After a failed prototype and some additional discussions we came to the conclusion that we need a delta submit implementation that is not spreading like cancer throughout the entire code base. Also it should be easily turned on or off.

The chosen implementation is supposed to truly calculate the difference in parameters between a previously sent submit and the current form submit. Only the added and removed parameters are sent to the server which is responsible to recreate the full form submission.

Calculating the difference between to sets of parameters is an expensive operation (for Javascript). The complementing of two sets is done by iterating over the elements of the complemented set, while testing if the current element is found in the complementing set. When the lookup is sucessful the element it is not added to the resulting set.

To improve the speed of lookup we need to implement a hashtable in Javascript. The lookup operations will be sped up considerably for sets larger than 3000 items.

Implemented Hashtable using a direct chaining strategy. See http://en.wikipedia.org/wiki/Hash_table#Separate_chaining .

Implemented SDBM hash function. See http://www.cse.yorku.ca/~oz/hash.html .

Implemented Hashset based on the hash table operations. This is the structure we need to hold the paramerters of a form submit to allow fast lookup to the contained elements.

Implemented complement operation for the Hashset. The operation is attached to the Hashset object to allow fast access to the internals of the underlying hashtable's primitive operations.

Created unit test to verify Hashtable and Hashset functionality and also empirical performance tests.

Started delta submit implementation.
Modified ice.submit function to calculate the complement between the sets of parameters generated by the previous ice.submit function invocation and paramaeters calculated for the current invocations.

The previous parameters are saved as a property on the form element.

Normally, the first form submit does not a previous set of parameters. To avoid sending a large form submit the initial parameters are calculated for each form on page load.

Introduced DeltaSubmitPhaseListener phase lister that reconstructs the full set of parameters by using the previous set of parameters (saved as attribute on the form component) the submitted delta parameters. The processing is done before apply-request-phase so that the components will the calculated parameters for decoding.

Make delta submit feature configurable. Setting 'org.icefaces.deltaSubmit' context parameter to 'true' enables the delta submit feature.