Ack message
Ack messages are produced by the receiving participant in a message exchange to acknowledge the receipt of a Guaranteed Message. Application acks tell the event broker that the application is done processing the message and that it can be removed from the queue or topic endpoint. There are two types of application ack messages:
  • Consumer acks are sent to the event broker when a Guaranteed Message is received by the consumer.
  • Publisher acks are sent to the publisher when a Guaranteed Message is received by the event broker
Access Control Lists manage client access to PubSub+ event brokers. There are three types of ACLs:
  • Connect ACLs control which clients are allowed to connect to the PubSub+ event broker.
  • Subscriber ACLs control which topics a client is allowed to subscribe to.
  • Publisher ACLs control which topics a client is allowed to publish to.
An Assured Delivery Blade is a card in a Solace appliance that enables guaranteed delivery of messages. ADBs have non-volatile memory where critical data-structures are stored and mirrored to an HA mate.
PubSub+ Cloud supports deployment to Azure Kubernetes Service.
An Amazon Machine Image is a virtual machine image format used in Amazon Elastic Compute Cloud (Amazon EC2). PubSub+ software event brokers are available as AMI packages for use on AWS.
Advanced Message Queuing Protocol is an open standard application layer protocol for message-oriented middleware. PubSub+ event brokers provide service for AMQP 1.0 clients on both appliances and software event brokers. For more information, see AMQP 1.0.
Anonymous Queue
Anonymous queues are queues whose name is generated by the API rather than being specified by the application. Anonymous queues are always non-durable. See also: Well-Known Queue.
API Token
An API token is a unique identifier that allows you to authenticate with an API. To use the PubSub+ Cloud REST API, you need an API token. The API token must be included in the Authorization Bearer header when you make a REST call. You can generate and manage API tokens at the account level it in the PubSub+ Cloud Console. For more information, see Managing API Tokens.
An application is a program, process, microservice, IoT device, integration component or other runnable consumer, producer, or processor that interacts with an event broker.
Application Domain
In Event Portal, an application domain is a space where you create and store applications, events, schemas, and enumerations. Within the application domain, you manage a suite of applications, events, and schemas that are isolated from other application domains. You can share events and schemas across application domains to integrate events and data between different organizational groups. For more information, see Application Domain.
PubSub+ Cloud supports deployment to Azure Red Hat OpenShift.
AsyncAPI is an open-source initiative that allows development teams to more easily create applications that communicate asynchronously through events. The AsyncAPI specification describes how to create an AsyncAPI document in JSON or YAML format that defines and annotates the different components of a specific Event-Driven API.
Availability zones are segments of a public cloud region that are isolated for fault tolerance. PubSub+ Cloud and PubSub+ software event brokers require three AZs for high availability; one for each of the primary messaging broker, the backup messaging broker, and the monitoring broker. See also High Availability.


Broker Manager
PubSub+ Broker Manager is a browser-based administration console packaged with the PubSub+ event broker. For more information, see PubSub+ Broker Manager.


