetsEncrypt) configuration is not documented anywhere

Editing window for full control doesn't open

https://linkeddatahub.com/proxml/test/admin/acl/authorizations/full-control#this

A UI trail of facet/parallax actions

Facet and parallax navigation generates a new container state with each action, the user should be able to go back to a previous state. Right now the only recourse is to refresh the page and go to the initial container state.

It should also be possible to generate URL for a state/restore state from a URL.

Cannot add new property

Something broken during bs2:PropertyControl refactoring

PUT changes dct:created value

PUT request should only add (update?) dct:modified value, leaving dct:created intact. Right now the dct:created value is updated instead.

CSV and RDF imports do not show success statistics or failure messages

This is a regression from the master branch which used to show an attached blank node with metadata like start/end datetime, triple and subject counts.

Failed to run properly on Ubuntu + Docker

Failing to start docker-compose for repository on Ubuntu 18.04 host system.

Docker version 18.09.7, build 2d0083d

Steps to reproduce:

1. Clone repository as of f6262e5 commit
2. Create .env with credentials (leave BASE_URI=https://localhost:4443/)
3. Run docker-compose up
4. Witness following logs:

sudo docker-compose up
Creating linkeddatahub_email-server_1 ...
Creating linkeddatahub_nginx_1 ...
Creating linkeddatahub_fuseki-end-user_1 ...
Creating linkeddatahub_linkeddatahub_1 ...
Creating linkeddatahub_email-server_1
Creating linkeddatahub_fuseki-admin_1 ...
Creating linkeddatahub_nginx_1
Creating linkeddatahub_fuseki-end-user_1
Creating linkeddatahub_linkeddatahub_1
Creating linkeddatahub_nginx_1 ... done
Attaching to linkeddatahub_email-server_1, linkeddatahub_fuseki-admin_1, linkeddatahub_linkeddatahub_1, linkeddatahub_fuseki-end-user_1, linkeddatahub_nginx_1
email-server_1     | + sed -ri '
email-server_1     |    s/^#?(dc_local_interfaces)=.*/\1='\''[0.0.0.0]:25 ; [::0]:25'\''/;
email-server_1     |    s/^#?(dc_other_hostnames)=.*/\1='\'''\''/;
email-server_1     |    s/^#?(dc_relay_nets)=.*/\1='\''172.23.0.4\/16'\''/;
email-server_1     |    s/^#?(dc_eximconfig_configtype)=.*/\1='\''internet'\''/;
email-server_1     | ' /etc/exim4/update-exim4.conf.conf
email-server_1     | + update-exim4.conf -v
email-server_1     | using non-split configuration scheme from /etc/exim4/exim4.conf.template
email-server_1     |     1 LOG: MAIN
email-server_1     |     1   exim 4.92 daemon started: pid=1, -q15m, listening for SMTP on port 25 (IPv4)
fuseki-admin_1     | Starting temporary server
fuseki-admin_1     | Temporary server started.
linkeddatahub_1    | ### Generating server certificate
fuseki-end-user_1  | Starting temporary server
fuseki-end-user_1  | Temporary server started.
nginx_1            | ### Waiting for linkeddatahub...
nginx_1            | ### linkeddatahub responded
fuseki-admin_1     | http://localhost:3333/ds/ not responding, exiting...
linkeddatahub_fuseki-admin_1 exited with code 1
fuseki-end-user_1  | http://localhost:3333/ds/ not responding, exiting...
linkeddatahub_fuseki-end-user_1 exited with code 1
linkeddatahub_1    |
linkeddatahub_1    | ### Quad store URL of the root admin service: http://fuseki-admin:3030/ds/
linkeddatahub_1    |
linkeddatahub_1    | ### Secretary's WebID URI: https://localhost:4443/admin/acl/agents/e413f97b-15ee-47ea-ba65-4479aa7f1f9e/#this
linkeddatahub_1    |
linkeddatahub_1    | ### Secretary WebID certificate's DName attributes: CN=LinkedDataHub,OU=LinkedDataHub,O=AtomGraph,L=Copenhagen,ST=Denmark,C=DK
linkeddatahub_1    |
linkeddatahub_1    | ### Secretary WebID certificate's modulus: c33d3ab2873ed78...
linkeddatahub_1    | ### Waiting for http://fuseki-admin:3030/ds/...
linkeddatahub_1    | ### URL http://fuseki-admin:3030/ds/ not responding after 20 seconds, exiting...
linkeddatahub_linkeddatahub_1 exited with code 

