Lift Packets for Processing in NoFlo

In a NoFlo program, how the program processes data is more important than the data structure. It is evident in that most NoFlo programs expect a rather flat data structure of a series of packets enclosed in one or two levels of groups.

When your program expects a more complex data structure, it is useful to be able to extract a subset of the structure, do some work, and plug it right back into where it was extracted from. noflo-lift allows you to literally "lift" a subset of the data structure by providing a pattern object for further processing on just that one piece. It then accepts some data structure that noflo-lift would then insert back in place.

In Ports

noflo-lift accepts data via these ports:

IN

Any valid NoFlo data structure

PATTERN

A pattern is a path-like array denoting the group structure to extract. For instance, in XML schematics, if you have an incoming data structure:

<GroupA>
  <GroupB>
    <GroupC>
      <Data1/>
      <Data2/>
    </GroupC>
    <Data3/>
    <Data4/>
  </GroupB>
  <GroupD>
    <Data5/>
    <Data6/>
  </GroupD>
</GroupA>

And you want to extract just GroupC for processing, you would pass in, in JSON:

[ "GroupA", "GroupB", "GroupC" ]

RETURN

The processed data structure must be returned to this port to continue its journal through the OUT port. See the PROCESS out port for details.

CACHESIZE

noflo-lift does not have a cache limit as it expects you to finish processing on all opened requests. You may optionally set a cache size if you deal with asynchronous operations that may fail.

Out Ports

noflo-lift emits data via these ports:

OUT

The data structure that has been processed and plugged back in is emitted to this port.

PROCESS

The extracted data structure is emitted here. It is grouped at the top-level by a token, which must group the processed data structure on return to the RETURN in port.