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#chartlet-0cad13a20646171f .chartlet-f-8{opacity:1}.chartlet-wrapper:has(#chartlet-0cad13a20646171f-focus-8:checked) #chartlet-0cad13a20646171f .chartlet-n-8 .chartlet-flow-node,.chartlet-wrapper:has(#chartlet-0cad13a20646171f-focus-8:checked) #chartlet-0cad13a20646171f .chartlet-n-8 .chartlet-seq-box{stroke-width:3}</style><details class="chartlet-focus"><summary>Focus</summary><fieldset><label><input type="radio" name="chartlet-0cad13a20646171f-focus" checked> Show all</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-0"> Learner</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-1"> Web app</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-2"> Booking API</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-3"> Job queue</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-4"> Worker</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-5"> Bookings</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-6"> Certificates</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-7"> Payment provider</label><label><input type="radio" name="chartlet-0cad13a20646171f-focus" class="chartlet-focus-node" id="chartlet-0cad13a20646171f-focus-8"> E-mail service</label></fieldset></details><figure class="chartlet-figure" data-viz="chart"><figcaption>Course booking: containers</figcaption><div class="chartlet-stage"><svg xmlns="http://www.w3.org/2000/svg" width="800" height="940" viewBox="0 0 800 940" id="chartlet-0cad13a20646171f" role="img" aria-labelledby="chartlet-0cad13a20646171f-title chartlet-0cad13a20646171f-description" class="chartlet-root"><title id="chartlet-0cad13a20646171f-title">Course booking: containers</title><desc id="chartlet-0cad13a20646171f-description">Architecture diagram with 9 components and 8 connections in 1 boundary. Course booking (software system): Web app, Booking API, Job queue, Worker, Bookings, Certificates. Main path: Learner → Web app → Booking API → Bookings. Most connected: Booking API (4 connections). Nothing leads into Learner. Bottlenecks: Booking API and Job queue; without either the diagram falls apart. Learner (person): connects to Web app (books a course, via HTTPS). Web app (frontend): connects to Booking API (calls, via JSON/HTTPS). Booking API (service): connects to Bookings (reads, writes, via SQL), Payment provider (takes payment, via HTTPS) and Job queue (queues jobs). Job queue (queue): connects to Worker (delivers). Bookings (database): no outgoing connection. Payment provider (external system): no outgoing connection. Worker (service): connects to Certificates (stores certificates) and E-mail service (sends confirmations, via SMTP). Certificates (storage): no outgoing connection. 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class="chartlet-f chartlet-f-0 chartlet-f-1"><polyline points="416,72 416,172" class="chartlet-flow-edge chartlet-flow-main"><title>Learner → Web app: books a course [HTTPS]</title></polyline><polyline points="412.5,172 416,180 419.5,172 412.5,172" class="chartlet-flow-head chartlet-flow-main-head"/></g><g class="chartlet-f chartlet-f-1 chartlet-f-2"><polyline points="416,244 416,312" class="chartlet-flow-edge chartlet-flow-main"><title>Web app → Booking API: calls [JSON/HTTPS]</title></polyline><polyline points="412.5,312 416,320 419.5,312 412.5,312" class="chartlet-flow-head chartlet-flow-main-head"/></g><g class="chartlet-f chartlet-f-2 chartlet-f-5"><polyline points="416,376 416,500" class="chartlet-flow-edge chartlet-flow-main"><title>Booking API → Bookings: reads, writes [SQL]</title></polyline><polyline points="412.5,500 416,508 419.5,500 412.5,500" class="chartlet-flow-head chartlet-flow-main-head"/></g><g class="chartlet-f chartlet-f-2 chartlet-f-7"><polyline points="440,376 440,479.79 616,479.79 616,512" class="chartlet-flow-edge"><title>Booking API → Payment provider: takes payment [HTTPS]</title></polyline><polyline points="612.5,512 616,520 619.5,512 