How to Call an API

[Layale Zakhour]

Dear All,

How do we call APIs in Cloverleaf?

For instance, how do I call this api:  http://api.wunderground.com/api/9276bc26d85ecb74/hourly10day/geolookup/q/39.8547,35.8623.json” class=”bbcode_url”>http://api.wunderground.com/api/9276bc26d85ecb74/hourly10day/geolookup/q/39.8547,35.8623.json and parse the results, in particular the tags under “hourly_forecast”.

Best Regards,

Layale Zakhour[/url]

Topic

[Levy Lazarre]

Layale,

It all depends on the API. It seems like you are making a call to a REST API, so you have many options.

If you are on Cloverleaf 6.2 and are licensed for the Web Services Adapter (CAA-WS), you can use the GUI since JSON support has been added to 6.2.

Otherwise, you can use a UPOC thread and write some code. You could use CURL to make the API call. Another alternative would be to use the ‘rest’ package to make the API call then the ‘json’ package to convert the json reply to a Tcl dictionary. Then use dict commands to parse the dictionary.

Code:

package require rest
package require json
 ….
::json::json2dict   the_json_reply

If you know Java, you have even more libraries to get and parse the JSON.

I hope this helps.

[Layale Zakhour]

Thank you for your reply Levy. I created a python script that calls the URL and parses the result. How can I pass input from a database table to the python script in Cloverleaf? and how can I write the output to the database?

[David Barr]

The normal way to call a Python script from Cloverleaf would be from a Tcl TPS proc. You can use an inbound database protocol thread to get your input data in a message, then your TPS proc can call “msgget” to get the data into a variable. You can pass that to your Python script either through command line arguments using the exec command (http://wiki.tcl.tk/exec) or through an IPC pipe (http://wiki.tcl.tk/14024). You can put the data back in your message with a “msgset” command, then route the message to an outbound database protocol thread to write the result back to the database. Another alternative is to have Cloverleaf call the Python script, and the script can query the database directly to get the data.

Is there a particular reason you want to do this from Cloverleaf instead of in a script outside of Cloverleaf?

[Layale Zakhour]

Thank you for the info. Well what’s the best way to call a REST web service and a SOAP web service in Cloverleaf? Im using version 6.2. how do we do that using the CAA-WS component?

[Levy Lazarre]

If you look in this forum, under the Sticky: BOX REPO, there is a BOX named ‘ws_samples’ that you can download and import into your system. These are good examples on how to use CAA-WS.

If you don’t want to leverage CAA-WS, you can always use a UPOC thread and write a TPS using one of several packages that are available to you: TclCurl, rest, http…

By the way, with Cloverleaf 6.2, support has been added for Python. You can write your TPS directly in Python. I haven’t had a chance to explore this new feature yet. A BOX has been provided with the install (‘JavascriptAndPython’) that you can use for learning.

[Author]

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