Event Portal Catalog is the storefront for all of the applications, events, and schemas created in the Event Portal. It provides a searchable index of all event-related objects within an enterprise. Objects discovered and committed in Discovery or created in Designer are automatically available in Catalog. For more information, see Catalog.
A channel is a connection within a DMR link. Each link has a single control channel that carries topology and subscription-control messages and one data channel per Message VPN that carries client data messages. See also DMR.
The Solace Command Line Interface is a text-based interface for configuring and monitoring Solace event brokers. It allows a user to perform event broker administration, configuration and provisioning, and network troubleshooting tasks. The CLI automatically starts after the event broker powers up. For more information, see Solace CLI.
A client is a customer application that connects to a Node.
Client Username
Client usernames are contained within a specific Message VPN and are used by client applications to authenticate with the event broker. They may be used to make multiple client connections.
Client Profile
Client profiles can be applied to client usernames. Sharing client profiles allows you to manage large groups of clients without having to make individual changes to each one.
Cluster Link Queue
in a DMR Cluster, cluster link queues help to manage the flow of data over the links by holding guaranteed messages until they are ready to be sent over the data connection to the neighboring nodes. See also DMR Cluster.
Cluster Manager
Cluster Manager in PubSub+Mission Control allows you to manage the life cycle of your event broker services. You can also use Cluster Manager to create, configure, and manage the lifecycle of your cluster. See also DMR Cluster.
Config-Sync automatically propagates changes in system and Message VPN level configuration between two event brokers to keep them in sync in high availability and replication setups. For more information, see Config-Sync Overview.
Connection Endpoint
A connection endpoint is a set of protocols and ports that allows users and applications to connect to an event broker service for messaging traffic, configuration, or administration. The connection endpoint can be either a public endpoint or private endpoint. Connection endpoints can be configured using the PubSub+ Cloud REST API or Cluster Manager in the PubSub+ Cloud Console. For more information, see Configuring Connection Endpoints and Ports for Event Broker Service 9.13 and Later Using the REST API and Configuring Endpoints and Ports for Event Broker Services 9.13 and Later.
A connector is software that enables data to be exchanged between PubSub+ event brokers and an external resource. The resource can be any source of content, such as a database, protocol, or API.
A consumer is an entity that receives event messages. A consumer is also referred to as a subscriber.
Consumer Egress Queue
A consumer egress queue stores event messages until the consumer retrieves them.
Consumer Flow
A consumer flow is an API object that allows a consumer to receive guaranteed messages from an endpoint. To receive guaranteed messages, a client must create a consumer flow within a session and bind that flow to a topic endpoint or queue that messages are published or attracted to.
Consumer Group
Consumer group is a Kafka term for a group of consumers that forms a “logical consumer” to read from a single topic. A consumer in a consumer group connects to a partition inside a Kafka topic and reads sequential log records from a partition file.
Container Image
A container image is an unchangeable, static file that includes the user-space and executables of an application. It is compiled from file system layers built onto a parent or base image. A container image can be used to create a container instance of the application.
Controlled Failover
A controlled failover occurs when activity is transferred from an active node to a standby node as the result of an administrative action. A controlled failover could occur between the active and standby event brokers in an HA group or between the active and standby nodes of a replication group. In both cases, if the procedure is properly followed, the controlled failover can occur with no message loss. See also High Availability and Replication
Class of service (COS) level controls which of the per‑client priority queues on the event broker messages are placed in and the rate at which they are sent out from the event broker to consuming clients.
The Solace Content Shortest Path First protocol is used to link neighboring event brokers and allow them to discover the complete messaging network topology that they belong to. For more information, see Basics of Multi-Node Routing.


