JS Client Service access

[martijnlammers]

I've set up a simple single node open network with 1 active member and I'm now trying to setup a client. I've already successfully made a python client following the documentation and can make http requests over TLS.

I will be working with AngularJS in the near future and was wondering if ccf also had a Javascript package to make signed/user/anonymous requests and if not, how I could achieve this in JS?

[eddyashton]

Hi @mAlyanak. No, we don't have any clients written in JS. We think it should be possible to write clients in any language, since they're speaking a standard protocol - HTTP over TLS - with common library support. We've successfully communicated with CCF nodes from a variety of existing tools (curl, k6, vegeta, artillery), and written clients in several languages (C++, Python, C#), so JS should be easy too.

The only tricky case is submitting signed requests, which must be compatible with a specific version of the draft RFC. There are libraries that do this in many languages (including JS), but checking they implement the same spec version may not be trivial.

[martijnlammers]

Yes, that's correct. I turned off all authentication policies on my endpoints just for sake of testing.

// read.js
import { typedKv } from '../node_modules/@microsoft/ccf-app/kv.js';
import { json, string } from '../node_modules/@microsoft/ccf-app/converters.js';
import '../node_modules/@microsoft/ccf-app/historical.js';
import '../node_modules/@microsoft/ccf-app/endpoints.js';

const kv = typedKv('kv', string, json());
function read(request) {
const data = request.body.json();
if (typeof (data['key']) != "string") {
return {
body: '{"status":"invalid key"}',
statusCode: 400
};
}
if (!kv.has(data['key'])) {
return {
body: '{"status":"key not found for sure"}',
statusCode: 400
};
}
return {
body: kv.get(data['key']),
statusCode: 200
};
}

export { read };

Sorry for the formatting, looks very unappealing without the indents.
I'm fairly certain the logic is fine as the python client does work.
App.json:

{
"endpoints": {
"/read": {
"get": {
"js_module": "endpoints/read.js",
"js_function": "read",
"forwarding_required": "never",
"authn_policies": [],
"mode": "readonly",
"openapi": {
}
}
},
"/write": {
"post": {
"js_module": "endpoints/write.js",
"js_function": "write",
"forwarding_required": "never",
"authn_policies": [],
"mode": "readwrite",
"openapi": {
}
}
},
"/aggregate": {
"get": {
"js_module": "endpoints/aggregate.js",
"js_function": "aggregate",
"forwarding_required": "never",
"authn_policies": [],
"mode": "readonly",
"openapi": {
}
}
}
}
}

[martijnlammers]

Aha, at last I did end up getting an error in my node output

2021-10-28T15:43:42.466252Z 0 [info ] ../src/enclave/main.cpp:173 | All threads are ready!
2021-10-28T15:46:35.389883Z -0.001 0 [info ] ../src/node/rpc/frontend.h:481 | Service state is OPEN, now accepting user transactions
2021-10-28T15:52:02.543694Z -0.001 0 [info ] ../src/js/wrap.cpp:713 | SyntaxError: unexpected end of input
2021-10-28T15:52:02.543727Z -0.001 0 [info ] ../src/js/wrap.cpp:735 | at :1
at json (native)
at read (/endpoints/read.js:8)

It took several minutes for me to realise it updated

[eddyashton]

The callstack says the error is on line 8, so during:

const data = request.body.json();

Presumably that means the body is either not present, or can't be parsed as JSON. A few ideas:

• Some of the framework code strips out request bodies for GET requests, since the HTTP spec says they shouldn't be used. I'm not sure if we do this for the JS endpoints, but we might. I guess if it's possible to GET that from Python with a body, we must not be stripping the body.
• I can't find documentation for the body field in the options object, and it's not listed under the fields here. Are you sure that's how a request body should be passed? The sample suggests there is a separate req.write(postData) to fill the body. If it can be set as a body field in options, it's possible there is some additional encoding happening (ie - it has decided this is a string, so converted it to the bytes "{...}" in the actual HTTP request body).
• You can add additional logging with console.log in the endpoints, which will be written to stdout. So you can log when the endpoint is entered, and log what the current value of request.body is before trying to parse it as JSON.

[martijnlammers]

Hmm yeah that has a very high probability to be the case. I'll immediately try scaffolding the sourcecodes (Client + endpoint) with output to find out what's actually happening, definitely should've done this earlier. I'll report back after my findings.

[martijnlammers]

I actually honestly have no idea what changed - evidently just wrong syntax on my side - but I just used the example in the link you've given me, changed the module from http to https, added my custom options and poof it magically worked. You can even see in the node output that the body is identical to the one before, however it doesn't throw an error this time.

Output using original method

2021-10-28T16:52:37.034344Z -0.002 0 [info ] ../src/js/wrap.cpp:713 | {"key":"hello1"}
2021-10-28T16:52:37.034377Z -0.002 0 [info ] ../src/js/wrap.cpp:713 | {"key":"hello1"}
2021-10-28T16:52:45.407024Z -0.001 0 [info ] ../src/js/wrap.cpp:713 | SyntaxError: unexpected end of input
2021-10-28T16:52:45.407057Z -0.001 0 [info ] ../src/js/wrap.cpp:735 | at :1
at json (native)
at read (/endpoints/read.js:8)

Output using second method

. . .
2021-10-28T17:02:26.753350Z -0.002 0 [info ] ../src/js/wrap.cpp:713 | {"key":"hello1"}
2021-10-28T17:02:26.753382Z -0.002 0 [info ] ../src/js/wrap.cpp:713 | {"key":"hello1"}

Thanks for the help again Eddy.