Make Spark Serving Easier to Use

[mhamilton723]

• Add option to fail when it cannot parse the input
• Add tests on ADB
• Add syntactic sugars for adding input parsers
• Add ability to reply with other types
• Fix offsets commited out of order exception

Repro:

import mmlspark
from pyspark.sql.functions import length, col, lit, from_json
from pyspark.sql.types import *

df = spark.readStream.server() \
    .address("localhost", 8888, "my_api") \
    .load()

server = df.withColumn("reply", length(col("value"))) \
    .withColumn("replyString", col("reply").cast(StringType()))\
    .writeStream \
    .server() \
    .option("name", "my_api") \
    .queryName("my_query") \
    .option("replyCol", "replyString") \
    .option("checkpointLocation", "checkpoints") \
    .start()


import requests

r = requests.post(data="{foo:1}", url="http://localhost:8888/my_api")
print(r.text)