diff --git a/LICENSE b/LICENSE
index f927b76..861f99b 100644
--- a/LICENSE
+++ b/LICENSE
@@ -203,8 +203,3 @@
     See the License for the specific language governing permissions and
     limitations under the License.
     -------------------------------------------------------------
-
-
-
-APPENDIX B: Additional licenses relevant to this product:
-    (none)
diff --git a/NOTICE b/NOTICE
index 01aca2a..8ff8dcf 100644
--- a/NOTICE
+++ b/NOTICE
@@ -1,5 +1,5 @@
-Apache DataSketches Server
-Copyright 2020 - The Apache Software Foundation
+Apache DataSketches-server
+Copyright 2021 The Apache Software Foundation
 
 This product includes software developed at
 The Apache Software Foundation (http://www.apache.org/).
diff --git a/README.md b/README.md
index 9b03b92..14f5224 100644
--- a/README.md
+++ b/README.md
@@ -10,9 +10,22 @@
 The repository is still in an early state and lacks both unit tests and
 robust documentation.
 
+## Installation and Running
+
+The server requires Java 8. There is no pre-built jar currently, so the server must be built
+locally. Running `mvn package` will download the relevant dependencies, including the
+DataSketches Java library and the Jetty web server. Once built, a stand-alone server is launched
+by running
+```
+java -cp <path_to_jar> org.apache.datasketches.server.SketchServer <json_config_file>
+```
+where the most convenient option will likely be the jar-with-dependencies. The configuration
+file format is described below.
+
+
 ## Interaction
 
-Configuration and interaction with the server are done via JSON. We will
+Configuration and interaction with the server happen via JSON. We will
 demonstrate the main features of the server by creating a simple configuration
 and using that for some example requests and responses.
 
@@ -21,7 +34,7 @@
 of an error partway through an array the server will return an error, but the
 effects of any requests processed up to that point will be retained.
 
-JSON input may be passed in via either POST or GET.
+The server accepts JSON input presented via either POST or GET.
 
 
 ### Sketch Families
diff --git a/pom.xml b/pom.xml
index 0f066bc..720cf15 100644
--- a/pom.xml
+++ b/pom.xml
@@ -65,6 +65,13 @@
             <version>9.4.31.v20200723</version>
         </dependency>
 
+        <!-- Annotation -->
+        <dependency>
+            <groupId>org.checkerframework</groupId>
+            <artifactId>checker-qual</artifactId>
+            <version>3.10.0</version>
+        </dependency>
+
         <!--Testing-->
         <dependency>
             <groupId>org.testng</groupId>
diff --git a/src/main/java/org/apache/datasketches/server/BaseSketchesQueryHandler.java b/src/main/java/org/apache/datasketches/server/BaseSketchesQueryHandler.java
index a3b1b8e..211733a 100644
--- a/src/main/java/org/apache/datasketches/server/BaseSketchesQueryHandler.java
+++ b/src/main/java/org/apache/datasketches/server/BaseSketchesQueryHandler.java
@@ -103,15 +103,6 @@
    */
   protected abstract JsonObject processQuery(JsonObject query);
 
-  /**
-   * Internal method to synchronize calls to subclasses
-   * @param query A JSON query to process
-   * @return A JSON response
-   */
-  final synchronized JsonObject callProcessQuery(final JsonObject query) {
-    return processQuery(query);
-  }
-
   @Override
   public void handle(final String target,
                      final Request baseRequest,
@@ -130,10 +121,10 @@
 
     try {
       if (query == null) {
-        result = callProcessQuery(null);
+        result = processQuery(null);
       } else if (query.isJsonArray()) {
         for (final JsonElement subQuery : query.getAsJsonArray()) {
-          final JsonObject subResult = callProcessQuery(subQuery.getAsJsonObject());
+          final JsonObject subResult = processQuery(subQuery.getAsJsonObject());
           if (subResult != null) {
             // lazy initialization to avoid possibly empty array
             if (result == null) {
@@ -143,7 +134,8 @@
           }
         }
       } else {
-        result = callProcessQuery((JsonObject) query);
+        //result = callProcessQuery((JsonObject) query);
+        result = processQuery((JsonObject) query);
       }
 
       if (result != null) {
diff --git a/src/main/java/org/apache/datasketches/server/DataQueryHandler.java b/src/main/java/org/apache/datasketches/server/DataQueryHandler.java
index 42f9aca..cac8f58 100644
--- a/src/main/java/org/apache/datasketches/server/DataQueryHandler.java
+++ b/src/main/java/org/apache/datasketches/server/DataQueryHandler.java
@@ -59,35 +59,39 @@
       throw new IllegalArgumentException("Invalid sketch name: " + key);
     }
 
-    final SketchStorage.SketchEntry se = sketches.getSketch(key);
     JsonObject result = new JsonObject();
 
-    // pre-populate with the sketch name, but may be overwritten with
-    // null depending on the queyr
-    result.addProperty(QUERY_NAME_FIELD, key);
+    // we do need to lock the sketch even for query processing
+    synchronized (key.intern()) {
+      final SketchStorage.SketchEntry se = sketches.getSketch(key);
 
-    switch (se.family) {
-      case UNION:
-      case HLL:
-      case CPC:
-        result = processDistinctQuery(result, query, se.family, se.sketch);
-        break;
+      // pre-populate with the sketch name, but may be overwritten with
+      // null depending on the query
+      result.addProperty(QUERY_NAME_FIELD, key);
 
-      case KLL:
-        result = processQuantilesQuery(result, query, se.family, se.sketch);
-        break;
+      switch (se.family_) {
+        case UNION:
+        case HLL:
+        case CPC:
+          result = processDistinctQuery(result, query, se.family_, se.sketch_);
+          break;
 
-      case FREQUENCY:
-        result = processFrequencyQuery(result, query, se.family, se.sketch);
-        break;
+        case KLL:
+          result = processQuantilesQuery(result, query, se.family_, se.sketch_);
+          break;
 
-      case RESERVOIR:
-      case VAROPT:
-        result = processSamplingQuery(result, query, se.family, se.sketch);
-        break;
+        case FREQUENCY:
+          result = processFrequencyQuery(result, query, se.family_, se.sketch_);
+          break;
 
-      default:
-        throw new IllegalStateException("Unexpected sketch family: " + se.family);
+        case RESERVOIR:
+        case VAROPT:
+          result = processSamplingQuery(result, query, se.family_, se.sketch_);
+          break;
+
+        default:
+          throw new IllegalStateException("Unexpected sketch family: " + se.family_);
+      }
     }
 
     return result;
diff --git a/src/main/java/org/apache/datasketches/server/MergeHandler.java b/src/main/java/org/apache/datasketches/server/MergeHandler.java
index f3c7fcf..d75fad1 100644
--- a/src/main/java/org/apache/datasketches/server/MergeHandler.java
+++ b/src/main/java/org/apache/datasketches/server/MergeHandler.java
@@ -64,6 +64,20 @@
     super(sketches);
   }
 
+  /**
+   *  Holds an entry in the list of sketches to merge.
+   *  <tt>name.intern()</tt> can be used to synchronize the sketch to avoid concurrency issues
+   */
+  static class MergeEntry {
+    final String name_;
+    final Object sketch_;
+
+    MergeEntry(final String name, final Object sketch) {
+      name_ = name;
+      sketch_ = sketch;
+    }
+  }
+
   @Override
   protected JsonObject processQuery(final JsonObject query) {
     // optional targets:
@@ -95,15 +109,23 @@
     Family dstFamily = null;
     if (dst != null) {
       se = sketches.getSketch(dst);
-      dstFamily = se.family;
+      dstFamily = se.family_;
     }
 
