soapbar

A SOAP library for Python — client, server, and WSDL handling.

soapbar implements SOAP 1.1 and 1.2 with all five binding styles, auto-generates WSDL from Python service classes, parses existing WSDL to drive a typed client, and integrates with any ASGI or WSGI framework via thin adapter classes. The XML parser is hardened against XXE attacks using lxml with resolve_entities=False.

Conformance — soapbar ships with an internal conformance suite of 116 tests across 11 spec-mapped classes (tests/audit/test_compliance.py) covering SOAP 1.1/1.2, WSDL 1.1, and WS-I Basic Profile 1.1 — including the WS-I BSP X.509 token profile — and the gaps found by earlier internal audits; all pass. This is a self-administered test suite, not an independent third-party audit.

Documentation

Full documentation lives at hitoshyamamoto.github.io/soapbar — quick start, client and server guides, WS-Security, MTOM, real-world service clients, architecture, and more.

Installation

pip install soapbar              # core + server + WSDL (lxml only)
pip install soapbar[client]      # + httpx for the HTTP client
pip install soapbar[security]    # + signxml + cryptography (XML Sig/Enc, mutual TLS)
pip install soapbar[all]         # everything (client + security)

Or with uv:

uv add soapbar
uv add "soapbar[client]"
uv add "soapbar[security]"
uv add "soapbar[all]"

Optional contrib extras install typed clients for real-world services: soapbar[vies], soapbar[witsml], soapbar[ana], soapbar[nfe] — see Real-world services.

Quick start — server

# app.py
from soapbar import SoapService, soap_operation, SoapApplication, AsgiSoapApp


class CalculatorService(SoapService):
    __service_name__ = "Calculator"
    __tns__ = "http://example.com/calculator"

    @soap_operation()
    def add(self, a: int, b: int) -> int:
        return a + b

    @soap_operation()
    def subtract(self, a: int, b: int) -> int:
        return a - b


soap_app = SoapApplication(service_url="http://localhost:8000")
soap_app.register(CalculatorService())

app = AsgiSoapApp(soap_app)
# Run: uvicorn app:app --port 8000
# WSDL: GET http://localhost:8000?wsdl

Mounting inside FastAPI/Flask, defining services, and binding styles are covered in the Quick start docs.

Quick start — client

Drive a typed client from an existing WSDL:

from soapbar import SoapClient

client = SoapClient(wsdl_url="http://localhost:8000?wsdl")
result = client.service.add(a=3, b=5)     # or client.call("add", a=3, b=5)

Async (await client.call_async(...)), WSDL-less SoapClient.manual(...), mutual TLS (HttpTransport(client_cert=..., ca_bundle=...), load_pkcs12(...)), and session cookies are covered in the Client docs.

Features

• SOAP 1.1 and 1.2 with all 5 WSDL/SOAP binding style combinations; version auto-detected, fault codes auto-translated
• SOAP server for any ASGI or WSGI framework (AsgiSoapApp / WsgiSoapApp), plus a sync and async WSDL-driven client
• Auto-generates WSDL from service classes and parses existing WSDL — no config files needed
• Hardened by default: XXE-safe lxml parser, SSRF guard on wsdl:import, message size and nesting depth limits, error scrubbing
• Continuously assured: CodeQL static analysis and property-based tests (Hypothesis) on every pull request, coverage-guided fuzzing (Atheris) weekly; holds the OpenSSF Best Practices passing badge
• WS-Security: UsernameToken (PasswordText/PasswordDigest), XML Signature (incl. Id-targeted SEFAZ NF-e profile), AES-256-GCM XML Encryption, WS-I BSP X.509 token profile
• MTOM/XOP binary attachments on both client and server
• Mutual TLS with PKCS#12 helper, session cookies, WS-Addressing 1.0, one-way MEP, opt-in WSDL schema validation
• XSD type registry (27 built-in types), complex types, SOAP arrays, multi-reference encoding
• Optional typed clients for real-world services: EU VIES, WITSML, SEFAZ NF-e, ANA (soapbar.contrib.*)
• Interoperable with zeep and spyne (the spyne suite runs on Python ≤ 3.11 — upstream spyne does not import on 3.12+); fully type-annotated (PEP 561); Python 3.10 – 3.14

Links

• Documentation
• Security — hardened parser, WS-Security, XML Signature and Encryption
• Security assurance case — threat model, trust boundaries, residual risk
• Security policy — private vulnerability reporting, supported versions, response times
• Verifying a release — Sigstore provenance and SBOM
• Real-world services — VIES, NF-e, WITSML, ANA, IRS MeF
• Comparison with alternatives — zeep, spyne, fastapi-soap, and why most other Python SOAP libraries are no longer actively released
• Stability policy — public surface, SemVer, deprecation process
• Roadmap — what is planned, and what is deliberately not
• Governance — decision model, roles, continuity

Sponsoring

soapbar is maintained by a single developer. If your organization depends on it — or on SOAP integrations with services such as VIES, NF-e, WITSML, or ANA — consider sponsoring its maintenance:

• GitHub Sponsors
• The repository publishes a machine-readable funding manifest for the FLOSS/fund directory

License

Apache License 2.0 — see LICENSE and NOTICE.