retrieve: Retrieve file references from remote locations

In RWebServices: Expose R functions as web services through Java/Axis/Apache

Description

This method retrieve files referenced by its first argument to locations determined by its second argument. The return value is a FileReferences object summarizing the destination.

Usage

retrieve(from, to, ...)

Arguments

from	The source from which objects will be retrieved; typically (or exclusively, depending on method) ‘remote’ locations accessible via, e.g., http.
to	The destination to which files will be copied; typically on the local file system.
...	Additional arguments, passed to the function performing the download.

Methods

from = "FileReferences", to = "character"

from contains remote urls; files must be retrievable using getBinaryURL from the RCurl package. ... arguments are passed to getBinaryURL. to is a directory name to which files will be copied; the directory is created if it does not exist. File names will be unique.

from = "FileReferences", to = "FileReferences"

from is as in retrieve,FileReferences,character-method. to specifies destination urls; urls(to) must have the same number of elements as urls{from}, must not already exist on the local file system, and must not require creation of new directories. localNames and types of to are replaced by corresponding elements from from.

from = "FileReferences", to = "missing"

from is as in the retrieve,FileReferences,character-method. The destination is created using tempfile(), and forwarding this as the second argument to retrieve,FileReferences,character-method. The effect is to retrieve files to R's temporary directory; these files will be removed when the R session ends.

Examples

try({ # fails when no internet available
    from <- FileReferences(c("http://bioconductor.org/biocLite.R",
                             "http://bioconductor.org/index.html"))
    ## to R's temporary directory
    to <- retrieve(from)
    urls(to)
    localNames(to)

    ## tell R where to copy files to
    toDir <- tempfile()
    dir.create(toDir, recursive=TRUE)
    toUrls <- file.path(toDir, localNames(from))
    retrieve(from, FileReferences(toUrls))
    list.files(toDir)
})

RWebServices documentation built on Oct. 5, 2016, 4:53 a.m.