HIPES Plugin¶

This is a remap plugin used in the HIPES system.

Configuration¶

urlp:<name>: Default: url Name of the query parameter for the service URL
path:<path>: Default: / Path to use for the service URL
ssl: Default: no Use SSL when connecting to the service
service: Service server, host[:port]
server: Default: hipes.yimg.com Name of HIPES server, host[:port]
active_timeout: The active connection timeout in ms
no_activity_timeout: The no activity timeout in ms
connect_timeout: The connect timeout in ms
dns_timeout: The DNS timeout

The timeout options override the server defaults (from `records.config), and only apply to the connection to the specific “service” host.

Notes on HIPES¶

HTTP Pipes (aka HIPES and pronounced “Hippies”) allows data services to be pipelined together, as illustrated by the example below.

Example¶

ATS is run on port 80 and apache HTTP web server is run on port 8080 on localhost (127.0.0.1)

The HIPES plugin is used in remap.config

map http://127.0.0.1/svc_case http://nosuchhost @plugin=hipes.so @pparam=service:127.0.0.1:8080 @pparam=path:svc_case.php @pparam=server:127.0.0.1
map http://127.0.0.1/svc_reverse http://nosuchhost @plugin=hipes.so @pparam=service:127.0.0.1:8080 @pparam=path:svc_reverse.php @pparam=server:127.0.0.1
map http://127.0.0.1/test.txt http://127.0.0.1:8080/test.txt

The plugin remaps the incoming URL such as

http://127.0.0.1/svc_reverse/svc_case;case=u/test.txt

to the following

http://127.0.0.1:8080/svc_reverse?url=http%3A%2F%2F127.0.0.1%2Fsvc_case%3Bcase%3Du%2Ftest.txt

The service svc_reverse.php fetches the url from the ATS again and the plugin remaps the URL
```
http://127.0.0.1/svc_case;case=u/test.txt
```

to this URL

http://127.0.0.1:8080/svc_case.php?case=u&url=http%3A%2F%2F127.0.0.1%2Ftest.txt

5. In this example, the service svc_case.php fetches and transforms the response of http://127.0.0.1/test.txt (which ATS proxies the request to a local file) to upper case. And subsequently the service svc_reverse.php receives the response and reverse the order before the response is sent back to the client by ATS.

Notes on reducing traffic¶

There can be significant overhead using HIPES because the data can traverse through ATS many times. Caching can be important to reduce traffic to services/through ATS and can be achieved via a proper Cache-Control header returned by the services. Another way to reduce traffic through ATS is to have ATS to return 302 redirects to url for the requests made by service, instead of proxying the requests to that url. However, the service must then be able to follow the redirect. The down side is that we cannot use ATS to cache intermediate results. Below is an example of using redirect.

Modification to above example to reduce traffic using redirect¶

1. The service svc_reverse.php is modified to add a header of X-HIPES-Redirect: 2 to the request made against url.

HIPES plugin will instruct ATS to return a redirect response to this url

http://127.0.0.1:8080/svc_case.php?case=u&url=http%3A%2F%2F127.0.0.1%2Ftest.txt

for the following request

http://127.0.0.1/svc_case;case=u/test.txt

3. The service svc_reverse.php is also modified to follow the redirect. Thus the response of the service of svc_case.php will not pass through ATS and will pass to svc_reverse.php service instead.