612.5,512" class="chartlet-flow-head"/></g><g class="chartlet-f chartlet-f-2 chartlet-f-3"><polyline points="392,376 392,479.79 264,479.79 264,504" class="chartlet-flow-edge"><title>Booking API → Job queue: queues jobs</title></polyline><polyline points="260.5,504 264,512 267.5,504 260.5,504" class="chartlet-flow-head"/></g><g class="chartlet-f chartlet-f-3 chartlet-f-4"><polyline points="264,568 264,624" class="chartlet-flow-edge"><title>Job queue → Worker: delivers</title></polyline><polyline points="260.5,624 264,632 267.5,624 260.5,624" class="chartlet-flow-head"/></g><g class="chartlet-f chartlet-f-4 chartlet-f-6"><polyline points="252,688 252,750.903 184,750.903 184,772" class="chartlet-flow-edge"><title>Worker → Certificates: stores certificates</title></polyline><polyline points="180.5,772 184,780 187.5,772 180.5,772" class="chartlet-flow-head"/></g><g class="chartlet-f chartlet-f-4 chartlet-f-8"><polyline points="276,688 276,750.903 296,750.903 296,868" class="chartlet-flow-edge"><title>Worker → E-mail service: sends confirmations [SMTP]</title></polyline><polyline points="292.5,868 296,876 299.5,868 292.5,868" class="chartlet-flow-head"/></g><g class="chartlet-f chartlet-n-0 chartlet-f-0 chartlet-f-1"></g><g class="chartlet-f chartlet-n-1 chartlet-f-0 chartlet-f-1 chartlet-f-2"></g><g class="chartlet-f chartlet-n-2 chartlet-f-1 chartlet-f-2 chartlet-f-3 chartlet-f-5 chartlet-f-7"></g><g class="chartlet-f chartlet-n-3 chartlet-f-2 chartlet-f-3 chartlet-f-4"></g><g class="chartlet-f chartlet-n-4 chartlet-f-3 chartlet-f-4 chartlet-f-6 chartlet-f-8"></g><g class="chartlet-f chartlet-n-5 chartlet-f-2 chartlet-f-5"></g><g class="chartlet-f chartlet-n-6 chartlet-f-4 chartlet-f-6"></g><g class="chartlet-f chartlet-n-7 chartlet-f-2 chartlet-f-7"></g><g class="chartlet-f chartlet-n-8 chartlet-f-4 chartlet-f-8"></g><g class="chartlet-f chartlet-f-0 chartlet-f-1"><rect x="420" y="77" width="98.32" height="36" class="chartlet-diagram-chip"/><text x="425" y="91" text-anchor="start" class="chartlet-diagram-chip-text">books a course</text><text x="425" y="106" text-anchor="start" class="chartlet-diagram-chip-text">[HTTPS]</text></g><g class="chartlet-f chartlet-f-1 chartlet-f-2"><rect x="420" y="249" width="102.52" height="36" class="chartlet-diagram-chip"/><text x="425" y="263" text-anchor="start" class="chartlet-diagram-chip-text">calls</text><text x="425" y="278" text-anchor="start" class="chartlet-diagram-chip-text">[JSON/HTTPS]</text></g><g class="chartlet-f chartlet-f-2 chartlet-f-5"><rect x="444" y="381" width="92.32" height="36" class="chartlet-diagram-chip"/><text x="449" y="395" text-anchor="start" class="chartlet-diagram-chip-text">reads, writes</text><text x="449" y="410" text-anchor="start" class="chartlet-diagram-chip-text">[SQL]</text></g><g class="chartlet-f chartlet-f-2 chartlet-f-7"><rect x="444" y="420" width="98.56" height="36" class="chartlet-diagram-chip"/><text x="449" y="434" text-anchor="start" class="chartlet-diagram-chip-text">takes payment</text><text x="449" y="449" text-anchor="start" class="chartlet-diagram-chip-text">[HTTPS]</text></g><g class="chartlet-f chartlet-f-2 chartlet-f-3"><rect x="310.08" y="381" width="77.92" height="21" class="chartlet-diagram-chip"/><text x="383" y="395" text-anchor="end" class="chartlet-diagram-chip-text">queues jobs</text></g><g class="chartlet-f chartlet-f-3 chartlet-f-4"><rect x="268" y="573" width="57.52" height="21" class="chartlet-diagram-chip"/><text x="273" y="587" text-anchor="start" class="chartlet-diagram-chip-text">delivers</text></g><g class="chartlet-f chartlet-f-4 chartlet-f-6"><rect x="119.44" y="693" width="128.56" height="21" class="chartlet-diagram-chip"/><text x="243" y="707" text-anchor="end" class="chartlet-diagram-chip-text">stores certificates</text></g><g class="chartlet-f chartlet-f-4 chartlet-f-8"><rect x="280" y="693" width="132.64" height="36" class="chartlet-diagram-chip"/><text x="285" y="707" text-anchor="start" class="chartlet-diagram-chip-text">sends