     // we'll process (and dedup) any stored sketches before we handle encoded inputs
     // but we'll run through all of them before doing anything
-    final ArrayList<Object> srcSketches = new ArrayList<>(srcList.size());
+    final ArrayList<MergeEntry> srcSketches = new ArrayList<>(srcList.size());
 
     dstFamily = prepareSketches(srcList, dstFamily, dst, srcSketches);
-    final byte[] skBytes = mergeSketches(dstFamily, k, se, srcSketches);
+    final byte[] skBytes;
+    // need to synchronize if we have a named sketch
+    if (se == null) {
+      skBytes = mergeSketches(dstFamily, k, null, srcSketches);
+    } else {
+      synchronized (se.name_.intern()) {
+        skBytes = mergeSketches(dstFamily, k, se, srcSketches);
+      }
+    }
 
     // skBytes == null if merging into another sketch; only non-null if returning a serialized image
     if (skBytes != null) {
@@ -115,7 +137,7 @@
     }
   }
 
-  private Family prepareSketches(final JsonArray sources, Family family, final String dst, final ArrayList<Object> sketchList) {
+  private Family prepareSketches(final JsonArray sources, Family family, final String dst, final ArrayList<MergeEntry> sketchList) {
     final HashSet<String> namedSet = new HashSet<>();
 
     // TODO: Check for sketch value types with distinct counting?
@@ -131,7 +153,7 @@
         // check family
         final String key = elmt.getAsString();
         final SketchStorage.SketchEntry entry = sketches.getSketch(key);
-        if (entry == null || (family != null && family != entry.family)) {
+        if (entry == null || (family != null && family != entry.family_)) {
           throw new SketchesException("Input sketches must exist and be of the same family as the target");
         }
 
@@ -139,14 +161,14 @@
         if (!namedSet.contains(key)) {
           namedSet.add(key);
           if (family == null) {
-            family = entry.family;
+            family = entry.family_;
           }
 
           // if we have a theta Union we need to get the result first
-          if (entry.family == Family.UNION) {
-            sketchList.add(((Union) entry.sketch).getResult());
+          if (entry.family_ == Family.UNION) {
+            sketchList.add(new MergeEntry(key, ((Union) entry.sketch_).getResult()));
           } else {
-            sketchList.add(entry.sketch);
+            sketchList.add(new MergeEntry(key, entry.sketch_));
           }
         }
       } else { // is JsonObject
@@ -166,8 +188,9 @@
         }
 
         // add to list, save family if we didn't have one yet
+        // use hashcode of sketch as name -- we'll later create a needless lock but cleaner than conditional locking
         final Object sketch = deserializeSketch(skFamily, skString);
-        sketchList.add(sketch);
+        sketchList.add(new MergeEntry(Integer.toString(sketch.hashCode()), sketch));
         if (family == null) {
           family = skFamily;
         }
@@ -213,7 +236,7 @@
 
   @SuppressWarnings("unchecked")
   private static byte[] mergeSketches(final Family family, final int k,
-                                      final SketchStorage.SketchEntry dstEntry, final ArrayList<Object> sketchList) {
+                                      final SketchStorage.SketchEntry dstEntry, final ArrayList<MergeEntry> sketchList) {
     if (family == null || sketchList.size() == 0) {
       return null;
     }
@@ -223,15 +246,17 @@
       case QUICKSELECT: {
         // for theta, the destination is already a union so no need to add explicitly
         final Union dst = dstEntry == null ? new SetOperationBuilder().setNominalEntries(1 << k).buildUnion()
-            : (Union) dstEntry.sketch;
-        for (final Object obj : sketchList) {
-          dst.union((CompactSketch) obj);
+            : (Union) dstEntry.sketch_;
+        for (final MergeEntry me : sketchList) {
+          synchronized (me.name_.intern()) {
+            dst.union((CompactSketch) me.sketch_);
+          }
         }
 
         if (dstEntry == null) {
           return dst.getResult().toByteArray();
         } else {
-          dstEntry.sketch = dst;
+          dstEntry.sketch_ = dst;
           return null;
         }
       }
@@ -239,7 +264,7 @@
       case HLL: {
         final org.apache.datasketches.hll.Union union = new org.apache.datasketches.hll.Union(k);
         if (dstEntry != null) {
-          union.update((HllSketch) dstEntry.sketch);
+          union.update((HllSketch) dstEntry.sketch_);
         }
         for (final Object obj : sketchList) {
           union.update((HllSketch) obj);
@@ -248,7 +273,7 @@
         if (dstEntry == null) {
           return union.getResult().toCompactByteArray();
         } else {
-          dstEntry.sketch = union.getResult();
+          dstEntry.sketch_ = union.getResult();
           return null;
         }
       }
@@ -256,7 +281,7 @@
       case CPC: {
         final CpcUnion union = new CpcUnion(k);
         if (dstEntry != null) {
-          union.update((CpcSketch) dstEntry.sketch);
+          union.update((CpcSketch) dstEntry.sketch_);
         }
         for (final Object obj : sketchList) {
           union.update((CpcSketch) obj);
@@ -265,14 +290,14 @@
         if (dstEntry == null) {
           return union.getResult().toByteArray();
         } else {
-          dstEntry.sketch = union.getResult();
+          dstEntry.sketch_ = union.getResult();
           return null;
         }
       }
 
       case KLL: {
         // Only merge(), no separate union. Slightly abusing terminology to call it union
-        final KllFloatsSketch union = dstEntry == null ? new KllFloatsSketch(k) : (KllFloatsSketch) dstEntry.sketch;
+        final KllFloatsSketch union = dstEntry == null ? new KllFloatsSketch(k) : (KllFloatsSketch) dstEntry.sketch_;
 
         for (final Object obj : sketchList) {
           union.merge((KllFloatsSketch) obj);
@@ -281,14 +306,14 @@
         if (dstEntry == null) {
           return union.toByteArray();
         } else {
-          dstEntry.sketch = union;
+          dstEntry.sketch_ = union;
           return null;
         }
       }
 
       case FREQUENCY: {
         // Only merge(), no separate union. Slightly abusing terminology to call it union
-        final ItemsSketch<String> union = dstEntry == null ? new ItemsSketch<>(k) : (ItemsSketch<String>) dstEntry.sketch;
+        final ItemsSketch<String> union = dstEntry == null ? new ItemsSketch<>(k) : (ItemsSketch<String>) dstEntry.sketch_;
 
         for (final Object obj : sketchList) {
           union.merge((ItemsSketch<String>) obj);
@@ -297,7 +322,7 @@
         if (dstEntry == null) {
           return union.toByteArray(new ArrayOfStringsSerDe());
         } else {
-          dstEntry.sketch = union;
+          dstEntry.sketch_ = union;
           return null;
         }
       }
@@ -305,7 +330,7 @@
       case RESERVOIR: {
         final ReservoirItemsUnion<String> union = ReservoirItemsUnion.newInstance(k);
         if (dstEntry != null) {
-          union.update((ReservoirItemsSketch<String>) dstEntry.sketch);
+          union.update((ReservoirItemsSketch<String>) dstEntry.sketch_);
         }
 
         for (final Object obj : sketchList) {
@@ -315,7 +340,7 @@
         if (dstEntry == null) {
          return union.getResult().toByteArray(new ArrayOfStringsSerDe());
         } else {
-          dstEntry.sketch = union.getResult();
+          dstEntry.sketch_ = union.getResult();
           return null;
         }
       }
@@ -323,7 +348,7 @@
       case VAROPT: {
         final VarOptItemsUnion<String> union = VarOptItemsUnion.newInstance(k);
         if (dstEntry != null) {
-          union.update((VarOptItemsSketch<String>) dstEntry.sketch);
+          union.update((VarOptItemsSketch<String>) dstEntry.sketch_);
         }
 
         for (final Object obj : sketchList) {
@@ -333,7 +358,7 @@
         if (dstEntry == null) {
           return union.getResult().toByteArray(new ArrayOfStringsSerDe());
         } else {
-          dstEntry.sketch = union.getResult();
+          dstEntry.sketch_ = union.getResult();
           return null;
         }
       }
diff --git a/src/main/java/org/apache/datasketches/server/ResetHandler.java b/src/main/java/org/apache/datasketches/server/ResetHandler.java
index ec22a47..493d9ab 100644
--- a/src/main/java/org/apache/datasketches/server/ResetHandler.java
+++ b/src/main/java/org/apache/datasketches/server/ResetHandler.java
@@ -50,30 +50,32 @@
       throw new IllegalArgumentException("Invalid sketch name: " + key);
     }
 
