Client-side log storage

A server application sends its logs to a log server or to the console. A client application (a desktop or mobile app) often has neither, and it needs to keep its own logs to show them on a diagnostics screen or to let the user export them. The package Arc4u.Diagnostics.Serilog.Sinks.RealmDb provides two Serilog sinks for that, one that keeps the entries in memory and one that stores them in a Realm database, and an ILogStore to read and clear them. They receive the same entries as any other sink of the fluent logging API.

Note

Realm was used by the mobile and desktop clients of earlier Arc4u versions. The package still builds for net10.0 and net11.0, but check the package support matrix before you start a new project with it. For server applications use the console, file or log server sinks described in Serilog.

Install

dotnet add package Arc4u.Diagnostics.Serilog.Sinks.RealmDb --prerelease

The package references Arc4u.Diagnostics.Serilog, Arc4u, Realm and Serilog.Sinks.PeriodicBatching. You also need a Serilog host integration such as Serilog.AspNetCore or Serilog.Extensions.Hosting.

Configuration

These sinks have no configuration section. The only setting is the Realm database, which is a static factory:

Member	Type	Default	Description
`RealmDBExtension.DefaultConfig`	`Func<RealmConfiguration>`	file `loggingDB.realm`, `SchemaVersion = 1`	Creates the Realm configuration used by `WriteTo.RealmDB()` and by `AddRealmDBLog()`. Assign it before you call either.

Both sinks batch the entries: at most 50 entries per batch, a batch every 500 ms (the first entry is written at once), and at most 10,000 entries waiting in the queue.

Common scenarios

Keep the entries in memory

WriteTo.MemoryLogDB() (namespace Arc4u.Diagnostics.Serilog.Sinks.Memory) stores each entry as a LogMessage in the static collection MemoryLogDbSink.LogMessages, a thread-safe MemoryLogMessages: the sink adds entries on a background thread while you read them, and enumerating the collection walks a snapshot. AddMemoryLogDB() registers that collection and an ILogStore over it as singletons.

// Program.cs
using Arc4u.Dependency;
using Arc4u.Diagnostics.Serilog.Sinks;
using Arc4u.Diagnostics.Serilog.Sinks.Memory;
using Serilog;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddILogger();
builder.Services.AddMemoryLogDB();

builder.Host.UseSerilog((context, configuration) => configuration
    .MinimumLevel.Information()
    .WriteTo.MemoryLogDB());

var app = builder.Build();

app.MapGet("/logs", (ILogStore store) => store.GetLogs("", 0, 50));

app.Run();

Logging Technical().Add("OrderId", 42).LogInformation("Order Shipped") and reading the store back gives one LogMessage:

2026-09-29T14:55:29.3585780+02:00 Information Technical Order Shipped {"OrderId":42}

The columns are Timestamp, MessageType, MessageCategory, Message and Properties.

Warning

The collection has no size limit and no eviction. It grows for the life of the process until you call ILogStore.RemoveAll().

Store the entries in a Realm database

WriteTo.RealmDB() (namespace Serilog) writes the entries to a Realm database as LogDBMessage objects. AddRealmDBLog() registers the RealmConfiguration and an ILogStore (RealmLoggingDbCtx) as singletons. A Realm instance can only be used on the thread that opened it, so the store opens one for each call to GetLogs or RemoveAll and closes it before returning. You can call it from any thread, for example from a web endpoint.

using Arc4u.Diagnostics.Serilog.Sinks.RealmDb;
using Realms;
using Serilog;

public static class RealmLogging
{
    public static void Register(WebApplicationBuilder builder, string path)
    {
        // Assign the factory before RealmDB() and AddRealmDBLog(), which both call it.
        RealmDBExtension.DefaultConfig = () => new RealmConfiguration(path) { SchemaVersion = 1 };

        builder.Services.AddRealmDBLog();

        builder.Host.UseSerilog((context, configuration) => configuration
            .MinimumLevel.Information()
            .WriteTo.RealmDB());
    }
}

Reading back an entry logged with realmLogger.Information("realm {A}", 1) gives:

REALM Information Technical realm 1 {"A":1}

Read and clear the entries

Inject ILogStore (namespace Arc4u.Diagnostics.Serilog.Sinks).

Member	Description
`GetLogs(criteria, skip, take)`	Returns a page of `LogMessage`. `criteria` is text that the message must contain, compared without regard to case; an empty value applies no filter.
`RemoveAll()`	Deletes all the stored entries.

The memory store returns the entries in the order they were written. The Realm store returns the most recent first. A LogMessage has the properties Timestamp, MessageCategory, Message, MessageType (the LogLevel name), ClassType, MethodName, ThreadId, ProcessId, Application, Identity, ActivityId, Stacktrace and Properties (the non-standard properties as a JSON object).

using Arc4u.Diagnostics.Serilog.Sinks;

public class LogPage(ILogStore store)
{
    public List<LogMessage> Latest() => store.GetLogs("", 0, 50);

    public void Clear() => store.RemoveAll();
}

Extensibility points

ILogStore and the sinks are independent of each other. Register your own ILogStore to read from another store, or write your own Serilog sink with the Arc4u helper.

Troubleshooting

A Realm page holds fewer entries than requested

With a criteria, RealmLoggingDbCtx.GetLogs skips skip entries, then looks at the next take entries and returns those that match. A page can therefore hold fewer than take entries even when more entries match further on.

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