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README.md
This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments
OPC Publisher for Azure IoT Edge
This reference implementation demonstrates how Azure IoT Edge can be used to connect to existing OPC UA servers and publishes JSON encoded telemetry data from these servers in OPC UA "Pub/Sub" format (using a JSON payload) to Azure IoT Hub. All transport protocols supported by Azure IoT Edge can be used, i.e. HTTPS, AMQP and MQTT (the default).
This application, apart from including an OPC UA client for connecting to existing OPC UA servers you have on your network, also includes an OPC UA server on port 62222 that can be used to manage what gets published.
The application is implemented using .NET Core technology and is able to run on the platforms supported by .NET Core.
Publisher implements a retry logic to establish connections to endpoints which have not responded to a certain number of keep alive requests, for example if the OPC UA server on this endpoint had a power outage.
For each distinct publishing interval to an OPC UA server it creates a separate subscription over which all nodes with this publishing interval are updated.
Publisher supports batching of the data sent to IoTHub, to reduce network load. This batching is sending a packet to IoTHub only if the configured package size is reached.
This application uses the OPC Foundations's OPC UA reference stack and therefore licensing restrictions apply. Visit http://opcfoundation.github.io/UA-.NETStandardLibrary/ for OPC UA documentation and licensing terms.
| Branch | Status |
|---|---|
| master |  |
Building the Application
The application requires the .NET Core SDK 2.0.
As native Windows application
Open the OpcPublisher.sln project with Visual Studio 2017 and build the solution by hitting F7.
As Docker container
Depending if you use Docker Linux or Docker Windows containers, there are different configuration files (Dockerfile or Dockerfile.Windows) to use for building the container. From the root of the repository, in a console, type:
docker build -f <docker-configfile-to-use> -t <your-container-name> .
The -f option for docker build is optional and the default is to use Dockerfile. Docker also support building directly from a git repository, which means you also can build a Linux container by:
docker build -t <your-container-name> https://github.com/Azure/iot-edge-opc-publisher
Configuring the OPC UA nodes to publish
The OPC UA nodes whose values should be published to Azure IoT Hub can be configured by creating a JSON formatted configuration file (defaultname: "publishednodes.json"). This file is updated and persisted by the application, when using it's OPC UA server methods "PublishNode" or "UnpublishNode".
The syntax of the configuration file is as follows:
[
{
// example for an EnpointUrl is: opc.tcp://win10iot:51210/UA/SampleServer
"EndpointUrl": "opc.tcp://<your_opcua_server>:<your_opcua_server_port>/<your_opcua_server_path>",
"OpcNodes": [
// Publisher will request the server at EndpointUrl to sample the node with the OPC sampling interval specified on command line (or the default value: OPC publishing interval)
// and the subscription will publish the node value with the OPC publishing interval specified on command line (or the default value: server revised publishing interval).
{
// The identifier specifies the NamespaceUri and the node identifier in XML notation as specified in Part 6 of the OPC UA specification in the XML Mapping section.
"ExpandedNodeId": "nsu=http://opcfoundation.org/UA/;i=2258"
},
// Publisher will request the server at EndpointUrl to sample the node with the OPC sampling interval specified on command line (or the default value: OPC publishing interval)
// and the subscription will publish the node value with an OPC publishing interval of 4 seconds.
// Publisher will use for each dinstinct publishing interval (of nodes on the same EndpointUrl) a separate subscription. All nodes without a publishing interval setting,
// will be on the same subscription and the OPC UA stack will publish with the lowest sampling interval of a node.
{
"ExpandedNodeId": "nsu=http://opcfoundation.org/UA/;i=2258",
"OpcPublishingInterval": 4000
},
// Publisher will request the server at EndpointUrl to sample the node with the given sampling interval of 1 second
// and the subscription will publish the node value with the OPC publishing interval specified on command line (or the default value: server revised interval).
// If the OPC publishing interval is set to a lower value, Publisher will adjust the OPC publishing interval of the subscription to the OPC sampling interval value.
{
"ExpandedNodeId": "nsu=http://opcfoundation.org/UA/;i=2258",
// the OPC sampling interval to use for this node.
