[sl4f] Add basic README.md for SL4F
BUG: CONN-26
Change-Id: Iea83007df861ad1a6faacc6723f1dfb5e09e5875
diff --git a/garnet/bin/sl4f/README.md b/garnet/bin/sl4f/README.md
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+SL4F
+=========
+
+The core of the project is an HTTP server called Scripting Layer for Fuchsia
+(SL4F), which runs on Fuchsia devices. The server processes JSON RPC requests
+from remote host driven test frameworks in the form of core service commands,
+parses these requests, and fulfills them with the appropriate Fuchsia
+equivalent (FIDL) commands.
+
+
+## Getting Started
+
+## SL4F Includes
+To include SL4F by default to the build include it with your build:
+`--with garnet/bin/sl4f:bin`
+
+
+## Pushing incremental changes
+1. Make sure SL4F is running.
+2. Build and push with this command `fx build-push sl4f`.
+3. Before changes will take effect make sure there are no actively running SL4F
+instances. Within `fx shell` run `killall sl4f.cmx`.
+4. Run SL4F within an `fx shell` instance:
+`run fuchsia-pkg://fuchsia.com/sl4f#meta/sl4f.cmx`. Note that you can tune your
+test framework to open an ssh connection to run SL4F in the background.
+
+## Facades
+Facades is a term used in SL4F to represent the actual wrapper for FIDL apis
+and maintain statefulness of the context. For example if there is an
+asyncronous event the Facade will keep track of anything important to verify
+for testing at a later time.
+
+## Logging
+In `garnet/bin/sl4f/server/sl4f.rs` there is a macro called `with_line`. Use
+this with your tag in your log lines.
+
+Example:
+```
+200: let tag = "GenericFacade::func";
+201: fx_log_info!(tag: &with_line!(tag), "{:?}", "Really important log.");
+```
+This outputs to
+```
+GenericFacade::func:201 Really important log.
+```