Delayed Delivery
Delayed delivery allows you to introduce a time delay between the time when a message is published to the event broker and the time when that message is delivered to a consumer. The delivery delay time is a configurable endpoint attribute that allows a single message to be delivered to different consumers with different time delays. For more information, see Configuring Delayed Delivery.
Event Portal Designer is a tool to design and view all aspects of your event-driven architectures. In Designer, you can create events and associate the payload schema to these events. Designer provides a graphical representation of application domains, applications, schemas, and events that allows you to visualize the interaction of events between applications and to provision your architecture into the Event Portal. For more information, see Designer.
Direct Messaging
Direct messaging provides a reliable, but not guaranteed, delivery of messages from the Solace message bus to consuming clients. It is the default message delivery system for PubSub+. By default, direct messaging is always available to all clients connecting to an event broker. For more information, see Message Delivery Modes.
Disaster Recovery
Disaster recovery (DR) involves a set of policies, tools, and procedures that enable the recovery or continuation of vital technology infrastructure and systems following a natural or human-induced disaster. PubSub+ supports DR using data center replication. See also Replication.
Event Portal Discovery is a tool to discover application, event, and schema interactions running over your event brokers. You can use Discovery Agent to scan event brokers such as PubSub+, Apache Kafka, Amazon MSK, and Confluent to discover, import, and then visualize event-driven architectures, including all associated applications, events, and schemas and their relationships.
A Dead Message Queue is a special queue where messages are sent when they are deemed to be undeliverable. For more information, see Dead Message Queues.
Dynamic Message Routing is a mechanism that allows connected event brokers to automatically determine how to forward event messages. For more information, see DMR Overview.
DMR Cluster
A DMR cluster connects event broker nodes with each other to form a mesh. Within a cluster, internal links allow each node to communicate directly with all of the others. External links connect DMR clusters with each other. Each cluster may be as simple as a single node, or may contain up to 15 nodes connected by internal links.
DMR Link
A DMR link is relationship between nodes. It is made up of the TCP connections that transmit topology information, subscriptions, and data. Internal links are connections between nodes within the same cluster. External links are connections between nodes in different clusters.
DMR Subscription Propagation
DMR subscription propagation uses SMRP to update the network-wide knowledge of subscriptions as changes occur. No manual intervention is required to keep subscription information current across the event mesh. For more information, see DMR Subscription Propagation and Data Forwarding.
Durable Endpoint
Durable queues and topic endpoints are provisioned objects on the event broker that have a life span independent of a particular client session. They also survive an event broker restart and are preserved as part of the event broker configuration for backup and restoration purposes.
A durable endpoint has an associated access type that determines how messages are delivered to bound consumer flows. Durable endpoints can be assigned exclusive access to allow only one bound flow to receive messages at a time, or nonexclusive to allow multiple consumers to be serviced in a round‑robin fashion. See also Endpoint.


An Event API Product is a bundle of events that you can create and give to external developers to help them build applications that can publish and subscribe to those events. An EAP can be composed of events from either Solace PubSub+ Event Broker or Kafka. For more information, see Event API Products (Beta).
Event-driven architecture is a software architecture paradigm that promotes the production, detection, consumption of, and reaction to events. Event-driven architecture lets information flow between applications, microservices, and connected devices in a real-time manner as events occur throughout your business, instead of periodically polling for updates.
PubSub+ Cloud supports Amazon Elastic Kubernetes Service. Self-managed software event brokers can also be deployed in EKS using the Kubernetes Quick Start.
Endpoints (or messaging endpoints) are objects created on an event broker to persist messages. There are two types of endpoints: queue endpoints (usually just called queues), and topic endpoints. See also Queue and Topic Endpoint. In the Solace documentation, the term endpoint refers to a messaging endpoint. There are other types of non-messaging endpoints, such as connection endpoints, public endpoints, and private endpoints.
Endpoint Template
Endpoint templates are configurable objects that administrators can use to specify custom attributes and parameters for any new client created endpoints. Any custom configuration associated with the endpoint template will be applied to the client created endpoints based upon the endpoint name.
Environments in PubSub+ Cloud represent the runtime environments within your organization. For example, you may have a development environment, a testing environment, a staging environment, and a production environment. Environments are added at the account level.
An event represents a business moment, action, or occurrence that can be communicated to interested applications. Within your EDA, “event” also refers to the message that communicates the occurrence.
When designing your EDA in Event Portal, an event is the object that specifies the type of moment or action that occurs and the contents of the metadata that describes and categorizes the event in the message that is sent. Each occurrence of an event type is an event instance.
Event Broker
An event broker is middleware software, an appliance, or SaaS used to transmit events between event producers and consumers. PubSub+ event brokers can be connected to form an event mesh.
Event Broker Service
An event broker service in PubSub+ Cloud is made up of either a standalone software event broker (Developer service class) or a high-availability group of three software event brokers (Enterprise service class).
Event-Driven Microservices
Event-driven microservices (EDM) allow for real-time microservices communication that enables data to be consumed in the form of events.
Event Mesh
An event mesh is an architecture layer composed of a network of event brokers that allows events from one application to be dynamically routed and received by any other application, no matter where these applications are deployed within your infrastructure, your private cloud, or in a public cloud. For more information, see Understanding Event Meshes and Mesh Manager.
Event Portal
PubSub+ Event Portal is a browser-based event management tool that enables you to design, create, discover, catalog, share, visualize, secure, and manage events and event-driven applications within your EDA. For more information, see PubSub+ Event Portal Overview.
Event Queue
An Event Queue is a type of queue that is specifically used for the Pub/Sub message exchange pattern. It does not support request/reply or point-to-point message exchange patterns.
Event Stream
An event stream is a continuous unbounded series of events with the start of the stream before the start of the process and the end of the stream at a point in the future. The order of events in the stream is based on the point in time of the event occurrence.
Event Threshold
An event threshold is a value setting for monitoring event brokers. It results in a system event being generated on a client or event broker, which is sent only to the event log on the broker. For example, you can set thresholds to generate events based on subscription levels or number of client connections. For more information, see Configuring System Event Thresholds
Event Type
An event type (or event as it is referred to when designing your EDA in Event Portal) represents a class of events produced in an EDA. The event type represents the allowed payload for the event.
Exclusive Queue
Exclusive queues allow only one consumer to receive a message at any one time, while additional consumers may be connected as standby.


