How to invoke a java external on a click of a button in a page

We have a requirement to make a Webservice/Database call on click of a button on a page. I was thinking java external would be the approach to take and there should be a way to invoke java external on click of the button. Looking at all example componeents which came with instalation I see we can invoke a javascript on button click but do not see a way to invoke external or invoke external from java script.

Is my understanding with respect to java external correct?Is it meant for such purpose to be invoked by end user or only at page creation level to input data to the page at creation time?

Any help would be appreciated!

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Bowker

Java Externals are executed during page construction before the page is returned to the browser.

What you will need is to return a page that has a button that, when pushed, will call a JavaScript function that may perform an AJAX call (passing any data necessary) or have the browser display a completely new page. That second request can (will/should) eventually reach LiveSite which can then produce a new "page" that's built using a Java External.

The two options you have (AJAX or new page) is up to you. If the button is supposed to populate some portion of the screen, then you should probably use AJAX or an iFrame. If you will be replacing all the content on the screen (a new page) then the button can do a simple document.location.href= (or equivalent).

So in summary you will need 2 "pages", one with the button and one to be called when you press the button.

Harykrzna

Hi

Make a java external call in the page and render all the parameters required from the DB and use or save the values of retrieved parameters in any variable. and when we come to button click - make a ajax call in your scripts. In that ajax call pass the required parameters with the help saved variable value which u render from the initial java externals call.

This is how we r currently using it in our pages for displaying results from DB and for further display inthe same screen we make ajax calls.......

regards
hary

Crsb

did you consider invoking a custom servlet instead of the OOTB external?

mdazeem

Yes we got away with implementing a servlet and iinvoking it on AJAX call on button click. I was wrong with my initial understanding that java external can be invoked dynamically on html events.

Crsb

did you make the servlet live within the LSDS container, or did you have it running as a standalone app?

mdazeem

I guess it shouldn't matter which server we use to deploy as long as its reachable over http. But if your question was more of a code pacjaging then we packaged it as a new webapplication which can be deployed in any application server. We did not club it with the content center webapplication.

Crsb

I am just trying to decide on best way to make it portable and easy to migrate between envs and at the same time well integrated with authoring app(TS) and the runtime app (LSDS). I think your approach of a standalone webapp might be the best to minimize configuration requirements from migrating between different envs.

mdazeem

Am not sure whether its a good idea to keep business logic(dynamic content) well integrated with the TS or LSDS.It has its own pros and cons.

To me keeping it as a standalone web application gives the main advantage of scalability and enables to have a build/deployment cycle independent of that of the Content Center infrastructure.

mdazeem

Just as a suggestion and little bit of over curiosity :-)

If the functionality you are trying to build in the servlet is minimal or is probably a service giving out some dynamic content, consider exposing it as a RESTful Web Service. In that way its a clean approach to integrate with the the AJAX call on any HTML event.

Crsb

Just as a suggestion and little bit of over curiosity :-)

If the functionality you are trying to build in the servlet is minimal or is probably a service giving out some dynamic content, consider exposing it as a RESTful Web Service. In that way its a clean approach to integrate with the the AJAX call on any HTML event.

Thanks for your curiosity Smiley Wink

. that's pretty much what I am trying to do.
I have a full url to a web service that returns true or false. Instead of calling it straight from my web page (Ajax) and have to deal with cross-domain restrictions using a proxy or anything that will require a third party/team to install or configure things. I decided to create a servlet that runs locally. the html form makes an Ajax call to the servlet which queries the proper web service and returns the web service response to the web page to consume. so no business logic here, all business logic is already handled by the web service. Whatever solution I come up with will have to seamlessly work in all stages of content cycle meaning teamsite, sitepublisher preview, staging, QA..prod envs. Now this is just an example, I eventually want to develop kinda of standards or a framework to handle this type of requirements with our livesite implementation.