Merge pull request #112 from make-software/ces-parser-example

Added example of using CES Parser with SSE stream

Author: davidatwhiletrue

Casper.Network.SDK/CES/CESEvent.cs

@@ -40,6 +40,7 @@ public class CESEvent
         /// The key in the global state that stores the event (dictionary item)
         /// Set by <see cref="CESParser.GetEvents"/>; <c>null</c> when parsed in isolation.
         /// </summary>
+        [JsonConverter(typeof(GlobalStateKey.GlobalStateKeyConverter))]
         public GlobalStateKey TransformKey { get; init; }
 
         /// <summary>

Docs/Articles/CasperEventStandard.md

@@ -244,3 +244,7 @@ if (buyEvent != null)
 var json = JsonSerializer.Serialize(events);
 Console.WriteLine(json);
 ```
+
+## Parsing CES events in the SSE stream
+
+See `Docs/Examples/CESParser/Program.cs` for a runnable sample that connects to the node SSE stream, listens to `TransactionProcessed` events, and pretty-prints parsed CES events.

Docs/Examples/CESParser/CESParser.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\..\Casper.Network.SDK\Casper.Network.SDK.csproj" />
+    </ItemGroup>
+
+</Project>

Docs/Examples/CESParser/Program.cs

@@ -0,0 +1,106 @@
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Threading.Tasks;
+using Casper.Network.SDK;
+using Casper.Network.SDK.CES;
+using Casper.Network.SDK.SSE;
+
+namespace Casper.NET.SDK.Examples
+{
+    public static class CESParserExample
+    {
+        private static string nodeAddress = "http://127.0.0.1:11101/rpc";
+        private static string sseHost = "127.0.0.1";
+        private static int ssePort = 18101;
+
+        private static NetCasperClient casperSdk;
+        private static IReadOnlyList<CESContractSchema> watchedSchemas;
+
+        public static void ListenEvents(int startFrom)
+        {
+            var sse = new ServerEventsClient(sseHost, ssePort);
+
+            sse.AddEventCallback(
+                EventType.TransactionProcessed,
+                "ces-parser-cb",
+                (SSEvent evt) =>
+                {
+                    try
+                    {
+                        var transaction = evt.Parse<TransactionProcessed>();
+                        var events = CESParser.GetEvents(
+                            transaction.ExecutionResult.Effect,
+                            watchedSchemas);
+
+                        Console.WriteLine("TransactionProcessed: " + transaction.TransactionHash);
+
+                        if (events.Count == 0)
+                            return;
+
+                        foreach (var parsedEvent in events)
+                        {
+                            Console.WriteLine("CES event:");
+                            Console.WriteLine(PrettyPrintEvent(parsedEvent));
+                        }
+                    }
+                    catch (Exception e)
+                    {
+                        Console.WriteLine(e);
+                    }
+                },
+                startFrom: startFrom);
+
+            sse.StartListening();
+
+            Console.WriteLine("Listening to TransactionProcessed events.");
+            Console.WriteLine("Press Enter to stop listening.");
+            Console.ReadLine();
+            Console.WriteLine("Terminating...");
+
+            sse.StopListening().Wait();
+
+            Console.WriteLine("Terminated");
+        }
+
+        public static async Task Main(string[] args)
+        {
+            var contractHash = args.Length > 0
+                ? args[0]
+                : "hash-1262d06e53125ea098187fb4d1d5b10a7afed48e5e5eef182ed992fc5b100349";
+
+            try
+            {
+                casperSdk = new NetCasperClient(nodeAddress);
+
+                Console.WriteLine("Loading CES schema for contract: " + contractHash);
+                var schema = await CESContractSchema.LoadAsync(casperSdk, contractHash);
+                watchedSchemas = new List<CESContractSchema> { schema };
+
+                Console.WriteLine("Resolved contract hash : " + schema.ContractHash);
+                Console.WriteLine("Schema events URef     : " + schema.EventsURef);
+                Console.WriteLine("Event types:");
+                foreach (var eventSchema in schema.Events)
+                {
+                    Console.WriteLine("- " + eventSchema.Key);
+                }
+
+                ListenEvents(0);
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine(e);
+            }
+        }
+
+        private static string PrettyPrintEvent(CESEvent evt)
+        {
+            var options = new JsonSerializerOptions()
+            {
+                WriteIndented = true,
+            };
+
+            return JsonSerializer.Serialize(evt, options);
+        }
+    }
+}