I'm not sure where does localhost:3333 comes from.

After consequent launch attempts the only thing changed is one more error line in the logs:

linkeddatahub_1    | keytool error: java.lang.Exception: Key pair not generated, alias <ldh> already exists

City Graph mapping query quality

CSV to RDF mapping queries in City Graph app are pretty poor:

• values do not match domain (e.g. schema:serviceOperator with string values)
• literals do not have datatypes (e.g. schema:maximumAttendeeCapacity values)
• properties misused, e,g, schema:maximumAttendeeCapacity used both as venue capacity (correct) and electric vehicle charger capacity (incorrect)
• schema.org namespace should change from http://schema.org to https://schema.org

Failed to execute script docker-compose

When trying to the follow the instructions to start LinkedDataHub, I encounter an error that prevent the application from starting (see startup.log). As a note, I was running the docker image on MacOS 10.15.7.

Has this issue been experienced before?

Chart axes get mixed up

It looks like that for ScatterChart and LineChart, the X/Y axes somehow get switched:
https://linkeddatahub.com:4443/demo/northwind-traders/charts/6616b879-d50d-4091-9e3d-63b488c57822/

WebID profile could not be loaded

Reported by @timbl and @timathom

Client certificate public key did not match public key of WebID 'https://www.w3.org/People/Berners-Lee/card#i’” at https://linkeddatahub.com/docs/administration/acl

Same for https://timathom.databox.me/profile/card#me

Could be due to the lack of @base in the RDF files.

Signed up Agent cannot change its profile

As explained in #4, agents should be able to edit their data (which resides in a named graph in the admin app) to add secretary URIs and new certificate keys.

Chart layout mode does not work on empty containers?

E.g. when looking at Root in Graph mode, ac:SVG mode throws an error in Saxon-CE:

SEVERE: XPathException in mode: '{http://saxonica.com/ns/interactiveXSLT}onclick' event: '[object MouseEvent]: An empty sequence is not allowed as the value of variable $min-x

Linked Data client fails to read XML resources

Returns 500 Internal Server Error due to

A message body reader for Java class org.apache.jena.rdf.model.Model, and Java type interface org.apache.jena.rdf.model.Model, and MIME media type text/xml was not found

Application not found + Ontology cannot be null errors while attempting to access service launched on Ubuntu host

Setup is basically the same as in the previous issue. All docker based services seem to start normally (the only issue is service startup time Server startup in 339410 ms, not sure why it is so big and whether it's fine) but when one tries to access the launched app via browser (Firefox) with generated owner.p12 certificate, the following error occurs and browser ending up with displaying a blank page.

Docker logs:

Attaching to linkeddatahub_fuseki-admin_1, linkeddatahub_linkeddatahub_1, linkeddatahub_fuseki-end-user_1, linkeddatahub_nginx_1, linkeddatahub_email-server_1
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO  Apache Jena Fuseki 3.13.0
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO  Configuration file /var/fuseki/config.ttl
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO  Path = /ds; Services = [""=>gsp-rw, ""=>query, ""=>update]
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO    Memory: 483.4 MiB
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO    Java:   1.8.0_111
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO    OS:     Linux 4.15.0-55-generic amd64
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:28] Server     INFO    PID:    1
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:29] Server     INFO  Start Fuseki (port=3030)
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:36] Fuseki     INFO  [1] GET http://fuseki-admin:3030/ds/
[33mlinkeddatahub_1    |[0m ### Generating server certificate
[33mlinkeddatahub_1    |[0m 
[33mlinkeddatahub_1    |[0m ### Quad store URL of the root admin service: http://fuseki-admin:3030/ds/
[33mlinkeddatahub_1    |[0m 
[33mlinkeddatahub_1    |[0m ### Loading default datasets into the end-user/admin triplestores...
[33mlinkeddatahub_1    |[0m ### URL http://fuseki-end-user:3030/ds/ responded
[33mlinkeddatahub_1    |[0m   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
[33mlinkeddatahub_1    |[0m                                  Dload  Upload   Total   Spent    Left  Speed
[33mlinkeddatahub_1    |[0m 
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100 46107    0    64  100 46043     90  64932 --:--:-- --:--:-- --:--:-- 64940
100 46108    0    65  100 46043     90  64348 --:--:-- --:--:-- --:--:-- 64305
[33mlinkeddatahub_1    |[0m { 
[33mlinkeddatahub_1    |[0m   "count" : 207 ,
[33mlinkeddatahub_1    |[0m   "tripleCount" : 0 ,
[33mlinkeddatahub_1    |[0m   "quadCount" : 207
[33mlinkeddatahub_1    |[0m }
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO  Apache Jena Fuseki 3.13.0
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO  Configuration file /var/fuseki/config.ttl
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO  Path = /ds; Services = [""=>gsp-rw, ""=>query, ""=>update]
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO    Memory: 483.4 MiB
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO    Java:   1.8.0_111
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO    OS:     Linux 4.15.0-55-generic amd64
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:28] Server     INFO    PID:    1
[35mnginx_1            |[0m ### Waiting for linkeddatahub...
[35mnginx_1            |[0m ### linkeddatahub responded
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:29] Server     INFO  Start Fuseki (port=3030)
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:34] Fuseki     INFO  [1] GET http://fuseki-end-user:3030/ds/
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:35] Fuseki     INFO  [1] 200 OK (474 ms)
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:35] Fuseki     INFO  [2] GET http://fuseki-end-user:3030/ds/
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:35] Fuseki     INFO  [2] 200 OK (186 ms)
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:35] Fuseki     INFO  [3] POST http://fuseki-end-user:3030/ds/
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:35] Fuseki     INFO  [3] Body: Content-Length=46043, Content-Type=application/n-quads, Charset=null => N-Quads : Count=207 Triples=0 Quads=207
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:36] Fuseki     INFO  [3] 200 OK (701 ms)
[31memail-server_1     |[0m + sed -ri '
[31memail-server_1     |[0m 	s/^#?(dc_local_interfaces)=.*/\1='\''[0.0.0.0]:25 ; [::0]:25'\''/;
[31memail-server_1     |[0m 	s/^#?(dc_other_hostnames)=.*/\1='\'''\''/;
[31memail-server_1     |[0m 	s/^#?(dc_relay_nets)=.*/\1='\''172.19.0.3\/16'\''/;
[31memail-server_1     |[0m 	s/^#?(dc_eximconfig_configtype)=.*/\1='\''internet'\''/;
[31memail-server_1     |[0m ' /etc/exim4/update-exim4.conf.conf
[31memail-server_1     |[0m + update-exim4.conf -v
[31memail-server_1     |[0m using non-split configuration scheme from /etc/exim4/exim4.conf.template
[31memail-server_1     |[0m     1 LOG: MAIN
[31memail-server_1     |[0m     1   exim 4.92 daemon started: pid=1, -q15m, listening for SMTP on port 25 (IPv4)
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:40] Fuseki     INFO  [1] 200 OK (3.585 s)
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:40] Fuseki     INFO  [2] GET http://fuseki-admin:3030/ds/
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:42] Fuseki     INFO  [2] 200 OK (2.332 s)
[33mlinkeddatahub_1    |[0m ### URL http://fuseki-admin:3030/ds/ responded
[33mlinkeddatahub_1    |[0m   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
[33mlinkeddatahub_1    |[0m                                  Dload  Upload   Total   Spent    Left  Speed
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:42] Fuseki     INFO  [3] POST http://fuseki-admin:3030/ds/
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:43] Fuseki     INFO  [3] Body: Content-Length=547638, Content-Type=application/n-quads, Charset=null => N-Quads : Count=2392 Triples=0 Quads=2392
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:43] Fuseki     INFO  [3] 200 OK (1.077 s)
[33mlinkeddatahub_1    |[0m 
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100  534k    0     0  100  534k      0   527k  0:00:01  0:00:01 --:--:--  527k
100  534k    0    67  100  534k     61   487k  0:00:01  0:00:01 --:--:--  487k
[33mlinkeddatahub_1    |[0m { 
[33mlinkeddatahub_1    |[0m   "count" : 2392 ,
[33mlinkeddatahub_1    |[0m   "tripleCount" : 0 ,
[33mlinkeddatahub_1    |[0m   "quadCount" : 2392
[33mlinkeddatahub_1    |[0m }
[33mlinkeddatahub_1    |[0m openjdk version "1.8.0_181"
[33mlinkeddatahub_1    |[0m OpenJDK Runtime Environment (build 1.8.0_181-8u181-b13-1~deb9u1-b13)
[33mlinkeddatahub_1    |[0m OpenJDK 64-Bit Server VM (build 25.181-b13, mixed mode)
[33mlinkeddatahub_1    |[0m      intx CompilerThreadStackSize                   = 0                                   {pd product}