"OpcSamplingInterval": 1000
}
]
},
// the format below (NodeId format) is only supported for backward compatibility. you need to ensure that the
// OPC UA server on the configured EndpointUrl has the namespaceindex you expect with your configuration.
// please use the ExpandedNodeId format as in the examples above instead.
{
"EndpointUrl": "opc.tcp://<your_opcua_server>:<your_opcua_server_port>/<your_opcua_server_path>",
"NodeId": {
"Identifier": "ns=0;i=2258"
}
}
// please consult the OPC UA specification for details on how OPC monitored node sampling interval and OPC subscription publishing interval settings are handled by the OPC UA stack.
// the publishing interval of the data to Azure IoTHub is controlled by the command line settings (or the default: publish data to IoTHub at least each 1 second).
]
Running the Application
Command line options
The complete usage of the application can be shown using the --help command line option and is as follows:
Usage: OpcPublisher.exe <applicationname> [<iothubconnectionstring>] [<options>]
OPC Edge Publisher to subscribe to configured OPC UA servers and send telemetry to Azure IoTHub.
To exit the application, just press ENTER while it is running.
applicationname: the OPC UA application name to use, required
The application name is also used to register the publisher under this name in the
IoTHub device registry.
iothubconnectionstring: the IoTHub owner connectionstring, optional
There are a couple of environment variables which can be used to control the application:
_HUB_CS: sets the IoTHub owner connectionstring
_GW_LOGP: sets the filename of the log file to use
_TPC_SP: sets the path to store certificates of trusted stations
_GW_PNFP: sets the filename of the publishing configuration file
Command line arguments overrule environment variable settings.
Options:
--pf, --publishfile=VALUE
the filename to configure the nodes to publish.
Default: 'D:\Repos\hg\iot-edge-opc-publisher\src\
publishednodes.json'
--sd, --shopfloordomain=VALUE
the domain of the shopfloor. if specified this
domain is appended (delimited by a ':' to the '
ApplicationURI' property when telemetry is sent
to IoTHub.
The value must follow the syntactical rules of a
DNS hostname.
Default: not set
--sw, --sessionconnectwait=VALUE
specify the wait time in seconds publisher is
trying to connect to disconnected endpoints and
starts monitoring unmonitored items
Min: 10
Default: 10
--mq, --monitoreditemqueuecapacity=VALUE
specify how many notifications of monitored items
could be stored in the internal queue, if the
data could not be sent quick enough to IoTHub
Min: 1024
Default: 8192
--di, --diagnosticsinterval=VALUE
shows publisher diagnostic info at the specified
interval in seconds. 0 disables diagnostic
output.
Default: 0
--vc, --verboseconsole=VALUE
the output of publisher is shown on the console.
Default: False
--ih, --iothubprotocol=VALUE
the protocol to use for communication with Azure
IoTHub (allowed values: Amqp, Http1, Amqp_
WebSocket_Only, Amqp_Tcp_Only, Mqtt, Mqtt_
WebSocket_Only, Mqtt_Tcp_Only).
Default: Mqtt
--ms, --iothubmessagesize=VALUE
the max size of a message which can be send to
IoTHub. when telemetry of this size is available
it will be sent.
0 will enforce immediate send when telemetry is
available
Min: 0
Max: 262144
Default: 4096
--si, --iothubsendinterval=VALUE
the interval in seconds when telemetry should be
send to IoTHub. If 0, then only the
iothubmessagesize parameter controls when
telemetry is sent.
Default: '1'
--lf, --logfile=VALUE the filename of the logfile to use.
Default: './Logs/<applicationname>.log.txt'
--pn, --portnum=VALUE the server port of the publisher OPC server
endpoint.
Default: 62222
--pa, --path=VALUE the enpoint URL path part of the publisher OPC
server endpoint.
Default: '/UA/Publisher'
--lr, --ldsreginterval=VALUE
the LDS(-ME) registration interval in ms. If 0,
then the registration is disabled.
Default: 0
--ot, --operationtimeout=VALUE
the operation timeout of the publisher OPC UA
client in ms.
