This concept gives an overview of IOM server health checks and how they can be used within an HA installation of IOM. The document is mainly addressed to application administration.
Application Programming Interface
|IOM||The abbreviation for Intershop Order Management|
|REST||Representational State Transfer|
|Watchdog||A tool of IOM to monitor and manage the availability of IOM application servers|
An application server is one single application server within a cluster of multiple application servers.
The health status of an application server reflects whether the server is able to adequately fulfill all tasks it is responsible for.
For Intershop Order Management, the status can be requested using the REST API. Additionally, the result will be persisted to the database as part of the cluster status.
The health check includes basic connecting to the database. Further checks, e.g., access to shared file-system is possible.
The main purpose of health status support is to enable server monitoring applications to manage the application cluster, i. e., not to host unhealthy/broken servers and/or to trigger the repair/restart of unhealthy/broken servers.
Especially in the case of HA health checks are required to always ensure a running application.
The IOM provides Watchdog to monitor the application server's health statuses and to control the application server based on this information.
The cluster status reflects the general health status of each application server of a server cluster. Basically, it can be used to give a quick overview of the healthiness of the server cluster.
The cluster status can be requested using REST API which returns the persisted results from the last health status check of each application server.
The REST response for the application server health status will return a status code that reflects the health status and can be used by the server monitoring application.
An additional payload gives detailed information on the processed checks and their results.
To offer the health check for an IOM application server, the artifact
oms.monitoring must be deployed.
The following list describes the current checks that are done by a health check.
|Database||A connection to the database will always be established.||Always performed|
Each performed check will be cached, and subsequent requests are served from that cache as long as the
lastCheck time was not older than the value configured with
Health checks are performed by a Java timer and cannot be triggered by the REST requests. The result will be cached for responding to REST calls.
With this improvement, the signification of the property
is.oms.healthcheck.cachelivetime has changed and
is.oms.healthcheck.recurringtime has been added.
The health check can be extended within
HealthServiceBean.java of artifact
oms.monitoring by adding a new check.
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