Universal Message Service (OMS) 7.4.x Reference Guide
Universal Message Service
Universal Message Service (OMS) is a message-oriented middleware component used to send and receive messages between Universal Automation Center product components distributed over a computer network.
Product components that currently utilize OMS are Universal Automation Center Agent (UAG) and the Universal Controller, referred to generally as OMS clients. OMS provides for asynchronous, secure, and reliable message communication between a large number of OMS clients.
The OMS component itself consists of an OMS Server and an OMS Administration Utility. Detailed information on both are documented on these pages.
OMS clients establish persistent TCP/IP socket connections with the OMS Server. The Transport Layer Security (TLS) protocol, commonly referred to as SSL/TLS, may be used to provide data privacy and integrity of all data transmitted between OMS clients and the OMS Server. SSL/TLS additionally provides the option for OMS clients to authenticate the OMS Server using digital certificates.
Application data is sent and received between the OMS clients as OMS messages. OMS provides for asynchronous communication, where an OMS client sends a message to an OMS queue that is maintained on the OMS server. An OMS queue represents a message destination from which OMS clients can send and receive messages. An OMS message will remain in the OMS queue until another OMS client receives the message from the OMS Server. Asynchronous communication allows for OMS clients to produce messages and consume messages at different times. The producers and the consumers of messages do not have to be connected to the OMS Server at the same time.
OMS provides for reliable message communication by placing all OMS queued messages in persistent storage in an OMS message database; data is retained even if power to that database is shut off.
OMS Server
The OMS Server is a central communication hub for OMS clients. The OMS Server maintains persistent OMS messages in a message database in order to provide message reliability. As messages are received, the OMS server routes messages to the appropriate OMS clients.
The OMS Server is deployed as a server component managed by the Universal Broker. The Universal Broker manages server components by providing the following services:
- Start and stop servers
- Manager server configuration data
- Monitor server status
- Provide server restart services
The OMS Server is defined as an auto-started server. As such, it is started and stopped automatically when Universal Broker is started and stopped.
OMS Administration Utility
The OMS Administration Utility is available to obtain information on the state of the OMS server and to provide support and diagnostic services. Access to the Administration Utility should be limited to the group responsible for administering the OMS server.
The Administration Utility is a command line program that interacts with the local OMS server. Access to its services can be controlled with UACL entries.
Detailed Information
The following pages provide detailed information for OMS: