Explain the execution flow of a synchronous service call in OFBiz?

A synchronous call runs to completion and returns its result map before the caller continues - used whenever the caller needs the outcome immediately, such as validating a form submission.

sequenceDiagram
    participant Caller
    participant Dispatcher
    participant Engine as Service Engine
    participant Impl as Implementation
    participant SECA
    Caller->>Dispatcher: runSync("serviceName", params)
    Dispatcher->>Engine: validate params against ModelService
    Engine->>Engine: check permissions
    Engine->>Engine: start or join transaction
    Engine->>Impl: invoke (Java/simple-method/Groovy)
    Impl-->>Engine: result map
    Engine->>SECA: fire matching SECA rules
    Engine-->>Dispatcher: result map
    Dispatcher-->>Caller: result map

If any step throws an error or the implementation returns an error response code, the transaction is rolled back (unless it was already running before the call as part of an outer caller's transaction), and the error propagates back to the caller inside the result map rather than as a raw exception in most cases.