Kevin and Nathan,
what is a good definition of an app?
I know node can execute JavaScript programs that have nothing to do with web apps or RESTful services. But I want a terminology to talk about using node for web apps and RESTful services.
Let me offer an example of how I would use "node app":
[begin example]
The tutorials I've read always have the "node app" listen to incoming HTTP requests on a particular port number. This is has always been accomplished using (a) the node.js http module, or (b) the ExpressJS app module. Consequently, a "node app" is basically the JavaScript code that gets executed as part of processing and responding to incoming HTTP requests at a particular port number.
One "node app" can be a reverse proxy for other "node apps." A developer can also create "sub-apps" or modules within a "node app" using ExpressJS router and module.exports. "Sub-apps" do not have their own port numbers.
A "node app" on the IBM i could use Toolkit for i to call a CL or COBOL program.
[end example]
If my use of "node app" is wrong or confusing, then I'm open to learning better terminology to describe: (a) what a node app is, and (b) what the correct or clearer term would be for what I was talking about in the example above.
Thanks,
Kelly Cookson
IT Project Leader
Dot Foods, Inc.
1.217.773.4486 ext. 12676
kcookson@xxxxxxxxxxxx
-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of Nathan Andelin
Sent: Tuesday, October 13, 2015 5:23 PM
To: Web Enabling the IBM i (AS/400 and iSeries)
Subject: Re: [WEB400] Hosting a Large Number of Node Apps on the IBM i
1. What happens when the reverse proxy goes down ...
Let me apologize up front for turning the question back on you. Beginning with the "reliability" concern - which is more likely to go down - a server which is performing "proxy" services? or one which is running "application"
code?
And how complex are the "applications", and how often do they have errors?
Regarding going down for maintenance, wouldn't the same rationale apply for Node HTTP services? How often will a Node.js HTTP service go down in order to apply a change to an application?
2. What happens when I ... want to add or modify a single reverse proxy
route...
The HTTP service must be restarted, which can be disruptive. To ameliorate the disruption, one option is to have a reverse proxy configured on 2 boxes. Use a network "router" to point HTTP traffic to the other HTTP proxy while the primary one is restarted, and visa versa.
3. What about all of those port numbers?
As Aaron pointed out, the network will not have a problem with that. The question is whether it adds work to an administrator's job to keep track of which services are on which port? Again, the same concern for doing "routing" within Node.js.
Some good questions and answers have been shared in this discussion. I would like to reiterate Kevin's question - what is a good definition of an app?
Back to the reliability concern. For a long time, I have maintained a rule; DON'T mix HTTP services and Application services in the same "process". For that matter, I recommend NOT mixing any kind of "socket" communications with "application logic" in the same JOB.
That "rule" is NOT a mainstream practice, so I'm relegated to the status of going against the grain. But I believe it has paid off - big time! Socket communications should not be "disrupted" by application errors.
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