analysis-path-processing-f7da7d5.md

Analysis Path Processing

The main purpose of the core module (sap.apf.core) is to handle and process analysis paths. A path and its steps are created, accessed, and processed using the APF API. During path processing, the following tasks are executed going through all steps in the order of their positions in the analysis path:

1. Execute the OData requests of the steps

2. Supply the representations of the steps with the response data

3. Notify the application UI using a callback function

In addition, the path logic accumulates filters that are derived from selections made in representations, and applies those filters in subsequent OData requests.

An analysis path contains an ordered sequence of one or more analysis steps.

A step is created using the APF API method createStep(<id>,<callback>). It is inserted at the end of the path. The first method parameter is a unique identifier, which refers to the configuration entity that defines the step. The second parameter supplies a callback function, which is called once after the step has been created and processed.

Path processing is triggered using the APF API method updatePath(<callback>). The callback function is called each time after a step has been processed.

Runtime Objects

The following runtime objects exist:

• A step object consists of a request object and a binding object.

• A request object defines an OData server request. It creates and processes the OData request, processes the response, and sends the response data to the corresponding step.

• The binding object sends the response data to the selected representation object. A binding object associates a step with one or more representation objects and identifies and handles the representation object that is currently selected. The binding object also defines how the selected representation translates its selection into a filter object.

• A representation object wraps a chart, a table, or any other representation of data. When the user switches the representation, a different representation object is selected and supplied with data.

• A filter object represents the selections made on the charts.

The relation between the objects described above is depicted in the following figure:

Runtime Objects of a Path

Processing of Runtime Objects

The steps are processed in the order of their positions in the path. The first step is processed first. The filter resulting from the first step is used to process the second step, and so on.

To describe the processing of an analysis path in more details, the following variables are relevant:

Variable	Description
S_1,..,S_n	Path of length n
S_i	Step
R_i	Request for step S_i
B_i	Binding for step S_i
RO_i_s	Selected representation object for step S_i
F_i	Filter object associated to step S_i
F_0	Filter for the entire path. This filter is either empty or it is the filter set by the APF API method addPathFilter()). This filter defines the OData filter for request R_1 of step S_1.

The processing of step S_i begins with requesting the filter F_(i-1) of the previous step. Note that for step S_1, this is filter F_0.

Step S_i is further processed by sending an OData request R_i to the server. The filter expression of request R_i is defined by the previous filter F_(i-1).

When request R_i returns successfully, it sends its response data to the selected representation object RO_i_s. This representation object then creates its own filter based on this data and its own UI selections. This filter can be requested by the subsequent step.

The filter F_i is defined as a conjunctive accumulation of the previous filter F_(i-1) and the filter defined by the selected representation object (RO_i_s). The filter F_i is used for processing step S_(i+1).

Filter F_0 is defined by URL parameters passed to the application, such as SAPCLIENT, and by filters. In the figure above, F_0 is represented as the "Filter/Context" object directly associated to the path object.