GLLM Core v0.3 to v0.4

Adding Custom Components

Overview

The Component API now supports an explicit main entrypoint via the @main decorator, with a resolver that determines which method to execute when calling run(). The legacy _run method remains supported as a fallback but is deprecated.

Resolution precedence for the main entrypoint:

1. Most derived method decorated with @main.

2. Method named by the __main_method__ class property.

3. Legacy _run method (deprecated fallback).

The input-parameter model (input_params) is generated from the resolved main method signature for the class.

Defining the main method (new)

1. Decorate an async instance method with @main.

2. Only one @main method per class is allowed.

3. If multiple ancestors define different @main methods, a TypeError is raised unless the subclass explicitly overrides with its own @main.

4. The __main_method__ class property is still supported but has lower precedence than @main. If both are present, a warning is logged and the decorator takes precedence.

5. The main method must be asynchronous.

Example:

import logging
from gllm_core.schema.component import Component, main

class MyComponent(Component):
    _default_log_level = logging.INFO

    @main
    async def execute(self, text: str) -> str:
        return text.upper()

Migrating from the old Component

If your component previously implemented _run, you should migrate to the new @main decorator pattern.

Recommended: Direct Migration (Remove _run)

Rename _run to a meaningful method name and apply @main:

from gllm_core.schema.component import Component, main

class MyComponent(Component):
    @main
    async def execute(self, text: str) -> str:
        """Process the input text."""
        return text.upper()

Benefits:

1. Full compatibility with as_tool() for LLM tool conversion

2. Clean, explicit signature for input_params validation

3. Future-proof (follows framework intent)

Breaking Changes:

1. Any code directly calling _run() must be updated to call the new method or use run()

2. If used in a Pipeline, the run_profile may be inconsistent until the framework is updated (see note below)

Pipeline Note: As of GLLM Pipeline v0.4.28, the run_profile implementation which analyzes _run for static input validation is still used. If you rely heavily on Pipeline and encounter input routing issues, you may need to temporarily keep _run as a stub or override _analyze_run_method() until the core framework is updated.

Alternative: Preserve Validation/Adapter Logic

If your _run method contains important validation or acts as an adapter (e.g., extracting specific keys from **kwargs), use this pattern:

from gllm_core.schema.component import Component, main
from gllm_core.schema import Chunk

class MyChunkProcessor(Component):
    @main
    async def execute(self, chunks: list[Chunk]) -> list[Chunk]:
        """Execute chunk processing with validation."""
        # Move validation from _run to here
        if not isinstance(chunks, list) or not all(isinstance(c, Chunk) for c in chunks):
            raise ValueError("chunks must be a list[Chunk]")
        
        return await self.process_chunks(chunks)
    
    async def process_chunks(self, chunks: list[Chunk]) -> list[Chunk]:
        """Process the chunks (implement in subclass)."""
        raise NotImplementedError
    
    # Optional: Keep _run temporarily for backwards compatibility
    async def _run(self, **kwargs):
        """Deprecated: Use execute() instead."""
        return await self.execute(**kwargs)

Benefits:

• Preserves validation logic at the entry point

• Maintains clean separation between validation and business logic

• Full compatibility with as_tool() and input_params

Trade-offs:

• Requires more refactoring than direct migration

• Need to update subclasses if they override _run

Avoid: Decorating _run with @main

Do not simply add @main to your existing _run method:

# ❌ DON'T DO THIS
class MyComponent(Component):
    @main
    async def _run(self, text: str) -> str:
        return text.upper()

Why this breaks:

• as_tool() explicitly rejects _run as the main method (raises RuntimeError)

• Keeps the deprecated method name, defeating the purpose of migration

• Not future-proof when _run is eventually removed

Backward compatibility (non-migrated components)

• Components that only implement _run continue to work. The resolver falls back to _run and logs a deprecation warning recommending the @main decorator.

• input_params continues to be generated from _run in this case, so existing pipelines keep working.

• If both @main and __main_method__ are defined, a warning is emitted and the decorator wins.

Multiple inheritance considerations

• If two different ancestors define different @main methods and the subclass does not explicitly override them, a TypeError is raised at resolution time.

• To resolve, explicitly define a @main method in the subclass to choose the desired entrypoint.

Example resolution:

class A(Component):
    @main
    async def a(self): ...

class B(Component):
    @main
    async def b(self): ...

class C(A, B):
    @main
    async def choose(self): ...  # Explicit override resolves the conflict

Troubleshooting

1. TypeError: "Main method '...' must be asynchronous" — ensure the method decorated with @main is async def.

2. TypeError: "Multiple main methods defined in X" — only one @main per class is allowed.

3. TypeError about conflicting main methods across ancestors — add a @main method in the subclass to explicitly resolve.

Notes and best practices

1. Prefer an async instance method for the main entrypoint. Avoid using @staticmethod or @classmethod with @main.

2. Keep the main method signature representative of the inputs you expect; input_params will be generated from it.

3. You do not need to document run_profile or input_params in your component’s docstring; these are derived and consumed by the pipeline.

Disabling Timeout with Retry Config

When defining a RetryConfig object, setting the timeout attribute to 0.0 will previously cause the timeout to be disabled. Now, setting it to 0.0 will raise an error. Instead, set it to None to disable timeout.

Disabling Timeout Example (v0.3) — Will Raise Error in v0.4

from gllm_core.utils import RetryConfig

retry_config = RetryConfig(timeout=0.0)

Disabling Timeout Example (v0.4)

from gllm_core.utils import RetryConfig

retry_config = RetryConfig(timeout=None)

Data Event Type Removal

The data event type is removed from the EventType constant. The special handling of the data event type across event handlers are also removed. This is a result of the simplification of the emitted event schema. For example, if a thinking event was previously formatted as such:

{
    "type": "data",
    "value": '{"data_type": "thinking", "value": "I'm thinking!"}',
    ...
}

Now, it should be simplified as such:

{
    "type": "thinking",
    "value": "I'm thinking!",
    ...
}