Deploying Distributed / Microservice Solutions
The ABP is designed to consider distributed and microservice systems, where you have multiple applications and/or services communicating internally. All of its features are compatible with distributed scenarios. This document highlights some points you should care about when you deploy your distributed or microservice solution.
Application Name & Instance Id
ABP provides the IApplicationInfoAccessor service that provides the following properties:
ApplicationName: A human-readable name for an application. It is a unique value for an application.InstanceId: A random (GUID) value generated by the ABP each time you start the application.
These values are used by the ABP in several places to distinguish the application and the application instance (process) in the system. For example, the audit logging system saves the ApplicationName in each audit log record written by the related application, so you can understand which application has created the audit log entry. So, if your system consists of multiple applications saving audit logs to a single point, you should be sure that each application has a different ApplicationName.
The ApplicationName property's value is set automatically from the entry assembly's name (generally, the project name in a .NET solution) by default, which is proper for most cases, since each application typically has a unique entry assembly name.
There are two ways to set the application name to a different value. In this first approach, you can set the ApplicationName property in your application's configuration. The easiest way is to add an ApplicationName field to your appsettings.json file:
{
"ApplicationName": "Services.Ordering"
}
Alternatively, you can set AbpApplicationCreationOptions.ApplicationName while creating the ABP application. You can find the AddApplication or AddApplicationAsync call in your solution (typically in the Program.cs file), and set the ApplicationName option as shown below:
await builder.AddApplicationAsync<OrderingServiceHttpApiHostModule>(options =>
{
options.ApplicationName = "Services.Ordering";
});
Using a Distributed Event Bus
ABP's Distributed Event Bus system provides a standard interface to communicate with other applications and services. While the name is "distributed", the default implementation is in-process. That means, your applications / services can not communicate with each other unless you explicitly configure a distributed event bus provider.
If you are building a distributed system, then the applications should communicate through an external distributed messaging server. Please follow the Distributed Event Bus document to learn how to install and configure your distributed event bus provider.
Warning: Even if you don't use the distributed event bus directly in your application code, the ABP and some of the modules you are using may use it. So, if you are building a distributed system, always configure a distributed event bus provider.
Info: Clustered deployment of a single application is not considered as a distributed system. So, if you only have a single application with multiple instances serving behind a load balancer, a real distributed messaging server may not be needed.
