Limit the memento headers to first, last, prev, next, timemap, timegate

Resolves #402

Author: acoburn

components/test/src/main/java/org/trellisldp/test/MementoBinaryTests.java

@@ -45,7 +45,7 @@ public interface MementoBinaryTests extends MementoResourceTests {
     default Map<String, String> getMementos() {
         final Map<String, String> mementos = new HashMap<>();
         try (final Response res = target(getBinaryLocation()).request().head()) {
-            getLinks(res).stream().filter(link -> link.getRel().equals("memento"))
+            getLinks(res).stream().filter(link -> link.getRels().contains("memento"))
                 .filter(l -> l.getParams().containsKey("datetime"))
                 .forEach(link -> mementos.put(link.getUri().toString(), link.getParams().get("datetime")));
         }
@@ -61,10 +61,10 @@ default void testCanonicalHeader() {
         getMementos().forEach((memento, date) -> {
             try (final Response res = target(memento).request().head()) {
                 assertEquals(SUCCESSFUL, res.getStatusInfo().getFamily(), "Check for a valid response");
-                assertTrue(getLinks(res).stream().filter(link -> link.getRel().equals("canonical"))
+                assertTrue(getLinks(res).stream().filter(link -> link.getRels().contains("canonical"))
                         .anyMatch(link -> link.getUri().toString().equals(memento)),
                         "Check for a rel=canonical Link header");
-                assertTrue(getLinks(res).stream().filter(link -> link.getRel().equals("describedby"))
+                assertTrue(getLinks(res).stream().filter(link -> link.getRels().contains("describedby"))
                         .anyMatch(link -> link.getUri().toString().equals(memento + "&ext=description")),
                         "Check for a rel=describedby Link header");
             }
@@ -84,10 +84,10 @@ default void testCanonicalHeaderDescriptions() {
             }
             try (final Response res = target(description).request().accept("text/turtle").head()) {
                 assertEquals(SUCCESSFUL, res.getStatusInfo().getFamily(), "Check for a valid response");
-                assertTrue(getLinks(res).stream().filter(link -> link.getRel().equals("canonical"))
+                assertTrue(getLinks(res).stream().filter(link -> link.getRels().contains("canonical"))
                         .anyMatch(link -> link.getUri().toString().equals(memento + "&ext=description")),
                         "Check for a rel=canonical Link header");
-                assertTrue(getLinks(res).stream().filter(link -> link.getRel().equals("describes"))
+                assertTrue(getLinks(res).stream().filter(link -> link.getRels().contains("describes"))
                         .anyMatch(link -> link.getUri().toString().equals(memento)),
                         "Check for a rel=describes Link header");
             }
@@ -108,12 +108,12 @@ default void testMementoContent() {
                 responses.put(memento, readEntityAsString(res.getEntity()));
             }
         });
-        assertEquals(3L, responses.size(), "Check for 3 mementos");
+        assertEquals(2L, responses.size(), "Check for 2 mementos");
         responses.forEach((response, content) ->
             assertTrue(content.startsWith("This is a text file."), "Check the binary content of the mementos"));
-        assertEquals(3L, responses.values().size(), "Check the number of Memento responses");
+        assertEquals(2L, responses.values().size(), "Check the number of Memento responses");
         final Set<String> values = new HashSet<>(responses.values());
-        assertEquals(3L, values.size(), "Check the number of distinct Memento responses");
+        assertEquals(2L, values.size(), "Check the number of distinct Memento responses");
     }
 
     /**

components/test/src/main/java/org/trellisldp/test/MementoResourceTests.java

@@ -58,22 +58,22 @@ public interface MementoResourceTests extends MementoCommonTests {
     default Map<String, String> getMementos() {
         final Map<String, String> mementos = new HashMap<>();
         try (final Response res = target(getResourceLocation()).request().get()) {
-            getLinks(res).stream().filter(link -> link.getRel().equals("memento"))
+            getLinks(res).stream().filter(link -> link.getRels().contains("memento"))
                 .filter(l -> l.getParams().containsKey("datetime"))
                 .forEach(link -> mementos.put(link.getUri().toString(), link.getParams().get("datetime")));
         }
         return mementos;
     }
 
