Purpose

This standalone and runnable Spring Boot application is an implementation of the OSIP specification that communicates with the subsystems, like a PLC or a Raspberry Pi, using the OSIP TCP/IP message format. This kind of subsystems lack of resources and do not provide a higher level protocol on top of TCP/IP. The implementation is aware of multiple tenants (e.g. projects) and may run in the cloud with different port settings. Note: Instantiating multiple instances of the driver component with same port settings is not possible. Each instance must have its own configuration, in particular its own TCP/IP port settings. A project (tenant) may have multiple drivers deployed, all running on different ports.

Resources

Find further documentation in the Wiki

Operation Modes

A driver instance can be started in different operation modes: Simplex or Duplex communication with either Client or Server connection mode. All four can be arbitrary combined.

Simplex Communication

Simplex communication means a client application connecting to the driver uses one socket for inbound communication and another socket for the outbound. So sending and receiving messages is handled through separated and dedicated socket connections.

With the simplex communication mode the inbound communication is configured differently as the outbound communication. This way the driver creates two separate ConnectionFactories, one for inbound and one for outbound. Each socket can be configured either in Client or Server mode. A Client configured Socket tries to connect to a listening server whereas configured as Server the driver opens a socket itself and listens for incoming connections.

A typical simplex configuration looks like:

owms:
  driver:
    connections:
      hostname: 0.0.0.0
      subsystems:
        - name: SPS01
          inbound:
            mode: server
            port: 30001
            so-receive-buffer-size: 200
          outbound:
            mode: client
            port: 30002
            so-send-buffer-size: 200
            identified-by-field: "RECV"
            identified-by-value: "SPS01"

Each communication direction is configured with a different port setting and with mode set to server and client. To correlate outbound messages with previously received ones, the identified-by-* fields are used.

Duplex Communication

In contrast to simplex connections the driver instance can also be configured for bidirectional duplex mode where only one socket is used for inbound and outbound communication. Instead of configuring inbound or outbound only one duplex configuration must be present.

owms:
  driver:
    connections:
      subsystems:
        - name: SPS03
          duplex:
            mode: server
            hostname: localhost
            port: 30003
            so-send-buffer-size: 200
            so-receive-buffer-size: 200
            identified-by-field: "RECV"
            identified-by-value: "SPS03"

Architecture

The module uses a couple of the well known Enterprise Integration Patterns (EIP), like a Router, Transformer or an Enricher. For that reason Spring Integration is used as integration framework. In addition this is a very convenient and flexible way to adopt new transport channels beside TCP/IP.

The overall integration architecture is shown below. The entry point is the inboundAdapter that is connected to a TcpNetServerConnectionFactory (not shown) and forwards incoming telegrams to the inboundChannel. A first transformer (telegramTransformer) terminates the ASCII string and converts into a Spring Message. This is done with support of the appropriate MessageMapper that must exist for each telegram type. For instance the TimesyncTelegramMapper knows best how to transform a String into a TimesyncRequest. After the telegram is transformed into a valid message type the generic messageRouter picks up the right queue and activates the proper ServiceActivator. Notice that the service activators queue name is built on the fly and follows a naming convention. This is one aspect to support requirements NR003.

Deployment

The TCP/IP driver can run completely independent of cloud infrastructure services. This could be the appropriate deployment model during development or for small projects where no central infrastructure services are required. In a larger project setup with lots of subsystems and where the driver component is instantiated multiple times it makes sense to keep configuration on a central config server, this is where OpenWMS.org Configuration comes into play.

Standalone Deployment

As said all required configuration must be passed at startup time because no infrastructure services are required to access. Without any configuration the driver is started with the provided default configuration that is suitable for one driver instance:

owms:
  driver:
    server:
      port: 30001

In case you want to override the port number on startup just set the environment variable accordingly. In the following example 2 drivers are started, with different ports.

$ java -Dowms.driver.server.port=30001 -jar tcpip-driver-exec.jar
$ java -Dowms.driver.server.port=30002 -jar tcpip-driver-exec.jar

Afterwards simply send a OSIP SYNQ telegram to driver with port 30001 to get a response telegram:

$ telnet localhost 30001
Trying ::1...
Connected to localhost.
Escape character is '^]'.
###00160SPS01MFC__00001SYNQ20171123225959***********************************************************************************************************************
###00160MFC__SPS0100002SYNC20180927152848***********************************************************************************************************************

The first telegram string (SYNQ) is sent to the driver, whereas the driver responds with a SYNC telegram to synchronize the current system time.

