Nodejs Tensorflow Serving Client Error 3

问题

I'm serving a pre-trained inception model, and I've followed the official tutorials to serve it up until now. I'm currently getting an Error Code 3, as follows:

{ Error: contents must be scalar, got shape [305]
  [[Node: map/while/DecodeJpeg = DecodeJpeg[_output_shapes=[[?,?,3]], acceptable_fraction=1, channels=3, dct_method="", fancy_upscaling=true, ratio=1, try_recover_truncated=false, _device="/job:localhost/replica:0/task:0/device:CPU:0"](map/while/TensorArrayReadV3)]]
  at /server/node_modules/grpc/src/client.js:554:15 code: 3, metadata: Metadata { _internal_repr: {} } }

I'm using the prediction_service.proto as it is from Tensorflow Serving's API. Here's my Nodejs file where I define the function:

const PROTO_PATH = "./pb/prediction_service.proto";
const TensorflowServing = grpc.load(PROTO_PATH).tensorflow.serving;

const testClient = new TensorflowServing.PredictionService(
    TF_TEST, grpc.credentials.createInsecure()
);

function getTestModelMsg(val){
    return {
        model_spec: { name: "inception", signature_name: "predict_images", version: 1},
        inputs: {
            images: {
                dtype: "DT_STRING",
                tensor_shape: {
                    dim: [{size: 220}, {size: 305}],
                    unknown_rank: false
                },
                string_val: val
            }
        }
    }
}


function predictTest(array, callback) {
    testClient.predict(getTestModelMsg(array), (error, response) => {
        if(error)
            return callback(error);

    callback(null, response.outputs)
})}

And I'm passing in the image as a binary image as follows:

fs.readFile('./test/Xiang_Xiang_panda.jpg', (err, data) => {
    if(err) {
        return res.json({message: "Not found"});
    }

    predictTest( data.toString('binary') , (error, outputs) => {
        if (error) {
            console.error(error);
            return res.status(500).json({ error });
        }
        res.status(200).json({ outputs });
    })
})

I've been stuck at this for a while so would really appreciate if anyone could help me out here! Any help would be great! Thanks in advance! :)

回答1:

Okay, so I finally managed to crack this. Posting it as an answer here in case someone faces this exact same problem.

So the inception model expects a base64 encoded image:

fs.readFile('./test/Xiang_Xiang_panda.jpg', (err, data) => {
    if(err) {
        return res.json({message: "Not found"});
    }

    predictTest( data.toString('base64') , (error, outputs) => {
        if (error) {
            console.error(error);
            return res.status(500).json({ error });
        }
        res.status(200).json({ outputs });
    })
})

Then looking at the inception_client.py from Tensorflow Serving, I found out the the tensor actually has the shape=[1]. So this makes the getTestModelMsg as:

function getTestModelMsg(val){
return {
    model_spec: { name: "inception", signature_name: "serving_default", version: 1},
    inputs: {
        images: {
            dtype: "DT_STRING",
            tensor_shape: {
                dim: [{size: 1}],
                unknown_rank: false
            },
            string_val: val
        }
    }
}

Hope that helps someone. Goodluck. :)

来源：https://stackoverflow.com/questions/47361889/nodejs-tensorflow-serving-client-error-3

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node.js

tensorflow

tensorflow-serving