[33mlinkeddatahub_1    |[0m     uintx ErgoHeapSizeLimit                         = 0                                   {product}
[33mlinkeddatahub_1    |[0m     uintx HeapSizePerGCThread                       = 87241520                            {product}
[33mlinkeddatahub_1    |[0m     uintx InitialHeapSize                          := 33554432                            {product}
[33mlinkeddatahub_1    |[0m     uintx LargePageHeapSizeThreshold                = 134217728                           {product}
[33mlinkeddatahub_1    |[0m     uintx MaxHeapSize                              := 524288000                           {product}
[33mlinkeddatahub_1    |[0m      intx ThreadStackSize                           = 1024                                {pd product}
[33mlinkeddatahub_1    |[0m      intx VMThreadStackSize                         = 1024                                {pd product}
[33mlinkeddatahub_1    |[0m ### Waiting for http://fuseki-end-user:3030/ds/...
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:43] Fuseki     INFO  [4] GET http://fuseki-end-user:3030/ds/
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:44] Fuseki     INFO  [4] 200 OK (173 ms)
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:44] Fuseki     INFO  [5] GET http://fuseki-end-user:3030/ds/
[32mfuseki-end-user_1  |[0m [2020-01-28 16:00:44] Fuseki     INFO  [5] 200 OK (112 ms)
[33mlinkeddatahub_1    |[0m ### URL http://fuseki-end-user:3030/ds/ responded
[33mlinkeddatahub_1    |[0m ### Waiting for http://fuseki-admin:3030/ds/...
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:44] Fuseki     INFO  [4] GET http://fuseki-admin:3030/ds/
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:46] Fuseki     INFO  [4] 200 OK (2.190 s)
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:46] Fuseki     INFO  [5] GET http://fuseki-admin:3030/ds/
[36mfuseki-admin_1     |[0m [2020-01-28 16:00:47] Fuseki     INFO  [5] 200 OK (1.391 s)
[33mlinkeddatahub_1    |[0m ### URL http://fuseki-admin:3030/ds/ responded
[33mlinkeddatahub_1    |[0m ### Waiting for nginx...
[33mlinkeddatahub_1    |[0m ### Host nginx responded
[33mlinkeddatahub_1    |[0m Listening for transport dt_socket at address: 8000
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:        Apache Tomcat/8.0.53
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.920 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:          Jun 29 2018 14:42:45 UTC
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.921 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server number:         8.0.53.0
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.922 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:               Linux
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.923 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:            4.15.0-55-generic
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.924 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:          amd64
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.925 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Java Home:             /usr/lib/jvm/java-8-openjdk-amd64/jre
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.927 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:           1.8.0_181-8u181-b13-1~deb9u1-b13
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.928 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:            Oracle Corporation
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.929 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:         /usr/local/tomcat
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.930 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:         /usr/local/tomcat
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.932 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.config.file=/usr/local/tomcat/conf/logging.properties
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.935 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.936 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=2048
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.937 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.protocol.handler.pkgs=org.apache.catalina.webresources
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.939 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.940 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Duser.timezone=Europe/Copenhagen
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.941 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dignore.endorsed.dirs=
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.943 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.base=/usr/local/tomcat
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.945 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=/usr/local/tomcat
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.947 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.io.tmpdir=/usr/local/tomcat/temp
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.948 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent Loaded APR based Apache Tomcat Native library 1.2.17 using APR version 1.5.2.
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.950 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:49.964 INFO [main] org.apache.catalina.core.AprLifecycleListener.initializeSSL OpenSSL successfully initialized (OpenSSL 1.1.0f  25 May 2017)
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:50.272 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-apr-8080"]
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:50.313 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["ajp-apr-8009"]
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:50.400 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-nio-8443"]
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:51.698 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:51.710 INFO [main] org.apache.catalina.startup.Catalina.load Initialization processed in 3387 ms
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:51.803 INFO [main] org.apache.catalina.core.StandardService.startInternal Starting service Catalina