Default: 120000
--oi, --opcsamplinginterval=VALUE
the publisher is using this as default value in
milliseconds to request the servers to sample
the nodes with this interval
this value might be revised by the OPC UA
servers to a supported sampling interval.
please check the OPC UA specification for
details how this is handled by the OPC UA stack.
a negative value will set the sampling interval
to the publishing interval of the subscription
this node is on.
0 will configure the OPC UA server to sample in
the highest possible resolution and should be
taken with care.
Default: 1000
--op, --opcpublishinginterval=VALUE
the publisher is using this as default value in
milliseconds for the publishing interval setting
of the subscriptions established to the OPC UA
servers.
please check the OPC UA specification for
details how this is handled by the OPC UA stack.
a value less than or equal zero will let the
server revise the publishing interval.
Default: 0
--ct, --createsessiontimeout=VALUE
specify the timeout in seconds used when creating
a session to an endpoint. On unsuccessful
connection attemps a backoff up to 5 times the
specified timeout value is used.
Min: 1
Default: 10
--ki, --keepaliveinterval=VALUE
specify the interval in seconds the publisher is
sending keep alive messages to the OPC servers
on the endpoints it is connected to.
Min: 2
Default: 2
--kt, --keepalivethreshold=VALUE
specify the number of keep alive packets a server
can miss, before the session is disconneced
Min: 1
Default: 5
--st, --opcstacktracemask=VALUE
the trace mask for the OPC stack. See github OPC .
NET stack for definitions.
To enable IoTHub telemetry tracing set it to 711.
Default: 285 (645)
--as, --autotrustservercerts=VALUE
the publisher trusts all servers it is
establishing a connection to.
Default: False
--tm, --trustmyself=VALUE
the publisher certificate is put into the trusted
certificate store automatically.
Default: True
--fd, --fetchdisplayname=VALUE
enable to read the display name of a published
node from the server. this will increase the
runtime.
Default: False
--at, --appcertstoretype=VALUE
the own application cert store type.
(allowed values: Directory, X509Store)
Default: 'X509Store'
--ap, --appcertstorepath=VALUE
the path where the own application cert should be
stored
Default (depends on store type):
X509Store: 'CurrentUser\UA_MachineDefault'
Directory: 'CertificateStores/own'
--tt, --trustedcertstoretype=VALUE
the trusted cert store type.
(allowed values: Directory, X509Store)
Default: Directory
--tp, --trustedcertstorepath=VALUE
the path of the trusted cert store
Default (depends on store type):
X509Store: 'CurrentUser\UA_MachineDefault'
Directory: 'CertificateStores/trusted'
--rt, --rejectedcertstoretype=VALUE
the rejected cert store type.
(allowed values: Directory, X509Store)
Default: Directory
--rp, --rejectedcertstorepath=VALUE
the path of the rejected cert store
Default (depends on store type):
X509Store: 'CurrentUser\UA_MachineDefault'
Directory: 'CertificateStores/rejected'
--it, --issuercertstoretype=VALUE
the trusted issuer cert store type.
(allowed values: Directory, X509Store)
Default: Directory
--ip, --issuercertstorepath=VALUE
the path of the trusted issuer cert store
Default (depends on store type):
X509Store: 'CurrentUser\UA_MachineDefault'
Directory: 'CertificateStores/issuers'
--dt, --devicecertstoretype=VALUE
the iothub device cert store type.
(allowed values: Directory, X509Store)
Default: X509Store
--dp, --devicecertstorepath=VALUE
the path of the iot device cert store
Default Default (depends on store type):
X509Store: 'My'
Directory: 'CertificateStores/IoTHub'
-h, --help show this message and exit
There are a couple of environment variables which can be used to control the application:
- _HUB_CS: sets the IoTHub owner connectionstring
- _GW_LOGP: sets the filename of the log file to use
- _TPC_SP: sets the path to store certificates of trusted stations
- _GW_PNFP: sets the filename of the publishing configuration file
Command line arguments overrule environment variable settings.