A failover is a change from an active system to a redundant standby system that happens when an error condition occurs in the active system. A failover could occur between the active and standby event brokers in an HA group or between the active and standby nodes of a replication group. The failover to the standby system can occur automatically to maintain service when an unexpected failure occurs. See also High Availability and Replication
Fan-out is the typical publish/subscribe messaging pattern where a message is published once to the PubSub+ event broker and forwarded to multiple clients who have expressed interest in receiving messages of that kind through topic subscriptions.
A consumer flow is an API object that allows applications to receive guaranteed messages from an Endpoint. A flow is created by a Solace session.


PubSub+ Cloud supports Google Cloud Platform.
PubSub+ Cloud supports Google Kubernetes Engine.
Guaranteed Messaging
Guaranteed Messaging ensures the delivery of a message between two applications, even in cases where the receiving application is offline, or there is a failure of a piece of network equipment. Messages are delivered in the order they were published. Guaranteed messages are maintained in a non-volatile store. They are most appropriate for messaging applications that require persistent storage of the messages they send or intend to receive. For more information, see Guaranteed Messages.


High Availability
High availability (HA) uses redundant systems to allow for continued service in the event of a failure. PubSub+ appliances and PubSub+ software event brokers can operate in HA redundant groups for fault tolerance. For more information, see High Availability (HA) Overview.
Host Bus Adapter
A Host Bus Adapter card connects the storage area network (SAN) to a PubSub+ appliance, which helps store and retrieve messages when the consumer is offline.


Infrastructure as a Service is a type of cloud-based service that provides high-level APIs used to abstract various low-level details of underlying network infrastructure like physical computing resources, location, data partitioning, scaling, security, and backup.


Java Content Subscription Management Protocol is a messaging protocol for Java. The Solace JCSMP API is a pure Java implementation that provides an object-oriented API for delivering high message throughput. For more information, see JCSMP API.
Java Message Service is an API that provides the facility to create, send and read messages. It provides loosely coupled, reliable and asynchronous communication. For more information, see JMS.
JMSToolBox is an open-source client that can perform a variety of tasks with PubSub+ event brokers using the JMS API. JMSToolBox can be used to automatically discover queues and topics, browse and view the contents of messages, generate messages using a templating scheme, and script the generation of messages. For more information, see JMSToolBox.
The Java Naming and Directory Interface is a Java API for a directory service that allows Java software clients to discover and look up data and resources by name. For more information, see Solace JNDI Objects.
JavaScript Object Notation is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute-value pairs and arrays.
Just-in-Time Provisioning
Just-in-time provisioning enables users to be successfully authenticated through the identity provider. The user is automatically assigned a role based on the existing role mapping.