-    final SketchStorage.SketchEntry se = sketches.getSketch(key);
+    synchronized (key.intern()) {
+      final SketchStorage.SketchEntry se = sketches.getSketch(key);
 
-    switch (se.family) {
-      case UNION:
-         ((Union) se.sketch).reset();
-        break;
-      case KLL:
-        se.sketch = new KllFloatsSketch(se.configK);
-        break;
-      case FREQUENCY:
-        ((ItemsSketch<String>) se.sketch).reset();
-        break;
-      case HLL:
-        ((HllSketch) se.sketch).reset();
-        break;
-      case CPC:
-        ((CpcSketch) se.sketch).reset();
-        break;
-      case RESERVOIR:
-        ((ReservoirItemsSketch<String>) se.sketch).reset();
-        break;
-      case VAROPT:
-        ((VarOptItemsSketch<String>) se.sketch).reset();
-        break;
+      switch (se.family_) {
+        case UNION:
+          ((Union) se.sketch_).reset();
+          break;
+        case KLL:
+          se.sketch_ = new KllFloatsSketch(se.configK_);
+          break;
+        case FREQUENCY:
+          ((ItemsSketch<String>) se.sketch_).reset();
+          break;
+        case HLL:
+          ((HllSketch) se.sketch_).reset();
+          break;
+        case CPC:
+          ((CpcSketch) se.sketch_).reset();
+          break;
+        case RESERVOIR:
+          ((ReservoirItemsSketch<String>) se.sketch_).reset();
+          break;
+        case VAROPT:
+          ((VarOptItemsSketch<String>) se.sketch_).reset();
+          break;
+      }
     }
 
     // nothing to return from reset calls
diff --git a/src/main/java/org/apache/datasketches/server/SerializationHandler.java b/src/main/java/org/apache/datasketches/server/SerializationHandler.java
index 8c285db..464667b 100644
--- a/src/main/java/org/apache/datasketches/server/SerializationHandler.java
+++ b/src/main/java/org/apache/datasketches/server/SerializationHandler.java
@@ -60,42 +60,47 @@
       throw new IllegalArgumentException("Invalid sketch name: " + name);
     }
 
-    final SketchStorage.SketchEntry se = sketches.getSketch(name);
-
     final byte[] bytes;
-    switch (se.family) {
-      case UNION:
-        bytes = ((Union) se.sketch).getResult().toByteArray();
-        break;
-      case KLL:
-        bytes = ((KllFloatsSketch) se.sketch).toByteArray();
-        break;
-      case FREQUENCY:
-        bytes = ((ItemsSketch<String>) se.sketch).toByteArray(new ArrayOfStringsSerDe());
-        break;
-      case HLL:
-        bytes = ((HllSketch) se.sketch).toCompactByteArray();
-        break;
-      case CPC:
-        bytes = ((CpcSketch) se.sketch).toByteArray();
-        break;
-      case RESERVOIR:
-        bytes = ((ReservoirItemsSketch<String>) se.sketch).toByteArray(new ArrayOfStringsSerDe());
-        break;
-      case VAROPT:
-        bytes = ((VarOptItemsSketch<String>) se.sketch).toByteArray(new ArrayOfStringsSerDe());
-        break;
-      default:
-        throw new IllegalStateException("Unexpected value: " + se.family);
+    final SketchStorage.SketchEntry se;
+
+    // need to lock the sketch even when just reading
+    synchronized (name.intern()) {
+      se = sketches.getSketch(name);
+
+      switch (se.family_) {
+        case UNION:
+          bytes = ((Union) se.sketch_).getResult().toByteArray();
+          break;
+        case KLL:
+          bytes = ((KllFloatsSketch) se.sketch_).toByteArray();
+          break;
+        case FREQUENCY:
+          bytes = ((ItemsSketch<String>) se.sketch_).toByteArray(new ArrayOfStringsSerDe());
+          break;
+        case HLL:
+          bytes = ((HllSketch) se.sketch_).toCompactByteArray();
+          break;
+        case CPC:
+          bytes = ((CpcSketch) se.sketch_).toByteArray();
+          break;
+        case RESERVOIR:
+          bytes = ((ReservoirItemsSketch<String>) se.sketch_).toByteArray(new ArrayOfStringsSerDe());
+          break;
+        case VAROPT:
+          bytes = ((VarOptItemsSketch<String>) se.sketch_).toByteArray(new ArrayOfStringsSerDe());
+          break;
+        default:
+          throw new IllegalStateException("Unexpected value: " + se.family_);
+      }
     }
 
     final String b64Sketch = Base64.getUrlEncoder().encodeToString(bytes);
 
     final JsonObject result = new JsonObject();
     result.addProperty(QUERY_NAME_FIELD, name);
-    result.addProperty(CONFIG_FAMILY_FIELD, se.family.getFamilyName());
-    if (se.type != null)
-      result.addProperty(CONFIG_TYPE_FIELD, se.type.getTypeName());
+    result.addProperty(CONFIG_FAMILY_FIELD, se.family_.getFamilyName());
+    if (se.type_ != null)
+      result.addProperty(CONFIG_TYPE_FIELD, se.type_.getTypeName());
     result.addProperty(QUERY_SKETCH_FIELD, b64Sketch);
 
     return result;
diff --git a/src/main/java/org/apache/datasketches/server/SketchConstants.java b/src/main/java/org/apache/datasketches/server/SketchConstants.java
index 6ef32c8..1e4059b 100644
--- a/src/main/java/org/apache/datasketches/server/SketchConstants.java
+++ b/src/main/java/org/apache/datasketches/server/SketchConstants.java
@@ -21,12 +21,12 @@
 
 public final class SketchConstants {
   // API call paths, relative to root
-  public static final String UPDATE_PATH = "/update";
-  public static final String SERIALIZE_PATH = "/serialize";
-  public static final String STATUS_PATH = "/status";
-  public static final String QUERY_PATH = "/query";
-  public static final String MERGE_PATH = "/merge";
-  public static final String RESET_PATH = "/reset";
+  public static final String UPDATE_PATH = "update";
+  public static final String SERIALIZE_PATH = "serialize";
+  public static final String STATUS_PATH = "status";
+  public static final String QUERY_PATH = "query";
+  public static final String MERGE_PATH = "merge";
+  public static final String RESET_PATH = "reset";
 
   // JSON Query/Update/Merge Field Names
   public static final String QUERY_NAME_FIELD = "name";
@@ -76,6 +76,7 @@
   public static final String RESPONSE_RESULT_MASS = "mass";
   public static final String RESPONSE_QUANTILE_LIST = "estimatedQuantiles";
   public static final String RESPONSE_RESULT_QUANTILE = "quantile";
+  public static final String RESPONSE_SKETCH_COUNT_FIELD = "count";
 
   // JSON Config Field Names
   public static final String CONFIG_PORT_FIELD = "port";
diff --git a/src/main/java/org/apache/datasketches/server/SketchServer.java b/src/main/java/org/apache/datasketches/server/SketchServer.java
index 4fefb9a..e0a8a0e 100644
--- a/src/main/java/org/apache/datasketches/server/SketchServer.java
+++ b/src/main/java/org/apache/datasketches/server/SketchServer.java
@@ -21,6 +21,7 @@
 
 import java.io.IOException;
 