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:51.807 INFO [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet Engine: Apache Tomcat/8.0.53
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:00:51.855 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDescriptor Deploying configuration descriptor /usr/local/tomcat/conf/Catalina/localhost/ROOT.xml
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:01:00.588 INFO [localhost-startStop-1] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
[35mnginx_1            |[0m 195.231.4.32 - - [28/Jan/2020:16:04:54 +0000] "GET login.cgi HTTP/1.1" 400 157 "-" "-"
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:06:30.989 WARNING [localhost-startStop-1] org.apache.catalina.util.SessionIdGeneratorBase.createSecureRandom Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [330,040] milliseconds.
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:06:31.054 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDescriptor Deployment of configuration descriptor /usr/local/tomcat/conf/Catalina/localhost/ROOT.xml has finished in 339,196 ms
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:06:31.063 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-apr-8080"]
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:06:31.107 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["ajp-apr-8009"]
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:06:31.114 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-nio-8443"]
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:06:31.122 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 339410 ms
[35mnginx_1            |[0m 161.142.234.65 [28/Jan/2020:16:14:43 +0000] TCP [] [upstream_server_https] 200 1416 7 6.556
[35mnginx_1            |[0m 161.142.234.65 [28/Jan/2020:16:14:43 +0000] TCP [] [upstream_server_https] 200 1416 7 6.315
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:14:50.068 INFO [http-nio-8443-exec-9] com.sun.jersey.server.impl.application.WebApplicationImpl._initiate Initiating Jersey application, version 'Jersey: 1.19 02/11/2015 03:25 AM'
[35mnginx_1            |[0m 161.142.234.65 [28/Jan/2020:16:14:55 +0000] TCP [] [upstream_server_https] 200 1467 1422 5.953
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:15:01.694 INFO [http-nio-8443-exec-9] com.sun.jersey.server.impl.application.DeferredResourceConfig$ApplicationHolder.<init> Instantiated the Application class com.atomgraph.linkeddatahub.Application
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:15:04.309 SEVERE [http-nio-8443-exec-9] com.sun.jersey.spi.container.ContainerResponse.mapException Exception mapper com.atomgraph.server.mapper.NotFoundExceptionMapper@45cf1f83 for Throwable com.atomgraph.core.exception.NotFoundException: Application not found threw a RuntimeException when attempting to obtain the response
[33mlinkeddatahub_1    |[0m 28-Jan-2020 17:15:04.315 SEVERE [http-nio-8443-exec-9] com.sun.jersey.spi.container.ContainerResponse.logException Mapped exception to response: 500 (Internal Server Error)
[33mlinkeddatahub_1    |[0m  java.lang.IllegalArgumentException: Ontology cannot be null
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.processor.util.TemplateMatcher.match(TemplateMatcher.java:229)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.processor.util.TemplateMatcher.match(TemplateMatcher.java:137)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateProvider.getTemplate(TemplateProvider.java:77)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateProvider.getTemplate(TemplateProvider.java:72)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateProvider.getContext(TemplateProvider.java:67)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateProvider.getContext(TemplateProvider.java:37)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateCallProvider.getTemplate(TemplateCallProvider.java:97)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateCallProvider.getTemplateCall(TemplateCallProvider.java:73)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateCallProvider.getContext(TemplateCallProvider.java:68)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.provider.TemplateCallProvider.getContext(TemplateCallProvider.java:38)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.mapper.ExceptionMapperBase.getTemplateCall(ExceptionMapperBase.java:164)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.mapper.ExceptionMapperBase.getResponseBuilder(ExceptionMapperBase.java:102)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.mapper.NotFoundExceptionMapper.toResponse(NotFoundExceptionMapper.java:35)
[33mlinkeddatahub_1    |[0m 	at com.atomgraph.server.mapper.NotFoundExceptionMapper.toResponse(NotFoundExceptionMapper.java:29)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.spi.container.ContainerResponse.mapException(ContainerResponse.java:480)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1479)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558)
[33mlinkeddatahub_1    |[0m 	at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:733)
[33mlinkeddatahub_1    |[0m 	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
[33mlinkeddatahub_1    |[0m 	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.filters.HttpHeaderSecurityFilter.doFilter(HttpHeaderSecurityFilter.java:126)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
[33mlinkeddatahub_1    |[0m 	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
[33mlinkeddatahub_1    |[0m 	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
[33mlinkeddatahub_1    |[0m 	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
[33mlinkeddatahub_1    |[0m 	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
[33mlinkeddatahub_1    |[0m 	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
[33mlinkeddatahub_1    |[0m 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[33mlinkeddatahub_1    |[0m 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[33mlinkeddatahub_1    |[0m 	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
[33mlinkeddatahub_1    |[0m 	at java.lang.Thread.run(Thread.java:748)
[33mlinkeddatahub_1    |[0m 
[35mnginx_1            |[0m 161.142.234.65 [28/Jan/2020:16:15:04 +0000] TCP [] [upstream_server_https] 200 1730 1789 15.191

