# WEB

This guide describes the instructions to configure WEB as Alluxio's under storage system.

## Initial Setup

The Alluxio binaries must be available on the machine.

## Configuring Alluxio

Alluxio unifies access to different storage systems through the [unified namespace](https://documentation.alluxio.io/ee-da-en/da-2.10/core-services/unified-namespace) feature. An WEB location can be either mounted at the root of the Alluxio namespace or at a nested directory.

### ROOT MOUNT

Configure Alluxio to use under storage systems by modifying `conf/alluxio-site.properties`. If it does not exist, create the configuration file from the template.

```console
$ cp conf/alluxio-site.properties.template conf/alluxio-site.properties
```

the following environment variable assignment needs to be added to `conf/alluxio-site.properties`, and we actually support both http\:// and https\:// protocols.

```
alluxio.master.hostname=localhost
# alluxio.master.mount.table.root.ufs=[https|http]://<HOSTNAME>:<PORT>/DIRECTORY/
# A sample for this article
alluxio.master.mount.table.root.ufs=https://downloads.alluxio.io/downloads/files/
```

Specify the settings for parsing a WEB page(Optional):

```
alluxio.underfs.web.connnection.timeout=<WEB_CONNECTION_TIMEOUT>
alluxio.underfs.web.header.last.modified=<WEB_HEADER_LAST_MODIFIED>
alluxio.underfs.web.parent.names=<WEB_PARENT_NAMES>
alluxio.underfs.web.titles=<WEB_TITLES>
```

Here, `alluxio.underfs.web.connnection.timeout` is the timeout setting for an http connection (unit: second, default: 60s). `alluxio.underfs.web.header.last.modified` represents the format to parse the last modified field for a directory or a file from an http response header (default: "EEE, dd MMM yyyy HH:mm:ss zzz"). `alluxio.underfs.web.parent.names` indicates the start row index of the files list, which can be set as multiple flags separated by commas (default: "Parent Directory,..,../"). `alluxio.underfs.web.titles` is a flag that can be used to check if a web page is a directory. It can also be set with multiple values separated by commas (default: "Index of ,Directory listing for ").

### NESTED MOUNT

An WEB location can be mounted at a nested directory in the Alluxio namespace to have unified access to multiple under storage systems. Alluxio's [Mount Command](https://documentation.alluxio.io/ee-da-en/da-2.10/operations/user-cli#mount) can be used for this purpose. For example, the following command mounts a directory inside an WEB directory into Alluxio directory `/web`:

```console
$ ./bin/alluxio fs mount \
  --option alluxio.underfs.web.connnection.timeout=<WEB_CONNECTION_TIMEOUT> \
  --option alluxio.underfs.web.header.last.modified=<WEB_HEADER_LAST_MODIFIED> \
  --option alluxio.underfs.web.parent.names=<WEB_PARENT_NAMES> \
  --option alluxio.underfs.web.titles=<WEB_TITLES> \
  /web [https|http]://<HOSTNAME>:<PORT>/DIRECTORY/ 
```

## Running Alluxio with WEB

Run the following command to start Alluxio filesystem.

```console
$ ./bin/alluxio format
$ ./bin/alluxio-start.sh local
```

To verify that Alluxio is running, you can visit [**http://localhost:19999**](http://localhost:19999), or see the log in the `logs` folder.

Visit your WEB volume by running the following command:

```console
$ ./bin/alluxio fs ls /
```

After waiting for a while, you can see the following result:

```
dr--r-----                                              0       PERSISTED 05-21-2019 12:53:22:000  DIR /1.4.0
dr--r-----                                              0       PERSISTED 05-21-2019 12:54:23:000  DIR /1.5.0
dr--r-----                                              0       PERSISTED 05-21-2019 12:55:06:000  DIR /1.6.0
dr--r-----                                              0       PERSISTED 05-21-2019 12:55:38:000  DIR /1.6.1
dr--r-----                                              0       PERSISTED 05-21-2019 12:57:00:000  DIR /1.7.0
dr--r-----                                              0       PERSISTED 05-21-2019 12:57:57:000  DIR /1.7.1
dr--r-----                                              0       PERSISTED 05-21-2019 13:00:25:000  DIR /1.8.0
dr--r-----                                              0       PERSISTED 05-21-2019 13:02:07:000  DIR /1.8.1
dr--r-----                                              0       PERSISTED 05-24-2019 05:16:31:000  DIR /2.0.0
dr--r-----                                              0       PERSISTED 05-21-2019 13:02:11:000  DIR /2.0.0-preview
```

Stop Alluxio by running:

```console
$ ./bin/alluxio-stop.sh local
```