How to read file changes in azure blob storage?

Question

I am trying to read a file from azure blob storage as byte stream as below:

    public static final String storageConnectionString =
            "DefaultEndpointsProtocol=https;AccountName=*;AccountKey=*;EndpointSuffix=core.windows.net";

    public static void main(String[] args) {
        try {
            CloudStorageAccount storageAccount = CloudStorageAccount.parse(storageConnectionString);
            CloudBlobClient blobClient = storageAccount.createCloudBlobClient();
            CloudBlobContainer container = blobClient.getContainerReference("inputfile");
            CloudBlob blob = container.getBlockBlobReference("test.txt");
            InputStream input =  blob.openInputStream();
            InputStreamReader inr = new InputStreamReader(input, "UTF-8");
            String output = IOUtils.toString(inr);
            System.out.println(output);

            System.out.println("read is success");

        } catch (Exception e) {
            // Output the stack trace.
            e.printStackTrace();
        }
    }

I am able to read the file from azure file storage. I am trying to create something like Java WatchService where if there is any change in file i want read the changes and print data for example below let say i have file test.txt file in blob initially it have data some thing like below

"Hello"

My program should print "Hello".

After some time i will update file with "world", now i want to print only "world" which is a new change in file.

Is it possible in azure blob storage? I saw the API of azure_blob_storage but didn't find any method like java WatchServices. Could you please help me how can i read file changes in azure blob storage?

Thiago Custodio Thiago Custodio · Accepted Answer · 2020-12-18T15:16:30

There's no such service. However, you can use Event Grid which is an event repository, and subscribe to changes in your Azure storage account (new / updates blobs), then, trigger some function (maybe an Azure Function) to return the changes to client.

And here's a step by step how to do it:

https://docs.microsoft.com/en-us/azure/event-grid/blob-event-quickstart-portal

How to read file changes in azure blob storage?

1 Answers