Enable streams in http, and add support for preferredTransports as parameter to createReadStream (as it was in p_f_createReadStream)

API.md

@@ -239,14 +239,26 @@ returns:            Dictionary of Key:Value pairs, note take care if this could
 ```
 
 ### Transports - other functions
-##### static async p_f_createReadStream(url, {wanturl})
+##### static async p_f_createReadStream(url, {wanturl, preferredTransports=[] })
 Provide a function of the form needed by <VIDEO> tag and renderMedia library etc
 ```
 url     Urls of stream
 wanturl True if want the URL of the stream (for service workers)
+preferredTransports: preferred order to select stream transports (usually determined by application)
 returns f(opts) => stream returning bytes from opts.start || start of file to opts.end-1 || end of file
 ```
 
+##### static createReadStream(urls, opts, cb)
+Different interface, more suitable when just want a stream, now.
+```
+urls:   Url or [urls] of the stream
+opts{
+    start, end:   First and last byte wanted (default to 0...last)
+    preferredTransports: preferred order to select stream transports (usually determined by application)
+}
+returns open readable stream from the net via cb or promise
+```
+
 ##### supports(url, funcl)
 Determines if the Transport supports url’s of this form. For example TransportIPFS supports URLs starting ipfs:
 ```
@@ -500,7 +512,8 @@ SupportFunctions (note YJS uses IPFS and supports some other functions):
 SupportFeatures: 
     fetch.range Not supported (currently April 2018))
     
-Currently there is code for p_f_createReadStream. It works but because of some other IPFS issues is disabled.
+Currently there is code for p_f_createReadStream. It works but because IPFS cannot return an error even if it 
+cannot open the stream, IPFS is usually set as the last choice transport for streams.
 
 ## TransportYJS
 A subclass of Transport for handling YJS connections.
@@ -520,8 +533,10 @@ When used with a SW, it will attempt to retrieve from the http backup URL that i
 In the SW it will also generate errors about trackers because the only reason to use trackers is to get the WebRTC links.
 
 supportURLS = `magnet:*` (TODO: may in the future support `dweb:/magnet/*`)
+
 supportFunctions:
-    `fetch, createReadStream`
+    `fetch`, `createReadStream`
+
 supportFeatures: 
     fetch.range Not supported (currently April 2018)
 
@@ -529,10 +544,17 @@ supportFeatures:
 A subclass of Transport for handling GUN connections (decentralized database)
 
 supportURLS = `gun:*` (TODO: may in the future support `dweb:/gun/*`)
-supportFunctions 
+
-    `add, list, listmonitor, newlisturls, connection, get, set, getall, keys, newdatabase, newtable, monitor`
+supportFunctions = `add`, `list`, `listmonitor`, `newlisturls`, `connection`, `get`, `set`, `getall`, `keys`, `newdatabase`, `newtable`, `monitor`
 supportFeatures: 
 
+## TransportWOLK 
+A subclass of Transport for handling the WOLK transport layer (decentralized, block chain based, incentivised storage)
+
+supportURLs = ['wolk'];
+
+supportFunctions = [ 'fetch',  'connection', 'get', 'set',  ]; // 'store' - requires chunkdata; 'createReadStream' not implemented
+
 ## Naming
 Independently from the transport, the Transport library can resolve names if provided an appropriate callback. 
 See p_resolveNames(urls) and resolveNamesWith(cb)

