Keep in Mind: It is not a comparison of the databases only. With Oracle we used the WinCC OA RDB Manager with OA Query-RDB Direct option, and the RDB-Manager has lot of more functionalities than the NoSQL Prototyp! The other databases were tested with a NoSQL Logger Prototyp written in Java, and the implementations for writing and reading are different, because there are different interfaces for each database – for PostgreSQL we used the PostgreSQL JDBC driver, MongoDB has it’s own Java API and InfluxDB uses REST/HTTP. So, not only the speed of the database itself is compared – also the interfaces to WinCC OA and the implementations of reading are taken into account.

Oracle and OA RDB-Manager Results:
2016.07.29 09:09:03.302[“start…”]
2016.07.29 09:09:39.628[36.326][33669]
2016.07.29 09:11:22.051[“start…”]
2016.07.29 09:11:36.213[14.159][33669]

MongoDB Results:
2016.07.29 09:10:37.449[“start…”]
2016.07.29 09:10:53.171[15.72][33669]
2016.07.29 09:11:42.932[“start…”]
2016.07.29 09:11:52.918[9.986][33669]

InfluxDB Results:
WCCOAui1:2016.07.29 09:47:33.441[“start…”]
WCCOAui1:2016.07.29 09:47:42.477[9.035][33668]
WCCOAui1:2016.07.29 09:48:12.733[“start…”]
WCCOAui1:2016.07.29 09:48:18.745[6.011][33668]

it is faster than MongoDB. And our InfluxDB is running on a MacMini (Hyper-V) and the data is stored on a shared Synology NAS for home usage (DS414 slim) – much less power for InfluxDB compared to the four 7.2k disks and to the i7 where the Oracle DB and MonogDB is running on.

PostgreSQL Results:
WCCOAui1:2016.07.29 09:56:55.062[“start…”]
WCCOAui1:2016.07.29 09:57:03.475[8.41][33669]
WCCOAui1:2016.07.29 09:57:14.767[“start…”]
WCCOAui1:2016.07.29 09:57:20.196[5.427][33669]

PostgreSQL is running on the same machine and disks as Oracle and MongoDB.

Complex Event Processing (CEP) and event series analysis are used for detecting situations among events. EsperTech provides the Event Processing Language (EPL) designed for concisely expressing situations and fast execution against both historical and currently-arriving events (Espertech.com).

The Esper EPL is quite powerful – details can be found in the Esper documentation. Found also some slides about Esper. The EPL is a CQL (continuous query language), after a statement is created it is running coninously and results are streamed to listeners – in this prototype a listener is sending the results back to WinCC OA datapoints.

A WinCCOA API-Frontend-Manager gathers all value changes from WinCC OA and publishes it by ZeroMQ. The WinCC OA CEP Manager, with the open source Esper-Engine, subscribes to the Frontend-Manager to get the value changes. The advantage is that many subscribers can be connected to the Frontend-Manager, without increasing the load on the WinCC OA system (based on the ideas from CERN).

With the WinCC OA CEP Manager we can define EPL / CQL statements in WinCC OA and the result streams are passed back to WinCC OA on datapoints, where the results can be processed further.

Some simple EPL examples:

Calculate 5 minute average values with intermediate results every 1 minute:

select avg(value), min(value), max(value) 
from event(tag='System1:Meter_Input.Watt').win:time(5 min) 
output snapshot at (*/1, *, *, *, *)

With pattern matching complex event sequences can be observed with EPL. A simple example is: detect if datapoint B is set after datapoint A (A->B), and its value is higher than the value of A.

select a.value, b.value
from pattern [a=Event(tag='System1:Analog1.Input') -> every b=Event(tag='System1:ExampleDP_Trend1.' and b.value>a.value)]

Get a notification when a datapoint is changing more than 100 times within 10 seconds:

select tag, count(value) 
from Event.win:time_batch(10 sec) 
group by tag having count(*) > 100

Get a notification when a datapoint changes and there is no following value change within the next 10 seconds. For example: if meters are normally changing every 5 seconds, possible broken meters/interfaces can be detected with EPL:

select a.tag, count(*) from pattern 
[every a=Event -> (timer:interval(10 sec) and not Event(tag=a.tag))] 
group by a.tag

Other examples can be found here.

Attached is a screenshot of a simple panel where EPL statements can be defined and observed.

Other examples for CEP with Esper: http://www.adrianmilne.com/complex-event-processing-made-easy/

Recently i implemented a JAVA API for WinCC Open Architecture. So, it is possible to implement WinCC OA API Manager in Java. I used this to implement a simple API Manager in Java to connect WinCC OA to MQTT.

MQTT is a machine-to-machine (M2M) “Internet of Things” connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport. It is useful for connections with remote locations where a small code footprint is required and/or network bandwidth is at a premium (http://mqtt.org/).

The example is connected to a WinCC OA datapoint in system 1, sends incoming values through MQTT to HiveMQ (http://www.hivemq.com/try-out/, there is a public available MQTT broker for testing available). Another Java API Manager is subscribed to the MQTT broker, receives the values changes by MQTT and sets it to the WinCC OA system 2…

I have implemented a Database Logger for WinCC OA which supports different databases.

I did now a first test to compare some databases with WinCC OA and time series logging.

The logger is writing 1000 values/second to four databases in parallel: MSSQL Server, InfluxDB, Phoenix (based on Hadoop/HBase) and Oracle.

There are now about 160.000.000 values in each database. About 3.600.000 values are added every hour…

Four Ctrl-Scripts are querying data with dpGetPeriod every 10 seconds, random time frames (between 1 and 2 hours of data).

Oracle seems to be slower (i think this is related to my test environment), but the access and response times are stable with growing amount of data in the database.

remark: at 10pm the Oracle DB backup starts.