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# Pipeline System
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Pre-built and custom pipeline templates for orchestrating component workflows including QA, search, generation, and indexing pipelines.
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## Core Imports
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```python
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from haystack import Pipeline
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from haystack.pipelines import ExtractiveQAPipeline, GenerativeQAPipeline, DocumentSearchPipeline
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```
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## Base Pipeline
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```python { .api }
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from haystack import Pipeline
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from haystack.nodes.base import BaseComponent
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from typing import Dict, List, Any, Optional
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class Pipeline:
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    def __init__(self):
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        """Initialize an empty pipeline."""
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    def add_node(self, component: BaseComponent, name: str, inputs: List[str]) -> None:
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        """
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        Add a component to the pipeline.
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        Args:
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            component: Component instance to add
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            name: Unique name for the component in pipeline
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            inputs: List of input names this component receives from
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        """
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    def run(self, query: Optional[str] = None, file_paths: Optional[List[str]] = None,
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            labels: Optional[List] = None, documents: Optional[List] = None,
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            meta: Optional[Dict[str, Any]] = None, **kwargs) -> Dict[str, Any]:
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        """
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        Run the pipeline with given inputs.
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        Args:
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            query: Query string for QA/search pipelines
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            file_paths: File paths for indexing pipelines
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            labels: Labels for evaluation pipelines
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            documents: Documents for processing
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            meta: Additional metadata
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        Returns:
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            Dictionary with pipeline results
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        """
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```
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## Extractive QA Pipeline
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```python { .api }
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from haystack.pipelines import ExtractiveQAPipeline
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from haystack.nodes.reader.base import BaseReader
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from haystack.nodes.retriever.base import BaseRetriever
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class ExtractiveQAPipeline(Pipeline):
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    def __init__(self, reader: BaseReader, retriever: BaseRetriever):
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        """
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        Initialize extractive QA pipeline.
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        Args:
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            reader: Reader component for answer extraction
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            retriever: Retriever component for document retrieval
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        """
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```
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## Generative QA Pipeline
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```python { .api }
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from haystack.pipelines import GenerativeQAPipeline
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class GenerativeQAPipeline(Pipeline):
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    def __init__(self, generator, retriever):
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        """
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        Initialize generative QA pipeline.
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        Args:
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            generator: Generator component for answer generation
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            retriever: Retriever component for document retrieval
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        """
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```
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## Document Search Pipeline
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```python { .api }
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from haystack.pipelines import DocumentSearchPipeline
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class DocumentSearchPipeline(Pipeline):
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    def __init__(self, retriever: BaseRetriever):
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        """
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        Initialize document search pipeline.
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        Args:
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            retriever: Retriever component for document search
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        """
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```