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
 import org.eclipse.jetty.server.handler.ContextHandler;
@@ -43,36 +44,48 @@
    * @param configFile Path to a configuration file following the <tt>SketchServerConfig</tt> format
    * @throws IOException on parse errors
    */
-  public SketchServer(final String configFile) throws IOException {
+  public SketchServer(@NonNull final String configFile) throws IOException {
     config = new SketchServerConfig(configFile);
   }
 
   // defines paths and registers the relevant handlers
   private void createServer() {
-    server = new Server(config.getPort());
+    server = new Server();
+
+    // configure port
+    final ServerConnector http = new ServerConnector(server);
+    http.setHost("localhost");
+    http.setPort(config.getPort());
+    server.addConnector(http);
 
     // Error page unless you have a correct URL
     final ContextHandler contextRoot = new ContextHandler("/");
-    contextRoot.setContextPath("/");
     contextRoot.setErrorHandler(new ErrorHandler());
 
-    final ContextHandler contextStatus = new ContextHandler(STATUS_PATH);
+    // Add specific handlers
+    final ContextHandler contextStatus = new ContextHandler("/" + STATUS_PATH);
     contextStatus.setHandler(new StatusHandler(sketches));
+    contextStatus.setAllowNullPathInfo(true);
 
-    final ContextHandler contextSerialize = new ContextHandler(SERIALIZE_PATH);
+    final ContextHandler contextSerialize = new ContextHandler("/" + SERIALIZE_PATH);
     contextSerialize.setHandler(new SerializationHandler(sketches));
+    contextSerialize.setAllowNullPathInfo(true);
 
-    final ContextHandler contextUpdate = new ContextHandler(UPDATE_PATH);
+    final ContextHandler contextUpdate = new ContextHandler("/" + UPDATE_PATH);
     contextUpdate.setHandler(new UpdateHandler(sketches));
+    contextUpdate.setAllowNullPathInfo(true);
 
-    final ContextHandler contextMerge = new ContextHandler(MERGE_PATH);
+    final ContextHandler contextMerge = new ContextHandler("/" + MERGE_PATH);
     contextMerge.setHandler(new MergeHandler(sketches));
+    contextMerge.setAllowNullPathInfo(true);
 
-    final ContextHandler contextQuery = new ContextHandler(QUERY_PATH);
+    final ContextHandler contextQuery = new ContextHandler("/" + QUERY_PATH);
     contextQuery.setHandler(new DataQueryHandler(sketches));
+    contextQuery.setAllowNullPathInfo(true);
 
-    final ContextHandler contextReset = new ContextHandler(RESET_PATH);
+    final ContextHandler contextReset = new ContextHandler("/" + RESET_PATH);
     contextReset.setHandler(new ResetHandler(sketches));
+    contextReset.setAllowNullPathInfo(true);
 
     final ContextHandlerCollection contexts =
         new ContextHandlerCollection(contextRoot,
@@ -116,6 +129,34 @@
     return -1;
   }
 
+  /**
+   * Returns the server's running status
+   * @return True for a running server, otherwise false
+   */
+  public boolean isRunning() {
+    return server != null && server.isRunning();
+  }
+
+  /**
+   * Stops the server from running. Cannot be be restarted without creating new sketches.
+   * @throws Exception Upon underlying server throwing an Exception
+   */
+  public void stop() throws Exception {
+    if (server != null) {
+      server.stop();
+      server.isStarted();
+    }
+  }
+
+  /**
+   * Package-private test method to get a specific SketchEntry
+   * @param name The name of the desired sketch
+   * @return The SketchEntry containing the sketch and type info
+   */
+  SketchStorage.SketchEntry getSketch(@NonNull final String name) {
+    return sketches.getSketch(name);
+  }
+
   public static void main(final String[] args) throws Exception {
     if (args.length < 1) {
       System.err.println("Usage: SketchServer <config_file>");
diff --git a/src/main/java/org/apache/datasketches/server/SketchServerConfig.java b/src/main/java/org/apache/datasketches/server/SketchServerConfig.java
index 31a2daf..447e36e 100644
--- a/src/main/java/org/apache/datasketches/server/SketchServerConfig.java
+++ b/src/main/java/org/apache/datasketches/server/SketchServerConfig.java
@@ -24,6 +24,7 @@
 import java.io.IOException;
 import java.io.Reader;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -36,6 +37,8 @@
 
 import static org.apache.datasketches.server.SketchConstants.*;
 
+import org.checkerframework.checker.nullness.qual.NonNull;
+
 /**
  * A class to hold the server configuration, along with a supporting subclass and file-parsing methods.
  *
@@ -54,25 +57,16 @@
       this.family = family;
       this.type = type;
     }
-
-    SketchInfo(final String name, final int k, final String family) {
-      this(name, k, family, null);
-    }
-
   }
 
   private int port = DEFAULT_PORT;
   private ArrayList<SketchInfo> sketchList;
 
-  SketchServerConfig(final String configFile) throws IOException {
+  SketchServerConfig(@NonNull final String configFile) throws IOException {
     final JsonElement config = readJsonFromFile(configFile);
     parseConfig(config);
   }
 
-  SketchServerConfig(final JsonElement config) throws IOException {
-    parseConfig(config);
-  }
-
   int getPort() {
     return port;
   }
@@ -83,16 +77,10 @@
 
   // output should have a list with full info per sketch, even if input allows a
   // more condensed format
-  private static JsonElement readJsonFromFile(final String configFile) {
-    JsonElement config = null;
-
-    try (final Reader reader = Files.newBufferedReader(Paths.get(configFile))) {
-      config = JsonParser.parseReader(reader);
-    } catch (final IOException e) {
-      e.printStackTrace();
-    }
-
-    return config;
+  private static JsonElement readJsonFromFile(final String configFile) throws IOException {
+    final Path configPath = Paths.get(configFile);
+    final Reader reader = Files.newBufferedReader(configPath);
+    return JsonParser.parseReader(reader);
   }
 
   private void parseConfig(final JsonElement config) throws IOException {
diff --git a/src/main/java/org/apache/datasketches/server/SketchStorage.java b/src/main/java/org/apache/datasketches/server/SketchStorage.java
index c6c8c89..e8bc491 100644
--- a/src/main/java/org/apache/datasketches/server/SketchStorage.java
+++ b/src/main/java/org/apache/datasketches/server/SketchStorage.java
@@ -31,6 +31,8 @@
 import org.apache.datasketches.sampling.ReservoirItemsSketch;
 import org.apache.datasketches.sampling.VarOptItemsSketch;
 import org.apache.datasketches.theta.SetOperationBuilder;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
 
 import com.google.gson.JsonArray;
 import com.google.gson.JsonObject;
@@ -43,7 +45,8 @@
  * order to ensure that data is presented in a consistent way.
  */
 public class SketchStorage {
-  private static final String SKETCH_COUNT_NAME = "count";
+  // the set of SketchEntries held by this object
+  HashMap<String, SketchEntry> sketchMap;
 
   /**
    * Returns true if the sketch family is for distinct counting.
@@ -55,38 +58,44 @@
   }
 
   static class SketchEntry {
-    public final Family family;
-    public final ValueType type;
-    public Object sketch;
-    public int configK;
+    public final Family family_;
+    public final ValueType type_;
+    public Object sketch_;
+    public final String name_;
+    public int configK_;
 
-    SketchEntry(final Family family, final ValueType type, final Object sketch, final int configK) throws IllegalArgumentException {
+    SketchEntry(@NonNull final Family family,
+                final ValueType type,
+                @NonNull final Object sketch,
+                @NonNull final String name,
+                final int configK) throws IllegalArgumentException {
       if (isDistinctCounting(family) && type == null)
         throw new IllegalArgumentException("Must specify a value type for distinct counting sketches");
 
-      this.family = family;
-      this.type = type;
-      this.sketch = sketch;
-      this.configK = configK;
+      family_ = family;
+      type_ = type;
+      sketch_ = sketch;
+      name_ = name;
+      configK_ = configK;
     }
 
