Amazon Product API with R

Question

I would like to use R to send requests to the Amazon Product API service.

Is there a way to authenticate and query the Amazon Product API with R without getting the following error:

"The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details."

Answer 1

Try this

This should perform a search using the Product Advertising API, which I think you mean.

You need to supply the AWSAccessKeyId and AWSsecretkey,

which can be acquired on: http://docs.amazonwebservices.com/AWSECommerceService/2011-08-01/GSG/

search.amazon <- function(Keywords, SearchIndex = 'All', AWSAccessKeyId, AWSsecretkey, AssociateTag, ResponseGroup = 'Small', Operation = 'ItemSearch'){
     library(digest)
     library(RCurl)

 base.html.string <- "http://ecs.amazonaws.com/onca/xml?"
 SearchIndex <- match.arg(SearchIndex, c('All',
                                             'Apparel',
                                             'Appliances',
                                             'ArtsAndCrafts',
                                             'Automotive',
                                             'Baby',
                                             'Beauty',
                                             'Blended',
                                             'Books',
                                             'Classical',
                                             'DigitalMusic',
                                             'DVD',
                                             'Electronics',
                                             'ForeignBooks',
                                             'Garden',
                                             'GourmetFood',
                                             'Grocery',
                                             'HealthPersonalCare',
                                             'Hobbies',
                                             'HomeGarden',
                                             'HomeImprovement',
                                             'Industrial',
                                             'Jewelry',
                                             'KindleStore',
                                             'Kitchen',
                                             'Lighting',
                                             'Magazines',
                                             'Marketplace',
                                             'Miscellaneous',
                                             'MobileApps',
                                             'MP3Downloads',
                                             'Music',
                                             'MusicalInstruments',
                                             'MusicTracks',
                                             'OfficeProducts',
                                             'OutdoorLiving',
                                             'Outlet',
                                             'PCHardware',
                                             'PetSupplies',
                                             'Photo',
                                             'Shoes',
                                             'Software',
                                             'SoftwareVideoGames',
                                             'SportingGoods',
                                             'Tools',
                                             'Toys',
                                             'UnboxVideo',
                                             'VHS',
                                             'Video',
                                             'VideoGames',
                                             'Watches',
                                             'Wireless',
                                             'WirelessAccessories'))
 Operation <- match.arg(Operation, c('ItemSearch',
                                             'ItemLookup',
                                             'BrowseNodeLookup',
                                             'CartAdd',
                                             'CartClear',
                                             'CartCreate',
                                             'CartGet',
                                             'CartModify',
                                             'SimilarityLookup'))
 ResponseGroup <- match.arg(ResponseGroup, c('Accessories',
                                             'AlternateVersions',
                                             'BrowseNodeInfo',
                                             'BrowseNodes',
                                             'Cart',
                                             'CartNewReleases',
                                             'CartTopSellers',
                                             'CartSimilarities',
                                             'Collections',
                                             'EditorialReview',
                                             'Images',
                                             'ItemAttributes',
                                             'ItemIds',
                                             'Large',
                                             'Medium',
                                             'MostGifted',
                                             'MostWishedFor',
                                             'NewReleases',
                                             'OfferFull',
                                             'OfferListings',
                                             'Offers',
                                             'OfferSummary',
                                             'PromotionSummary',
                                             'RelatedItems',
                                             'Request',
                                             'Reviews',
                                             'SalesRank',
                                             'SearchBins',
                                             'Similarities',
                                             'Small',
                                             'TopSellers',
                                             'Tracks',
                                             'Variations',
                                             'VariationImages',
                                             'VariationMatrix',
                                             'VariationOffers',
                                             'VariationSummary'),
                            several.ok = TRUE)
 version.request = '2011-08-01'
 Service = 'AWSECommerceService'
 if(!is.character(AWSsecretkey)){
  message('The AWSsecretkey should be entered as a character vect, ie be qouted')
 }

 pb.txt <- Sys.time()

 pb.date <- as.POSIXct(pb.txt, tz = Sys.timezone)

 Timestamp = strtrim(format(pb.date, tz = "GMT", usetz = TRUE, "%Y-%m-%dT%H:%M:%S.000Z"), 24)

 str = paste('GET\necs.amazonaws.com\n/onca/xml\n',
        'AWSAccessKeyId=', curlEscape(AWSAccessKeyId),
             '&AssociateTag=', AssociateTag,
             '&Keywords=', curlEscape(Keywords),
             '&Operation=', curlEscape(Operation),
             '&ResponseGroup=', curlEscape(ResponseGroup),
             '&SearchIndex=', curlEscape(SearchIndex),
             '&Service=AWSECommerceService',
             '&Timestamp=', gsub('%2E','.',gsub('%2D', '-', curlEscape(Timestamp))),
             '&Version=', version.request,
             sep = '')

 ## signature test
 Signature = curlEscape(base64(hmac( enc2utf8((AWSsecretkey)), enc2utf8(str1), algo = 'sha256', serialize = FALSE,  raw = TRUE)))

 AmazonURL <- paste(base.html.string,
             'AWSAccessKeyId=', AWSAccessKeyId,
             '&AssociateTag=', AssociateTag,
             '&Keywords=', Keywords,
             '&Operation=',Operation,
             '&ResponseGroup=',ResponseGroup,
             '&SearchIndex=', SearchIndex,
             '&Service=AWSECommerceService',
             '&Timestamp=', Timestamp,
             '&Version=', version.request,
             '&Signature=', Signature
             sep = '')
 AmazonResult <- getURL(AmazonURL)
 return(AmazonResult)
}

The URL which we get from running this code wont give a signature address. To get a signature address use the following web address and paste the URL over there and click on Display Signed URL.

http://associates-amazon.s3.amazonaws.com/signed-requests/helper/index.html

Answer 2

See this post as well as Amazon's Signed Requests Helper. This posting, as well as the two links I've shared helped me get up and running with Amazon's Product Advertising API.