JuliaWebAPI.jl

Facilitates wrapping Julia functions into a remote callable API via ZMQ and HTTP. Combined with JuliaBox, it helps deploy Julia packages and code snippets as publicly hosted, auto-scaling REST APIs.

JuliaWebAPI can also be connected to other server/messaging frontends with a little bit of plumbing that can marshal messages to and from the ZMQ based protocol followed here.

Standalone Usage

Example usage to create a simple wrapper.

Assume a file srvr.jl that contains the definition of the following code

# Load required packages
using JuliaWebAPI
using Compat

# Define functions testfn1 and testfn2 that we shall expose
function testfn1(arg1, arg2; narg1=1, narg2=2)
    return (parse(Int, arg1) * parse(Int, narg1)) + (parse(Int, arg2) * parse(Int, narg2))
end

testfn2(arg1, arg2; narg1=1, narg2=2) = testfn1(arg1, arg2; narg1=narg1, narg2=narg2)

# Expose testfn1 and testfn2 via a ZMQ listener
process([(testfn1, true), (testfn2, false)], "tcp://127.0.0.1:9999"; bind=true)

Start the server process in the background. This process will run the ZMQ listener.

julia srvr.jl &

Then, in a Julia REPL, run the following code

julia> using JuliaWebAPI   #Load package

#Create the ZMQ client that talks to the ZMQ listener above
julia> const apiclnt = APIInvoker("tcp://127.0.0.1:9999")
APIInvoker(Context(Ptr{Void} @0x00007f8f62539d70,[Socket(Ptr{Void} @0x00007f8f6366a800)]),Socket(Ptr{Void} @0x00007f8f6366a800))

julia> run_rest(apiclnt, 8888)         #Starts the HTTP server in current process
19-Dec 22:56:29:INFO:root:listening on port 8888...

Then, in your browser, navigate to http://localhost:8888/testfn1/4/5?narg1=6&narg2=4

This will return the following JSON response to your browser, which is the result of running the testfn1 function defined above: {"data"=>44,"code"=>0}

JuliaBox Deployment

Deploying on JuliaBox takes care of most of the boilerplate code. To expose a simple fibonacci generator on JuliaBox, paste the following code as the API command:

fib(n::AbstractString) = fib(parse(Int, n));
fib(n::Int) = (n < 2) ? n : (fib(n-1) + fib(n-2));
process([(fib, false)]);

Notice that we need to specify a lot less detail on JuliaBox. JuliaBox connects the API servers to a queue, instead of the server having to listen for requests. The obvious packages are aleady imported.

The JuliaBox API command must however be concisely expressed within 512 bytes without new lines. To run larger applications, simply package up the code as a Julia package and install the package as part of the command. For an example, see the Juliaset API package.