Differentiate between WML-Script and Web-based scripting languages.
WML Script is a lightweight procedural scripting language, optimized for small-memory, low-power CPU wireless devices. This has its roots in the ECMA- Script scripting language, a standard version of JavaScript based upon core features of such language.
WML Script language syntax, constructs, flow control structures and etc. All are similar to those of JavaScript due to this inheritance. This provides an optimized and extended subset of JavaScript for the narrowband wireless network-depend devices as mobile phones, PDAs, and two-way pagers.
Difference among WML script and other web based languages:
- WML Script is loosely coupled along with WML and can be used independently like a standalone tool
- The method WML Script is transferred from the WAP gateway to be executed upon the wireless client is diverse from the way JavaScript is transferred over the Web for execution upon the client browser. But JavaScript is transferred in clear text, whereas WML Script is compiled through the WAP gateway in byte code before being transmitted to the wireless client. The benefit of this approach is, the byte code is usually much smaller in size than WML Script source code. It enables faster download of WML Script along with less bandwidth consumption. This also permits low-memory capacity of the wireless device to store many application data.
- The other key difference is that the WS code is not embedded along with the WML source file but is remained as an independent module.
- WML Script does not support global variables; simply variables declared in functions or passed like functions parameters are permitted.
- Language support for arrays is not available.
- Support for low-level binary arithmetic operations is available also in the form of bit-wise operators.
The wireless device requires a WML Script virtual machine to interpret such WS byte code. If the device does not have a WS VM, this can ignore the reference to WML Script in a WML file. While the WML document interpreter comes across a reference to WML Script, this asks the WAP gateway for the referred WML Script module (as compilation).