[SPARK-16114][SQL] structured streaming network word count examples

## What changes were proposed in this pull request?

Network word count example for structured streaming

## How was this patch tested?

Run locally

Author: James Thomas <jamesjoethomas@gmail.com>
Author: James Thomas <jamesthomas@Jamess-MacBook-Pro.local>

Closes #13816 from jjthomas/master.

1 files changed, 76 insertions, 0 deletions

diff --git a/examples/src/main/python/sql/streaming/structured_network_wordcount.py b/examples/src/main/python/sql/streaming/structured_network_wordcount.py
new file mode 100644
index 0000000000..32d63c52c9
--- /dev/null
+++ b/examples/src/main/python/sql/streaming/structured_network_wordcount.py
@@ -0,0 +1,76 @@
+#
+# 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.
+#
+
+"""
+ Counts words in UTF8 encoded, '\n' delimited text received from the network every second.
+ Usage: structured_network_wordcount.py <hostname> <port>
+   <hostname> and <port> describe the TCP server that Structured Streaming
+   would connect to receive data.
+
+ To run this on your local machine, you need to first run a Netcat server
+    `$ nc -lk 9999`
+ and then run the example
+    `$ bin/spark-submit examples/src/main/python/sql/streaming/structured_network_wordcount.py
+    localhost 9999`
+"""
+from __future__ import print_function
+
+import sys
+
+from pyspark.sql import SparkSession
+from pyspark.sql.functions import explode
+from pyspark.sql.functions import split
+
+if __name__ == "__main__":
+    if len(sys.argv) != 3:
+        print("Usage: structured_network_wordcount.py <hostname> <port>", file=sys.stderr)
+        exit(-1)
+
+    host = sys.argv[1]
+    port = int(sys.argv[2])
+
+    spark = SparkSession\
+        .builder\
+        .appName("StructuredNetworkWordCount")\
+        .getOrCreate()
+
+    # Create DataFrame representing the stream of input lines from connection to host:port
+    lines = spark\
+        .readStream\
+        .format('socket')\
+        .option('host', host)\
+        .option('port', port)\
+        .load()
+
+    # Split the lines into words
+    words = lines.select(
+        explode(
+            split(lines.value, ' ')
+        ).alias('word')
+    )
+
+    # Generate running word count
+    wordCounts = words.groupBy('word').count()
+
+    # Start running the query that prints the running counts to the console
+    query = wordCounts\
+        .writeStream\
+        .outputMode('complete')\
+        .format('console')\
+        .start()
+
+    query.awaitTermination()