streamConnect (version 0.0-4)

DSD_ReadWebService: A DSD That Reads for a Web Service

Description

Reads from a web service that published 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, ...)

Value

A stream::DSD object.

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.

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

# 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

# create a DSD that connects to the web service
dsd <- DSD_ReadWebService(paste0("http://localhost", ":", port))
dsd

get_points(dsd, n = 10)

plot(dsd)

# end the DSD process. Note: that closing the connection above
# may already kill the process.
rp1$kill()
rp1