diff --git a/shared/apc/index.mjs b/shared/apc/index.mjs
new file mode 100644
index 0000000..4fbdd1d
--- /dev/null
+++ b/shared/apc/index.mjs
@@ -0,0 +1,15 @@
+import { Buffer } from 'buffer';
+
+export class AsyncProcedureCallEndpoint {
+	/**
+	 * Constructs an AsyncProcedureCallEndpoint object.
+	 * @param {any} input - stream of data sent by remote.
+	 * @param {any} output - stream of data to send to remote.
+	 */
+	constructor(input, output) {
+		this.buf = Buffer();
+		input.ondata = () => {
+
+		};
+	}
+};
diff --git a/shared/apc/package.json b/shared/apc/package.json
new file mode 100644
index 0000000..1ab705e
--- /dev/null
+++ b/shared/apc/package.json
@@ -0,0 +1,11 @@
+{
+	"name": "@og/async-procedure-call",
+	"type": "module",
+	"main": "index.mjs",
+	"dependencies": {
+		"buffer": "^6.0.3",
+		"@og/error-utils": "file:../error-utils",
+		"@og/uuid": "file:../uuid",
+		"@og/binary-struct": "file:../bstruct"
+	}
+}
\ No newline at end of file
diff --git a/shared/error-utils/index.mjs b/shared/error-utils/index.mjs
index 3357e13..ddc25a3 100644
--- a/shared/error-utils/index.mjs
+++ b/shared/error-utils/index.mjs
@@ -9,3 +9,15 @@ export class VirtualMethodNotImplementedError extends Error {
 		super('virtual method not implemented.');
 	}
 };
+
+/**
+ * Represents an error that is thrown when called a function with invalid arguments.
+ * @class
+ * @extends {Error}
+ */
+export class InvalidArgumentError extends Error {
+	/** @constructor */
+	constructor(name, reason) {
+		super(`argument ${name} is invalid: ${reason}.`);
+	}
+};