Application wide PropertyBag

ServiceStack
1

Is there something like a PropertyBag available that can store application wide values? Something akin to IRequest.Items but across the entire appHost (at HostContext/AppHost level?) rather than per-request?

I’ve had a search and can’t see anything that fits the bill.

We have a number of plugins and we don’t want to have hard dependencies against them but in some instances there is the need to fetch a primitive-type in PluginA that was set by PluginB.

The value is not essential to the functionality of PluginA but if it’s there then it can be used. I was thinking that if there is something like IRequest.Items then PluginA and PluginB would only need to share a common PropertyBag key rather than anything more (such as a DTO type).

If such a thing doesn’t exist what would be the best way to store values that can be shared across plugins? ICacheClient?

2

You can register your own shared type in IOC container in AppHost.Configure and get access to it in Plugins using IAppHost interface. Example: register it in AppHost.cs

public override void Configure(Container container)
{
     .....
   container.Register<SharedType> (new SharedType ());
}

get it in plugin:

public class CustomPlugin : IPlugin
{
     public void Register (IAppHost appHost)
     {
          Container container = appHost.GetContainer();
          SharedType obj = container.Resolve<SharedType>();
          ....
     }
}
3

If you just want to share State registered in your Plugin to make it available to all your Services then you can register an object instance in the IOC as @xplicit has shown.

But if you just want to be able access a different plugin properties you can just get the registered plugin directly from the AppHost.Plugins collection, e.g from within Plugin B:

var pluginA = appHost.GetPlugin<PluginA>();
if (pluginA.HasFeature) {
    //...
}

You can also access plugins anywhere from in or outside of ServiceStack via the HostContext, e.g:

var pluginA = HostContext.GetPlugin<PluginA>();
4

Two other options:

a) Service.LocalCache

b) If you want it at the AppHost level … why not just add it at the AppHost level?

class BigBag : Dictionary<string,object> {}

class FerminAppHost : AppSelfHostBase {
    public BigBag BigBag { get; set; }
}

... elsewhere
var foo = (AppHost.Instance as FerminAppHost).BigBag["foo"];
1 Like
5

We wanted to avoid taking any type dependencies between plugins hence a more indirect approach.

As it turns out, we wanted to pass the discovery registration identifier to the IAppSettings provider but we already have a unique service identifier in the AppHost IP:Port/path so we’re just using that instead.

A nice update for the ConsulAppSettings is coming soon to have fidelity over configuration of a single service > versioned named services > named.services and global. All without touching your running services.

Use what’s OOTB whenever possible :wink:

2 Likes