Hoy, dentro de mi aburrido día en el trabajo, mientras leía un manual, para pasar el tiempo, he encontrado esta pieza maravillosa. Compara la ejecución de un Job con un ejemplo, de esos de los que hacia el tipejo de Dogville, que se basa en ir a un restaurante y pedir.
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ABCs of z/OS System Programming Volume 1
Capitulo 3. TSO/E, ISPF, JCL, and SDSF página 129
"One way of thinking about JCL is to compare it to a menu in a restaurant. If you are a customer at a restaurant, you and the other customers don’t just walk into the kitchen and start cooking your own dinners—that would defeat the very purpose of going to a restaurant.
Instead, from a menu describing all the restaurant has to offer, you select items to make up an order, specifying which entrees you want, which salad dressing you prefer, and any other special requests you have. You then ask the waiter to take your order to the kitchen. In the kitchen, a team of chefs divides up the work and the appropriate ingredients in order to prepare each dish as quickly and efficiently as possible. While the meals are being prepared, you and your friends can ignore what’s going on in the kitchen, engaging instead in dinner conversation, catching up on the latest news. When the waiter brings your meal out, you concentrate on your enjoyment of the meal.
Now imagine yourself back at the office using your MVS system, and think of JCL as the menu. In the same way that you and the other diners select items from the menu and place orders for the waiter to take to the team of chefs, you and other MVS users use JCL to define work requests (called jobs), and use a job entry subsystem (JES) to submit those jobs to MVS.
Using the information that you and the other users provide with JCL statements, MVS allocates the resources needed to complete all of your jobs just as the kitchen chefs divided up the work to prepare the orders of all the customers.
And just as the chefs worked in the kitchen while you and the other diners devoted your attention to what was going on at your tables, MVS completes the submitted jobs in the background of the system, enabling you and the other users to continue working on other activities in the foreground.
And just as the waiter conveys the results of the chefs’ work to you, JES presents the output of the jobs to you."
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Muy bueno el primer párrafo: “una forma de ver los JCL es compararlos con el menú de un restaurante. Si eres cliente en un restaurante, tu y los demás clientes no vais directamente a la cocina y os ponéis a cocinar vosotros mismo- esto entraría en contradicción con el propósito de ir a un restaurante.” Y un final apoteósico donde te devuelve a la realidad, después de una descripción del proceso de “cómo pedir en un restaurante”. Narra así: “Ahora imagínate de vuelta en la oficina utilizando tu sistema MVS, y piensa en el JCL como un menú….”. Y por si fuera poco hace una comparación final sobre las distintas partes de los dos procesos, los camareros son el JES, el menú el JCL, etc etc. En fin, yo me partía solo, allí, rodeado de cajas ortoédricas que hace kjjjjjj todo el rato sin parar, y piiii. Y a veces me pregunto cual es la razón para tener todas esas ideas contradictorias...
Y lo malo de esto, es que en ciento cincuenta páginas que llegué a leer de este, fue lo único gracioso que me encontré
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