xowf

When shared workflow definition are used, a different management of

object specific code is necessary, since one definition seves for many

objects, and it is not freshly created per object. Therefore, a new

concept is introduced for workflow definitions, named "object-specifc"

Instead of writing in a workflow definition

Action save

state initial -actions {save}

[my object] proc foo {} { ns_log notice "===foo==="}

one has to write now:

Action save

state initial -actions {save}

:object-specific {

:proc foo {} { ns_log notice "===foo==="}

}

where the object-specific is evaluated once per request for every

involved workflow instance in the context of the object (a [self]

in this block refers to the object).

In case a [my object] is encountered and sharedWorkflowDefinition is

activated, a warning is produced and the code falls back to old-style

shared workflow definitions.

Background: so far, xowf stored workflow definitions in the workflow

context, which is generated for every instantiated workflow instance

due to the needs of the State Pattern. While the old approach works

perfectly fine, when pre request only one or a few workflow instances

are created, but is inefficient, when e.g. 100 or more instances of

the workflow definition are created.

Now, the instances can share the definition, which is shared based on

the revision_id of the workflow FormPage.

OLD: obj <-> obj::wf_ctx

NEW: obj <-> obj::wf_ctx <(n)----> wf_definition

OLD scenario:

- the wf_definition was part of the context (no distinction)

- navigation from wf_ctx (and wf_definition) to object was possible

via "info parent"

NEW scenario:

- the wf_definition is separate

- one wf_definition can be used for multiple wf_ctx

- new methods are required instead of "info parent"

to navigate between these cooperating objects

* xowf::WorkflowPage.wf_context

* xowf::WorkflowConstruct.wf_context

* xowf::Context.wf_container

The navigation from a WorkflowConstruct (e.g. State) to the wf_ctx

is slow and fragile if not following usual programming conventions

and should e avoided (the methods of these constructs have the obj

passed in, so this path should not be necessary in most situations)

- as long the contents of the wf_container is constant, it can be

shared in the per-thread cache.

For now, the new feature is turned off by default via variable

::xowf::sharedWorkflowDefinition, but this will change in the future.