Merge pull request #10 from digitalocean/mdl-readme

README: add ovs, ovsdb examples

Author: mdlayher

README.md

@@ -1,21 +1,72 @@
 go-openvswitch [![Build Status](https://travis-ci.org/digitalocean/go-openvswitch.svg?branch=master)](https://travis-ci.org/digitalocean/go-openvswitch) [![GoDoc](https://godoc.org/github.com/digitalocean/go-openvswitch?status.svg)](https://godoc.org/github.com/digitalocean/go-openvswitch) [![Go Report Card](https://goreportcard.com/badge/github.com/digitalocean/go-openvswitch)](https://goreportcard.com/report/github.com/digitalocean/go-openvswitch)
 ==============
 
-Go packages which enable interacting with Open vSwitch. Apache 2.0 Licensed.
+Go packages which enable interacting with Open vSwitch and related tools. Apache 2.0 Licensed.
 
 - `ovs`: Package ovs is a client library for Open vSwitch which enables programmatic control of the virtual switch.
+- `ovsdb`: Package ovsdb implements an OVSDB client, as described in RFC 7047.
 - `ovsnl`: Package ovsnl enables interaction with the Linux Open vSwitch generic netlink interface.
 
 ovs
 ---
 
-Not yet open source; coming soon!
+Package `ovs` is a wrapper around the `ovs-vsctl` and `ovs-ofctl` utilities, but
+in the future, it may speak OVSDB and OpenFlow directly with the same interface.
+
+```go
+// Create a *ovs.Client.  Specify ovs.OptionFuncs to customize it.
+c := ovs.New(
+    // Prepend "sudo" to all commands.
+    ovs.Sudo(),
+)
+
+// $ sudo ovs-vsctl --may-exist add-br ovsbr0
+if err := c.VSwitch.AddBridge("ovsbr0"); err != nil {
+    log.Fatalf("failed to add bridge: %v", err)
+}
+
+// $ sudo ovs-ofctl add-flow ovsbr0 priority=100,ip,actions=drop
+err := c.OpenFlow.AddFlow("ovsbr0", &ovs.Flow{
+    Priority: 100,
+    Protocol: ovs.ProtocolIPv4,
+    Actions:  []ovs.Action{ovs.Drop()},
+})
+if err != nil {
+    log.Fatalf("failed to add flow: %v", err)
+}
+```
+
+ovsdb
+-----
+
+Package `ovsdb` allows you to communicate with an instance of `ovsdb-server` using
+the OVSDB protocol, specified in [RFC 7047](https://tools.ietf.org/html/rfc7047).
+
+```go
+// Dial an OVSDB connection and create a *ovsdb.Client.
+c, err := ovsdb.Dial("unix", "/var/run/openvswitch/db.sock")
+if err != nil {
+	log.Fatalf("failed to dial: %v", err)
+}
+// Be sure to close the connection!
+defer c.Close()
+
+// Ask ovsdb-server for all of its databases.
+dbs, err := c.ListDatabases()
+if err != nil {
+	log.Fatalf("failed to list databases: %v", err)
+}
+
+for _, d := range dbs {
+	log.Println(d)
+}
+```
 
 ovsnl
 -----
 
 Package `ovsnl` allows you to utilize OvS's Linux generic netlink interface to
-pull data from the kernel.  Here's an example:
+pull data from the kernel.
 
 ```go
 // Dial a generic netlink connection and create a *ovsnl.Client.