Using Advanced Program-to-Program Communication › Send Operations › Data Mapping for NCL Tokens

Data Mapping for NCL Tokens

When sending NCL tokens, a map name of $NCL is sent by default with the data to indicate that the data is comprised of one or more NCL tokens. If the receiving system understands the $NCL structure, it can decompose the datastream into the individual tokens sent. In this way NCL allows a single send to specify multiple tokens as a range or list, and in the target system a single receive can re-create such a range or list. For example, the request:

&APPC SEND_DATA VARS=A* RANGE=(1,10)

can be sent, and satisfies a remote request:

&APPC RECEIVE_AND_WAIT VARS=B*

such that the variables B1,B2,...,B10 in the remote system are created with the same values as A1,A2,...,A10 in the sending system.

You can override the map name sent. However, if a map name other than $NCL is specified the tokens are not structured as above for output, but are simply concatenated together to form the single GDS variable which is the unit of transmission. When communicating with a non-NCL system, this may let you construct the appropriate pieces of the data in separate tokens before sending them as a single datastream. The interpretation of the block of data received in the remote system is then implied by the map name sent.