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https://github.com/youngkin/erl-web-zookeeper
Sample app demonstrating use of Erlang supervision, release with multiple apps, web interface, and quorum election via Zookeeper.
https://github.com/youngkin/erl-web-zookeeper
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Sample app demonstrating use of Erlang supervision, release with multiple apps, web interface, and quorum election via Zookeeper.
- Host: GitHub
- URL: https://github.com/youngkin/erl-web-zookeeper
- Owner: youngkin
- License: apache-2.0
- Created: 2014-07-01T19:04:54.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2014-10-02T13:17:45.000Z (about 10 years ago)
- Last Synced: 2023-08-27T00:01:06.889Z (about 1 year ago)
- Language: Erlang
- Size: 449 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# erl-web-zookeeper
"ez" is an application that demonstrates the usage of:
1. Rebar - see the rebar.config file in the project root directory for details.
2. Starting multiple, dependent, applications. For example, this project depends on lager and zookeeper. See the start.sh file for more details, particularly the application:ensure_all_started() directive. This starts all the applications listed in the application resource file's, src/ez.app.src, {applications, [...]} tuple for the complete set of applications.
3. Lager as a logging replacement for the standard Erlang logger. See the erl-zookeeper.config file for Lager configuration settings.
4. Cowboy to enable support for a ReSTful interface to the application. n this application the interface is used to get and set weather data.
5. Zookeeper is used as the data store for weather data.
# Prerequisites
[http://zookeeper.apache.org/](Apache Zookeeper) is one of the cornerstones for this project. Most all other external dependencies are handled by rebar.
* At least one zookeeper instance should be available. The src/ez.app.src file contains the configuration for Zookeeper. The `{hosts {...}}` tuple should be modified to match up with the Zookeeper installation.
# Building
This could be better, i.e., with make handling all this.
1. `$ ./rebar get-deps`
2. `$ ./rebar compile`
# Running
Before running the app you'll need to take a look at the src/ez.app.sr file. For example, the `{hosts, [...]}`
tuple needs to be modified to point to the Zookeeper instance that supports the app. The values included
should be sufficient for cases where Zookeeper is running locally using the Zookeeper configuration defaults.
The `{env, [{http_host, xxx}, {http_port, xxx}]}` needs to reflect your local runtime environment for the
application. The defaults will be sufficient in most cases.
If these configuration settings have been changed you'll need to rebuild the app as described above.
Do one of the following to start the app:
1. `$ ./start`
2. Or `$ ./start_in_shell` to start the service in an Erlang shell
# Take it for a spin
1. Retrieve service status in JSON, HTTP, or plain text formats
`curl -i -H "Accept: application/json" http://localhost:8080/status`
`curl -i -H "Accept: text/html" http://localhost:8080/status`
`curl -i -H "Accept: text/plain" http://localhost:8080/status`
2. POST data (weather) to service (for Denver). Change the value of the last node to whatever city desired to set the weather conditions for that city.
`curl -i -X POST -H "Content-Type: application/json" -d 'clear' http://localhost:8080/weather/city/denver`
3. GET data (weather) from service (for Denver). Change the value of the last node to whatever city desired to get the weather conditions for that city.
`curl -i -H "Accept: text/plain" http://localhost:8080/weather/city/denver`
3. GET data (weather) from service for all available cities with associated weather conditions.
`curl -i -H "Accept: text/plain" http://localhost:8080/weather/cities`
# REST API
## http://example.com/status
### GET
Returns the current status of the application
Success: 200
Returns application/json, text/plain, text/html formatted data (see below)
### PUT
Not supported
Error: 405, Method not allowed, no retry
### POST
Not supported
Error: 405, Method not allowed, no retry
### DELETE
Not supported
Error: 405, Method not allowed, no retry
## http://example.com/weather/cities
### GET
Returns the URLs of all currently defined cities.
Success: 200
Error: 404 NOT FOUND
Error: 400 if the URL has a bad path element (e.g., /weather/sites vs. /weather/cities or /weather/city)
Returns application/json, text/plain, text/html formatted data (see below)
### PUT
Not supported
Error: 405, Method not allowed, no retry
### POST
Not supported
Error: 405, Method not allowed, no retry
### DELETE
Not supported
Error: 405, Method not allowed, no retry
## http://example.com/weather/city/some_city_name
### GET
Returns the weather data of the specified city or a 404 NOT FOUND
Error: 400 if the URL has a bad path element (e.g., /weather/sites vs. /weather/cities or /weather/city)
Returns application/json, text/plain, text/html formatted data (see below)
## PUT
Not supported
Error: 405, Method not allowed, no retry
### POST
Adds/updates the specified city
Success: 204, Created or updated;
Error: 400, bad request, don’t retry
Error: 500, server error, retry
Accepts only application/json formatted data (see below)
### DELETE
Not supported
Error: 405, Method not allowed, no retry
## Example output
### Status
`{ �Cowboy port�: number }`
```
application/json GET Example (status)
{ �Cowboy port�: 8080 }
```
```
text/plain GET Example (status)
{ �Cowboy port�: 8080 }
```
```
text/html GET Example (status)
EZ Status
EZ Status
Cowboy Port: 8080
```
### Weather JSON
```
{ �city�: string,
�weather�: string}
```
PUT Example (weather/city/city_name)
```
{ �city� : �denver�,
�weather� : �clear� }
```
GET Example (weather/cities)
```
{ �city� : �http://example.com/weather/city/denver�,
�city� : �http://example.com/weather/city/seattle�,
�
}
```
GET Example (weather/city)
```
{ �city� : �denver�,
�weather� : �clear� }
```
# Additional information
## Release - TODO
## Zookeeper - TODO
## Cowboy - TODO
# TODO:
1. Package as a release and distribute. Document how to do this.
2. Implement better support for accepting actual JSON content on POST requests
3. Protect against GET requests for non-existent city weather data. Should return a 404 NOT FOUND. It currently returns 500.
4. Get cities from Zookeeper instead of being hardcoded like it currently is. As is, it returns a
hard-coded city list of [denver, tucson, seattle].