Grasp binding to Virtuoso / DBpedia

README_OPL.md

@@ -0,0 +1,108 @@
+# Grasp - Binding to Virtuoso and DBpedia
+
+2021-May-27  
+Carl Blakeley
+
+Branch `opl_develop` includes slight changes to how Grasp POSTs queries to a SPARQL endpoint, to allow it to work against Virtuoso. Two simple GraphQL query examples have been added to demonstrate Grasp querying [DBpedia](https://www.dbpedia.org/).
+
+## Requirements
+
+Node.js 14 or later
+
+## To Install
+
+```
+git clone https://github.com/OpenLinkSoftware/grasp.git
+cd grasp
+git checkout opl_develop
+npm install
+```
+
+## To Run
+
+If using nvm  
+`$ nvm use system`
+
+`$ RESOURCES_DIR=./examples npm run watch`
+
+This loads the example resource definitions from `./examples`. The resource definitions targetting DBpedia are contained in `./examples/dbpediaBook.graphql` and `./examples/dbpediaBooks.graphql`
+
+Visit <http://localhost:4000>. You will see GraphQL Playground.
+
+Enter either of the following GraphQL queries into the query editor.
+
+### Example 1: Select a single object
+
+```
+query {
+  dbpediaBook(iri: "http://dbpedia.org/resource/Corona_(novel)") {
+    iri
+    bookTitle
+    authorUri
+    authorName
+  }
+}
+```
+
+**Result**
+
+```
+{
+  "data": {
+    "dbpediaBook": {
+      "iri": "http://dbpedia.org/resource/Corona_(novel)",
+      "bookTitle": "Corona (novel)",
+      "authorUri": "http://dbpedia.org/resource/Greg_Bear",
+      "authorName": "Greg Bear"
+    }
+  }
+}
+```
+
+### Example 2: Select multiple objects
+
+```
+query {
+  dbpediaBooks(iris: 
+	[ 
+		"http://dbpedia.org/resource/AI_Superpowers"
+		"http://dbpedia.org/resource/A_History_of_British_Birds"
+		"http://dbpedia.org/resource/A_Brief_History_of_Time"
+	]
+   ) {
+    iri
+    bookTitle
+    authorUri
+    authorName
+  }
+}
+```
+
+**Result**
+
+```
+{
+  "data": {
+    "dbpediaBooks": [
+      {
+        "iri": "http://dbpedia.org/resource/AI_Superpowers",
+        "bookTitle": "AI Superpowers",
+        "authorUri": "http://dbpedia.org/resource/Kai-Fu_Lee",
+        "authorName": "Kai-Fu Lee"
+      },
+      {
+        "iri": "http://dbpedia.org/resource/A_Brief_History_of_Time",
+        "bookTitle": "A Brief History of Time",
+        "authorUri": "http://dbpedia.org/resource/Stephen_Hawking",
+        "authorName": "Stephen Hawking"
+      },
+      {
+        "iri": "http://dbpedia.org/resource/A_History_of_British_Birds",
+        "bookTitle": "A History of British Birds",
+        "authorUri": "http://dbpedia.org/resource/Thomas_Bewick",
+        "authorName": "Thomas Bewick"
+      }
+    ]
+  }
+}
+```

examples/dbpediaBook.graphql

@@ -0,0 +1,37 @@
+"""
+--- endpoint ---
+https://dbpedia.org/sparql
+
+--- sparql ---
+PREFIX : <https://github.com/dbcls/grasp/ns/>
+PREFIX dbo: <http://dbpedia.org/ontology/> 
+PREFIX foaf: <http://xmlns.com/foaf/0.1/>
+PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
+PREFIX schema: <http://schema.org/>
+
+CONSTRUCT {
+  ?iri :iri ?iri .
+  ?iri :bookTitle ?title .
+  ?iri :authorUri ?author . 
+  ?iri :authorName ?authorName . 
+}
+WHERE
+{
+  ?iri a schema:Book ;
+    rdfs:label ?title ;
+    dbo:author ?author . 
+  FILTER (LANG(?title) = 'en') 
+
+  ?author foaf:name ?authorName . 
+  FILTER (LANG(?authorName) = 'en') 
+
+  {{#if iri}}VALUES ?iri { {{join " " (as-iriref iri)}} }{{/if}}
+}
+"""
+type DbpediaBook {
+  iri: String!
+  bookTitle: String
+  authorUri: String
+  authorName: String
+}
+

examples/dbpediaBooks.graphql

@@ -0,0 +1,39 @@
+"""
+--- endpoint ---
+https://dbpedia.org/sparql
+
+--- sparql ---
+PREFIX : <https://github.com/dbcls/grasp/ns/>
+PREFIX dbo: <http://dbpedia.org/ontology/> 
+PREFIX foaf: <http://xmlns.com/foaf/0.1/>
+PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
+PREFIX schema: <http://schema.org/>
+
+CONSTRUCT {
+  ?iri :iri ?iri .
+  ?iri :bookTitle ?title .
+  ?iri :authorUri ?author . 
+  ?iri :authorName ?authorName . 
+}
+WHERE
+{
+  ?iri a schema:Book ;
+    rdfs:label ?title ;
+    dbo:author ?author . 
+  FILTER (LANG(?title) = 'en') 
+
+  ?author foaf:name ?authorName . 
+  FILTER (LANG(?authorName) = 'en') 
+
+  {{#if iris}}
+    VALUES ?iri { {{join " " (as-iriref iris)}} }
+  {{/if}}
+}
+"""
+type DbpediaBooks {
+  iri: String!
+  bookTitle: String
+  authorUri: String
+  authorName: String
+}
+

examples/index.graphql

@@ -10,4 +10,6 @@ type Query {
   datasets(iri: [String!]!): [Dataset!]!
   pubmed(iri: String!): Pubmed
   pubmeds(iri: [String!], id: [String!]): [Pubmed!]!
+  dbpediaBook(iri: String): DbpediaBook
+  dbpediaBooks(iris: [String!]): [DbpediaBooks!]!
 }

resource.ts

@@ -145,17 +145,16 @@ export default class Resource {
       throw new Error('query template and endpoint should be specified in order to query');
     }
     const sparqlQuery = this.queryTemplate(args);
+    const body = sparqlQuery.replace(/\n/g, " ");
 
     console.log('--- SPARQL QUERY ---', sparqlQuery);
 
-    const sparqlParams = new URLSearchParams();
-    sparqlParams.append('query', sparqlQuery);
-
     const opts = {
       method: 'POST',
-      body: sparqlParams,
+      body,
       headers: {
-        Accept: 'application/sparql-results+json'
+        Accept: 'application/sparql-results+json',
+       'Content-Type': 'application/sparql-query'
       }
     };