Developing Blockifiers#

To develop a blockifier, first follow the instructions in Developing Plugins to create a new plugin project. This will result in a full, working plugin scaffold that you could deploy and use immediately.

Then, read below details about how to modify that scaffold for your own needs.

The Blockifier Contract#

Blockifiers are responsible for transforming raw data into Steamship Block Format. Using our SDK, that means implementing the following method:

class MyBlockifier(Blockifier):
    def run(
       self, request: PluginRequest[RawDataPluginInput]
    ) -> Union[

How to Structure Blocks and Tags#

The biggest design question you will face when implementing a blockifier is how to structure your blocks and tags.

At the platform level, we leave this open-ended on purpose, but we do encourage a few conventions of common convergence.

See the Data Model section for a discussion of how to think effectively about blocks and tags.

Synchronous Example: A Pseudo-Markdown Blockifier#

A trivial implementation of this contract would be a pseudo-Markdown blockifier.

Let’s say this blockifier assumes the input data is UTF-8, assumes that empty new lines represent paragraph breaks. You could implement such a blockifier with this following code:

class PretendMarkdownBlockifier(Blockifier):
    def run(self, request: PluginRequest[RawDataPluginInput]) -> Union[PluginRequest[BlockAndTagPluginOutput], BlockAndTagPluginOutput]:
        # Grab the raw bytes.
        text =

        # Decode it as UTF-8
        if isinstance(text, bytes):
            text = text.decode("utf-8")

       # Split it into paragraphs based on a double newline
       paragraphs = data.split("\n\n")

       # Create a block for each paragraph and add a tag marking it as a paragraph
       blocks = [
         Block.CreateRequest(text=paragraph, tags=[
             Tag.CreateRequest(kind="my-plugin", name="paragraph")
         ]) for paragraph in paragraphs

       # Return a BlockAndTagPluginOutput object
       return BlockAndTagPluginOutput(file=File.CreateRequest(blocks=blocks))

From the standpoint of the Steamship Engine, this PretendMarkdownBlockifier now provides a way to transform any bytes claiming to be of this pseudo-markdown type into Steamship Block Format.

Asynchronous Blockifiers#

Some blockifiers will need to call third-party APIs that are asynchronous. Image-to-text (OCR) and speech-to-text (S2T) are two common examples. When this occurs, you should make your blockifier asynchronous as well.

See the Developing Asynchronous Plugins section for details.