HTTP POST method: http://scn.sap.com/community/abap/connectivity/blog/2014/11/09/calling-an-external-restful-service-from-abap--http-method-post
I have made inline code explanation. Please go through step by step description.
Scenario: GET operation to access: http://hostname.com:55400/vendavo/rest/agreements/XYZ
1) Create a RFC destination of type (HTTP Connections to External Server)
content-type: application/json
DATA: lo_http_client TYPE REF TO if_http_client,
lo_rest_client TYPE REF TO cl_rest_http_client,
lv_url TYPE string,
lv_body TYPE string,
token TYPE string,
agreements TYPE string,
"Create a structure(or deep) that exactly matches your JSON response
abap_response TYPE zca_serno_ln,
lo_response TYPE REF TO if_rest_entity.
* Create HTTP intance using RFC restination created
* You can directly use the REST service URL as well
cl_http_client=>create_by_destination(
EXPORTING
destination = 'VENDAVO' " Logical destination (specified in function call)
IMPORTING
client = lo_http_client " HTTP Client Abstraction
EXCEPTIONS
argument_not_found = 1
destination_not_found = 2
destination_no_authority = 3
plugin_not_active = 4
internal_error = 5
OTHERS = 6
).
* If you are using cl_http_client=>create_by_url use this code to supress and pass your
* HTTP basic authenication
* lo_http_client->propertytype_logon_popup = lo_http_client->co_disabled.
* DATA l_username TYPE string.
* DATA l_password TYPE string.
* l_username = 'user'.
* l_password = 'password'.
* CALL METHOD lo_http_client->authenticate
* EXPORTING
* username = l_username
* password = l_password.
* Create REST client instance
CREATE OBJECT lo_rest_client
EXPORTING
io_http_client = lo_http_client.
* Set HTTP version
lo_http_client->request->set_version( if_http_request=>co_protocol_version_1_0 ).
IF lo_http_client IS BOUND AND lo_rest_client IS BOUND.
DATA(id) = 'XYZ'.
CONCATENATE 'agreements/' id INTO lv_url.
* Set the URI if any
cl_http_utility=>set_request_uri(
EXPORTING
request = lo_http_client->request " HTTP Framework (iHTTP) HTTP Request
uri = lv_url " URI String (in the Form of /path?query-string)
).
* Set request header if any
CALL METHOD lo_rest_client->if_rest_client~set_request_header
EXPORTING
iv_name = 'auth-token'
iv_value = token.
* HTTP GET
lo_rest_client->if_rest_client~get( ).
* HTTP response
lo_response = lo_rest_client->if_rest_client~get_response_entity( ).
* HTTP return status
DATA(http_status) = lo_response->get_header_field( '~status_code' ).
* HTTP JSON return string
DATA(json_response) = lo_response->get_string_data( ).
* Class to convert the JSON to an ABAP sttructure
DATA lr_json_deserializer TYPE REF TO cl_trex_json_deserializer.
CREATE OBJECT lr_json_deserializer.
lr_json_deserializer->deserialize( EXPORTING json = json_response IMPORTING abap = abap_response ).