A collection of basic example services.

The nstack version HelloWorld, this service is created by default when initialising an empty python project (i.e. nstack init python) It exports a single function,

numChars : Text -> Integer

that simply returns the number of characters in a input text message. Build using nstack build.

A sample workflow module that uses the service above (Demo.NumChars) and exposes over HTTP. Similarly, this service is created by default when initialising an empty python project (i.e. nstack init workflow).

It exports this single workflow, exposing the service over HTTP and sending the result to the service log

def w = Sources.http<Text> { http_path = "/demo" } | D.numChars | Sinks.log<Integer>;

Build using nstack build, and run using nstack start Demo.Workflow.0.0.1.w. From here you can use the nstack send command to send messages to the running workflow as follows and view the output using nstack log,

$ nstack build
$ nstack start Demo.Workflow.0.0.1.w
> Service started successfully as process 5
$ nstack send "/demo" '"HelloWorld"'
> Event sent successfully
$ nstack log 5
> ...
> Output : 10

A trivial classifier that demonstrates sending data into an nstack service

You can build and run this service in a single step using the nstack notebook feature that provides a mini-REPL (you can also redirect a file/stream into the notebook command to provide for rapid service testing and development),

$ cd Demo.Classify
$ nstack build
$ nstack notebook
import Demo.Classify:0.0.3 as D;
Sources.http<Text> { http_path = "/classify" } | D.classify | Sinks.log<Text>
<Ctrl-D>
> Service started successfully as process 5
$ nstack send "/classify" '"orange"'

This is a little example demonstrating the environmental configuration feature, that are used in a similar manner to OS application environment variables.

It is a module that takes the first name via the a static configuration argument, last name from the input stream, and concatenates the two.

As mentioned above, this example demonstrates piping input into the nstack notebook command to start an ad-hoc workflow,

$ cd Demo.FirstLastName
$ nstack build
$ echo 'import Demo.FirstLastName:0.0.1 as FLN; Sources.http<Text> { http_path = "/fln" } | FLN.full_name { first_name = "John" } | Sinks.log<Text>' | nstack notebook
> Service started successfully as process 5
$ nstack send "/fln" '"Nash"'