Typically you specify the IoTHub owner connectionstring only on the first start of the application. The connectionstring will be encrypted and stored in the platforms certificiate store. On subsequent calls it will be read from there and reused. If you specify the connectionstring on each start, the device which is created for the application in the IoTHub device registry will be removed and recreated each time.
Native on Windows
Open the OpcPublisher.sln project with Visual Studio 2017, build the solution and publish it. You can start the application in the 'Target directory' you have published to with:
dotnet OpcPublisher.dll <applicationname> [<iothubconnectionstring>] [options]
Using a self-built container
Build your own container and then start the container:
docker run <your-container-name> <applicationname> [<iothubconnectionstring>] [options]
Using a container from hub.docker.com
There is a prebuilt container available on DockerHub. To start it, just do:
docker run microsoft/iot-edge-opc-publisher <applicationname> [<iothubconnectionstring>] [options]
Important when using a container
Access to the Publisher OPC UA server
The Publisher OPC UA server listens by default on port 62222. To expose this inbound port in a container, you need to use docker run option -p:
docker run -p 62222:62222 microsoft/iot-edge-opc-publisher <applicationname> [<iothubconnectionstring>] [options]
Enable intercontainer nameresolution
To enable name resolution from within the container to other containers, you need to create a user define docker bridge network and connect the container to this network using the --network option.
Additionally you need to assign the container a name using the --name option as in this example:
docker network create -d bridge iot_edge
docker run --network iot_edge --name publisher microsoft/iot-edge-opc-publisher <applicationname> [<iothubconnectionstring>] [options]
The container can now be reached by other containers via the name publisherover the network.
Access other hosts from within the container
Hosts which are implemented in other containers, could be reached with the parameters described in the "Enable intercontainer nameresolution" paragraph.
If the environment has DNS working, then accessing the host on which the docker runtime executes as was as any other DNS reachable host is no issue.
Problems occur in a network with Windows NetBIOS name resolution. To enable access to hosts (including the one on which the docker runtime executes) you need to start your container using the --add-host option.
docker run --add-host mydevbox:192.168.178.23 microsoft/iot-edge-opc-publisher <applicationname> [<iothubconnectionstring>] [options]
Assigning a hostname
Publisher uses the hostname of the machine is running on for certificate and endpoint generation. docker chooses a random hostname if there is none set by the -h option. Here an example to set the internal hostname of the container to publisher:
docker run -h publisher microsoft/iot-edge-opc-publisher <applicationname> [<iothubconnectionstring>] [options]
Using bind mounts (shared filesystem)
In certain use cases it may make sense to read configuration information from or write log files to locations on the host and not keep them in the container file system only. To achieve this you need to use the -v option of docker run in the bind mount mode.
Store for X509 certificates
Storing X509 certificates does not work with bind mounts, since the permissions of the path to the store need to be rw for the owner. Instead you need to use the -v option of docker run in the volume mode.
Performance and memory considerations
Commandline parameters contolling performance and memory
When running Publisher you need to be aware of your performance requirements and the memory resources you have available on your platform. Since both are interdependent and both depend on the configuration of how many nodes are configured to publish, you should ensure that the parameters you are using for:
- IoTHub send interval (
--si) - IoTHub message size (
--ms) - Monitored Items queue capacity (
--mq) do meet your requirements.
The --mq parameter controls the upper bound of the capacity of the internal queue, which buffers all notifications if a value of an OPC node changes. If Publisher is not able to send messages to IoTHub fast enough,
then this queue buffers those notifications. The parameter sets the number of notifications which could be buffered. If you seen the number of items in this queue increasing in your test runs, you need to:
- decrease the IoTHub send interval (
--si) - increase the IoTHub message size (
--ms) otherwise you will loose the data values of those OPC node changes. The--mqparameter at the same time allows to prevent controlling the upper bound of the memory resources used by Publisher.
The --si parameter enforces Publisher to send messages to IoTHub as the specified interval. If there is an IoTHub message size specified via the --ms parameter (or by the default value for it),
then a message will be sent either when the message size is reached (in this case the interval is restarted) or when the specified interval time has passed. If you disable the message size by --ms 0, Publisher
uses the maximal possible IoTHub message size of 256 kB to batch data.