Last Value Cache
Solace PubSub+ Cache is an in-memory last value message cache for non-persistent messaging. It lets applications request the latest messages for a topic when they come online or subscribe to a new topic. For more information, see Solace PubSub+ Cache.
Last Value Queues
A last value queue has a maximum spool value of 0, which means that the queue stores only the last value received. See also Queue.
Link Costs
Link costs help identify a preferred route. To prefer one route over another (for example, to specify a default link), you can change the routing link costs to set the preferred message route. See also MNR.
Link Initiator
The link initiator is the node that establishes the underlying TCP connection between nodes. Each end of the link must agree upon the initiator, or a topology error occurs. After the link is initiated, messages are exchanged in both directions over the link. See also DMR Link
Link Transport Method
Link transport settings specify whether the transport is encrypted, compressed, or both. While the choice to use encryption and compression is independent for every link, the control and data channels of each individual link share the same encryption and compression settings. See also DMR Link
Live Message
A live message is a published message that has not been sent to all consuming clients. The message exists somewhere in the data path; that is, it was either received on ingress, sent via egress, or exists in one or more endpoints.
Logged Message
A logged message is a message that has been set aside in the replay log for later replay. See also Message Replay.


Mesh Manager
Mesh Manager is a tool that helps you connect multiple event broker services that span different data centers to create an event mesh. For more information, see Mesh Manager (Beta).
A message is a packet of information about an event. Messages contain a header that includes the topic of the message, properties, and the payload. Messages are exchanged by clients of an event broker or mesh. For more information, see Core Messaging Concepts.
Message Backbone
The message backbone is an object that contains all PubSub+ event broker messaging interfaces that messaging clients and other event brokers connect to.
Message Eliding
Message eliding allows client applications to receive only the most current direct messages published to topics that they subscribe to, at a rate they can manage. It can be useful in situations where there are slow consumers, or where a slower message rate is required. Only direct messages can be elided. For more information, see Message Eliding.
Message Replay
Message replay allows an event broker to resend messages to new or existing clients that request them, hours or even days after those messages were first received by the event broker. Message replay is available if a Replay log is configured for the Message VPN. Messages are kept in the replay log until the log is full, at which point, the oldest messages are discarded. For more information, see Message Replay Overview.
Message Spool
The message spool hold guaranteed messages received by an event broker in a spool file until the messages are delivered to all matching registered topic subscriptions and queues that match the destination the message was published to. When the message has been delivered to all matching subscribers, the message is deleted from the spool. For more information, see Message Spooling.
Message VPN
Message Virtual Private Networks are managed objects on PubSub+ event brokers that allow for the segregation of topic space and clients. Message VPNs allow for many separate applications to share a single PubSub+ event broker while remaining independent and separated. For more information, see Message VPNs.
Message VPN Bridge
A Message VPN bridge allows messages published to one Message VPN to be transferred to another Message VPN. For more information, see Message VPN Bridges Overview.
Messaging Client
Messaging clients are client applications that connect to the event broker services to publish and subscribe to event messages.
Messaging Endpoint
See Endpoint .
A microgateway is a mode of operation for the REST messaging service that uses a lightweight, distributed API proxy that enforces policies and business logic at or near the service endpoints. It is an inner gateway paired with a microservice instance that is ready to spin up and provide communication connections. For more information, see Microgateways Overview.
Mission Control
PubSub+ Mission Control helps you deploy event brokers, create event meshes, and optimize and monitor the health and performance of your event-driven system. Mission Control is a section in the PubSub+ Cloud Console that enables you to access event brokers, visualize and manage your event broker services, and visualize and design event meshes. Mission Control includes Cluster Manager and Mesh Manager to help you to create event broker services and manage your event mesh. For more information, see Mission Control Overview.
Mission Control Agent
The Mission Control Agent is a microservice that manages the lifecycle of event broker services in the deployment, including the creation, deletion, and configuration of all event broker services in the data center. For more information, see Solace Mission Control Agent.
Multi-Node Routing allows multiple PubSub+ event brokers to be networked together so that direct messages published from clients connected to one event broker can be delivered to clients connected to other event brokers. For more information, see Basics of Multi-Node Routing.
Modeled Event Mesh
In Event Portal, a modeled event mesh represents an Operational Event Mesh in specific runtime environments. The modeled event mesh helps you define and visualize event flows between publishing and subscribing applications. For more information, see Modeled Event Meshes.
The Oasis Message Queuing Telemetry Transport standard was designed to send and receive information between connected devices and mobile applications using very little bandwidth or client-side processing power.


