Handling compressed/zipped responses in httpclient.

Application uses the httpclient to make a request to a web service. 
The response to the request needs to be used in subsequent requests.
Using the TYPE-OF API, the response seems to be a memptr.
How can the json format string be extracted from the payload?

 

RequestBuilder call included the following:        :AddHeader("Accept-Encoding","gzip,deflate") 
The response from the service is encoded in gzip format.

The httpclient does not directly support gzipped payloads.

Do not include a header that allows gzip encoded responses.

There is no straight forward method for handling gzip encoded payloads.
The following multi-step process could be used:

1) This first step is a code snippet showing how to extract the encoded payload from the response entity and write it to a file.
/* assume an httpclient request has already been created  in variable oRequest */
DEFINE VARIABLE oMyEntity AS Object NO-UNDO.
DEFINE VARIABLE mRsp AS OpenEdge.core.MEMPTR.
DEFINE VARIABLE mPtrResp AS MEMPTR NO-UNDO.
DEFINE VARIABLE oRequest AS IHttpRequest NO-UNDO.
DEFINE VARIABLE oResponse AS IHttpResponse NO-UNDO.
oResponse = ClientBuilder:Build():Client:Execute(oRequest).
oMyEntity = oResponse:Entity.
IF TYPE-OF (oMyEntity, Memptr) THEN DO:
        mRsp = CAST(oMyEntity, OpenEdge.Core.Memptr).
        mPtrResp = mRsp:VALUE.
        COPY-LOB mPtrResp to file session:temp-dir + "entity.zip".
END.

This results in a gzip file being created, named entity.zip. It contains a file named entity.
2) Use OS-COMMAND to call an unzip program.
The output file might be called entity.json.
3) Read in file entity.json via ObjectModelParser 
     For example ObjectModelParser('entity.json').
 

References to other Documentation:
https://docs.progress.com/bundle/openedge-abl-reference-117/page/ParseFile-method.html
https://docs.progress.com/bundle/openedge-abl-develop-http-clients/page/Execute-an-HTTP-request.html
https://documentation.progress.com/output/oehttpclient/117/index.html?OpenEdge.Net.HTTP.HttpClient.html
https://documentation.progress.com/output/ua/OpenEdge_latest/index.html#page/dvpin/openedge.net.http.httpclient.html

Progress Article(s):
 Is there an HTTP client for OpenEdge?

Please note:
The following code gets to the same result but might be a little more memory efficient:

IF TYPE-OF (oMyEntity, Memptr) THEN DO:
    COPY-LOB CAST(oMyEntity, OpenEdge.Core.Memptr):VALUE to file session:temp-dir + "entity.zip".
END.