## Prerequisites

Install Dex by following [Dex Getting Started Guide](https://dexidp.io/docs/getting-started/)

### Start Dex

```

	ListVols(ctx context.Context) (vols []VolInfo, err error)
	StatVol(ctx context.Context, volume string) (vol VolInfo, err error)
	DeleteVol(ctx context.Context, volume string, forceDelete bool) (err error)

	// WalkDir will walk a directory on disk and return a metacache stream on wr.
	WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) error

	// Metadata operations

<img src="/img/tutorial/sub-applications/image02.png">

If you try interacting with any of the two user interfaces, they will work correctly, because the browser will be able to talk to each specific app or sub-app.

### Technical Details: `root_path`

    assertFailsToDecode(base64(), "Wf2!", "Unrecognized character: !");
    // This sentence just isn't base64() encoded.
    assertFailsToDecode(base64(), "let's not talk of love or chains!");
    // A 4n+1 length string is never legal base64().
    assertFailsToDecode(base64(), "12345", "Invalid input length 5");

		sort.Strings(closestCommands)
		// Suggest other close commands - allow missed, wrongly added and
		// even transposed characters
		for _, value := range commandsTree.Walk(commandsTree.Root()) {
			if sort.SearchStrings(closestCommands, value) < len(closestCommands) {
				continue
			}
			// 2 is arbitrary and represents the max
			// allowed number of typed errors

    # rules should be exported to. Currently only one value can be provided in this list. This value
    # should be one of the following two options:
    # * implies these objects are visible to all namespaces, enabling any sidecar to talk to any other sidecar.
    # . implies these objects are visible to only to sidecars in the same namespace, or if imported as a Sidecar.egress.host
    defaultConfigVisibilitySettings: []

    # rules should be exported to. Currently only one value can be provided in this list. This value
    # should be one of the following two options:
    # * implies these objects are visible to all namespaces, enabling any sidecar to talk to any other sidecar.
    # . implies these objects are visible to only to sidecars in the same namespace, or if imported as a Sidecar.egress.host
    defaultConfigVisibilitySettings: []

the configuration for all the goals outside the execution block we need to account for creating the right configuration element which includes only those configuration elements for a particular goal that that particular goal understands. We need to walk through the parameters of the Mojo in question and only take the configuration options that apply....

The install is organized in 'environments' - each environment consists of a set of components
in different namespaces that are configured to work together. Regardless of 'environment',
workloads can talk with each other and obey the Istio configuration resources, but each environment
can use different Istio versions and different configuration defaults.

#### Framed protocols

Framed protocols like http/2 don't lend themselves to blocking APIs. Each application-layer thread wants to do blocking I/O for a specific stream, but the streams are multiplexed on the socket. You can't just talk to the socket, you need to cooperate with the other application-layer threads that you're sharing it with.