SPARQL result caching causes 404 Not Found

I've created an LDH app that adds document data to a container. I can see the container and links to the resources in the container, but when I click on the links to the resources, I get a 404. Stopping and then restarting the containers (with docker-compose down followed by docker-compose up -d fixes the issue. @namedgraph recommended this remedy after suspecting a caching issue.

WebID cache with expiration

getSystem().getWebIDModelCache() optimizes authentication by avoiding having to load Agent data with each authentication. It should have an expiration period however. Similarly, we need to introduce getSystem().getOIDCModelCache().

One possible solution for this is using Guava's CacheBuilder.

Leverage browser caching of static resources

• https://linkeddatahub.com:4443/static/com/atomgraph/client/css/bootstrap.css (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/client/js/UUID.js (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/client/js/jquery.js (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/css/bootstrap.css (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/baseline-cloud-24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/baseline_arrow_upward_white_18dp.png (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/folder.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_blur_on_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_border_all_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_code_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_details_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_file_download_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_file_upload_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_grid_on_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_location_on_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_map_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_navigate_before_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_new_releases_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_search_white_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_show_chart_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_transform_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/icons/ic_view_list_black_24px.svg (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/js/SPARQLBuilder.js (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/js/SPARQLMap.js (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/js/jquery.js (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/js/saxon-js/SaxonJS2.rt.js (expiration not specified)
• https://linkeddatahub.com:4443/static/com/atomgraph/linkeddatahub/xsl/client.xsl.sef.json (expiration not specified)
• https://linkeddatahub.com:4443/static/css/bootstrap-responsive.css (expiration not specified)
• https://linkeddatahub.com:4443/static/css/bootstrap.css (expiration not specified)
• https://linkeddatahub.com:4443/static/js/bootstrap.js (expiration not specified)
• https://linkeddatahub.com:4443/static/js/jquery.min.js (expiration not specified)

