Export an ONNX Model

ONNX model serving with MMS is very simple. You can download a model from the ONNX Model Zoo then use mxnet-model-export to covert it to a .model file.

Note: Some ONNX model authors upload their models to the zoo in the .pb or .pb2 format. Just change the extension to .onnx before attempting an export.

Let's use the SqueezeNet ONNX model as an example. To export a model for MMS, recall that you also need to download or create a signature file, and optionally provide a labels file (synset.txt). So here you will utilize the following three files:

• SqueezeNet ONNX model: a .onnx model file from the ONNX Model Zoo
• signature file: defines the input layer and the outputs
• label file: has the labels for 1,000 ImageNet classes

Create a new directory and download the files:

mkdir onnx-squeezenet && cd onnx-squeezenet
curl -O https://s3.amazonaws.com/model-server/models/onnx-squeezenet/squeezenet.onnx
curl -O https://s3.amazonaws.com/model-server/models/onnx-squeezenet/signature.json
curl -O https://s3.amazonaws.com/model-server/models/onnx-squeezenet/synset.txt

Since the model has the .onnx extension, it will be detected and the managed accordingly using the onnx-mxnet converter. The converter comes preinstalled with MMS v0.2 or later.

Now you can use the typical export command to output onnx-squeezenet.model in the current working directory.

mxnet-model-export --model-name onnx-squeezenet --model-path .

Now start the server:

mxnet-model-server --models squeezenet=onnx-squeezenet.model

After your server starts, you can use the following command to see the prediction results.

curl -X POST http://127.0.0.1:8080/squeezenet/predict -F "input_0=@kitten.jpg"

Note: The data name for ONNX models is input_0 instead of data as with other examples. Make sure you update this in your curl call. The reason is that ONNX models' input layer defaults to input_0, and you can't override this in your signature.json file when you define data_name. You can compare this by looking at the signature file you downloaded for this ONNX example, versus the signature you downloaded for an MXNet model example.