Error: Cannot find module 'coap'

[dpapdpap]

Hi,
I try your project but i face a problem running node ota-server.js ota-image-example.bin
I receive
internal/modules/cjs/loader.js:638
throw err;
^

Error: Cannot find module 'coap'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15) at Function.Module._load (internal/modules/cjs/loader.js:562:25) at Module.require (internal/modules/cjs/loader.js:692:17) at require (internal/modules/cjs/helpers.js:25:18) at Object.<anonymous> (/home/argyro/contiki/examples/ota-server/ota-server.js:1:12) at Module._compile (internal/modules/cjs/loader.js:778:30) at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10) at Module.load (internal/modules/cjs/loader.js:653:32) at tryModuleLoad (internal/modules/cjs/loader.js:593:12) at Function.Module._load (internal/modules/cjs/loader.js:585:3)
I have put the ota-server directory in examples directory. Where is "coap" ?
I need your help, please