In addition to using the Connect API in web pages, you can use it with Node.js to run Javascript programs from the command line. This enables you to communicate with ESP from any platform supporting Node.js (which is about all of them).
To use the API with Node.js, perform the following steps (this assumes you have Node.js and npm installed).
- change to your HOME directory.
- Install the Connect API from the directory where you downloaded it (the module name is @sassoftware/esp-connect):
$ npm install @work@/js/connect- change directory to @work@/esp/node
- run a test using the following command (use your own ESP server):
$ node connect.mjs --server http://espsrv01:7777 --modelConnect provides the connect.mjs utility to allow you to run ESP connect commands against an ESP server. This utility contains JSON objects which are sent to the ESP server in order to perform tasks such as loading projects, subscribing to events, and model viewing.
You can get a list of options by running the command with --help specified:
$ node connect.mjs --helpconnect(1) ESP Connect Node.js Commands connect(1)
NAME
connect -- Run ESP Connect commands
SYNOPSIS
node connect.mjs [--load-project] [--delete-project] [--collection] [--stream] [--model] [--xml] [--stats] [--logs] [--publish-data] [--publish-url] [--loggers] [--load-router] [--router] [--eventsource] [--project-updates] [--k8s-projects] [--k8s-log] [--k8s-ls] [--k8s-get] [--k8s-put] [--k8s-cat] [--k8s-rm] [--k8s-restart] [--k8s-exec]
DESCRIPTION
Run ESP Connect commands
OPTIONS
--load-project
Load a project from a file
--delete-project
Delete a project
--collection
Subscribe to an ESP event collection
--stream
Subscribe to an ESP event stream
--model
Display one or more ESP models from an ESP server
--xml
Display project XML from an ESP server
--stats
Display ESP server statistics
--logs
View realtime ESP server logs
--publish-data
Publish ESP events from a file
--publish-url
Publish ESP events from a URL
--loggers
Display and set ESP logging contexts
--load-router
Load an ESP router from a file
--router
Run a javascript router
--eventsource
Read a configuration file and create event sources to publish data into
an ESP server
--project-updates
Listen for and report project load and delete events
--k8s-projects
List ESP projects in a Kubernetes cluster
--k8s-log
Retrieve the log from a K8S pod. The URL must contain both a namespace and a
project name
--k8s-ls
Execute a file listing in a pod. The URL must contain both a namespace and a
project name
--k8s-get
Retrieve a file from a pod
--k8s-put
Copy a file into a pod
--k8s-cat
Display file contents from a pod
--k8s-rm
Remove a file from a pod
--k8s-restart
Restart a project in a pod. The URL must contain both a namespace and a project
name.
--k8s-exec
Execute a command in the pod. Any text after the -- characters will be sent
to the pod to be executed.
SEE ALSO
ESP User Guide https://go.documentation.sas.com/?cdcId=espcdc&cdcVersion=6.2&docsetId=espov&docsetTarget=home.htm&locale=en
SAS ESP Connect Thu Mar 04 2021 SAS ESP ConnectNote that there are several available Kubernetes commands you can use to communicate with ESP servers in K8S Clusters. All of the other commands work seamlessly with ESP servers in Kubernetes.
To get usage information on a specific command, run with the specified command and --help. For example, to get usage information on event collections:
$ node connect.mjs --collection --helpconnect(1) ESP Connect Node.js Commands connect(1)
NAME
connect -- Run ESP Connect commands
SYNOPSIS
node connect.mjs --server --collection --window [--format] [--pagesize] [--schema] [--sort]
DESCRIPTION
This command subscribes to an ESP window for events.
OPTIONS
--server ESP server
ESP Server to which to connect in the form http://espserver:7777
--collection
subscribe to an ESP event collection
--window ESP window
ESP window in the form of project/contquery/window
--format xml | json | ubjson
format of events sent to the client (defaults to ubjson)
--pagesize numevents
page size of the collection (defaults to 50).
--schema true | false
return schema on start, defaults to true.
--sort field
sort field
SEE ALSO
ESP User Guide https://go.documentation.sas.com/?cdcId=espcdc&cdcVersion=6.2&docsetId=espov&docsetTarget=home.htm&locale=en
SAS ESP Connect Thu Mar 04 2021 SAS ESP ConnectTo write your own Node.js programs you will need to follow a couple simple steps. Begin your javascript file with the following code to get a handle to the Connect API:
import {connect as esp} from "@sassoftware/esp-connect";Then you just use the API handle as you would in a web page. The following code is the basic.js program included in the package. You can use this as a starting point for NodeJS programs.
import {connect as esp} from "@sassoftware/esp-connect";
var opts = esp.getArgs();
var server = opts.getOpt("server");
if (server == null)
{
showUsage();
process.exit(0);
}
esp.connect(server,{ready:ready});
function
ready(connection)
{
connection.getModel().then(
function(model) {
model.projects.forEach((p) => {
console.log(p.name);
p.contqueries.forEach((cq) => {
console.log(" " + cq.name);
cq.windows.forEach((w) => {
console.log(" " + w.name + " (" + w.type + ")");
});
});
});
process.exit(0);
}
);
}
function
showUsage()
{
esp.usage({
name:"basic",
summary:"template for NodeJS programs",
options:[
{name:"server",arg:"ESP server",description:"ESP Server to which to connect in the form http://espserver:7777",required:true}
],
description:"This command provides a template for users to use to create their own NodeJS programs."
});
}