Downloading Files via Java SDK in response to Instructions

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This document describes the file download mechanism on the edge via the Java SDK. This download can be triggered from the platform by means of an instruction. More details on how to achieve this are provided below

Generate a new ssh key pair

In case you have not done it already, you should generate a ssh key pair using instructions given in this document.

Once you are done, share the public key with the Altizon team so that they can add access for you. Note that you do not need to share the private key.

Download latest Java SDK

Next, download the latest Java SDK and make it ready for your use.

Apart from the Standard configuration mentioned in the steps that come with the SDK, you will need to do following changes in addition to those:

Keep sftp details handy

You will need to have following inputs

  • username to access the sftp server
  • path to a file containing the host information (known hosts file) for
  • path to a file containing the private key part from the key pair you generated for

In case you are using Windows and you do not know how to generate the host information file, you may want to try following unix command on a Unix box:

ssh-keyscan -t rsa >> ~/.ssh/fs_known_hosts

Alternatively, you can get it from Altizon team

Specifying configuration in the

Add following lines into your properties file

"protocol": "mqtts",
"ssh_host": "",
"ssh_username": "< your ssh username >",
"ssh_known_hosts_path": "< path to known hosts file>",
"ssh_private_key_path": "< path to private key file>"

Sample download program

There is a new sample that showcases the mechanism to download files via an instruction handler: SampleAgentWithDownload. Modify it with thing keys corresponding to your things.

There is a special instruction handler (setupBiDirectionalCommunication) in this program that contains code to download files dynamically as per specified instruction. You may want to customize this logic (download path etc.) as per your needs. You may event want to add logic to restart services etc. within this handler.

Creating an Instruction on cloud

Now, you need to create an instruction on the cloud that indicates the path to download a file.

In the instructions section create a new instruction as per screenshot below:


Note that the path has forward slashes replaced by pipe notation. This is a temporary workaround due to a known issue on the platform

Executing the instruction

Once you have defined the instruction, you can then try executing it against the thing configured in your SDK.

This should trigger the download of the file at the required location