Add Introduction section to Java API docs

docs/0.5/programming_guides/java.markdown

@@ -28,12 +28,11 @@ Java API
 Introduction
 ------------
 
-Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
-tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
-quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
-consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
-cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
-proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
+Analysis programs in Stratosphere are regular Java Programs that implement transformations on data sets (e.g., filtering, , mapping, joining, grouping). The data sets are initially created from certain sources (e.g., by reading files, or from collections). The results are returned by sinks, which may for example write the data to (distributed) files, or print it to the command line. The sections on the [program skeleton](#skeleton) and [transformations](#transformations) show the general template of a program and describe the available transformations.
+
+Stratosphere programs can run in a variety of contexts, for example locally as standalone programs, locally embedded in other programs, or on clusters of many machines (see [program skeleton](#skeleton) for how to define different environments). All programs are executed lazily: When the program is run and the transformation method on the data set is invoked, it creates a specific transformation operation. That transformation operation is only executed once program execution is triggered on the environment. Whether the program is executed locally or on a cluster depends on the environment of the program.
+
+The Java API is strongly typed: All data sets and transformations accept typed elements. This allows to catch typing errors very early and supports safe refactoring of programs.
 </section>
 
 <section id="example">