confirmations</text><text x="285" y="722" text-anchor="start" class="chartlet-diagram-chip-text">[SMTP]</text></g><g class="chartlet-f chartlet-n-0 chartlet-f-0 chartlet-f-1"><rect x="364" y="18.5" width="104" height="56" class="chartlet-diagram-shadow"/><rect x="364" y="16" width="104" height="56" class="chartlet-flow-node chartlet-role-violet"><title>Learner</title></rect><circle cx="416" cy="27" r="6" class="chartlet-arch-head"/><text x="416" y="56.5" text-anchor="middle" class="chartlet-flow-label">Learner</text></g><g class="chartlet-f chartlet-n-1 chartlet-f-0 chartlet-f-1 chartlet-f-2"><rect x="360" y="182.5" width="112" height="64" class="chartlet-diagram-shadow"/><rect x="360" y="180" width="112" height="64" class="chartlet-flow-node chartlet-role-blue"><title>Web app – single-page app</title></rect><line x1="360" y1="192" x2="472" y2="192" class="chartlet-flow-inner"/><circle cx="368" cy="186" r="1.8" class="chartlet-arch-dot"/><circle cx="374" cy="186" r="1.8" class="chartlet-arch-dot"/><circle cx="380" cy="186" r="1.8" class="chartlet-arch-dot"/><text x="416" y="215.5" text-anchor="middle" class="chartlet-flow-label">Web app</text><text x="416" y="229.5" text-anchor="middle" class="chartlet-flow-sublabel">single-page app</text></g><g class="chartlet-f chartlet-n-2 chartlet-f-1 chartlet-f-2 chartlet-f-3 chartlet-f-5 chartlet-f-7"><rect x="360" y="322.5" width="112" height="56" class="chartlet-diagram-shadow"/><rect x="360" y="320" width="112" height="56" class="chartlet-flow-node chartlet-role-blue"><title>Booking API – API application</title></rect><text x="416" y="345.5" text-anchor="middle" class="chartlet-flow-label">Booking API</text><text x="416" y="359.5" text-anchor="middle" class="chartlet-flow-sublabel">API application</text></g><g class="chartlet-f chartlet-n-3 chartlet-f-2 chartlet-f-3 chartlet-f-4"><rect x="212" y="510.5" width="112" height="56" class="chartlet-diagram-shadow"/><rect x="212" y="508" width="112" height="56" class="chartlet-flow-node chartlet-role-violet"/><rect x="208" y="514.5" width="112" height="56" class="chartlet-diagram-shadow"/><rect x="208" y="512" width="112" height="56" class="chartlet-flow-node chartlet-role-violet"><title>Job queue – message queue</title></rect><text x="264" y="537.5" text-anchor="middle" class="chartlet-flow-label">Job queue</text><text x="264" y="551.5" text-anchor="middle" class="chartlet-flow-sublabel">message queue</text></g><g class="chartlet-f chartlet-n-4 chartlet-f-3 chartlet-f-4 chartlet-f-6 chartlet-f-8"><rect x="208" y="634.5" width="112" height="56" class="chartlet-diagram-shadow"/><rect x="208" y="632" width="112" height="56" class="chartlet-flow-node chartlet-role-blue"><title>Worker – background jobs</title></rect><text x="264" y="657.5" text-anchor="middle" class="chartlet-flow-label">Worker</text><text x="264" y="671.5" text-anchor="middle" class="chartlet-flow-sublabel">background jobs</text></g><g class="chartlet-f chartlet-n-5 chartlet-f-2 chartlet-f-5"><polyline points="348,515.5 348,569.5 350.317,570.794 357.11,572 367.917,573.036 382,573.83 398.4,574.33 416,574.5 433.6,574.33 450,573.83 464.083,573.036 474.89,572 481.683,570.794 484,569.5 484,515.5 481.683,514.206 474.89,513 464.083,511.964 450,511.17 433.6,510.67 416,510.5 398.4,510.67 382,511.17 367.917,511.964 357.11,513 350.317,514.206 348,515.5 348,515.5" class="chartlet-diagram-shadow"/><polyline points="348,513 348,567 350.317,568.294 357.11,569.5 367.917,570.536 382,571.33 398.4,571.83 416,572 433.6,571.83 450,571.33 464.083,570.536 474.89,569.5 481.683,568.294 484,567 484,513 481.683,511.706 474.89,510.5 464.083,509.464 450,508.67 433.6,508.17 416,508 398.4,508.17 382,508.67 367.917,509.464 357.11,510.5 350.317,511.706 348,513 348,513" class="chartlet-flow-node chartlet-role-teal"><title>Bookings – relational database</title></polyline><polyline points="348,513 350.317,514.294 357.11,515.5 367.917,516.536 382,517.33 398.4,517.83 