[
https://issues.apache.org/jira/browse/JENA-1267?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15754889#comment-15754889
]
ASF GitHub Bot commented on JENA-1267:
--------------------------------------
Github user rvesse commented on a diff in the pull request:
https://github.com/apache/jena/pull/197#discussion_r92840274
--- Diff: jena-rdfconnection/Documentation.md ---
@@ -0,0 +1,205 @@
+# RDF Connection : SPARQL operations API
+
+`RDFConnection` provides a unified set of operations for working on RDF
+with SPARQL operations. It provides <a
+href="http://www.w3.org/TR/sparql11-query/";>SPARQL Query</a>, <a
+href="http://www.w3.org/TR/sparql11-update/";>SPARQL Update</a> and the <a
+href="http://www.w3.org/TR/sparql11-http-rdf-update/";>SPARQL Graph
+Store</a> operations. The interface is uniform - the same interface
+applies to local data and to remote data using HTTP and the SPARQL
+protocols ( <a href="http://www.w3.org/TR/sparql11-protocol/";>SPARQL
+protocol</a> and <a
+href="http://www.w3.org/TR/sparql11-http-rdf-update/";>SPARQL Graph Store
+Protocol</a>).
+
+## Outline
+
+`RDFConnection` provides a number of different styles for working with RDF
+data in Java. It provides support for try-resource and functional code
+passing styles, as well the more basic sequence of methods calls.
+
+`try-resources` to manage the connection, and two operations, one to load
+some data, and one to make a query:
+
+```
+try ( RDFConnection conn = RDFConnectionFactory.connect(...) ) {
+ conn.load("data.ttl") ;
+ conn.querySelect("SELECT DISTINCT ?s { ?s ?p ?o }", (qs)->
+ Resource subject = qs.getResource("s") ;
+ System.out.println("Subject: "+subject) ;
+ }) ;
+}
+```
+This could have been written as (approximately -- the error handling is
better
+in the example above):
+
+```
+RDFConnection conn = RDFConnectionFactory.connect(...)
+conn.load("data.ttl") ;
+QueryExecution qExec = conn.query("SELECT DISTINCT ?s { ?s ?p ?o }") ;
+ResultSet rs = qExec.execSelect() ;
+while(rs.hasNext()) {
+ QuerySolution qs = rs.next() ;
+ Resource subject = qs.getResource("s") ;
+ System.out.println("Subject: "+subject) ;
+}
+qExec.close() ;
+conn.close() ;
+```
+
+Jena also provides a separate
+[SPARQL over JDBC
driver](http://jena.staging.apache.org/documentation/jdbc/index.html)
+library.
+
+## Transactions
+
+Transactions are the preferred way to work with RDF data.
+Operations on an `RDFConnection` outside of an application-controlled
+transaction will cause the system to add one for the duration of the
+operation. This "autocommit" feature may lead to inefficient operations due
+to excessive overhead.
+
+The `Txn` class provides a Java8-style transaction API. Transactions are
+code passed in the `Txn` library that handles the transaction lifecycle.
+
+```
+try ( RDFConnection conn = RDFConnectionFactory.connect(...) ) {
+ Txn.execWrite(conn, ()-> {
+ conn.load("data1.ttl") ;
+ conn.load("data2.ttl") ;
+ conn.querySelect("SELECT DISTINCT ?s { ?s ?p ?o }", (qs)->
+ Resource subject = qs.getResource("s") ;
+ System.out.println("Subject: "+subject) ;
+ }) ;
+ }) ;
+}
+```
+
+The traditional style of explicit `begin`, `commit`, `abort` is also
available.
+
+```
+try ( RDFConnection conn = RDFConnectionFactory.connect(...) ) {
+ conn.begin(ReadWrite.WRITE) ;
+ try {
+ conn.load("data1.ttl") ;
+ conn.load("data2.ttl") ;
+ conn.querySelect("SELECT DISTINCT ?s { ?s ?p ?o }", (qs)->
+ Resource subject = qs.getResource("s") ;
+ System.out.println("Subject: "+subject) ;
+ }) ;
+ conn.commit() ;
+ } finally { conn.end() ; }
+}
+```
+
+The use of `try-finally` ensures that transactions are properly finished.
+The `conn.end()` provides an abort in case an exception occurs in the
+transaction and a commit has not been issued. The use of `try-finally`
+ensures that transactions are properly finished.
+
+`Txn` is wrapping these steps up and calling the application supplied code
+for the transaction body.
+
+### Remote Transactions
+
+SPARQL does not define a remote transaction standard protocol. Each remote
+operation shuld be atomic (all happens or nothing happens) - this is the
+responsibility of the remote server.
+
+An `RDFConenction` will at least provide the client-side locking features.
+This means that overlapping operations that chnage data are naturally
--- End diff --
Typo: chnage -> change
> RDFConnection
> -------------
>
> Key: JENA-1267
> URL: https://issues.apache.org/jira/browse/JENA-1267
> Project: Apache Jena
> Issue Type: New Feature
> Affects Versions: Jena 3.1.1
> Reporter: Andy Seaborne
> Assignee: Andy Seaborne
> Fix For: Jena 3.2.0
>
>
> RDFConnection is an API to bring together the 3 parts of SPARQL : Query,
> Update and Graph Store Protocol.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