The --ms parameter allows you to enable batching of messages sent to IoTHub. Depending on the protocol you are using, the overhead to send a message to IoTHub is high compared to the actual time of sending the payload.
If your scenario allows latency for the data ingested, you should configure Publisher to use the maximal message size of 256 kB.
Before you use Publisher in production scenarios, you need to test the performance and memory under production conditions. You could use the --di commandline parameter to specify a interval in seconds,
which will trigger the output of diagnostic information at this interval.
Test measurements
Here are some measurements with different values for --si and --ms parameters publishing 497 nodes with an OPC publishing interval of 1 second.
Publisher was used as debug build on Windows 10 natively for 120 seconds. The IoTHub protocol was configured to use HTTP (--ih Http1).
Default configuration (--si 1 --ms 4096)
======================================================================
OpcPublisher status @ 25.10.2017 11:08:25
---------------------------------
OPC sessions: 1
connected OPC sessions: 1
connected OPC subscriptions: 1
OPC monitored items: 497
---------------------------------
monitored items queue bounded capacity: 8192
monitored items queue current items: 8107
monitored item notifications enqueued: 57076
monitored item notifications enqueue failure: 28551
monitored item notifications dequeued: 20418
---------------------------------
messages sent to IoTHub: 1200
bytes sent to IoTHub: 4772773
avg msg size: 3977
time in ms for sent msgs: 113744
min time in ms for msg: 84
max time in ms for msg: 441
avg time in ms for msg: 94
msg send failures: 0
time in ms for failed msgs: 0
avg time in ms for failed msg: 0
messages too large to sent to IoTHub: 0
times we missed send interval: 0
---------------------------------
current working set in MB: 90
======================================================================
The default configuration sends data to IoTHub each second or when 4kB of data to ingest is available. In this configuration we loose 28551 OPC node value updates (monitored item notifications enqueue failure).
Constant send inverval (--si 1 --ms 0)
======================================================================
OpcPublisher status @ 25.10.2017 11:18:20
---------------------------------
OPC sessions: 1
connected OPC sessions: 1
connected OPC subscriptions: 1
OPC monitored items: 497
---------------------------------
monitored items queue bounded capacity: 8192
monitored items queue current items: 0
monitored item notifications enqueued: 56682
monitored item notifications enqueue failure: 0
monitored item notifications dequeued: 56682
---------------------------------
messages sent to IoTHub: 114
bytes sent to IoTHub: 13130523
avg msg size: 115180
time in ms for sent msgs: 14454
min time in ms for msg: 100
max time in ms for msg: 705
avg time in ms for msg: 126
msg send failures: 0
time in ms for failed msgs: 0
avg time in ms for failed msg: 0
messages too large to sent to IoTHub: 0
times we missed send interval: 0
---------------------------------
current working set in MB: 87
======================================================================
When the message size is set to 0 and there is a send interval configured (or the default of 1 second is used), then Publisher does use internally batch data using the maximal supported IoTHub message size, which is 256 kB. As you see in the diagnostic output,
the average message size is 115180 byte. In this configuration we do not loose any OPC node value udpates. The average time to send a message to IoTHub (avg time in ms for msg) was only 22ms higher than in the
default configuration, which has a average message size of 3877 byte.
Send each OPC node value update (--si 0 --ms 0)
======================================================================
OpcPublisher status @ 25.10.2017 10:08:03
---------------------------------
OPC sessions: 1
connected OPC sessions: 1
connected OPC subscriptions: 1
OPC monitored items: 497
---------------------------------
monitored items queue bounded capacity: 8192
monitored items queue current items: 8192
monitored item notifications enqueued: 57323
monitored item notifications enqueue failure: 48116
monitored item notifications dequeued: 1015
---------------------------------
messages sent to IoTHub: 1014
bytes sent to IoTHub: 237292
avg msg size: 234
time in ms for sent msgs: 114268
min time in ms for msg: 84
max time in ms for msg: 330
avg time in ms for msg: 112
msg send failures: 0
time in ms for failed msgs: 0
avg time in ms for failed msg: 0
messages too large to sent to IoTHub: 0
times we missed send interval: 0
---------------------------------
current working set in MB: 92
======================================================================
This configuration sends for each OPC node value change a message to IoTHub. You see the average message size of 234 byte is pretty small and the average time required to send such a message was
112 ms - which is compared to larger message sizes - a high value. The advantage of this configuration is that Publisher does not add any latency to the ingest data path. The number of
lost OPC node value updates (monitored item notifications enqueue failure: 48116) is the highest of all compared configurations.
