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Help consuming a REST webservice with HTTPAPI.
Hello everyone.
I need to consume a REST Web service and I'm going to use HTTPAPI to do
it. I just need a bit of help getting started. I've consumed SOAP
services before with HTTPAPI but this is my first crack at consuming a
REST. I've looked at the examples provided with HTTPAPI but I couldn't
find one that is doing exactly what this vendor requires. From the
vendor's web site here is the pertinent documentation for the service I
need to consume:
----------
Overview
Spireon API makes it easy to retrieve, create, and update resources on
your account through our REST endpoints. The HTTP methods we support
are GET, POST, PUT, and DELETE. The base URL endpoint is
[1]https://api.us.spireon.com/api.
Authentication
To make requests to Spireon API, you need to supply the Authorization
header for every request you make. We ensure that your credentials are
secure because all requests must be made over HTTPS.
Below is a cURL example on how to make a GET request. Note that we
require both the Authorization and Account headers to authenticate your
request.
% curl -H "Authorization: Basic [your auth string]"
-H "Account: [your account ID]"
[2]https://api.us.spireon.com/api/asset
Your auth string is your username and password combined into a string
and encoded in Base64, like so:
Base64("username:password")
----------
"Getting Traffic" is the specific service I want to consume:
----------
Getting Traffic
Fetching account traffic is done through an HTTP GET operation, and
synchronisation is based on time intervals:
1) The client specifies the startAt timestamp.
2) The server responds with the sequential events from startAt up to a
limit, and returns the endAt time to the client.
3) The client uses the server endAt marker as its startAt marker for
the next call.
Performance Considerations
The server limits the response at 2000 events (LIMIT).
The traffic HTTP GET operation can return within a minute with LIMIT
points in a two hour span. The server prioritizes a fast return over a
large response, and may set the endAt time before LIMIT.
The system performs best if the client adheres to the following
guidelines:
1) The client shall not specify start times older than 7 days; the
traffic server may discard traffic older than 7 days.
2) The client should query traffic in non-overlapping [startAt, endAt[
intervals. Server traffic pre-fetching will cause a substantial
performance hit on out of order or overlapping time intervals. Those
shall only be used for error recovery.
3) The client should issue back-to-back calls without pause to the
server until the response is empty.
Example
Request:
GET api.spireon.com/api/asset/traffic?limit=50&startAt=1367853959918
----------
I've been given access to a test "sandbox" for this web site with:
Username = newcoke
Password = password
Account ID = 73718
I'm not sure if the "Authentication" part is supposed to be included in
the GET statement or if the security is done with a separate procedure
prior to the GET. It's mainly the "Authentication" pert that is holding
me up. I've tried playing around with a slightly modified version of
EXAMPLE05 called MYXAMPLE05 to see if I can figure out what is going
on. Here is the code I've been working with:
----------
*---------------------------------------------------------------------
---*
* MYXAMPLE05 - Copied from LIBHTTP/QRPGLESRC/EXAMPLE05
*
*---------------------------------------------------------------------
---*
*
H DFTACTGRP(*NO) ACTGRP(*NEW) BNDDIR('HTTPAPI')
*
D/copy qrpglesrc,httpapi_h
*
D cmd pr extpgm('QCMDEXC')
D command 200A const
D length 15P 5 const
*
D rc S 10I 0
D err S 10I 0
D basic S 1N
D digest S 1N
D realm S 124A
D userid S 50A
D pass S 50A
D URL s 256A
D msg S 50A
D http_getauthLog...
D S 1000A varying
*
C eval *inlr = *on
*
C eval URL = 'https://api.spireon.com/api' +
C '/asset/traffic?limit=50' +
C '&startAt=1'
C
*
C dou rc = 1
C eval rc = http_url_get( URL
C :
'/fleetLocate/restTest/testAuth.html')
C if rc <> 1
C callp http_error(err)
C if err <> HTTP_NDAUTH
C callp http_crash
C return
C endif
C exsr getpasswd
C endif
C enddo
*
C callp cmd('DSPF '+
C
'/fleetLocate/restTest/testauth.html'''
C : 200)
*
*---------------------------------------------------------------------
---*
* getpassword -
*
*---------------------------------------------------------------------
---*
*
Csr getpasswd begsr
*
/free
http_getauthLog = '/fleetLocate/restTest/http_getauthLog.txt';
http_debug(*on : http_getauthLog);
/end-free
C eval rc = http_getauth(basic: digest: realm)
C if rc < 0
C eval msg = HTTP_ERROR
C dsply msg
C return
C endif
*
C eval userid = 'enter userid for ' + realm
C dsply userid
*
C eval pass = 'enter passwd for ' + realm
C dsply pass
*
C if Digest
C callp http_setauth(HTTP_AUTH_MD5_DIGEST:
C userid: pass)
C else
C callp http_setauth(HTTP_AUTH_BASIC:
C userid: pass)
C endif
*
Csr endsr
----------
The above code stops on the http_getauth procedure. As you can see I've
added a debug and here is what it says:
----------
HTTPAPI Ver 1.24 released 2012-01-23
OS/400 Ver V7R1M0
http_getauth(): entered
SetError() #39: Server did not ask for authentication!
----------
The testAuth.html file is blank.
I'm not sure if this is even a good example to use for what I need.
I've read through the ftpapi@xxxxxxxxxxxxxxxxxxxxxx archives and didn't
find anything that I thought I could use (maybe I missed something). If
anyone could give me some help/direction with this is would be greatly
appreciated as I've been working on this for a few days and I am kind
of stuck.
Thanks again in advance, Paul.
___________________________________________________________
Paul Reid
Application Developer III
Erb Group of Companies | 290 Hamilton Road | New Hamburg, Ontario | N3A
1A2
Phone: 519.662.6133 ext. 2363
Web: [3]http://www.erbgroup.com/
References
1. https://api.us.spireon.com/api
2. https://api.us.spireon.com/api/asset
3. http://www.erbgroup.com/
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