Moved module under geomesa-kafka

docs/user/kafka/spring_stream_binder.rst

@@ -0,0 +1,191 @@
+Spring Cloud Stream Geomesa Kafka Datastore Binder
+==================================================
+
+The Spring Cloud Stream Geomesa Kafka Datastore Binder provides an easy way for Spring Cloud Stream apps to hook into
+Geomesa Kafka Datastore to process events.
+
+If you are unfamiliar with Spring Cloud Stream, see the official documentation for an introduction:
+https://spring.io/projects/spring-cloud-stream
+
+Input/Output Types
+------------
+
+This binder will provide all ``KafkaFeatureEvent`` s from kafka datastore to your configured function definitions. Each
+function will have to do it's own type comparison to see if the event is a ``KafkaFeatureEvent.KafkaFeatureChanged``,
+``KafkaFeatureEvent.KafkaFeatureRemoved``, or another event type.
+
+The module also ships with a SimpleFeature converter, which allows you to configure function definitions that consume
+or produces ``SimpleFeature`` s and avoid working with ``KafkaFeatureEvent`` s directly.
+
+.. note::
+
+    The SimpleFeature converter extracts the SimpleFeature out of ``KafkaFeatureEvent.KafkaFeatureChanged`` events and
+    ignores all others. Any function definition that consumes SimpleFeatures will miss the
+    ``KafkaFeatureEvent.KafkaFeatureRemoved`` and ``KafkaFeatureEvent.KafkaFeatureCleared`` messages. And any function
+    definition that only writes SimpleFeatures will not be able to send those messages.
+
+Configuration
+-------------
+
+The configuration options are under spring.cloud.stream.kafka-datastore.binder. This binder will accept any
+configuration options for the standard java geomesa kafka-datastore, with the periods ('.') replaced with dashes ('-').
+For example, to specify kafka.catalog.topic for the binder, set:
+
+.. code-block:: yaml
+
+    spring:
+      cloud:
+        stream:
+          kafka-datastore:
+            binder:
+              kafka-catalog-topic: geomesa-catalog-topic
+
+For a full list of configuration options, see: https://www.geomesa.org/documentation/stable/user/kafka/usage.html
+
+Examples
+--------
+
+Simple Logger App
+-----------------
+
+.. code-block:: java
+
+    @Bean
+    public Consumer<KafkaFeatureEvent> log() {
+        return obj -> logger.info(obj.toString());
+    }
+
+.. code-block:: yaml
+
+    spring:
+      cloud:
+        function:
+          definition: log
+        stream:
+          kafka-datastore.binder:
+                kafka-brokers: kafka:9092
+                kafka-zookeepers: zookeeper:2181
+          function.bindings:
+            log-in-0: input
+          bindings:
+            input:
+              destination: messages
+              group: logger
+
+Simple Enricher App
+-------------------
+
+.. code-block:: java
+
+    @Bean
+    public Function<SimpleFeature, SimpleFeature> attachSourceField() {
+        return sf -> {
+            sf.setAttribute("source", "un-labelled source");
+            return sf;
+        };
+    }
+
+.. code-block:: yaml
+
+    spring:
+      cloud:
+        function:
+          definition: attachSourceField
+        stream:
+          kafka-datastore.binder:
+              kafka-brokers: kafka:9092
+              kafka-zookeepers: zookeeper:2181
+          function.bindings:
+            attachSourceField-in-0: input
+            attachSourceField-out-0: output
+          bindings:
+            input:
+              destination: un-labelled-source-ob
+              group: sft-reader
+            output:
+              destination: observations
+              group: sft-writer
+
+Simple Filter App
+-------------------
+
+.. code-block:: java
+
+    @Bean
+    public Function<SimpleFeature, SimpleFeature> excludeMoving() {
+        return sf -> {
+            if (sf.getAttribute("status").equals("IN_TRANSIT")) {
+                return null;
+            }
+            return sf;
+        };
+    }
+
+
+.. code-block:: yaml
+
+    spring:
+      cloud:
+        function:
+          definition: filterMoving
+        stream:
+          kafka-datastore.binder:
+              kafka-brokers: kafka:9092
+              kafka-zookeepers: zookeeper:2181
+          function.bindings:
+            filterMoving-in-0: input
+            filterMoving-out-0: output
+          bindings:
+            input:
+              destination: movingAndUnmovingThings
+              group: sft-reader
+            output:
+              destination: unMovingThings
+              group: sft-writer
+
+Multiple Datastore App
+----------------------
+
+In the case of multi-bindings, you simply need to submit override the proper kafka-datastore fields in the environment
+field.
+
+.. code-block:: java
+
+    @Bean
+    public Function<KafkaFeatureEvent, KafkaFeatureEvent> passThrough() {
+        return event -> event;
+    }
+
+.. code-block:: yaml
+
+    spring:
+      cloud:
+        function:
+          definition: passThrough
+        stream:
+          kafka-datastore.binder:
+              kafka-brokers: kafka:9092
+              kafka-zookeepers: zookeeper:2181
+          function.bindings:
+            passThrough-in-0: input
+            passThrough-out-0: output
+          binders:
+            kds-start:
+              type: kafka-datastore
+              environment:
+                spring.cloud.stream.kafka-datastore.binder:
+                    kafka-zk-path: geomesa/start
+            kds-end:
+              type: kafka-datastore
+              environment:
+                spring.cloud.stream.kafka-datastore.binder:
+                    kafka-zk-path: geomesa/end
+          bindings:
+            input:
+              destination: observations
+              group: sft-reader
+              binder: kds-start
+            output:
+              destination: observations
+              group: sft-writer
+              binder: kds-end