add basic extractor/collector pattern

docs/00_Prepare_everything.md

@@ -1,8 +1,8 @@
 # Prepare everything
 
-Welcome to the NewPipe tutorial. This tutorial will guide you through the process of creating your own NewPipeExtractor service
+Welcome to the NewPipe tutorial. This tutorial will guide you through the process of creating your own NewPipeExtractor
-with which NewPipe will gain support for a dedicated streaming service like YouTube, Vimeo or SournCloud.
+service with which NewPipe will gain support for a dedicated streaming service like YouTube, Vimeo or SournCloud. Let's
-Let's dive right. ;D
+dive right. ;D
 
 ## Setup your dev environment
 

docs/01_Basic_concept_of_the_extractor.md

@@ -0,0 +1,33 @@
+# Basic Concept of the Extractor
+
+## Collector/Extractor pattern
+
+Before we can start coding our own service we need to understand the basic concept of the extractor. There is a pattern
+you will find all over the code. It is called to __extractor/collector__ pattern. The idea behind this pattern is that
+the [extractor](https://teamnewpipe.github.io/NewPipeExtractor/javadoc/org/schabi/newpipe/extractor/Extractor.html)
+would produce single peaces of data, and the collector would take it and form usable data for the front end out of it.
+The collector also controls the parsing process, and takes care about error handling. So if the extractor fails at any
+point the collector will decide weather it should continue parsing or not. This requires the extractor to be made out of
+many small methods. One method for every data field the collector wants to have. The collectors are provided by NewPipe.
+You need to take care of the extractors.
+
+### Usage in the front end
+
+So typical call for retrieving data from a website would look like this:
+```java
+Info info;
+try {
+    Extractor extractor = new Extractor(ome_meta_info);   // Create a new Extractor with a given context provided as parameter.
+    info = Info.getInfo(extractor);                       // Retrieves the data form extractor and builds info package.
+} catch(Exception e) {
+    // handler errors when collector decided to break up extraction
+}
+```
+
+
+
+
+
+
+
+