Today we will take a break from AWS architecture papers to discuss wire framing tools.

UI Customizations: 

Introduction:  

The web page of an application is proprietary to it. When the web page is displayed to the user as part of a workflow for another application using HTTP redirects, the pages have to be customized for seamless experience to the user This involves propagating the brand or the logo through the cross domain pages, modifying text and links and user controls on the shared page. A classic example for this is the login page. Many clients want to customize the login page to suit their needs. Consequently, the login provider needs to provide some sort of wireframing tool to help these clients. We discuss the design of one such wireframing tool. 

Design: 

A wire framing tool that enables in browser experience works universally on all devices. Therefore, hosting the wireframed pages and templates as a web application will be helpful to most clients. Additionally, if this web application was in the form of REST based APIs, it will benefit the client to come up with a tool for themselves that doesn't necessarily pose the restrictions that a provider may have. Sample API could involve something like 

GET displays/v1/prototypes/{id}/pages/{id}.json?api_key=client_dev_key 

Here we use json notation to describe the wire-framing artifacts. These include entities for prototypes, pages and layers. A prototype becomes the container for all pages and layers associated with the mockup that the client would like to achieve. It has attributes such as name, version, timestamps etc. A page also has similar attributes but contains elements and might also show layers. A page is the unit of display in a workflow when user navigates from one user interface to another.  A layer is a group of elements that can be shared between pages. It is similar in nature to templates and used in conjunction with a page. 

As with all REST APIs, there is possibility to create, update and delete these pages so that we can let the clients manage their lifetimes. The purpose of organizing this way is to keep the wireframes simpler to compose.  

The styling and scripting are elements that can be added separately or as strings that can be embedded in placeholders. The placeholder itself works with identifiers and therefore can have any text displayed with it as a literal or as an HTML element. Since the wire framing tool renders them, there is full flexibility in custom injection by the clients. 

Workflows are enabled by association pages with controls. Since this is a wireframe only, data from a page is passed to the next page via the association specified. This provides a seamless replay of pages for a workflow. 

Conclusion:  

A wireframing tool is useful for user interface customization and can work with different clients for the same shared resource. 

#codingexercise

We were discussing finding the largest sum submatrix in a matrix of integers.

As we evaluated the growing range from column to column, we iterated inwards to outwards but the reverse is more efficient.

The advantage here is that the outer bounds of the entire matrix has the largest possible array to apply Kadane's algorithm which we discussed earlier as the one used for finding the max subarray.

Since we find the maximum subarray (i1,i2) along the rows and (j1,j2) along the columns at the first and last row and column of the matrix, the submatrix with a large sum will lie within (i1,0) (i1, col-max), (i2,0)and (i2,col-max) or within (0,j1),(0,j2), (row-max, j1) and (row-max, j2).We merely refine it with every iteration that shrinks the matrix.

Note that we can use the min common (i-topleft,j-topleft) and (i-bottom-right,j-bottom-right) from the first and last row and column subarray determinations.

In this case we could terminate if the entire bounded subarray contributes to max sum. The idea is that we use row major analysis and column major analysis one after the other and pick the better answer of the two. The notion that linear dimension subarray sum will contribute towards the solution lets us exclude the arrays that won't contribute towards the result. However, since the values can be skewed we have to iterate in steps in one dimension only  and updating the max sum as we go.