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Libraries for processing ebCore CPPA version 3 documents

Project description

A package to process ebCore CPPA3 documents.


The CPPA3 package provides a collection of Python modules to process OASIS ebCore CPPA3 documents and related functionality. CPPA3 is version 3 of the ebXML Collaboration Protocol Profile and Agreement specification. A CPP is an XML document representing a party’s technical and business collaboration capabilities. A CPA is an XML document representing the agreed collaboration parameters of two parties. It can be used to configure B2B messaging systems used to exchange messages between two parties using the agreed settings. The ebCore Technical Committee (ebXML Core) is maintaining and enhancing the CPPA specification.

The development of this package tracks the development of the ebCore CPPA3 schema and specification. This release of the package is compatible with:

Those versions of the specification and schema support:

Currently, eight modules are provided:

  • provides functionality to automatically form a CPA from two CPPs.

  • provides functionality to match a CPA with a CPP it is based on

  • allows CPPs or CPAs that reference “ChannelProfile” to pull in defaults specified for those profiles

  • provides functionality to generate a (set of) P-Modes from a CPA.

  • cppa23 is a new module that converts v2 CPP or CPA documents to the version 3 schema.

  • has utilities to work with the CPPA3 schema.

  • provides functionality to map between CPP3 and SMP XML.

  • provides functionality to create a view on a CPP for a particular viewer.

An earlier version of this library include an incomplete experimental module that converts a subset of v3 CPAs to version 2.0 CPA. But ability to upconvert seems to make more sense, so this module is no longer maintained.

As the CPPA3 schema is still under development, it may change in backward-incompatible ways, and this library will be updated accordingly.

Both Python 2.7.* and CPython 3.7.1 are supported.

This module defines a single function:

  • unify.

This function operates on two CPP XML documents, parsed into element trees using the Python lxml library, and returns a CPA, if one exists. If no CPA can be created, a UnificationException is thrown instead.

Internally in the module, the unify function instantiates an object of the CPABuilder class, and invokes the unify method of that object with the specified CPP documents. CPA formation is similar to unification in logic programming and involves exploring many (successful or unsuccessful) paths, possibly repeatedly. The unify function memoizes partial search results, and the class provides data structures to locally store those results (which are specific to the two input CPPs and therefore not useful in other contexts). The purpose of memoization is to some extent optimization, but also keeps the logging human-readable.

This function could be used by one of the two parties in data exchange, or a third party management service provider, to create a configuration for the exchange that is compatible with the profiles of the individual parties.

This module defines a single function

  • match

This function takes a CPA and a CPP and determines whether the CPA matches the CPP. A CPA matches a CPP if it could have been derived from it by unifying it with some other (unspecified) CPP. This means that one of the two parties in the CPA relates to the party in the CPP. Also, all other structures, such as service and action bindings, channels, transport etc. all need to be linkable to a structure in the CPP. As in unification, presented party certificates can be checked against specified trust anchor sets.

This function could be used by a party to verify, before accepting it, that a presented CPA (possibibly created by a communication partner or by a third party service provider) is compatible with its own configuration, whether related to networking, messaging, security, business content or process.

This module defines a ChannelProfileHandler class, which has two main methods:

  • load_profile_config

This method loads XML files containing definitions of Channels with a ChannelProfile element. The other content is interpreted as default values for that profile.

  • apply_profile_config

This method processes a CPP or CPA file and adds, for each Channel with a configured ChannelProfile, the relevant defaults. The CPP or CPA can override these values.

This module provides a basic automated conversion from CPPA2 to CPPA3.

  • cpp23

This function converts an lxml.etree.Element or lxml.etree.ElementTree representing a version 2 CollaborationProtocolProfile document to a version 3 CPP document. Since there is no counterparty role information in a version 2 document, the counterparty role is set to a default role value.

  • cpa23

This function converts an lxml.etree.Element or lxml.etree.ElementTree representing a version 2 CollaborationProtocolAgreement document to a version 3 CPA document.

It supports the full CollaborationRole hierarchy, with HTTP and SMTP transport, signing, encryption, reliable messaging, and partial support for packaging. It supports asynchronous user messages and asynchronous or synchronous signals. Nested CanSend and CanReceipt structures are not supported, only flat action bindings.

Version 2 packaging is supported, provided the document references the ebXML header as a Constituent in a Composite element that is the last item in a CompositeList. For the payload parts, PayloadProfile elements are generated and SOAPWithAttachmentsEnvelope elements that reference the related payload parts. This function is tested for (minor variants of) the samples provided in the CPPA2 standard, and for an anonimized large real-life sample.

An earlier version of this library included a module that downconverted v3 to v2. As upconversion makes more sense, this module is now deprecated. It is still included in the library but should not be used as it was incomplete.

This module defines the following functions:

  • load_pmodes_from_cpa

  • validate_pmode

The load_pmodes_from_cpa function operates on a CPA document and returns a list of processing modes. Using optional parameters, the function can be restricted to processing modes involving a particular named or identified party. If partyname is specified, it will skip any definitions not involving a party with that name. If partyid is specified, it will skip any definitions not involving a party with that name.

