A DSD That Reads from a Web Service

Reads from a web service that publishes an operation called get_points which takes a parameter n and returns n data points in CSV or json format. The request is retried with httr::RETRY() if it fails the first time.

Usage

DSD_ReadWebService(url, verbose = FALSE, ...)

Arguments

url

endpoint URI address in the format http://host:port/<optional_path>.

verbose

logical; display connection information.

...

further arguments are passed on to httr::RETRY(). Pass httr::verbose() as parameter config to get detailed connection info.

Value

A stream::DSD object.

See also

Other WebService: DSC_WebService(), publish_DSC_via_WebService(), publish_DSD_via_WebService()

Other dsd: DSD_ReadSocket(), publish_DSD_via_Socket(), publish_DSD_via_WebService()

Examples

# find a free port
port <- httpuv::randomPort()
port
#> [1] 30037

# create a background DSD process sending data to the port
rp1 <- publish_DSD_via_WebService("DSD_Gaussians(k = 3, d = 3)", port = port)

## use json for the transport layer instead of csv
# rp1 <- publish_DSD_via_WebService("DSD_Gaussians(k = 3, d = 3)", 
#              port = port, serialize = "json")
rp1
#> PROCESS 'R', running, pid 7326.

# create a DSD that connects to the web service
dsd <- DSD_ReadWebService(paste0("http://localhost", ":", port))
dsd
#> Web Service Data Stream: Gaussian Mixture (d = 3, k = 3)
#> Served from: http://localhost:30037 
#> Class: DSD_ReadWebService, DSD_R, DSD 

get_points(dsd, n = 10)
#> # A tibble: 10 × 4
#>         X1      X2     X3 .class
#>      <dbl>   <dbl>  <dbl>  <dbl>
#>  1 0.0277  -0.0106 0.0584      2
#>  2 0.129    0.0793 0.0704      2
#>  3 0.126    0.0894 0.170       2
#>  4 0.00667  0.706  0.560       3
#>  5 0.0446   0.674  0.603       3
#>  6 0.415    0.942  0.280       1
#>  7 0.243    0.925  0.416       1
#>  8 0.325    0.915  0.382       1
#>  9 0.216    0.902  0.471       1
#> 10 0.0977   0.0465 0.152       2

plot(dsd)


# end the DSD process. Note: that closing the connection above
# may already kill the process.
rp1$kill()
#> [1] TRUE
rp1
#> PROCESS 'R', finished.