You can register subscriptions with the Event Bus. This creates DES Event Services that hold published events in memory and a corresponding event mashable in MashZone NextGen.
Starting with MashZone NextGen 10.2, Event Service subscribes using a durable subscription. The durable subscription remains active until the Event Source is deleted, that is, Universal Messaging will buffer events until MashZone NextGen Event Service consumes them. This ensures that no event data is lost in situations where MashZone NextGen Event Service is unavailable. Event Service uses the defined alias name (see below) as the subscription’s identifier. Thus, you need to make sure that there must not be configured two independent Event Service installations that access the same Universal Messaging Channel using the same alias name. That is, if you operate two Event Service Clusters (single or multi-node) and they share a single Universal Messaging Instance, make sure to use different alias names for the same channels.
Procedure
The DES Event Service is created and listed by alias name.
DES Event Services properties
Property |
Required |
Description |
Alias |
yes |
Enter a unique name for this event source. |
Start event source automatically on server startup |
|
This option is set by default, which automatically starts this event source when MashZone NextGen Server starts. Clear this option if you need to manually control startup for this event source. |
Event type |
yes |
Select the type of the event this event source should subscribe to. The XML schema files for these event types must exist in the Event Type Store directory of MashZone NextGen Event Service. The Event Type Store directory cab be configured using Command Central. |
Strategy |
yes |
The strategy that this event source uses for saving and removing events published from the Event Bus. Valid strategies are:
|
Consider dimension |
|
Available only when Strategy is set to BUFFER. Set this option to save events in separate series (or buckets) for each unique value of the Dimension attribute. |
Dimension attribute |
conditional |
Available only when Strategy is set to BUFFER and required when the Consider dimension option is set. Select the event attribute whose unique values determine separate event series (buckets) for this event source. |
Max. number of dimension values |
conditional |
Available only when Strategy is set to BUFFER and required when the Consider dimension option is set. Enter the maximum number of unique dimension values (buckets) that can be tracked. Thus this is the maximum number of series that can store events. Default value: 1 (Max: 100.000). The product of Max. number of dimension values and Capacity per dimension value must not be greater than 100.000. |
Dimension Squeeze-out |
|
Available only when Strategy is set to BUFFER and required when the Consider dimension option is set. Determines how additional events are handled if they have new unique values for the dimension that defines buckets in this event source but the maximum number of unique values (buckets) has already been reached. This option is clear by default which discards new events with new unique dimension values once the maximum number of buckets has been reached. Set this option to change the bucket strategy to FIFO (first-in, first-out) which discards events for older series (buckets) and stores the newer event in a new series (bucket). Default value: false |
Capacity per dimension value |
conditional |
Available only when Strategy is set to BUFFER and required when the Consider dimension option is set. Enter the maximum number of events that can be stored in a specific event series (bucket) for each unique dimension value. Default value: 10 The product from Max number of dimension values and Capacity per dimension value must not be more than 100 000. |
Event ID attribute |
yes |
Available only when Strategy is set to DELTA. Select the attribute that identifies an event. The event ID and command determines which events are stored, updated or removed in this event source. |
Command attribute |
yes |
Available only when Strategy if set to DELTA. Select the attribute that contains the event command (Insert or Remove). The event ID and command determines which events are stored, updated or removed in this event source. |
Capacity |
yes |
Enter the maximum number of events to store in this event source. (Max: 100.000) Default value: 10 |
Memory model |
|
Determines where events are stored:
|
Throttling |
|
Controls the speed and volume of event data that is pushed to views that subscribe to this event source. By default, event sources push event data every 500 milliseconds. You can:
See Example below. |
Exception |
|
Set this option to support a hybrid throttling strategy, typically involving both time and event limitations. Then set the exception criteria (Default=1):
See Example below. |
Simple and Hybrid Throttling Strategies
Simple throttling strategies cause an event source to wait for either a specific time interval or for the receipt of a specific number of events and then push all new events to any subscribing real-time views. Throttling can slow event updates to real-time views when the volume or frequency for events causes rendering issues.
The default behavior is to push events to views based on a time interval of every 500 milliseconds. You can change the time interval or change the criteria to push events once a minimum count of events are received, such as 10 events. For example:
Simple strategies may still not even out event flow adequately. Instead, you can create hybrid strategies, such as "generally push every 50 milliseconds, but at most 10 events."
Hybrid strategies define the general throttling with the Throttling fields. You set the Exception option and define the exception that should break the general rule in the Exception criteria fields:
With the example hybrid throttling strategy shown above:
On the EDA Event Source overview page you can click on the Alias to show a preview of the specific Event Source properties.