Timezones get lost in date/time rendering

After 3 edits, dct:created value is shown as being later than dct:modified:

Date Created
    21 August 2020 12:11
Date Modified
    21 August 2020 10:13
    21 August 2020 10:18
    21 August 2020 10:27

However in the RDF data the values correct, only the timezones are different (GMT+2 and GMT (Z)):

<http://purl.org/dc/terms/created>
    "2020-08-21T12:11:10.412+02:00"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
<http://purl.org/dc/terms/modified>
    "2020-08-21T10:27:31.125Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> , "2020-08-21T10:18:24.954Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> , "2020-08-21T10:13:28.324Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;

Document restricted parameters

Web-Client parameters such as uri, endpoint, query, mode, accept are handled separately, before the Processor parameters (such as limit, offset etc). That should be documented under https://linkeddatahub.com/docs/administration/sitemap/#parameters

Multiple dropdowns open

Dropdown menus do not close:

Fix Chart mode layout

Chart controls do not flow nicely on a lower resolution:

Signup validation

Some comments from a test user:

• "Personal mailbox" - not clear that it's email address
• email address without @ was accepted

Linked Data client fails to read JSON resources

Fails with 500 Internal Server Exception due to java.lang.NoClassDefFoundError: Could not initialize class com.github.jsonldjava.utils.JsonUtils

Do not show pagination when the container is empty

Info windows on geo markers show broken layout

Some XSLT UI glitch:

WebID delegation is broken

All tests passing even though WebID delegation was disabled :/

Create a test under http-tests.

Link to layout mode is broken

At least on items, the links in the mode dropdown are wrong, e.g.:
https://linkeddatahub.com:4443/demo/city-graph/copenhagen/electric-car-chargers/?mode=http%3A%2F%2Fatomgraph.com%2Fns%2Fclient%23MapMode

When it should be this:
https://linkeddatahub.com:4443/demo/city-graph/copenhagen/electric-car-chargers/elbil_ladestander.14?mode=http%3A%2F%2Fatomgraph.com%2Fns%2Fclient%23MapMode

Linked Data client fails to load system namespaces

When accessing for example the DH ontology URL https://www.w3.org/ns/ldt/document-hierarchy/domain in browser mode, we get

[line: 1, col: 1 ] Expected BNode or IRI: Got [DIRECTIVE: base]

Saving LD resource or query result

Add a [Save] button in LD browser mode and SPARQL query editor to save the current RDF graph.

We don't want to render hidden RDF/POST forms with a lot of data, so this needs some client-side logic. The prerequiste is probably that we load the data on the client-side in the first place, which is currently not the case for the LD browser.

Does it make sense to provide a container choice? We would need to attach all documents to it, but some resources might remain disconnected.

Maybe we need to store it in a "user-space" named graph and provide access to it through a new Graphs container, while keeping system named graphs hidden(?).

Implement Accept-Post and Accept-Put methods

https://tools.ietf.org/html/rfc7231#section-4.3.7
https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/OPTIONS

Imports can cause concurrent write requests to the triplestore

LinkedDataHub has no problem sending concurrent streams of outbound RDF data, but it turns out the Graph Store Protocol fails on concurrent write (POST, PUT, DELETE) requests. At least Dydra fails, Fuseki needs to be further tested.

The solution would be to queue outbound requests in ImportListener. Possibly as easy as turning down the number of Executor threads to 1.