Service Task

The Service Task extracts content from a http service.

Example

The following shows a simple example using this task as part of a workflow.

from txtai.workflow import ServiceTask, Workflow
workflow = Workflow([ServiceTask(url="https://service.url/action)])
workflow(["parameter"])

Configuration-driven example

This task can also be created with workflow configuration.

workflow:
  tasks:
    - task: service
      url: https://service.url/action

Methods

Python documentation for the task.

Source code in txtai/workflow/task/base.py

def __init__(
    self,
    action=None,
    select=None,
    unpack=True,
    column=None,
    merge="hstack",
    initialize=None,
    finalize=None,
    concurrency=None,
    onetomany=True,
    **kwargs,
):
    """
    Creates a new task. A task defines two methods, type of data it accepts and the action to execute
    for each data element. Action is a callable function or list of callable functions.
    Args:
        action: action(s) to execute on each data element
        select: filter(s) used to select data to process
        unpack: if data elements should be unpacked or unwrapped from (id, data, tag) tuples
        column: column index to select if element is a tuple, defaults to all
        merge: merge mode for joining multi-action outputs, defaults to hstack
        initialize: action to execute before processing
        finalize: action to execute after processing
        concurrency: sets concurrency method when execute instance available
                     valid values: "thread" for thread-based concurrency, "process" for process-based concurrency
        onetomany: if one-to-many data transformations should be enabled, defaults to True
        kwargs: additional keyword arguments
    """
    # Standardize into list of actions
    if not action:
        action = []
    elif not isinstance(action, list):
        action = [action]
    self.action = action
    self.select = select
    self.unpack = unpack
    self.column = column
    self.merge = merge
    self.initialize = initialize
    self.finalize = finalize
    self.concurrency = concurrency
    self.onetomany = onetomany
    # Check for custom registration. Adds additional instance members and validates required dependencies available.
    if hasattr(self, "register"):
        self.register(**kwargs)
    elif kwargs:
        # Raise error if additional keyword arguments passed in without register method
        kwargs = ", ".join(f"'{kw}'" for kw in kwargs)
        raise TypeError(f"__init__() got unexpected keyword arguments: {kwargs}")

Adds service parameters to task. Checks if required dependencies are installed.

Parameters:

Source code in txtai/workflow/task/service.py

def register(self, url=None, method=None, params=None, batch=True, extract=None):
    """
    Adds service parameters to task. Checks if required dependencies are installed.
    Args:
        url: url to connect to
        method: http method, GET or POST
        params: default query parameters
        batch: if True, all elements are passed in a single batch request, otherwise a service call is executed per element
        extract: list of sections to extract from response
    """
    if not XML_TO_DICT:
        raise ImportError('ServiceTask is not available - install "workflow" extra to enable')
    # pylint: disable=W0201
    # Save URL, method and parameter defaults
    self.url = url
    self.method = method
    self.params = params
    # If True, all elements are passed in a single batch request, otherwise a service call is executed per element
    self.batch = batch
    # Save sections to extract. Supports both a single string and a hierarchical list of sections.
    self.extract = extract
    if self.extract:
        self.extract = [self.extract] if isinstance(self.extract, str) else self.extract