Distributed Deployment

In case of multiple driver components and lots of microservices it makes sense to keep service configuration at a central place and the OpenWMS.org Configuration server is the right choice. This infrastructure service takes the configuration of each process from a configured Git repository and passes it down to the processes at process startup. By using a configuration sever it is also possible to change configuration at runtime without the need to restart processes. Configuration is pushed down into the microservices and the service configuration is refreshed dynamically.

To run the driver component in a distributed fashion, the Spring profile "DISTRIBUTED" must be enabled. It's also a good practice to provide unique application names, at least when the driver is instantiated multiple times:

$ java -Dspring.profiles.active=DISTRIBUTED -Dspring.application.name=tcpip-palett1 -jar tcpip-driver-exec.jar
$ java -Dspring.profiles.active=DISTRIBUTED -Dspring.application.name=tcpip-palett2 -jar tcpip-driver-exec.jar

Each driver is now starting up and looking for a configuration server. The application name is used to load the appropriate driver configuration from. For example the Git repository KARL includes YAML configuration files for all processes used in KARL project, same is true for tcpip-palett1.yml and tcpip-palett2.yml.

tcpip-palett1.yml

owms:
  tenant: KARL
  driver:
    server:
      port: 30001
      so-timeout: 300000
      so-receive-buffer-size: 160
      so-send-buffer-size: 160
      routing-service-name: routing-service # is default

tcpip-palett2.yml

owms:
  tenant: KARL
  driver:
    server:
      port: 30002
      so-timeout: 300000
      so-receive-buffer-size: 160
      so-send-buffer-size: 160
      routing-service-name: routing-service # is default

Communication Protocols

The way how the driver communicates to other OpenWMS.org microservices can be defined by setting a Spring profile. In ASYNCHRONOUS mode the driver uses AMQP and sends the messages to RabbitMQ exchanges. In SYNCHRONOUS mode the driver calls defined REST endpoints of microservices.

Synchronous communication is used by default.

Synchronous Communication

Either set the SYNCHRONOUS profile explicitly or omit it.

$ java -Dspring.profiles.active=SYNCHRONOUS -Dspring.application.name=tcpip-palett1 -jar tcpip-driver-exec.jar

Asynchronous Communication (RabbitMQ)

To enable asynchronous communication over RabbitMQ set the Spring profile ASYNCHRONOUS

$ java -Dspring.profiles.active=ASYNCHRONOUS -Dspring.application.name=tcpip-palett1 -jar tcpip-driver-exec.jar

Configuration

Important configuration properties of the driver component are the following.

Logging

The driver component is configured for tenant aware logging. If, for instance, the tenant is configured to 'myProject' (owms.tenant=myProject) a tslog file (Technical Service Log) is written with name 'myProject-COMMON.tslog' that contains the time consumption processing each telegram took. An example tslog file looks like:

myProject COMMON 2018-09-27 15:26:27.280  INFO  �[MEASURED                                ] : [TSL]>> ErrorMessageServiceActivator#wakeUp
myProject COMMON 2018-09-27 15:26:27.305  INFO  �[MEASURED                                ] : [TSL]<< ErrorMessageServiceActivator#wakeUp took 26 [ms]
myProject COMMON 2018-09-27 15:27:01.586  INFO  �[MEASURED                                ] : [TSL]>> TimesyncServiceActivator#wakeUp
myProject COMMON 2018-09-27 15:27:01.587  INFO  �[MEASURED                                ] : [TSL]<< TimesyncServiceActivator#wakeUp took 1 [ms]
myProject COMMON 2018-09-27 15:28:48.638  INFO  �[MEASURED                                ] : [TSL]>> TimesyncServiceActivator#wakeUp
myProject COMMON 2018-09-27 15:28:48.657  INFO  �[MEASURED                                ] : [TSL]<< TimesyncServiceActivator#wakeUp took 22 [ms]
myProject COMMON 2018-09-27 15:28:50.704  INFO  �[MEASURED                                ] : [TSL]>> TimesyncServiceActivator#wakeUp

Build and Release

$ mvn deploy -Prelease,gpg -Ddebug.info=true