-    SketchEntry(final Family family, final Object sketch, final int configK) throws IllegalArgumentException {
+    SketchEntry(@NonNull final Family family,
+                @NonNull final Object sketch,
+                @NonNull final String name,
+                final int configK) throws IllegalArgumentException {
       if (isDistinctCounting(family))
         throw new IllegalArgumentException("Must specify a value type for distinct counting sketches");
 
-      this.family = family;
-      this.type = null;
-      this.sketch = sketch;
-      this.configK = configK;
+      family_ = family;
+      type_ = null;
+      sketch_ = sketch;
+      name_ = name;
+      configK_ = configK;
     }
   }
 
-  HashMap<String, SketchEntry> sketchMap;
-
-  SketchStorage(final List<SketchServerConfig.SketchInfo> sketchList) {
-    if (sketchList != null) {
-      createSketches(sketchList);
-    }
+  SketchStorage(@NonNull final List<SketchServerConfig.SketchInfo> sketchList) {
+    createSketches(sketchList);
   }
 
   JsonObject listSketches() {
@@ -96,17 +105,17 @@
     for (final Map.Entry<String, SketchEntry> e : sketchMap.entrySet()) {
       final JsonObject item = new JsonObject();
       item.addProperty(CONFIG_SKETCH_NAME_FIELD, e.getKey());
-      switch (e.getValue().family) {
+      switch (e.getValue().family_) {
         case UNION:
-          item.addProperty(CONFIG_TYPE_FIELD, e.getValue().type.getTypeName());
+          item.addProperty(CONFIG_TYPE_FIELD, e.getValue().type_.getTypeName());
           item.addProperty(CONFIG_FAMILY_FIELD, SKETCH_FAMILY_THETA);
           break;
         case CPC:
-          item.addProperty(CONFIG_TYPE_FIELD, e.getValue().type.getTypeName());
+          item.addProperty(CONFIG_TYPE_FIELD, e.getValue().type_.getTypeName());
           item.addProperty(CONFIG_FAMILY_FIELD, SKETCH_FAMILY_CPC);
           break;
         case HLL:
-          item.addProperty(CONFIG_TYPE_FIELD, e.getValue().type.getTypeName());
+          item.addProperty(CONFIG_TYPE_FIELD, e.getValue().type_.getTypeName());
           item.addProperty(CONFIG_FAMILY_FIELD, SKETCH_FAMILY_HLL);
           break;
         case FREQUENCY:
@@ -125,7 +134,7 @@
       sketchList.add(item);
     }
 
-    summary.addProperty(SKETCH_COUNT_NAME, sketchMap.size());
+    summary.addProperty(RESPONSE_SKETCH_COUNT_FIELD, sketchMap.size());
     summary.add(SketchConstants.CONFIG_SKETCHES_PREFIX, sketchList); // bare prefix, sketches fully qualified
 
     return summary;
@@ -150,38 +159,39 @@
 
       SketchEntry sketchEntry = null;
       final Family family = BaseSketchesQueryHandler.familyFromString(info.family);
+      final int k = info.k; // to reduce derferences in code later
 
       switch (family) {
         case QUICKSELECT:
           // make a Union so we can handle merges later
           sketchEntry = new SketchEntry(Family.UNION, ValueType.stringToType(info.type),
-              new SetOperationBuilder().setNominalEntries(1 << info.k).buildUnion(), info.k);
+              new SetOperationBuilder().setNominalEntries(1 << k).buildUnion(), info.name, k);
           break;
 
         case HLL:
           sketchEntry = new SketchEntry(Family.HLL, ValueType.stringToType(info.type),
-              new HllSketch(info.k), info.k);
+              new HllSketch(k), info.name, k);
           break;
 
         case CPC:
           sketchEntry = new SketchEntry(Family.CPC, ValueType.stringToType(info.type),
-              new CpcSketch(info.k), info.k);
+              new CpcSketch(k), info.name, k);
           break;
 
         case KLL:
-          sketchEntry = new SketchEntry(Family.KLL, new KllFloatsSketch(info.k), info.k);
+          sketchEntry = new SketchEntry(Family.KLL, new KllFloatsSketch(k), info.name, k);
           break;
 
         case FREQUENCY:
-          sketchEntry = new SketchEntry(Family.FREQUENCY, new ItemsSketch<String>(info.k), info.k);
+          sketchEntry = new SketchEntry(Family.FREQUENCY, new ItemsSketch<String>(k), info.name, k);
           break;
 
         case RESERVOIR:
-          sketchEntry = new SketchEntry(Family.RESERVOIR, ReservoirItemsSketch.<String>newInstance(info.k), info.k);
+          sketchEntry = new SketchEntry(Family.RESERVOIR, ReservoirItemsSketch.<String>newInstance(k), info.name, k);
           break;
 
         case VAROPT:
-          sketchEntry = new SketchEntry(Family.VAROPT, VarOptItemsSketch.<String>newInstance(info.k), info.k);
+          sketchEntry = new SketchEntry(Family.VAROPT, VarOptItemsSketch.<String>newInstance(k), info.name, k);
           break;
       }
 
diff --git a/src/main/java/org/apache/datasketches/server/UpdateHandler.java b/src/main/java/org/apache/datasketches/server/UpdateHandler.java
index eb8c97a..84dc15a 100644
--- a/src/main/java/org/apache/datasketches/server/UpdateHandler.java
+++ b/src/main/java/org/apache/datasketches/server/UpdateHandler.java
@@ -80,10 +80,12 @@
         throw new IllegalArgumentException("Attempt to call update with missing name or sketch not found");
       }
 
-      if (data.isJsonArray()) {
-        processBatchUpdate(se, data.getAsJsonArray());
-      } else {
-        processSingleUpdate(se, data);
+      synchronized (name.intern()) {
+        if (data.isJsonArray()) {
+          processBatchUpdate(se, data.getAsJsonArray());
+        } else {
+          processSingleUpdate(se, data);
+        }
       }
     }
 
@@ -94,54 +96,54 @@
   @SuppressWarnings("unchecked")
   private static void processBatchUpdate(final SketchStorage.SketchEntry entry,
                                          final JsonArray data) {
-    switch (entry.family) {
+    switch (entry.family_) {
       case UNION: // theta
-        assert(entry.type != null);
-        switch (entry.type) {
+        assert(entry.type_ != null);
+        switch (entry.type_) {
           case FLOAT: case DOUBLE:
-            for (final JsonElement e : data) { ((Union) entry.sketch).update(e.getAsDouble()); }
+            for (final JsonElement e : data) { ((Union) entry.sketch_).update(e.getAsDouble()); }
             break;
           case INT: case LONG:
-            for (final JsonElement e : data) { ((Union) entry.sketch).update(e.getAsLong()); }
+            for (final JsonElement e : data) { ((Union) entry.sketch_).update(e.getAsLong()); }
             break;
           case STRING: default:
-            for (final JsonElement e : data) { ((Union) entry.sketch).update(e.getAsString()); }
+            for (final JsonElement e : data) { ((Union) entry.sketch_).update(e.getAsString()); }
             break;
         }
         break;
 
       case CPC:
-        assert(entry.type != null);
-        switch (entry.type) {
+        assert(entry.type_ != null);
+        switch (entry.type_) {
           case FLOAT: case DOUBLE:
-            for (final JsonElement e : data) { ((CpcSketch) entry.sketch).update(e.getAsDouble()); }
+            for (final JsonElement e : data) { ((CpcSketch) entry.sketch_).update(e.getAsDouble()); }
             break;
           case INT: case LONG:
-            for (final JsonElement e : data) { ((CpcSketch) entry.sketch).update(e.getAsLong()); }
+            for (final JsonElement e : data) { ((CpcSketch) entry.sketch_).update(e.getAsLong()); }
             break;
           case STRING: default:
-            for (final JsonElement e : data) { ((CpcSketch) entry.sketch).update(e.getAsString()); }
+            for (final JsonElement e : data) { ((CpcSketch) entry.sketch_).update(e.getAsString()); }
             break;
         }
         break;
 