TransportHTTP.js

@@ -31,7 +31,7 @@ class TransportHTTP extends Transport {
         this.options = options;
         this.urlbase = options.urlbase;
         this.supportURLs = ['contenthash', 'http','https'];
-        this.supportFunctions = ['fetch', 'store', 'add', 'list', 'reverse', 'newlisturls', "get", "set", "keys", "getall", "delete", "newtable", "newdatabase"]; //Does not support: listmonitor - reverse is disabled somewhere not sure if here or caller
+        this.supportFunctions = ['fetch', 'store', 'add', 'list', 'reverse', 'newlisturls', "get", "set", "keys", "getall", "delete", "newtable", "newdatabase", "createReadStream"]; //Does not support: listmonitor - reverse is disabled somewhere not sure if here or caller
         // noinspection JSUnusedGlobalSymbols
         this.supportFeatures = ['fetch.range'];
         this.name = "HTTP";             // For console log etc
@@ -164,6 +164,7 @@ class TransportHTTP extends Transport {
         Node.js readable stream docs: https://nodejs.org/api/stream.html#stream_readable_streams
 
         :param string url: URL of object being retrieved of form  magnet:xyzabc/path/to/file  (Where xyzabc is the typical magnet uri contents)
+        :param boolean wanturl True if want the URL of the stream (for service workers)
         :resolves to: f({start, end}) => stream (The readable stream.)
         :throws:        TransportError if url invalid - note this happens immediately, not as a catch in the promise
          */

TransportIPFS.js

@@ -362,6 +362,7 @@ class TransportIPFS extends Transport {
         :param string url: URL of object being retrieved of form:
             magnet:xyzabc/path/to/file  (Where xyzabc is the typical magnet uri contents)
             ipfs:/ipfs/Q123
+        :param boolean wanturl True if want the URL of the stream (for service workers)
         :resolves to: f({start, end}) => stream (The readable stream.)
         :throws:        TransportError if url invalid - note this happens immediately, not as a catch in the promise
          */

TransportWEBTORRENT.js

@@ -235,6 +235,7 @@ class TransportWEBTORRENT extends Transport {
         Node.js readable stream docs: https://nodejs.org/api/stream.html#stream_readable_streams
 
         :param string url: URL of object being retrieved of form  magnet:xyzabc/path/to/file  (Where xyzabc is the typical magnet uri contents)
+        :param boolean wanturl True if want the URL of the stream (for service workers)
         :resolves to: f({start, end}) => stream (The readable stream.)
         :throws:        TransportError if url invalid - note this happens immediately, not as a catch in the promise
          */

Transports.js

@@ -299,6 +299,7 @@ class Transports {
     static async p_f_createReadStream(urls, {wanturl=false, preferredTransports=[]}={}) { // Note options is options for selecting a stream, not the start/end in a createReadStream call
         /*
         urls:   Url or [urls] of the stream
+        wanturl True if want the URL of the stream (for service workers)
         returns:    f(opts) => stream returning bytes from opts.start || start of file to opts.end-1 || end of file
          */
         let tt = this.validFor(urls, "createReadStream", {}); //[ [Url,t],[Url,t]]  // Can pass options TODO-STREAM support options in validFor
@@ -331,16 +332,19 @@ class Transports {
         debugtransports("Opening stream to %o failed on all transports", urls);
         throw new errors.TransportError(errs.map((err)=>err.message).join(', '));  //Throw err with combined messages if none succeed
     }
-    static createReadStream(urls, opts, cb) { //TODO-API
+    static createReadStream(urls, opts, cb) {
         /*
             Different interface, more suitable when just want a stream, now.
             urls:   Url or [urls] of the stream
-            opts{start, end}:   First and last byte wanted (default to 0...last)
+            opts{
+                start, end:   First and last byte wanted (default to 0...last)
+                preferredTransports: preferred order to select stream transports (usually determined by application)
+            }
             cb(err, stream): Called with open readable stream from the net.
             Returns promise if no cb
          */
         if (typeof opts === "function") { cb = opts; opts = {start: 0}; } // Allow skipping opts
-        DwebTransports.p_f_createReadStream(urls)
+        DwebTransports.p_f_createReadStream(urls, {preferredTransports: (opts.preferredTransports || [])})
             .then(f => {
                 let s = f(opts);
                 if (cb) { cb(null, s); } else { return(s); }; // Callback or resolve stream