A Nack, or negative acknowledgment, is sent to the message publisher when the event broker fails to spool a message in any of the subscriber queues, which results in message roll back on all cooperating queues.
Neighbor Queues
Neighbor queues are used as part of MNR to enqueue messages before they are sent over the data connection to neighbor event brokers. These TCP transmit queues manage the flow of data that is transmitted from an event broker over the routing links to its neighbors. See also Queue.
A DMR node can be a single software event broker, a high availability (HA) group of software event brokers, a single appliance, an HA (active / standby) pair of appliances, or a PubSub+ Cloud event broker service. Nodes exist within a DMR Cluster. A gateway node is a node with an external link to another cluster. See also DMR Cluster.
Non-Exclusive Queue
A non-exclusive queue allows multiple consumers to bind to the queue. Each consumer is serviced in a round‑robin fashion to provide load-balancing. If a connection fails, unacknowledged messages are delivered to another consumer with the re-delivered flag set. See also Queue.
Non-Persistent Message
Non-Persistent messages are received, at most, once by a consumer. Under normal operations, messages are delivered once, but they can never be delivered more than once to the same consumer. Non-persistent messages can be transported using Guaranteed or Direct message modes.


OAuth Authentication
OAuth is an open standard for access delegation, commonly used as a way for users to grant websites or applications access to their information on other websites without giving them access to their passwords. It specifies a process for resource owners to authorize third-party access to their server resources without sharing their credentials. For more information, see Configuring OAuth Authentication for management access and Configuring OAuth Authorization for messaging clients.
One-Shot Events
One-shot events are system events that are sent only once to the event log, even if the originating condition recurs. They must be cleared and reset to receive them again. For more information, see Clearing One-Shot Events.
Operational Event Mesh
In Event Portal, an operational event mesh is an event mesh in the runtime that is represented by a Modeled Event Mesh in the Runtime Event Manager. See also Event Mesh.