       case HLL:
-        assert(entry.type != null);
-        switch (entry.type) {
+        assert(entry.type_ != null);
+        switch (entry.type_) {
           case FLOAT: case DOUBLE:
-            for (final JsonElement e : data) { ((HllSketch) entry.sketch).update(e.getAsDouble()); }
+            for (final JsonElement e : data) { ((HllSketch) entry.sketch_).update(e.getAsDouble()); }
             break;
           case INT: case LONG:
-            for (final JsonElement e : data) { ((CpcSketch) entry.sketch).update(e.getAsLong()); }
+            for (final JsonElement e : data) { ((CpcSketch) entry.sketch_).update(e.getAsLong()); }
             break;
           case STRING: default:
-            for (final JsonElement e : data) { ((CpcSketch) entry.sketch).update(e.getAsString()); }
+            for (final JsonElement e : data) { ((CpcSketch) entry.sketch_).update(e.getAsString()); }
             break;
         }
         break;
 
       case KLL:
-        for (final JsonElement e : data) { ((KllFloatsSketch) entry.sketch).update(e.getAsFloat()); }
+        for (final JsonElement e : data) { ((KllFloatsSketch) entry.sketch_).update(e.getAsFloat()); }
         break;
 
       case FREQUENCY:
@@ -154,15 +156,15 @@
             }
             final String item = inputPair.get(QUERY_PAIR_ITEM_FIELD).getAsString();
             final int weight = inputPair.get(QUERY_PAIR_WEIGHT_FIELD).getAsInt();
-            ((ItemsSketch<String>) entry.sketch).update(item, weight);
+            ((ItemsSketch<String>) entry.sketch_).update(item, weight);
           } else {
-            ((ItemsSketch<String>) entry.sketch).update(e.getAsString());
+            ((ItemsSketch<String>) entry.sketch_).update(e.getAsString());
           }
         }
         break;
 
       case RESERVOIR:
-        for (final JsonElement e : data) { ((ReservoirItemsSketch<String>) entry.sketch).update(e.getAsString()); }
+        for (final JsonElement e : data) { ((ReservoirItemsSketch<String>) entry.sketch_).update(e.getAsString()); }
         break;
 
       case VAROPT:
@@ -175,69 +177,69 @@
             }
             final String item = inputPair.get(QUERY_PAIR_ITEM_FIELD).getAsString();
             final double weight = inputPair.get(QUERY_PAIR_WEIGHT_FIELD).getAsDouble();
-            ((VarOptItemsSketch<String>) entry.sketch).update(item, weight);
+            ((VarOptItemsSketch<String>) entry.sketch_).update(item, weight);
           } else {
-            ((VarOptItemsSketch<String>) entry.sketch).update(e.getAsString(), 1.0);
+            ((VarOptItemsSketch<String>) entry.sketch_).update(e.getAsString(), 1.0);
           }
         }
         break;
 
       default:
-        throw new IllegalArgumentException("Unsupported sketch type: " + entry.family);
+        throw new IllegalArgumentException("Unsupported sketch type: " + entry.family_);
     }
   }
 
   @SuppressWarnings("unchecked")
   private static void processSingleUpdate(final SketchStorage.SketchEntry entry,
                                           final JsonElement data) {
-    switch (entry.family) {
+    switch (entry.family_) {
       case UNION:
-        assert(entry.type != null);
-        switch (entry.type) {
+        assert(entry.type_ != null);
+        switch (entry.type_) {
           case FLOAT: case DOUBLE:
-            ((Union) entry.sketch).update(data.getAsDouble());
+            ((Union) entry.sketch_).update(data.getAsDouble());
             break;
           case INT: case LONG:
-            ((Union) entry.sketch).update(data.getAsLong());
+            ((Union) entry.sketch_).update(data.getAsLong());
             break;
           case STRING: default:
-            ((Union) entry.sketch).update(data.getAsString());
+            ((Union) entry.sketch_).update(data.getAsString());
             break;
         }
         break;
 
       case CPC:
-        assert(entry.type != null);
-        switch (entry.type) {
+        assert(entry.type_ != null);
+        switch (entry.type_) {
           case FLOAT: case DOUBLE:
-            ((CpcSketch) entry.sketch).update(data.getAsDouble());
+            ((CpcSketch) entry.sketch_).update(data.getAsDouble());
             break;
           case INT: case LONG:
-            ((CpcSketch) entry.sketch).update(data.getAsLong());
+            ((CpcSketch) entry.sketch_).update(data.getAsLong());
             break;
           case STRING: default:
-            ((CpcSketch) entry.sketch).update(data.getAsString());
+            ((CpcSketch) entry.sketch_).update(data.getAsString());
             break;
         }
         break;
 
       case HLL:
-        assert(entry.type != null);
-        switch (entry.type) {
+        assert(entry.type_ != null);
+        switch (entry.type_) {
           case FLOAT: case DOUBLE:
-            ((HllSketch) entry.sketch).update(data.getAsDouble());
+            ((HllSketch) entry.sketch_).update(data.getAsDouble());
             break;
           case INT: case LONG:
-            ((HllSketch) entry.sketch).update(data.getAsLong());
+            ((HllSketch) entry.sketch_).update(data.getAsLong());
             break;
           case STRING: default:
-            ((HllSketch) entry.sketch).update(data.getAsString());
+            ((HllSketch) entry.sketch_).update(data.getAsString());
             break;
         }
         break;
 
       case KLL:
-        ((KllFloatsSketch) entry.sketch).update(data.getAsFloat());
+        ((KllFloatsSketch) entry.sketch_).update(data.getAsFloat());
         break;
 
       case FREQUENCY:
@@ -249,14 +251,14 @@
           }
           final String item = inputPair.get(QUERY_PAIR_ITEM_FIELD).getAsString();
           final int weight = inputPair.get(QUERY_PAIR_WEIGHT_FIELD).getAsInt();
-          ((ItemsSketch<String>) entry.sketch).update(item, weight);
+          ((ItemsSketch<String>) entry.sketch_).update(item, weight);
         } else {
-          ((ItemsSketch<String>) entry.sketch).update(data.getAsString());
+          ((ItemsSketch<String>) entry.sketch_).update(data.getAsString());
         }
         break;
 
       case RESERVOIR:
-        ((ReservoirItemsSketch<String>) entry.sketch).update(data.getAsString());
+        ((ReservoirItemsSketch<String>) entry.sketch_).update(data.getAsString());
         break;
 
       case VAROPT:
@@ -268,14 +270,14 @@
           }
           final String item = inputPair.get(QUERY_PAIR_ITEM_FIELD).getAsString();
           final double weight = inputPair.get(QUERY_PAIR_WEIGHT_FIELD).getAsDouble();
-          ((VarOptItemsSketch<String>) entry.sketch).update(item, weight);
+          ((VarOptItemsSketch<String>) entry.sketch_).update(item, weight);
         } else {
-          ((VarOptItemsSketch<String>) entry.sketch).update(data.getAsString(), 1.0);
+          ((VarOptItemsSketch<String>) entry.sketch_).update(data.getAsString(), 1.0);
         }
         break;
 
       default:
-        throw new IllegalArgumentException("Unsupported sketch type: " + entry.family);
+        throw new IllegalArgumentException("Unsupported sketch type: " + entry.family_);
     }
   }
 
