=================================================================== Notes on input argument usage when invoking a web service operation =================================================================== :Authors: Jurko Gospodnetić :Date: 2014-01-23 =========== Definitions =========== message parts WSDL schema defines message parts representing a web service operation's input data. Each such part's data structure is defined by mapping the message part to XSD element or type. input parameters Suds library's view of a web service operation's input data. Each message part may correspond to 1 or more input parameters. See the `Bare/wrapped web service operation input parameters`_ section for more detailed information. input arguments Values passed to suds library's Python function or function object invoking a web service operation. Suds attempts to map each input argument to a single web service operation input parameter. =================================================== Bare/wrapped web service operation input parameters =================================================== When suds library models a web service operation, it can be configured to map each of its message parts to a single input parameter expecting values directly matching the data type defined for that message part in the web service's WSDL schema. Such input parameters are called ``bare``. If a particular message part has a type which is actually a structure containing a collection of simpler elements, then suds may be configured to map each of those simpler elements to a single input parameter. Such input parameters are called 'wrapped'. If an input parameter is represented by structured XSD element containing other elements, suds may treat it as either ``bare`` or ``wrapped``. If it is considered ``wrapped``, then suds library's web service operation invocation function will take values for the input parameter's internal elements as input arguments, instead of taking only a single wrapper object as a value for the external wrapper element. ``wrapped`` input parameter support has been implemented to make the interface simpler for the user/programmer using suds to invoke web service operations. It does not affect how the the resulting web service operation invocation request is constructed, i.e. passing a suds object as a single ``bare`` input parameter value, or passing matching contained element values as separate wrapped input parameter values results in the same web service operation invocation request being constructed. Example: -------- Consider an operation taking the following element as its only message part:: Suds may be configured to map that message part into with a single ``bare`` or three ``wrapped`` input parameters. If a ``bare`` input parameter is used, the operation invocation function would take only a single argument: * a suds object argument for element ``unga`` If ``wrapped`` input parameters are used, the operation invocation function would take the following input arguments: * a string argument for element ``a`` * an integer argument for element ``b`` * a suds object argument for element ``c`` ================================================================== Input parameter values in original and current suds implementation ================================================================== * A user may or may not specify a value for a specific input parameter. * We refer to unspecified or ``None`` input parameter values as `undefined`. * We refer to all other input parameter values `defined`. Original suds library implementation: ------------------------------------- * An element may be explicitly marked as optional. * ``choice`` input parameter structures not supported. * A defined input parameter value is used directly. * An undefined optional input parameter value is ignored. * An undefined non-optional input parameter value is interpreted as an empty string. * Multiple values specified for a single input parameter are ignored. * Extra input arguments are ignored. Defects: * ``choice`` input parameter structures not supported correctly. When used, result in incorrectly constructed web service operation invocation requests. * An ``all``/``choice``/``sequence`` input parameter structure may be explicitly marked as optional, but this is ignored when deciding whether a specific input parameter inside that structure is optional or not. * No error when multiple values are specified for a single input parameter. * No error on extra input arguments. Current suds library implementation: ------------------------------------ * An element may be explicitly marked as optional. * ``choice`` input parameter structures supported. * Input parameters contained inside a ``choice`` input parameter structure (either directly or indirectly) are always considered optional. * An input parameter structure containing at least one input parameter with a defined value (either directly or indirectly) is considered to have a defined value. * A defined input parameter value is used directly. * An undefined optional input parameter value is ignored. * An undefined non-optional input parameters value is treated as an empty string. Configurable features: * Multiple values specified for a single input parameter may be reported as an error. * ``choice`` input parameter structure directly containing multiple input parameters and/or input parameter structures with defined values may be reported as an error. * Extra input argument may be reported as an error. Defects (demonstrated by existing unit tests): * An ``all``/``choice``/``sequence`` input parameter structure may be explicitly marked as optional, but this is ignored when deciding whether a specific input parameter inside that structure is optional or not. * Undefined value for a non-optional input parameter contained directly inside an ``all``/``sequence`` input parameter structure contained inside a ``choice`` input parameter structure should be treated as an empty string if the ``all``/``sequence`` input parameter structure has a defined value. * A ``choice`` input parameter structure directly containing an input parameter structure with no elements should be considered optional. Still missing features: ----------------------- * Non-optional ``choice`` input parameter structure with no defined value should be treated as if its first input parameter's value had been specified as an empty string.