Persistent Event Stream
In a persistent event stream, messages are stored in non-volatile storage media when they arrive on the broker until they are delivered. Persistent messages are suitable for application design patterns where the event messages must be processed in order of receipt, available to consumers (even if they are offline), and able to survive the loss of an event broker. For more information, see Persistent Event Streams.
Persistent Message
Persistent messages received by the event broker are placed in non-volatile storage media until they can be delivered. For more information, see Message Delivery Modes.
A point-to-point message exchange pattern involves a single publishing client sending messages to the event broker, which are then received by a single subscribing client. For more information, see Point-to-Point.
Private Endpoint
A private endpoint is set of protocols and ports that client applications and users can use to connect to an event broker service using private IP addresses, which are typical of a private network . A private endpoint is a type of connection endpoint.
Public Endpoint
A public endpoint is a set of protocols and ports that client applications and users can use to connect to an event broker service using public Internet (public connectivity). A public endpoint is a type of connection endpoint.
Publish-Subscribe is a message exchange pattern where messages sent by the producer are processed multiple times by different consumers. Each consumer receives its own copy of the message for processing. For more information, see Publish-Subscribe.
A publisher is an application that generates and sends event messages. Publishers supply information about a subject without needing to know anything about the consumers.
PubSub+ Cache
PubSub+ Cache is a scalable, in-memory message cache for direct messaging. It allows client applications connecting to PubSub+ to request the most current messages for a topic of interest when they come online, or when they start subscribing to topics that they were not originally subscribed to. For more information, see Solace PubSub+ Cache.
PubSub+ Cloud
PubSub+ Cloud is a complete event streaming, management, and insights platform, available as a service in your favorite public and virtual private clouds and on-premises environments. For more information, see What is PubSub+ Cloud?.
PubSub+ Cloud Console
The PubSub+ Cloud Console is the "single pane of glass" that gives you access to the PubSub+ Platform—a complete event streaming and management platform. For more information, see PubSub+ Cloud Console.
PubSub+ Cloud REST API
The PubSub+ Cloud REST API is a RESTful API that you can use to manage your data in PubSub+ Cloud. Use the REST API to integrate other applications, systems, or client applications with Event Portal, and model or retrieve your event-driven architectures from your own client applications. For more information, see Understanding the PubSub+ Cloud REST API.
PubSub+ Insights
PubSub+ Insights helps operations and applications teams monitor their event broker service and event mesh infrastructure to ensure they are available and ready for use by business applications. PubSub+ Insights provides centralized, at-a-glance status on the availability of various aspects of the event mesh, including resource usage, message flow, HA status, message spool utilization, and capacity utilization. For more information, see PubSub+ Insights Overview.


A queue is both a destination that clients can publish messages to and an endpoint that clients can bind consumers to and consume messages from. A queue is typically used in a point-to-point (PTP) messaging environment. Queues can provide exclusive access to one consumer or access to multiple consumers where each is serviced in a round‑robin fashion. Clients can have permissions to consume, delete, or modify topics in the queue. See also Endpoint.


Replicated Topic Subscription
Replicated topic subscriptions for a Message VPN indicate which messages should be replicated between active and standby site. You can replicate a topic subscription or a queue name subscription. If a published message matches both a replicated topic subscription and an endpoint on the active site, then the message is replicated to the standby site. See also High Availability.
Replication provides business continuity by transferring messages to a standby site, allowing mission‑critical applications to continue to function during a major service outage that affects an entire data center. A typical deployment model for replicated data center infrastructure is to have a pair of replication sites located many kilometers apart. These sites are considered replication mates and are known collectively as a replication group. For more information, see Replication Overview.
Reserved Topics
PubSub+ uses Reserved Topics to implement some specific messaging features. Each reserved topic subscription begin with the # character, followed by a specific, reserved sequence of characters. For more information, see Reserved Topics.
A REST delivery point is a provisioned object on a Message VPN that facilitates message delivery to REST consumers. For more information, see Managing REST Delivery Points.
PubSub+ Remote Monitoring and Management Service (RMMS) is a complete, proactive, worry-free service that ensures your entire event broker estate, including appliances, software brokers, and cloud services, is always available for the applications that rely on it. For more information, see PubSub+ Remote Monitoring and Management Service.


