This time a short artic­le abo­ut an inte­re­sting con­struc­tion. It was descri­bed by Rebecca Wirfs-Brock in 1999 (Miller & Wirfs-Brock, 1999) . The idea did not gain much popu­la­ri­ty at the time, but now, in the era of pat­terns based on micro­se­rvi­ces and micro appli­ca­tions, it has a chan­ce to come back into favo­ur. I’ve been using it for a long time (see inter­fa­ce-orien­ted design). The abbre­via­tions HLD and LLD are High-Level Design and Low-Level Design, respec­ti­ve­ly. These are the levels of abs­trac­tion in the PIM model. It is also a descrip­tion of the design sty­le of an inter­fa­ce-orien­ted sys­tem archi­tec­tu­re (inter­fa­ce-orien­ted architecture).