Changes between Version 18 and Version 19 of TopdlLibrary

Timestamp:

Oct 8, 2012 2:27:10 PM (12 years ago)

Author:

faber

Comment:

--

TopdlLibrary

@@ -547 +547 @@
 The next few examples will build on one another to show a more complex change to a topology.  We will take a topology, find the degrees of nodes, assign operating systems to them based on that degree, and output DETER-ready ns2.
 
-To try this we need a more complex topology.  The program below creates a topology with {{{nrouters}}} completely connected routers, each of which has {{{nleaves}}} leaves, except for one central router that has none.  Here is an image of the topology when {{{nrouters}}}=4 and {{{nleaves}}}=4:
+To try this we need a more complex topology.  The program below creates a topology  with {{{nrouters}}} completely connected routers, each of which has {{{nleaves}}} leaves, except for one central router that has none.  Here is an image of the topology ([attachment:topo.xml in topdl]) when {{{nrouters}}}=4 and {{{nleaves}}}=4:
 
 [[Image(topo.png)]]
 
-We leave one router without leaves for aecthetics.
+(One router is leafless because it makes the image more aesthetic).
 
 Here is the program that generates that topology:
@@ -620 +620 @@
 
 The code takes a few more shortcuts in construction,  e.g.,  most elements and substrates are appended directly to the lists rather than being assigned to variables, but is not fundamentally different from the start topology generator.
+
+== Annotating A Topology ==
+
+The first step in out transformation is to take a topology and add attributes that will be used by other applications.  In our example, the other applications will be further refinements in the same program.
+
+Here is a function that walks a topology, determines the degree of each computer, and adds an [TopdlLibrary#AttributeClass attribute] to each computer with that attribute in it.  It demostrates editing a topology using the [TopdlLibrary#TopdlClassFeatures set_attribute] function  common to topdl classes.
+
+{{{
+def annotate_degree(top):
+    '''
+    Add an attribute (node_degree) to each Computer in the topology (top) that
+    lists its degree
+    '''
+    for e in top.elements:
+        # Skip elements that are not computers
+        if not isinstance(e, topdl.Computer): continue
+        # degree is the number of interfaces
+        deg = len(e.interface)
+        # Save a string-valued attribute
+        e.set_attribute('node_degree', '%s' % deg)
+    return top
+}}}
+
+== Adding Other Classes ==
+
+This function takes a topology that has been through the {{{annotate_degree}}} function above and adds an [TopdlLibrary#OperatingSystemClass OperatingSystem nested object] to each Computer in the topology, based on the {{{node_degree}}} attribute.  This demonstrates adding a nested object directly, rather rthan through [TopdlLibrary#TopdlClassFeatures set_attribute].
+
+{{{
+def add_operating_system(top):
+    '''
+    Add an OperatingSystem class to each computer in the topology (top).  If
+    the node is a leaf (degree 1) make it Ubuntu Linux, otherwise make it
+    FreeBSD.  annotate_degree() must have been called on the topology as this
+    routine uses the node_degree attribute to make decisions.
+    '''
+
+    for e in top.elements:
+        # Skip non-Computers
+        if not isinstance(e, topdl.Computer): continue
+        a = e.get_attribute('node_degree')
+        # if there is a node_degree attribute, assign an OS
+        if a:
+            # Covnert the string attribute into an integer
+            try:
+                deg = int(a)
+            except ValueError, e:
+                sys.exit('%s has a non-integer degree %s!?' % (e.name, a))
+            # Assign the os - includes a distribution for Linux
+            if deg == 1:
+                e.os.append(topdl.OperatingSystem(name='Linux',
+                    distribution='Ubuntu'))
+            else:
+                e.os.append(topdl.OperatingSystem(name='FreeBSD'))
+    return top
+
+}}}