A schema defines the meaning of each data value in the payload of an event so that the publisher and all subscribers understand what each value means. You manage schemas in Event Portal. For more information, see Schema.
SDKPerf is a tool for validating performance, checking configuration, and exploring features associated with your PubSub+ event broker. For more information, see SDKPerf.
Solace Element Management Protocol version 1 is a programmatic interface that can be used to manage and monitor PubSub+event brokers.
SEMP version 2 is a RESTful API that you can use to perform the same tasks. For more information, see SEMP.
Sequenced Topic
In a guaranteed messaging setup, a sequenced topic is a topic subscription for which any matching messages received on the Message VPN are assigned a sequence number that is monotonically increased by a value of one per message. See also Guaranteed Messaging
Service Class
Service classes are preset configurations with defined limits on underlying resources. When you create an event broker service in PubSub+ Cloud, you choose the service class to meet your needs. Service limits exist for the number of queues, maximum message size, unique subscriptions, non-unique topic subscriptions, and client connections. For more information, see Service Class Options for Event Broker Services.
Shared Events
In Event Portal, shared events can be referenced by applications in application domains other than the one they belong to. For another application domain to reference your events and schemas, the event or schema must be marked as shared. For more information, see Application Domain.
Shared Subscriptions
Shared subscriptions can be used to load balance large volumes of client data across multiple instances of backend data center applications when using direct messaging. They are especially useful in situations where those applications publish messages in parallel.
Solace Message Format is a wireline protocol used by PubSub+ and Solacemessaging APIs. PubSub+ event broker also implements AMQP , MQTT, and REST open standard wirelines for use with third party and open source APIs. For more information, see SMF Topics.
The Solace Subscription Management Routing Protocol enables linked neighboring event brokers to propagate topic subscriptions added by the clients of one event broker throughout the messaging network. SMRP is used for both DMR and MNR.
Solace Control Utility (solacectl)
The machine image packages of the PubSub+ software event broker include a command-line utility called solacectl. This utility automates common tasks in the Linux host environment. For more information, see Using the Solacectl Utility.
Solace Home Cloud
The Solace Home Cloud is a collection of microservices that provides the control plane for PubSub+ Cloud deployments. These microservices provide a number of backend functions, including event broker management (Mission Control), event cataloging and design (Event Portal), and monitoring management (Insights). The Home Cloud fronts the backend services with a single user interface called the PubSub+ Cloud Console. For more information, see Solace Home Cloud.
SolAdmin Desktop application
SolAdmin is a management application for PubSub+ event brokers that can be used with a CLI user account. While the Command Line Interface (CLI) provides access to all management features for event brokers, SolAdmin provides a simplified graphical interface for managing event broker properties. For more information, see SolAdmin.
Spool Files
Guaranteed messages are spooled to an event broker through the use of spool files. If the event broker’s spool files are all in use, it cannot receive any more messages until some spooled messages are acknowledged, which could free some space in the message spool. See also Guaranteed Messaging.
A subscriber is an entity that consumes event messages. Subscribers consume information about a topic without needing to know anything else about the publishers except for the subject (name or topic) of the event messages.


Temporary Endpoint
Temporary queue and topic endpoints are dynamically created and destroyed by client applications. Temporary queues and topic endpoints are typically used as temporary destinations for service requests. See also Endpoint.
Topics are a means of classifying events in a hierarchical structure. This structure provides a subject that producers can publish messages to and consumers can subscribe to. The topic hierarchy allows consumers to subscribe to relevant topics from multiple publishers without having to know exactly which events they need to consume or which application publishes the events. For more information, see Understanding Topics.
Topic Endpoint
A topic endpoint attracts messages published to a topic for which the topic endpoint has a matching topic subscription. The topic subscription for the topic endpoint is specified in the client request to bind a flow to that topic endpoint. See also: Endpoint.
A topology is a specific arrangement of links between nodes in a network (or event mesh). An internal topology is defined by its internal links within a DMR cluster. An external topology is defined by its external links between DMR clusters. See also DMR Cluster.
Transacted Sessions
Transacted Sessions enable client applications to group multiple message send and/or receive operations together in single, atomic units known as local transactions. Each transacted session can support a single series of transactions.


Uncontrolled Failover
A controlled failover occurs when activity is transferred from an active node to a standby node as the result of an external event beyond the control of network operators. In an HA group, an uncontrolled failover can occur automatically between the active and standby event brokers when they detect the failure. In a replication group, an operator must initiate the failover to the standby node. See also High Availability and Replication


Well-Known Queue
A well-known queue is any durable or non-durable queue with a commonly recognized name. The well-known queue name is configured for the application rather than generated by the API. See also: Anonymous Queue .
Windowed Acknowledgment
Windowed Acknowledgment is a mode of acknowledging guaranteed messages where a single acknowledgment event acknowledges the last message published and implicitly acknowledges all of the preceding messages.