AWS plugin: Add support for a compressed payload

AWS imposes a limit of 16MB in my testing for the payload of a lambda. Compressing it enables us to pass x2-3 more data, thanks to the inefficiencies of JSON

plugins/tiddlywiki/aws/docs/lambda.tid

@@ -39,6 +39,17 @@ The Lambda boot code looks for an array of tiddlers to load in `event.tiddlers`,
 
 ```
 
+The event data can optionally be compressed by passing a JSON object with a single property `compressed` that contains a base64 encoded GZIP compressed representation of the JSON payload data. For example:
+
+```
+var strPayload = JSON.stringify(payload);
+require("zlib").gzip(strPayload,function(err,buff) {
+	var compressedPayload = {compressed: new Buffer(buff).toString("base64")};
+	// Invoke lambda with compressed payload
+	...
+});
+```
+
 ! Return data
 
 If the Lambda function successfully executes it returns an object with the following fields:

plugins/tiddlywiki/aws/templates/lambda/handler.tid

@@ -16,15 +16,29 @@ exports.handler = function(event,context,callback) {
 	$tw.packageInfo = lambdaPackageInfo;
 	// Load any tiddlers from the package
 	$tw.preloadTiddlerArray(lambdaTiddlers);
-	// Load any tiddlers from the event
-	if(event.tiddlers) {
-		$tw.preloadTiddlerArray(event.tiddlers);	
+	// Decompress the event data if required
+	if(typeof event.compressed === "string") {
+		require("zlib").gunzip(Buffer.from(event.compressed,"base64"),function(err,buff) {
+			if(err) {
+				return callback(err);
+			}
+			boot(JSON.parse(buff.toString()));
+	  });
+	} else {
+		boot(event);
+	}
+
+	function boot(event) {
+		// Load any tiddlers from the event
+		if(event.tiddlers) {
+			$tw.preloadTiddlerArray(event.tiddlers);	
+		}
+		// Load the commands from the event
+		$tw.boot.argv = (event.commands || []).slice(0);
+		// Boot the TW5 app
+		_boot($tw);
+		$tw.boot.boot(function() {
+			callback(null,$tw["lambda-result"]);
+		});	
 	}
-	// Load the commands from the event
-	$tw.boot.argv = (event.commands || []).slice(0);
-	// Boot the TW5 app
-	_boot($tw);
-	$tw.boot.boot(function() {
-		callback(null,$tw["lambda-result"]);
-	});
 }