416,518 433.6,517.83 450,517.33 464.083,516.536 474.89,515.5 481.683,514.294 484,513" class="chartlet-diagram-rim"/><text x="416" y="540.5" text-anchor="middle" class="chartlet-flow-label">Bookings</text><text x="416" y="554.5" text-anchor="middle" class="chartlet-flow-sublabel">relational database</text></g><g class="chartlet-f chartlet-n-6 chartlet-f-4 chartlet-f-6"><polyline points="120,782.5 248,782.5 240,838.5 128,838.5 120,782.5" class="chartlet-diagram-shadow"/><polyline points="120,780 248,780 240,836 128,836 120,780" class="chartlet-flow-node chartlet-role-teal"><title>Certificates – file store</title></polyline><text x="184" y="805.5" text-anchor="middle" class="chartlet-flow-label">Certificates</text><text x="184" y="819.5" text-anchor="middle" class="chartlet-flow-sublabel">file store</text></g><g class="chartlet-f chartlet-n-7 chartlet-f-2 chartlet-f-7"><rect x="544" y="522.5" width="144" height="40" class="chartlet-diagram-shadow"/><rect x="544" y="520" width="144" height="40" class="chartlet-flow-node chartlet-flow-external chartlet-role-gray"><title>Payment provider</title></rect><text x="616" y="544.5" text-anchor="middle" class="chartlet-flow-label">Payment provider</text></g><g class="chartlet-f chartlet-n-8 chartlet-f-4 chartlet-f-8"><rect x="236" y="878.5" width="120" height="40" class="chartlet-diagram-shadow"/><rect x="236" y="876" width="120" height="40" class="chartlet-flow-node chartlet-flow-external chartlet-role-gray"><title>E-mail service</title></rect><text x="296" y="900.5" text-anchor="middle" class="chartlet-flow-label">E-mail service</text></g></svg><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-0" for="chartlet-0cad13a20646171f-focus-0"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-1" for="chartlet-0cad13a20646171f-focus-1"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-2" for="chartlet-0cad13a20646171f-focus-2"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-3" for="chartlet-0cad13a20646171f-focus-3"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-4" for="chartlet-0cad13a20646171f-focus-4"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-5" for="chartlet-0cad13a20646171f-focus-5"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-6" for="chartlet-0cad13a20646171f-focus-6"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-7" for="chartlet-0cad13a20646171f-focus-7"></label><label class="chartlet-hotspot" id="chartlet-0cad13a20646171f-hs-8" for="chartlet-0cad13a20646171f-focus-8"></label></div><details class="chartlet-data" data-viz-text><summary>Show chart data</summary><table><caption>Data for Course booking: containers</caption><thead><tr><th scope="col">Component</th><th scope="col">Kind</th><th scope="col">Boundary</th><th scope="col">Connects to</th></tr></thead><tbody><tr><th scope="row">Learner</th><td>person</td><td></td><td>Web app (books a course, via HTTPS)</td></tr><tr><th scope="row">Web app</th><td>frontend</td><td>Course booking (software system)</td><td>Booking API (calls, via JSON/HTTPS)</td></tr><tr><th scope="row">Booking API</th><td>service</td><td>Course booking (software system)</td><td>Bookings (reads, writes, via SQL), Payment provider (takes payment, via HTTPS), Job queue (queues jobs)</td></tr><tr><th scope="row">Job queue</th><td>queue</td><td>Course booking (software system)</td><td>Worker (delivers)</td></tr><tr><th scope="row">Bookings</th><td>database</td><td>Course booking (software system)</td><td></td></tr><tr><th scope="row">Payment provider</th><td>external system</td><td></td><td></td></tr><tr><th scope="row">Worker</th><td>service</td><td>Course booking (software system)</td><td>Certificates (stores certificates), E-mail service (sends confirmations, via SMTP)</td></tr><tr><th scope="row">Certificates</th><td>storage</td><td>Course booking (software system)</td><td></td></tr><tr><th scope="row">E-mail service</th><td>external system</td><td></td><td></td></tr></tbody></table></details></figure></div>