Behind the Scenes: The Creators of Sentinel

Mathematics Master Miguel Bayona P’12 ’18 never thought that six years ago, he would establish the foundation of the current Sentinel system when teaching his Honors Computer Programming class.

Mathematics Master Miguel Bayona P’12 ’18 never thought that six years ago, he would establish the foundation of the current Sentinel system when teaching his Honors Computer Programming class. His students developed an application for the iPad and iPhone, and as they worked on these applications, the idea for having a “duty system application” arose. Bayona later devoted his summer to design the “Duty App.”

For Bayona, the primary challenge he faced when programming the application was “[saving] all the data in the database that could be [referenced] later for other uses.” Initially, the Duty App was only available on iPads because it was written in Objective-C—the programming language that was used by Apple to produce applications for iPads—so it was only used in five to six Houses.

Science Master Keith Voss helped expand the application later by converting the duty system into a web-based system with another programming language, Voss developed a server so that he could host everything himself through an online database, and he invested much of his time into “developing the database and managing how the data flows in and out and gets saved, stored, and presented.”

Since he developed Sentinel, Voss has made constant updates by adding new components to the application based on feedback from students and peers within the faculty. The initial version of Sentinel was originally only used for duty masters to check in students but with feedback, Voss later reprogrammed the system to the Sentinel system we know today, where students can sign themselves in and out, and Housemasters can also view their signout status.

Based on the newest revisions with the Visitation Policy, Voss also added a new Visitation option in Sentinel. Regarding this modification, Voss said, “I was worried at first that making changes on Sentinel would be complicated.” He realized that it was much easier than he thought when he saw that “the system that is already in place for the sign-outs” and he only had to make minor changes to it.

Sentinel is also programmed so that it is user-specific. For example, faculty members who are Housemasters or duty masters have access to additional features in Sentinel. When they log into the Sentinel application, they are automatically redirected to the ‘check-in’ page. Housemasters and duty masters also have the option of utilizing a photo-based check-in page, through which they can check students in based on their photo rather than their name. Additionally, Voss developed the Fast Sign-Out option because students generally use Sentinel on their phones. Therefore, a single button sign-out was implemented to make signing in and out easier.

In addition, Voss also developed features that are not sign-out based. The 2017-2018 Student Council proposed the idea of LQ Trivia, which is based on the HQ Trivia game, to Voss last year.

“[Former School President Brianna Thompson ’18] was in one of my classes, and she asked me if I could design something like HQ for Lawrenceville,” Voss said.

On creating LQ, Voss said, “I had to create an editor so that the questions could be made and make sure that the game utilizes bidirectional communication. This form of communication is used for signing out and checking in as well. When someone checks in, their face will disappear on the app. If another person connects with the server, it will automatically update on my page, which is how LQ works.”

“There has to be a pulse of information that is sent out to all of the users simultaneously [...] In a webpage you have to ask for information. The difference in LQ is that when the game is started, information is sent to you,” Voss added.

When students click on an answer during the game, their responses are sent to LQ, where it is checked with the correct answer. A student’s device does not know whether the answer is correct or not, but the correct response is sent back to the device from the LQ server.

Voss then developed the Face Game when faculty members approached him and asked if there was a way to learn students’ names in the House through Sentinel.

“It took me about three hours to write the initial Face Game program, and then I put in another 20 hours to develop the aesthetics,” Voss said.

According to Voss, another unique feature of Sentinel is the system’s ability to “interact with Veracross and update a student’s information every 12 hours.”

Initially, Bayona had to request a spreadsheet of data from Housemasters, which he manually imported into the original Duty App software. Now, Sentinel automatically updates itself based on changes in Veracross. For example, if a student goes on medical leave, his or her name will no longer be on the check-in list in Sentinel.

According to Voss, “As of now, Veracross shares ‘static information’ with Sentinel, which includes a student’s name, address, and House. The goal is for Veracross to share information such as academic memos so that Housemasters are reminded to discuss it with the student.”

On the challenges he faced, Voss said, “I’d spend eight hours coding one part of the system and realize that it wasn’t the best way to do it. I’d end up starting over, and even though I threw away code, I didn’t throw away what I had learned. The next time I did it, I’d know a better way to do it.”

The ultimate goal of Sentinel is “keeping track of where students are,” Bayona said. In the future, Voss plans to “make Sentinel more efficient and phone-friendly.”


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