From 03e3b002ebf86de5a8d43ce22060cdd17e50d3a2 Mon Sep 17 00:00:00 2001
From: Andrew Brown <andrew.brown@intel.com>
Date: Tue, 13 Aug 2024 15:14:52 -0700
Subject: [PATCH] Remove `set-input`, `get-output`

As discussed in #43, there is no requirement to set up tensors prior to
calling `compute` as well as retrieving them separately afterwards. As
of #59, passing around tensors is cheap (they're resources now), so
there is no data copy necessary if we adopt this PR. This change
proposes removing the `set-input` and `get-output` functions, moving all
of the tensor-passing to `compute`. Closes #43.
---
 ml.md           | 42 +++++++++++-------------------------------
 wit/wasi-nn.wit | 18 ++++++------------
 2 files changed, 17 insertions(+), 43 deletions(-)

diff --git a/ml.md b/ml.md
index bce656f..6aa242d 100644
--- a/ml.md
+++ b/ml.md
@@ -179,49 +179,29 @@ e.g., cannot access a hardware feature requested
 #### <a name="tensor"></a>`type tensor`
 [`tensor`](#tensor)
 <p>
-#### <a name="tensor_data"></a>`type tensor-data`
-[`tensor-data`](#tensor_data)
-<p>
-#### <a name="graph_execution_context"></a>`resource graph-execution-context`
+#### <a name="named_tensor"></a>`tuple named-tensor`
+<p>Identify a tensor by name; this is necessary to associate tensors to
+graph inputs and outputs.</p>
+<h5>Tuple Fields</h5>
+<ul>
+<li><a name="named_tensor.0"></a><code>0</code>: <code>string</code></li>
+<li><a name="named_tensor.1"></a><code>1</code>: own&lt;<a href="#tensor"><a href="#tensor"><code>tensor</code></a></a>&gt;</li>
+</ul>
+<h4><a name="graph_execution_context"></a><code>resource graph-execution-context</code></h4>
 <p>Bind a <a href="#graph"><code>graph</code></a> to the input and output tensors for an inference.</p>
 <h2>TODO: this may no longer be necessary in WIT
 (https://github.com/WebAssembly/wasi-nn/issues/43)</h2>
 <h3>Functions</h3>
-<h4><a name="method_graph_execution_context_set_input"></a><code>[method]graph-execution-context.set-input: func</code></h4>
-<p>Define the inputs to use for inference.</p>
-<h5>Params</h5>
-<ul>
-<li><a name="method_graph_execution_context_set_input.self"></a><code>self</code>: borrow&lt;<a href="#graph_execution_context"><a href="#graph_execution_context"><code>graph-execution-context</code></a></a>&gt;</li>
-<li><a name="method_graph_execution_context_set_input.name"></a><code>name</code>: <code>string</code></li>
-<li><a name="method_graph_execution_context_set_input.tensor"></a><a href="#tensor"><code>tensor</code></a>: own&lt;<a href="#tensor"><a href="#tensor"><code>tensor</code></a></a>&gt;</li>
-</ul>
-<h5>Return values</h5>
-<ul>
-<li><a name="method_graph_execution_context_set_input.0"></a> result&lt;_, own&lt;<a href="#error"><a href="#error"><code>error</code></a></a>&gt;&gt;</li>
-</ul>
 <h4><a name="method_graph_execution_context_compute"></a><code>[method]graph-execution-context.compute: func</code></h4>
 <p>Compute the inference on the given inputs.</p>
-<p>Note the expected sequence of calls: <code>set-input</code>, <code>compute</code>, <code>get-output</code>. TODO: this
-expectation could be removed as a part of
-https://github.com/WebAssembly/wasi-nn/issues/43.</p>
 <h5>Params</h5>
 <ul>
 <li><a name="method_graph_execution_context_compute.self"></a><code>self</code>: borrow&lt;<a href="#graph_execution_context"><a href="#graph_execution_context"><code>graph-execution-context</code></a></a>&gt;</li>
+<li><a name="method_graph_execution_context_compute.inputs"></a><code>inputs</code>: list&lt;<a href="#named_tensor"><a href="#named_tensor"><code>named-tensor</code></a></a>&gt;</li>
 </ul>
 <h5>Return values</h5>
 <ul>
-<li><a name="method_graph_execution_context_compute.0"></a> result&lt;_, own&lt;<a href="#error"><a href="#error"><code>error</code></a></a>&gt;&gt;</li>
-</ul>
-<h4><a name="method_graph_execution_context_get_output"></a><code>[method]graph-execution-context.get-output: func</code></h4>
-<p>Extract the outputs after inference.</p>
-<h5>Params</h5>
-<ul>
-<li><a name="method_graph_execution_context_get_output.self"></a><code>self</code>: borrow&lt;<a href="#graph_execution_context"><a href="#graph_execution_context"><code>graph-execution-context</code></a></a>&gt;</li>
-<li><a name="method_graph_execution_context_get_output.name"></a><code>name</code>: <code>string</code></li>
-</ul>
-<h5>Return values</h5>
-<ul>
-<li><a name="method_graph_execution_context_get_output.0"></a> result&lt;own&lt;<a href="#tensor"><a href="#tensor"><code>tensor</code></a></a>&gt;, own&lt;<a href="#error"><a href="#error"><code>error</code></a></a>&gt;&gt;</li>
+<li><a name="method_graph_execution_context_compute.0"></a> result&lt;list&lt;<a href="#named_tensor"><a href="#named_tensor"><code>named-tensor</code></a></a>&gt;, own&lt;<a href="#error"><a href="#error"><code>error</code></a></a>&gt;&gt;</li>
 </ul>
 <h2><a name="wasi_nn_graph_0_2_0_rc_2024_06_25"></a>Import interface wasi:nn/graph@0.2.0-rc-2024-06-25</h2>
 <p>A <a href="#graph"><code>graph</code></a> is a loaded instance of a specific ML model (e.g., MobileNet) for a specific ML
diff --git a/wit/wasi-nn.wit b/wit/wasi-nn.wit
index 872e8cd..e3580dd 100644
--- a/wit/wasi-nn.wit
+++ b/wit/wasi-nn.wit
@@ -110,25 +110,19 @@ interface graph {
 /// `graph` to input tensors before `compute`-ing an inference:
 interface inference {
     use errors.{error};
-    use tensor.{tensor, tensor-data};
+    use tensor.{tensor};
+
+    /// Identify a tensor by name; this is necessary to associate tensors to
+    /// graph inputs and outputs.
+    type named-tensor = tuple<string, tensor>;
 
     /// Bind a `graph` to the input and output tensors for an inference.
     ///
     /// TODO: this may no longer be necessary in WIT
     /// (https://github.com/WebAssembly/wasi-nn/issues/43)
     resource graph-execution-context {
-        /// Define the inputs to use for inference.
-        set-input: func(name: string, tensor: tensor) -> result<_, error>;
-
         /// Compute the inference on the given inputs.
-        ///
-        /// Note the expected sequence of calls: `set-input`, `compute`, `get-output`. TODO: this
-        /// expectation could be removed as a part of
-        /// https://github.com/WebAssembly/wasi-nn/issues/43.
-        compute: func() -> result<_, error>;
-
-        /// Extract the outputs after inference.
-        get-output: func(name: string) -> result<tensor, error>;
+        compute: func(inputs: list<named-tensor>) -> result<list<named-tensor>, error>;
     }
 }