# Application Management Microservices-based architecture is replacing legacy monolithic applications in the industry. This helps to break down a huge monolithic application into a discrete set of services (also called micro-services) that can talk to each other through APIs. Spinnaker's application management feature helps to manage these services across various cloud platforms. Regardless of the cloud architecture of each individual cloud platform, they are referred to as: * [**Server Groups**](#server-groups) * [**Clusters**](#clusters) * [**Applications** ](#applications) * [**Load Balancer**](#load-balancer) * [**Firewall**](#firewall) ### **Server Groups** The basic unit of an application, The server group is the target environment in which the code is deployed, such as a virtual machine, cloud, or Docker image. Also considers basic configurations like metadata, number of instances, etc. A server group becomes a collection of instances of the currently running software after it is deployed. ### **Clusters** Clusters are logical collections of server groups in Spinnaker**.** ### **Applications** An application is a collection of clusters including firewalls and load balancers. It also includes the specific service which is to be deployed, all the configurations of that service and all the necessary infrastructure on which the service will run. ### Load Balancer Load balancers are responsible for maintaining traffic balance among instances in server groups. Also can enable health checks along with defined health criteria and the health check point. A load balancer is always connected with an ingress protocol and port range. ### Firewall A firewall is a set of rules defined by an IP address range (CIDR) accompanied by a communication protocol and a port range. ![](https://lh5.googleusercontent.com/22_jaQIRdHZYWCHi1VOydpiyrWBuZwZDhqrm6t_OUIiDLHFYcuMUpSGodrFRtDCjhEeALODU3D258r7twGn8HADyd_gN41uHW6DPGYDO0g_OXTKefFQwCDGTvrWY4puFmO7sAzw2) Take note of the following in the image above: * Both Applications 1 and 2 are cluster collections. * Each cluster is a collection server group. * The Load Balancer controls the traffic for server groups 1 and 2. * The firewall controls the communication using a set of rules and protocols. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.opsmx.com/opsmx-1/opsmx-context-engine/opsmx-intelligent-software-delivery-isd-platform-spinnaker/orchestration-module-opsmx-enterprise-for-spinnaker-oes/oes-concepts/application-management.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.