Migration from xml to json

[Cong Huan Nguyen]

Hello guys,

we recently updated to blockly 9.1.1 and we used to save our workspaces/blocks in xml format.

Now, we want to change our database from xml format to json format. Is there any way convert the existing xml code to json format?

I'd use a script which runs through our databases but I could not find any function which converts xml to json in the blockly documentation.

Did someone went through this migration?

Thanks and kind regards

Nguyen

[Beka Westberg]

Hello!

You can convert XML to JSON by running it through a headless workspace.

Eg:

```

const workspace = new Blockly.Workspace();

Blockly.Xml.domToWorkspace(getMyXml(), workspace);

const json = Blockly.serialization.workspaces.save(workspace);

storeMyJson(json);

```

I hope that helps! If you have any further questions please reply =)

--Beka

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[Dummy PG]

@OP/@Beka,

Is JSON faster than XML in terms of de/serialization?  I wonder if JSON takes less overhead than XML?
Reason for asking is that we currently use XML and its quite slow to load xml -> textToDom -> domToWorkspace
Takes about ~15s to load ~4K blocks, this is on i7/3060 gaming laptop btw.

[ewpa...@gmail.com]

App Inventor is also interested in this process and I expect we will collect some data before/after to see how it goes. My understanding at least is that DOM interactions are fairly slow whereas manipulating JSON objects is pretty well optimized. The JSON payload should also in theory be smaller due to not having to repeat the closing tags, so there is less data to download and process as a result.

Hopefully that helps.

Cheers,

Evan

[Christopher Allen]

 Hello,

Is JSON faster than XML in terms of de/serialization?  I wonder if JSON takes less overhead than XML?
Reason for asking is that we currently use XML and its quite slow to load xml -> textToDom -> domToWorkspace
Takes about ~15s to load ~4K blocks, this is on i7/3060 gaming laptop btw.

I'm not sure we've actually benchmarked this (and the colleague who would know is on holiday at the moment), and of course it's going to be highly dependent on the speed of the implementation of the underlying JS APIs (which will vary from platform to platform) but I would be surprised if the JSON implementation was not at least somewhat faster than XML in most cases.

App Inventor is also interested in this process and I expect we will collect some data before/after to see how it goes.

I hope you will share this; we'd be most interested as I am sure would many other developers.

 

My understanding at least is that DOM interactions are fairly slow whereas manipulating JSON objects is pretty well optimized. The JSON payload should also in theory be smaller due to not having to repeat the closing tags, so there is less data to download and process as a result.

It is also worth considering that what we describe as the JSON serializer is actually only a converter that encodes Blockly data in the form of Plain Old JavaScript Objects in a way that is compatible with JSON.serialize, so if  ultimate performance is the goal you may be able to get faster (de)serialisation—and smaller data size—by substituting a different object-to-bytestream serializer, such as MessagePack, for JSON.serialize / .parse.

Best wishes,

Christopehr