Transaction

Workflows

flowchart TD
    subgraph Transaction1
        subgraph Workflow1
            wf1_start["Start"] --> wf1_fb1("Function Block")
            wf1_fb1 --> wf1_wf2("Workflow (embdeded)")
            wf1_wf3("Workflow (dispatched)") --> wf1_fb2("Function Block")
            wf1_fb2 --> wf1_end["End"]
        end
        style Workflow1 fill:#B9EAC9,stroke:#333,stroke-width:2px

        subgraph Workflow2
            wf1_wf2 --> wf2_start["Start"]
            wf2_start --> wf2_fb1("Function Block")
            wf2_fb1 --> wf2_end["End"]
            wf2_end --> wf1_wf3
        end
        style Workflow2 fill:#FFCFCFFF,stroke:#333,stroke-width:2px
    end

    subgraph Transaction2
        subgraph Workflow3
            wf1_wf3 --> wf3_start["Start"]
            wf3_start --> wf3_fb1("Function Block")
            wf3_fb1 --> wf3_end["End"]
        end
        style Workflow3 fill:#FFEBA8FF,stroke:#333,stroke-width:2px
    end

Aquiring and locking

Aquiring is done to populate the context of a workflow and apply locks on entities. All entities can have a lock applied, if a workflow/function block/step is run on them.

flowchart LR
    subgraph Acquisition phase
        entities["Acquire entities"] --> aquire_global["Acquire global"]
        aquire_global --> aquire_step["Acquire per step"]
        aquire_step --> lock(("Create lock"))
    end

    subgraph Transation
        lock --> step1("Step 1")
        step1 --> step2("Step 2")
        step2 --> step3("Step 3")
    end

Steps

• Acquire entities: Selected entities getting aquired.
• Acquire global: Acquiring statically defined entities (add & remove functionallity)
• Acquire per step: Dynamic acquisition of entities based on configuration of each step (embeded/sub workflow, function block)
• Lock: Create lock on acquired entities based on locking type and strategy
• Transation: Start execution the steps of the worklow

Locking types

Typ	Read	Write
Read lock	ok Multiple users or processes can read the entity concurrently when it is under a read lock.	nok No user or process is allowed to modify the entity while it is under a read lock.
Write lock	nok No users or processes can access the entity for reading while it is under a write lock.	nok Only the user who holds the lock can write or modify the entity.

Locking strategy

Strategy	Read lock behavior	Write lock behavior
Normal	same Multiple reads allowed, no writes	same Only one user can write; all others blocked
Loose	same Multiple reads allowed, no writes	Multiple writes allowed, reads also permitted