The Methods & Tools Special Interest Group (M&T SIG) met from 5 pm till 6:30 pm Central European Time.


U.S. Environmental Protection Agency (represented by Bill BARRETT), AmsterCHEM (represented by Jasper van BATEN), Bryan Research & Engineering (represented by Michael HLAVINKA), Michel PONS (contractor to CO-LaN as Chief Technology Officer)

Agenda: development of Persistence Common interface specification.


The conference call was devoted to the development of the Persistence Common interface specification. So far, in the CAPE-OPEN standard, persistence mechanisms provided by middleware such as COM and CORBA have been used. With the development of a CAPE-OPEN specific middleware (COBIA), CO-LaN develops its own interface specification for persistence. The proposed interface specification introduces two general concepts: Persistence Host (PH), most likely a PME (but not only), and Persistable Object (PO), typically a Process Modelling Component that may be configured (Unit Operations implementing ICapeUtilities::Edit are examples).

M&T SIG reviewed the modifications proposed by Bill BARRETT to the requirements section of the interface specification.

Wording of requirement labelled REQ-PH-03, pertaining to the need for any software object which is persistable, to advertise such a functionality, was revised to make it more general and to reflect the design choice that the persistability is detected through the presence of the ICapePersist interface on such an object rather than to consider  a specific CATID to register a software component as a persistable object.

Next, M&T SIG revised the wording of the rationale behind requirement labelled REQ-PH-04, pertaining to the need for the Persistence Host to provide the data store necessary to the Persistable Object for storing its internal data. It led to a clarification in the introduction section that the proposed specification standardizes the mechanism of storing and restoring CAPE-OPEN Process Modelling Components (PMCs) present within a Flowsheet but does not standardize how to store and restore a Flowsheet. It was also discussed that a PMC may use the proposed persistence mechanism on secondary Process Modelling Components.

Next M&T SIG addressed the wording of requirement stating that a PO must be able to store its internal data in the data store provided by the PH in a human-readable format. Such a requirement has been often heard and is now specifically taken into consideration. The wording made more obvious that this is a need of any PO that must be met by any PH.

In another requirement, it was clearly expressed that each node of the tree structure given to the data store by the PH, is a CAPE-OPEN object but not a Primary PMC. Still being a CAPE-OPEN Object means that a node needs to implement ICapeIdentification that will be especially useful for logging purposes. It is further required that the Name property of the ICapeIdentification interface implemented on a node be the node path.

The rationale was improved for requirement fulfilled by the AddNode operation of the ICapePersistWriter interface: each PO must be able to create the tree structure most appropriate for storage of its internal data.

The next conference call is scheduled for March 4, 2020.


Picture of Bill BARRETT (US EPA representative) in December 2018Contact Bill BARRETT (representative of US Environmental Protection Agency, leader of the Methods & Tools Special Interest Group) should you wish to join the Methods & Tools Special Interest Group. Its charter is: “Improve integration, and expand utilization of Computer-Aided Process Engineering (CAPE) applications within the enterprise through identification and resolution of existing cross-cutting issues with the CAPE-OPEN platform, develop mechanisms for use of CAPE within other application domains, and incorporate advances in information technology into the CAPE-OPEN platform.”