Maximum batching (--si 0 --ms 262144)
======================================================================
OpcPublisher status @ 25.10.2017 10:05:23
---------------------------------
OPC sessions: 1
connected OPC sessions: 1
connected OPC subscriptions: 1
OPC monitored items: 497
---------------------------------
monitored items queue bounded capacity: 8192
monitored items queue current items: 0
monitored item notifications enqueued: 57086
monitored item notifications enqueue failure: 0
monitored item notifications dequeued: 57086
---------------------------------
messages sent to IoTHub: 50
bytes sent to IoTHub: 13096746
avg msg size: 261934
time in ms for sent msgs: 8648
min time in ms for msg: 136
max time in ms for msg: 596
avg time in ms for msg: 172
msg send failures: 0
time in ms for failed msgs: 0
avg time in ms for failed msg: 0
messages too large to sent to IoTHub: 0
times we missed send interval: 0
---------------------------------
current working set in MB: 89
======================================================================
This configuration batches as much OPC node value udpates as possible. The maximum IoTHub message size is 256 kB, which is configured here. There is no send interval requested, which makes the time when data is ingested completly controlled by the data itself. This configuration has the least probability of loosing any OPC node values and could be used for publishing a high number of nodes. When using this configuration you need to ensure, that your scenario does not have conditions where high latency is introduced (because the message size of 256 kB is not reached).
Debugging the Application
Native on Winodws
Open the OpcPublisher.sln project with Visual Studio 2017 and start debugging the app by hitting F5.
If you need to access the OPC UA server in the publisher, you should ensure that the firewall setting allow access to the port the server is listening on (default: 62222).
In a docker container
Visual Studio 2017 supports debugging of application in docker container. This is done by using docker-compose. Since this does not allow to pass command line parameters it is not convenient.
Another debugging option VS2017 supports is to debug via ssh. In the root of the repository the docker build configuration file Dockerfile.ssh can be used to create a SSH enabled container by:
docker build -f .\Dockerfile.ssh -t publisherssh .
The container can now be started for publisher debugging purposes with:
docker run -it publisherssh
In the container you need to manually start the ssh daemon with:
service ssh start
At this point you should be able to create an ssh session as user root with the password Passw0rd.
To prepare debugging of the application in the container you need to do the following additional steps:
On the host side create a launch.json:
{
"version": "0.2.0",
"adapter": "<path>\\plink.exe",
"adapterArgs": "root@localhost -pw Passw0rd -batch -T ~/vsdbg/vsdbg --interpreter=vscode",
"languageMappings": {
"C#": {
"languageId": "3F5162F8-07C6-11D3-9053-00C04FA302A1",
"extensions": [ "*" ]
}
},
"exceptionCategoryMappings": {
"CLR": "449EC4CC-30D2-4032-9256-EE18EB41B62B",
"MDA": "6ECE07A9-0EDE-45C4-8296-818D8FC401D4"
},
"configurations": [
{
"name": ".NET Core Launch",
"type": "coreclr",
"cwd": "~/publisher",
"program": "Opc.Ua.Publisher.dll",
"args": "<put-the-publisher-command-line-options-here>",
"request": "launch"
}
]
}
Build your project and publish it to a directory of your choice.
Use a tool like WinSCP to copy over the published files to the container into the directory /root/publisher (this can be also a different directory, but needs to be in sync with the cdw property of launch.json.
Now you could start debugging with the following command in Visual Studio's Command Window (View->Other Windows->Command Window): DebugAdapterHost.Launch /LaunchJson:"<path-to-the-launch.json-file-you-saved>"