Hot deployment of packages is the process of seamlessly upgrading custom packages in Integration Server in a production environment while ensuring that the Integration Server assets are available for processing without any noticeable downtime. Integration Server supports hot deployment of packages using Integration Server Administrator as well as Deployer.

When you deploy a new version of a package, Integration Server unloads the existing package information from memory and loads new versions of the package and its contents into its memory. While the package is being upgraded, it is possible that some assets might be unavailable for some time and this could cause serious issues such as denial of service or disrupt the in-flight tasks. Hot deployment of packages ensures that the packages are available at all times, thus, ensuring that there is no downtime, which is crucial in a production environment.

Traditionally, to upgrade the packages in an Integration Server cluster without shutting down the entire cluster, a rolling quiesce and upgrade process is used. During the rolling upgrade of a cluster, each Integration Server in the cluster is individually quiesced, upgraded, and restarted while the other servers in the cluster continue to process the requests. The limitation with this approach is that while Integration Server is quiesced, all the external ports are disabled and Integration Servers will not be in a state to process requests or execute services. Hot deployment of packages makes it easier to deploy packages without having to quiesce each Integration Server. In case of hot deployment, only the assets that are part of or dependent on the packages being deployed are affected and not the entire server. However, quiesce mode in Integration Server is essential to perform tasks such as installing fixes and performing other maintenance tasks.