diff --git a/src/test/java/org/apache/datasketches/server/ServerTestBase.java b/src/test/java/org/apache/datasketches/server/ServerTestBase.java
new file mode 100644
index 0000000..8c0d7f5
--- /dev/null
+++ b/src/test/java/org/apache/datasketches/server/ServerTestBase.java
@@ -0,0 +1,140 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.server;
+
+import static org.testng.Assert.fail;
+
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.util.Objects;
+import java.io.DataOutputStream;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.testng.annotations.AfterClass;
+import org.testng.annotations.BeforeClass;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+
+public class ServerTestBase {
+  final static String RESPONSE_FIELD = "response";
+
+  SketchServer server_ = null;
+  String serverUri_ = null;
+
+  @BeforeClass
+  public void launchServer() {
+    final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+    try {
+      server_ = new SketchServer(Objects.requireNonNull(classLoader.getResource("test_config.json")).getFile());
+      server_.start();
+      serverUri_ = server_.getURI();
+    } catch (final Exception e) {
+      fail();
+    }
+  }
+
+  @AfterClass
+  public void shutdownServer() {
+    if (server_ != null) {
+      try {
+        server_.stop();
+      } catch (final Exception e) {
+        fail();
+      }
+    }
+  }
+
+  int postData(@NonNull final String path,
+               @NonNull final JsonObject data,
+               @NonNull final JsonObject response) {
+    HttpURLConnection http = null;
+    int status = -1;
+
+    try {
+      // set up the POST
+      final URL url = new URL(serverUri_ + path);
+      http = (HttpURLConnection) url.openConnection();
+      http.setDoInput(true);
+      http.setDoOutput(true);
+      http.setRequestMethod("POST");
+      http.setRequestProperty("Content-Type", "application/json");
+      http.setRequestProperty("Accept", "application/json");
+
+      final byte[] jsonBytes = data.toString().getBytes(StandardCharsets.UTF_8);
+      http.setRequestProperty("Content-length", Integer.toString(jsonBytes.length));
+
+      // write JSON data to to stream
+      try (final DataOutputStream os = new DataOutputStream(http.getOutputStream())) {
+        os.write(jsonBytes);
+      }
+
+      status = http.getResponseCode();
+      if (status == HttpServletResponse.SC_OK) {
+        // read response, if any, and put into a JSON element
+        try (final InputStreamReader isr = new InputStreamReader(http.getInputStream())) {
+          response.add(RESPONSE_FIELD, JsonParser.parseReader(isr));
+        }
+      }
+    } catch (final IOException e) {
+      fail();
+    } finally {
+      if (http != null)
+        http.disconnect();
+    }
+
+    return status;
+  }
+
+  int getData(@NonNull final String path,
+              @NonNull final JsonObject data,
+              @NonNull final JsonObject response) {
+    HttpURLConnection http = null;
+    int status = -1;
+
+    try {
+      // set up the POST
+      final URL url = new URL(serverUri_ + path + "?" + data);
+      http = (HttpURLConnection) url.openConnection();
+      http.setDoInput(true);
+      http.setRequestProperty("Content-Type", "application/json");
+      http.connect();
+
+      status = http.getResponseCode();
+      if (status == HttpServletResponse.SC_OK) {
+        // read response, if any, and put into a JSON element
+        try (final InputStreamReader isr = new InputStreamReader(http.getInputStream())) {
+          response.add(RESPONSE_FIELD, JsonParser.parseReader(isr));
+        }
+      }
+    } catch (final IOException e) {
+      fail();
+    } finally {
+      if (http != null)
+        http.disconnect();
+    }
+
+    return status;
+  }
+}
diff --git a/src/test/java/org/apache/datasketches/server/SketchServerConfigTest.java b/src/test/java/org/apache/datasketches/server/SketchServerConfigTest.java
new file mode 100644
index 0000000..861d58a
--- /dev/null
+++ b/src/test/java/org/apache/datasketches/server/SketchServerConfigTest.java
@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.server;
+
+import static org.apache.datasketches.server.SketchConstants.DEFAULT_PORT;
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.fail;
+
+import java.io.IOException;
+import java.util.Objects;
+
+import org.testng.annotations.Test;
+
+public class SketchServerConfigTest {
+
+  @Test
+  public void invalidFile() {
+    try {
+      new SketchServerConfig("fileDoesNotExist");
+      fail();
+    } catch (final IOException e) {
+      // expected
+    }
+  }
+
+  @Test
+  public void parseTestConfig() {
+    final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+    try {
+      final SketchServerConfig serverConf =
+          new SketchServerConfig(Objects.requireNonNull(classLoader.getResource("config_with_port.json")).getFile());
+      assertEquals(serverConf.getSketchList().size(), 2);
+      assertEquals(serverConf.getPort(), 8080);
+    } catch (final IOException e) {
+      fail();
+    }
+  }
+
+  @Test
+  public void parseJsonArrayConfig() {
+    final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+    try {
+      final SketchServerConfig serverConf =
+          new SketchServerConfig(Objects.requireNonNull(classLoader.getResource("array_config.json")).getFile());
+      assertEquals(serverConf.getSketchList().size(), 2);
+      assertEquals(serverConf.getPort(), DEFAULT_PORT);
+    } catch (final IOException e) {
+      fail();
+    }
+  }
+}
diff --git a/src/test/java/org/apache/datasketches/server/SketchServerTest.java b/src/test/java/org/apache/datasketches/server/SketchServerTest.java
new file mode 100644
index 0000000..4a2a15d
--- /dev/null
+++ b/src/test/java/org/apache/datasketches/server/SketchServerTest.java
@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.server;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertFalse;
+import static org.testng.Assert.assertNotNull;
+import static org.testng.Assert.assertNull;
+import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.fail;
+
+import java.io.IOException;
+import java.util.Objects;
+
+import org.testng.annotations.Test;
+
+public class SketchServerTest {
+  @Test
+  public void createServer() {
+    final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+    SketchServer server = null;
+    try {
+      server = new SketchServer(Objects.requireNonNull(classLoader.getResource("config_with_port.json")).getFile());
+    } catch (final IOException e) {
+      fail();
+    }
+
+    // check that port and URI are invalid before starting the server
+    assertNotNull(server);
+    assertFalse(server.isRunning());
+    assertNull(server.getURI());
+    assertEquals(server.getPort(), -1);
+    try {
+      server.start();
+      assertTrue(server.isRunning());
+
+      // add the few tests in the try block for code simplicity
+      assertEquals(server.getPort(), 8080);
+      // initial testing suggests it's just using the host's IP address so just checking that the port
+      // is working correctly
+      assertTrue(server.getURI().endsWith(":" + server.getPort() + "/"));
+
+      server.stop();
+      assertFalse(server.isRunning());
+    } catch (final Exception e) {
+      fail();
+    }
+  }
+}
diff --git a/src/test/java/org/apache/datasketches/server/SketchStorageTest.java b/src/test/java/org/apache/datasketches/server/SketchStorageTest.java
new file mode 100644
index 0000000..03f4b5c
--- /dev/null
+++ b/src/test/java/org/apache/datasketches/server/SketchStorageTest.java
@@ -0,0 +1,75 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.server;
+
+import static org.apache.datasketches.server.SketchConstants.RESPONSE_SKETCH_COUNT_FIELD;
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertNotNull;
+import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.fail;