The validate_pmode function operates on list of processing modes and validates this list against a JSON schema for processing modes that is part of the library.

This module defines the following function:

  • cpp2smp

The cpp2smp function exports a subset of the content of a CPPA3 CPP document to a list of SMP (Service Metadata Publisher) XML documents (as lxml.etree objects), the first of which is an SMP ServiceGroup and the others are SignedServiceMetadata elements.

This module defines the function:

  • view_cpp

The view_cpp functions takes as arguments a list of viewer parties and a parsed CPP, where viewer parties is a list of Party ID, Party Type pairs. It returns a view on that CPP that takes into account the allowed and denied authorization attributes and the supplied party identies, or a ViewException if at least one of the party identifies is block at CPP top level. Unreferenced structures are removed from the output. An anonymous view is created by passing an empty viewer list as parameter.

Test Suite

Test suites are provided for all modules. When you run a test suite, you can optionally validate the CPP or CPA documents against the draft CPPA3 XML schema. To do this, you must download the schema to a readable location on the filesystem, and set the CPPA3XSDDIR environment variable to this location. If the variable is not set, no validation is done.


v0.43 updated to WD12.

v0.42, full support for CPython 3.7.1. (Previously we worked with 2.7.10)

v0.39, some cleanups to SMP export.

v0.38, view now omits unreferenced structures (channels, transports, certs etc.)

v0.37, 2017-11-25, new “view” module and “view_cpp” function.

v0.35, 0.36 2017-11-16 Packaging fixes

v0.34 2017-11-16 AMQP messaging, transport and security; SFTP transport and SSH keys; StartTLS and TLS SNI; bug fix in part property matching; leaf certificate presence requirement checks; schema validation in tests uses a catalog to load local copies of schemas. More and more interesting examples, clean up.

v0.33 2017-09-29 PayloadProfileId element; multiple alternative PayloadProfileId elements; multiple ActionBinding elements with same direction and action name supported; CertificateDefauls always retained in CPA; some clean up.

v0.32 2017-09-19 WebSocket transport support in unify. Match module functionality adds delegation, named channel, payload profile, authorization (allowed/denied) features.

v0.31 2017-08-25 First release of match module

v0.30 2017-08-19 First release of new SMP module

v0.29 2017-08-15 PKI updates: clean up of redundant code, CertificateRequired, Trust Anchors in CPA if no Cert at unification time; naming consistent with current draft XSD. Added missing CanonicalizationMethod unification.

v0.28 2017-07-07 Updates for ebBP attribute support. Better support for AS2 in the profile and unify modules.

v0.27 2017-07-25 Completed module cppa23 up to good enough status.

v0.26 2017-06-09 First release with new module cppa23

v0.25 2017-06-01 Activation and expiration intervals can now be set a ServiceBinding level.

v0.23 2017-05-10 Unreferenced certificates are not in CPA; bug in trust anchor checks fixed; more tests for ebMS2.

v0.22 2017-04-02 Improvements in profile handler in combination with channel features. Updated tests. New

v0.21 2017-03-30 Some fixes and more test samples, covering DATA AND PAYMENT STANDARDS MESSAGE ORCHESTRATION AND PROFILES from

v0.20 2017-03-27 Fix to for AS4 compression

v0.19 2017-03-27 More flexibile profiling: separate templates for “send” en “receiving” channel profiles; default certificates for signing, encryption, client and server authentication; ebMS3 Split/Join/Compress feature; IPv4 and IPv6 checks; HTTP configuration covers HTTP 1.1 and HTTP/2. Support for Web Services Reliable Messaging protocols (WS-ReliableMessaging and WS-Reliability).

v0.18 2017-03-18 Delegation, CertificateDefaults. Aligned with OASIS spec WD05 and ebCore schema #14.

v0.17 2017-02-09 EDIINT (AS1, AS2, AS3) support including features. WS-Addressing support.

v0.16 2017-01-31 SAML token supports and WS-Addressing improvements

v0.15.1 2017-01-27 Multihop improvements

v0.14, 2017-01-04 Support SecurityPolicy in

v0.13, 2016-12-27 Fixed a bug in the JSON Pmode generator. Also fixed some tests that had expiration or activation around 2017-01-01. ..

v0.12, 2016-12-14 Support for the “allowed” and “denied” control attributes.

v0.11, 2016-11-07 Payload security; bug in handling of cppa:Expression

v0.10, 2016-11-01 New module “” for ChannelProfile.

v0.9 2016-10-06 Renamed agreementid to agreementidfun. Updated to do list.

v0.8 2016-10-02. Various Fixes, more tests.

v0.7.8 2016-09-21. Updated readme. PullHandling. More Channel Features.

v0.7.1 2016-09-20. Channel feature support for security and reliable messaging. Tests added correspondingly.

v0.6.1, 2016-08-31. Customizable AgreementIdentifier; JSON schema fixes.

v0.5.3, 2016-08-26. Some changes to ensure generated CPAs are schema-valid; cleaned up test suite.

v0.4, 2016-04-01. Experimental CPA2 module; fixes to certificates and trust anchor handling.

v0.3.9, 2016-03-16. First public release.

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