Agents are internal modules oriented to expand its functionality without having to alter its core. The installation is based on the principle of Plug & Play: they are recognized by the system and started automatically to be up and running.
Every agent is a process that acts as a subscriber for the Publish/Subcribe platform. These processes will subscribe directly to Redis as a independent clients. This subscription will provide the input data to do the underlying business logic (store in a relational database, process alarms, generate statistics, ...)
The following diagram shows the design that every agent should follow:
- When agent is started, it subscribes as client to Redis for the event that wants to receive notifications.
- When Redis receives a publication of any of these data, the agent is automatically notified with a new message.
- The message is processed and transferred to the corresponding agent's service responsible to carry out the underlying business logic.
As mentioned above, Sentilo currently provides two agents:
Relational database agent
This agent stores all information received from PubSub platform into a set of relational databases (the number of relational databases is fully configurable).
It could be configured to filter the data to store according to a business rules through a configuration file.
To do this, when the agent is started it makes a subscription to the desired information in Redis (observations, orders and/or alarms), that has previously been defined in a properties file:
//In this example we indicate to persist any data using a DataSource with srDs identifier, //and also to store any data from provider with PARKING identifier, //on a different DataSource whose identifier is parkingDs. //Finally, we can indicate more than one DataSource destination to persist the same data. data\:PARKING*=parkingDs data\:*=srDs order\:*=srDs alarm\:*=srDs,parkingDs
It is imperative that the DataSources are defined in the context of the agent with the same identifier:
<bean id="srDs" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> ... </bean> <bean id="parkingDs" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> ... </bean>
This context is defined in the file:
This agent processes each internal alert defined in the catalog and publish a notification (a.k.a. alarm) when any of the configured integrity rules are not met.
Due to the type of available rules, this validation process integrity is divided into two threads:
- An internal process that runs every minute, evaluates the status of each sensor that have associated (frozen type) alerts.
- Additionally, each time a Redis notification is received, alerts associated with the data received are evaluated.
Finally, an internal process regularly synchronize the alert list, to synchronize the information stored in memory with the catalog repository.
Activity Monitor agent
This agent subscribes itself to the list of events and uploads them to an ElasticSearch database. More on its configuration and an overview of Sentilo monitoring is on this.
Likewise the Activity Monitor Agent, this module also subscribes itself to the list of events and uploads them to an OpenTSDB database. More on its configuration is on this.