+
+import java.io.IOException;
+import java.util.Objects;
+
+import org.apache.datasketches.Family;
+import org.apache.datasketches.cpc.CpcSketch;
+import org.apache.datasketches.hll.HllSketch;
+import org.testng.annotations.Test;
+
+
+import com.google.gson.JsonObject;
+
+public class SketchStorageTest {
+
+  @Test
+  public void invalidSketchEntry() {
+    try {
+      new SketchStorage.SketchEntry(Family.CPC, null, new CpcSketch(12), "cpcSketch", 12);
+      fail();
+    } catch (IllegalArgumentException e) {
+      // expected
+    }
+
+    try {
+      new SketchStorage.SketchEntry(Family.HLL, new HllSketch(10), "hllSketch", 10);
+      fail();
+    } catch (IllegalArgumentException e) {
+      // expected
+    }
+  }
+
+  @Test
+  public void loadSketches() {
+    final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+    SketchServerConfig serverConfig = null;
+    try {
+      serverConfig = new SketchServerConfig(Objects.requireNonNull(classLoader.getResource("test_config.json")).getFile());
+    } catch (final IOException e) {
+      fail();
+    }
+    assertNotNull(serverConfig);
+
+    final SketchStorage storage = new SketchStorage(serverConfig.getSketchList());
+    final JsonObject sketches = storage.listSketches();
+    assertTrue(sketches.has(RESPONSE_SKETCH_COUNT_FIELD));
+    assertEquals(sketches.get(RESPONSE_SKETCH_COUNT_FIELD).getAsInt(), 15);
+    assertTrue(storage.contains("cpcOfNumbers"));
+  }
+}
diff --git a/src/test/java/org/apache/datasketches/server/UpdateHandlerTest.java b/src/test/java/org/apache/datasketches/server/UpdateHandlerTest.java
new file mode 100644
index 0000000..a77369b
--- /dev/null
+++ b/src/test/java/org/apache/datasketches/server/UpdateHandlerTest.java
@@ -0,0 +1,142 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.server;
+
+import static org.apache.datasketches.server.SketchConstants.QUERY_PAIR_ITEM_FIELD;
+import static org.apache.datasketches.server.SketchConstants.QUERY_PAIR_WEIGHT_FIELD;
+import static org.apache.datasketches.server.SketchConstants.UPDATE_PATH;
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertTrue;
+
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.datasketches.cpc.CpcSketch;
+import org.testng.annotations.Test;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+
+
+public class UpdateHandlerTest extends ServerTestBase {
+  /* The tests here are going to be structured very similarly. It might be possible
+   * to find a common framework and reduce the amount o repetition? But not clear with
+   * type erasure as opposed to C++-style templates.
+   */
+
+  @Test
+  public void cpcUpdate() {
+    final JsonObject response = new JsonObject();
+    final String sketchName = "cpcOfNumbers";
+    final int nPoints = 1000;
+
+    // testing using both GET and POST
+    int status;
+
+    JsonObject request = new JsonObject();
+    JsonArray data = new JsonArray();
+    for (int i = 0; i < nPoints; ++i)
+      data.add(i);
+    request.add(sketchName, data);
+    status = postData(UPDATE_PATH, request, response);
+    assertEquals(status, HttpServletResponse.SC_OK);
+
+    request = new JsonObject();
+    data = new JsonArray();
+    for (int i = nPoints; i < 2 * nPoints; ++i)
+      data.add(i);
+    request.add(sketchName, data);
+    status = getData(UPDATE_PATH, request, response);
+    assertEquals(status, HttpServletResponse.SC_OK);
+
+    final JsonElement element = response.get(RESPONSE_FIELD);
+    assertTrue(element.isJsonNull());
+
+    final SketchStorage.SketchEntry entry = server_.getSketch(sketchName);
+    final CpcSketch sk = (CpcSketch) entry.sketch_;
+    assertEquals(sk.getEstimate(), 2 * nPoints, 2 * nPoints * 1e-2);
+  }
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void fiUpdate() {
+    final JsonObject response = new JsonObject();
+    final String sketchName = "topItems";
+
+    // single item
+    JsonObject request = new JsonObject();
+    request.addProperty(sketchName, "item1");
+    assertEquals(postData(UPDATE_PATH, request, response), HttpServletResponse.SC_OK);
+
+    // item with weight
+    request = new JsonObject();
+    JsonObject data = new JsonObject();
+    data.addProperty(QUERY_PAIR_ITEM_FIELD, "item2");
+    data.addProperty(QUERY_PAIR_WEIGHT_FIELD, 5);
+    request.add(sketchName, data);
+    assertEquals(postData(UPDATE_PATH, request, response), HttpServletResponse.SC_OK);
+
+    // array of items with and without weights
+    request = new JsonObject();
+    final JsonArray dataArray = new JsonArray();
+    dataArray.add("item1"); // increases count to 2
+    data = new JsonObject();
+    data.addProperty(QUERY_PAIR_ITEM_FIELD, "item3");
+    data.addProperty(QUERY_PAIR_WEIGHT_FIELD, 10);
+    dataArray.add(data);
+    request.add(sketchName, dataArray);
+    assertEquals(postData(UPDATE_PATH, request, response), HttpServletResponse.SC_OK);
+
+    final JsonElement element = response.get(RESPONSE_FIELD);
+    assertTrue(element.isJsonNull());
+
+    final SketchStorage.SketchEntry entry = server_.getSketch(sketchName);
+    final org.apache.datasketches.frequencies.ItemsSketch<String> sk = (org.apache.datasketches.frequencies.ItemsSketch<String>) entry.sketch_;
+    assertEquals(sk.getEstimate("item1"), 2);
+    assertEquals(sk.getEstimate("item2"), 5);
+    assertEquals(sk.getEstimate("item3"), 10);
+  }
+
+  @Test
+  public void hllUpdate() {
+    // update multiple sketches from an array
+  }
+
+  @Test
+  public void kllUpdate() {
+
+  }
+
+  @Test
+  public void thetaUpdate() {
+
+  }
+
+  @Test
+  public void reservoirUpdate() {
+
+  }
+
+  @Test
+  public void voUpdate() {
+
+  }
+
+}
diff --git a/src/test/resources/array_config.json b/src/test/resources/array_config.json
new file mode 100644
index 0000000..7c718ee
--- /dev/null
+++ b/src/test/resources/array_config.json
@@ -0,0 +1,12 @@
+[
+  { "name": "cpcOfNumbers",
+    "k": 12,
+    "type": "long",
+    "family": "cpc"
+  },
+  { "name": "cpcOfStrings",
+    "k": 14,
+    "type": "string",
+    "family": "cpc"
+  }
+]
\ No newline at end of file
diff --git a/src/test/resources/config_with_port.json b/src/test/resources/config_with_port.json
new file mode 100644
index 0000000..f148049
--- /dev/null
+++ b/src/test/resources/config_with_port.json
@@ -0,0 +1,15 @@
+{
+  "port": 8080,
+  "sketches_A": [
+    { "name": "cpcOfNumbers",
+      "k": 12,
+      "type": "long",
+      "family": "cpc"
+    },
+    { "name": "cpcOfStrings",
+      "k": 14,
+      "type": "string",
+      "family": "cpc"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/example/example_config.json b/src/test/resources/test_config.json
similarity index 64%
rename from example/example_config.json
rename to src/test/resources/test_config.json
index 2c0b24c..a685c17 100644
--- a/example/example_config.json
+++ b/src/test/resources/test_config.json
@@ -1,20 +1,20 @@
 {
-    "port": 8080,
-    "bookstoreSketches": [
-	{ "name": "cpc_int",
+	"port": 0,
+    "sketches_A": [
+	{ "name": "cpcOfNumbers",
 	  "k": 12,
-	  "type": "int",
+	  "type": "long",
 	  "family": "cpc"
 	},
-	{ "name": "cpc_string",
-	  "k": 12,
+	{ "name": "cpcOfStrings",
+	  "k": 14,
 	  "type": "string",
 	  "family": "cpc"
-	}	
+	}
     ],
-    "bookGenreDurationSet": {
+    "set1": {
 	"family": "hll",
-	"type": "double",
+	"type": "string",
 	"k": 14,
 	"names": [
 	    "hll1",
@@ -26,7 +26,7 @@
     "set2": {
 	"k": 12,
 	"family": "theta",
-	"type": "float",
+	"type": "int",
 	"names": [
 	    "theta0",
 	    "theta1",
@@ -36,16 +36,11 @@
 	]
     },
     "sketches_B": [
-	{ "name": "kll",
+	{ "name": "duration",
 	  "k": "160",
 	  "family": "kll"
 	},
-	{ "name": "cpc",
-	  "k": "14",
-	  "type": "string",
-	  "family": "cpc"
-	},
-	{ "name": "fi",
+	{ "name": "topItems",
 	  "k": "128",
 	  "family": "frequency"
 	},
@@ -59,4 +54,3 @@
 	}	
     ]
 }
-