     /**
-     * Test the presence of three mementos.
+     * Test the presence of two memento links.
      */
     @Test
-    @DisplayName("Test the presence of three mementos")
+    @DisplayName("Test the presence of two memento links")
     default void testMementosWereFound() {
         final Map<String, String> mementos = getMementos();
         assertFalse(mementos.isEmpty(), "Check that mementos were found");
-        assertEquals(3, mementos.size(), "Check that 3 mementos were found");
+        assertEquals(2, mementos.size(), "Check that 2 mementos were found");
     }
 
     /**
@@ -165,7 +165,7 @@ default void testMementoContent() {
 
         final IRI subject = rdf.createIRI(getResourceLocation());
         final List<IRI> urls = mementos.keySet().stream().sorted().map(rdf::createIRI).collect(toList());
-        assertEquals(3L, urls.size(), "Check that three mementos were found");
+        assertEquals(2L, urls.size(), "Check that two mementos were found");
         assertTrue(dataset.getGraph(urls.get(0)).isPresent(), "Check that the first graph is present");
         dataset.getGraph(urls.get(0)).ifPresent(g -> {
             assertTrue(g.contains(subject, type, SKOS.Concept), "Check for a skos:Concept type");
@@ -176,20 +176,8 @@ default void testMementoContent() {
             assertEquals(3L, g.size(), "Check for three triples");
         });
 
-        assertTrue(dataset.getGraph(urls.get(1)).isPresent(), "Check that the second graph is present");
+        assertTrue(dataset.getGraph(urls.get(1)).isPresent(), "Check that the last graph is present");
         dataset.getGraph(urls.get(1)).ifPresent(g -> {
-            assertTrue(g.contains(subject, type, SKOS.Concept), "Check for a skos:Concept type");
-            assertTrue(g.contains(subject, SKOS.prefLabel, rdf.createLiteral("Resource Name", "eng")),
-                    "Check for a skos:prefLabel property");
-            assertTrue(g.contains(subject, DC.subject, rdf.createIRI("http://example.org/subject/1")),
-                    "Check for a dc:subject property");
-            assertTrue(g.contains(subject, DC.title, rdf.createLiteral("Title")),
-                    "Check for a dc:title property");
-            assertEquals(4L, g.size(), "Check for four triples");
-        });
-
-        assertTrue(dataset.getGraph(urls.get(2)).isPresent(), "Check that the third graph is present");
-        dataset.getGraph(urls.get(2)).ifPresent(g -> {
             assertTrue(g.contains(subject, type, SKOS.Concept), "Check for a skos:Concept type");
             assertTrue(g.contains(subject, SKOS.prefLabel, rdf.createLiteral("Resource Name", "eng")),
                     "Check for a skos:prefLabel property");

core/http/src/main/java/org/trellisldp/http/core/TimemapGenerator.java

@@ -101,6 +101,6 @@ default Stream<Triple> asRdf(String identifier, List<Link> mementos) {
      * @return true if this is a valid link; false otherwise
      */
     default boolean isMementoLink(Link link) {
-        return MEMENTO.equals(link.getRel()) && link.getParams().containsKey(DATETIME);
+        return link.getRels().contains(MEMENTO) && link.getParams().containsKey(DATETIME);
     }
 }

core/http/src/main/java/org/trellisldp/http/impl/GetHandler.java

@@ -257,7 +257,8 @@ public ResponseBuilder addMementoHeaders(final ResponseBuilder builder, final So
         // Only show memento links for the user-managed graph (not ACL)
         if (!ACL.equals(getRequest().getExt())) {
             builder.link(getIdentifier(), "original timegate")
-                .links(MementoResource.getMementoLinks(getIdentifier(), mementos)
+                .links(MementoResource.getMementoHeaders(getIdentifier(), mementos, isMemento ?
+                            getResource().getModified() : null)
                         .map(link -> MementoResource.filterLinkParams(link, !includeMementoDates))
                         .toArray(Link[]::new));
         }