Merge pull request #497 from tdas/docs-update

Updated Spark Streaming Programming Guide

Here is the updated version of the Spark Streaming Programming Guide. This is still a work in progress, but the major changes are in place. So feedback is most welcome.

In general, I have tried to make the guide to easier to understand even if the reader does not know much about Spark. The updated website is hosted here -

http://www.eecs.berkeley.edu/~tdas/spark_docs/streaming-programming-guide.html

The major changes are:
- Overview illustrates the usecases of Spark Streaming - various input sources and various output sources
- An example right after overview to quickly give an idea of what Spark Streaming program looks like
- Made Java API and examples a first class citizen like Scala by using tabs to show both Scala and Java examples (similar to AMPCamp tutorial's code tabs)
- Highlighted the DStream operations updateStateByKey and transform because of their powerful nature
- Updated driver node failure recovery text to highlight automatic recovery in Spark standalone mode
- Added information about linking and using the external input sources like Kafka and Flume
- In general, reorganized the sections to better show the Basic section and the more advanced sections like Tuning and Recovery.

Todos:
- Links to the docs of external Kafka, Flume, etc
- Illustrate window operation with figure as well as example.

Author: Tathagata Das <tathagata.das1565@gmail.com>

== Merge branch commits ==

commit 18ff10556570b39d672beeb0a32075215cfcc944
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Tue Jan 28 21:49:30 2014 -0800

    Fixed a lot of broken links.

commit 34a5a6008dac2e107624c7ff0db0824ee5bae45f
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Tue Jan 28 18:02:28 2014 -0800

    Updated github url to use SPARK_GITHUB_URL variable.

commit f338a60ae8069e0a382d2cb170227e5757cc0b7a
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Mon Jan 27 22:42:42 2014 -0800

    More updates based on Patrick and Harvey's comments.

commit 89a81ff25726bf6d26163e0dd938290a79582c0f
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Mon Jan 27 13:08:34 2014 -0800

    Updated docs based on Patricks PR comments.

commit d5b6196b532b5746e019b959a79ea0cc013a8fc3
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Sun Jan 26 20:15:58 2014 -0800

    Added spark.streaming.unpersist config and info on StreamingListener interface.

commit e3dcb46ab83d7071f611d9b5008ba6bc16c9f951
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Sun Jan 26 18:41:12 2014 -0800

    Fixed docs on StreamingContext.getOrCreate.

commit 6c29524639463f11eec721e4d17a9d7159f2944b
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Thu Jan 23 18:49:39 2014 -0800

    Added example and figure for window operations, and links to Kafka and Flume API docs.

commit f06b964a51bb3b21cde2ff8bdea7d9785f6ce3a9
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Wed Jan 22 22:49:12 2014 -0800

    Fixed missing endhighlight tag in the MLlib guide.

commit 036a7d46187ea3f2a0fb8349ef78f10d6c0b43a9
Merge: eab351d a1cd185
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Wed Jan 22 22:17:42 2014 -0800

    Merge remote-tracking branch 'apache/master' into docs-update

commit eab351d05c0baef1d4b549e1581310087158d78d
Author: Tathagata Das <tathagata.das1565@gmail.com>
Date:   Wed Jan 22 22:17:15 2014 -0800

    Update Spark Streaming Programming Guide.

1 files changed, 39 insertions, 5 deletions

diff --git a/docs/css/main.css b/docs/css/main.css
index 31122d5633..8566400f07 100755
--- a/docs/css/main.css
+++ b/docs/css/main.css
@@ -87,20 +87,54 @@ a:hover code {
   max-width: 914px;
 }
 
-/**
- * Make dropdown menus in nav bars show on hover instead of click
- * using solution at http://stackoverflow.com/questions/8878033/how-
- * to-make-twitter-bootstrap-menu-dropdown-on-hover-rather-than-click
- **/
 .dropdown-menu {
   /* Remove the default 2px top margin which causes a small
     gap between the hover trigger area and the popup menu */
   margin-top: 0;
+  /* Avoid too much whitespace at the right for shorter menu items */
+  min-width: 50px;
 }
+
+/**
+ * Make dropdown menus in nav bars show on hover instead of click
+ * using solution at http://stackoverflow.com/questions/8878033/how-
+ * to-make-twitter-bootstrap-menu-dropdown-on-hover-rather-than-click
+ **/
 ul.nav li.dropdown:hover ul.dropdown-menu{
   display: block;
 }
+
 a.menu:after, .dropdown-toggle:after {
   content: none;
 }
 
+/** Make the submenus open on hover on the parent menu item */
+ul.nav li.dropdown ul.dropdown-menu li.dropdown-submenu:hover ul.dropdown-menu {
+  display: block;
+}
+
+/** Make the submenus be invisible until the parent menu item is hovered upon */
+ul.nav li.dropdown ul.dropdown-menu li.dropdown-submenu ul.dropdown-menu {
+  display: none;
+}
+
+/**
+ * Made the navigation bar buttons not grey out when clicked.
+ * Essentially making nav bar buttons not react to clicks, only hover events.
+ */
+.navbar .nav li.dropdown.open > .dropdown-toggle {
+  background-color: transparent;
+}
+
+/**
+ * Made the active tab caption blue. Otherwise the active tab is black, and inactive tab is blue.
+ * That looks weird. Changed the colors to active - blue, inactive - black, and
+ * no color change on hover.
+ */
+.nav-tabs > .active > a, .nav-tabs > .active > a:hover {
+  color: #08c;
+}
+
+.nav-tabs > li > a, .nav-tabs > li > a:hover {
+  color: #333;
+}