# CS 591 K1: Data Stream Processing and Analytics Spring 2020 ## 1 /28: Stream ingestion and pub/sub systems Vasiliki (Vasia) Kalavri vkalavri@bu.edu ## Streaming sources  subscriber notify() subscriber publisher notify() ## Pub/Sub levels of de-coupling • Space: interacting parties do not need to know each other • Publishers |Message-passing|||| |RPC/RMI|||| |Asynchronous RPC|||| |Futures|||| |Message Queues|||| |Pub/Sub|Yes|Yes|Yes| ### Pub/Sub vs. other paradigms |Paradigm|Space Decoupling|Time Decoupling|Synchronization Decoupling|

дерево двома типами: // Операция для виконання над двома під-виразами. enum Operation { Add, Sub, Mul, Div, } }} /// Вираз у вигляді дерева. enum Expression { /// Операция над двома підвиразами test_value() { ... } /// Операция для виконання над двома під-виразами. enum Operation { Add, Sub, Mul, Div, } /// Вираз у вигляді дерева. enum Expression { /// Операція над двома підвиразами Expression::Op { op: Operation::Mul, left: Box::new(Expression::Op { op: Operation::Sub, left: Box::new(Expression::Value(3)), right: Box::new(Expression::Value(4))

Standard Library, visit the link above. ## Hello World hello.zig const std = @import("std"); pub fn main() !void { const stdout = std.io.getStdOut().writer(); try stdout.print("Hello, For this common case, there is a simpler API: hello_again.zig const std = @import("std"); pub fn main() void { std.debug.print("Hello, world!\n", .{}); } Shell $ zig build-exe hello_again Shell zig test -femit-docs main.zig comments.zig const print = @import("std").debug.print; pub fn main() void { // Comments in Zig start with "//" and end at the next LF byte (end of

Dependency management/caching * build scripting * global installation * It is also extensible with sub command plugins as well (such as cargo clippy). – Read more from the official Cargo Book ### 2.2 with two types: /// An operation to perform on two subexpressions. enum Operation { Add, Sub, Mul, Div, } /// An expression, in tree form. enum Expression { /// An operation on two test_value() { ... } /// An operation to perform on two subexpressions. enum Operation { Add, Sub, Mul, Div, } /// An expression, in tree form. enum Expression { /// An operation on two

Password for client connection permissions: - action: Operation type of permission. `pub` means publish permission, `sub` - means subscription permission. permit: List of topics allowed by the operation Username for client ssl connection permissions: - action: Operation type of permission. `pub` means publish permission, `sub` means subscription permission. permit: List of topics allowed by the operation type - action: 'pub' permit: ['tls/#'] - action: 'sub' permit: ['tls/#'] - username: test password: hahaha permissions: - action: 'pub' permit:

client connection - permissions: - action: Operation type of permission. 'pub' means publish permission, 'sub' - means subscription permission. - permit: List of topics allowed by the ssl connection - permissions: - action: Operation type of permission. 'pub' means publish permission, 'sub' - means subscription permission. - permit: List of topics allowed by the 'pub' permit: ['tls/#'] (continues on next page) - action: 'sub' permit: ['tls/#'] - username: test password: hahaha permissions: - action: 'pub'

Password for client connection permissions: - action: Operation type of permission. `pub` means publish permission, `sub` means subscription permission. permit: List of topics allowed by the operation type Username for client ssl connection permissions: - action: Operation type of permission. `pub` means publish permission, `sub` means subscription permission. permit: List of topics allowed by the operation type - action: 'pub' permit: ['tls/#'] - action: 'sub' permit: ['tls/#'] - username: test password: hahaha permissions: - action: 'pub' permit:

tempo de execução $ ^{*} $ Criar scripts * Instalação global * Também é extensível com plugins de sub-comando (tais como cargo clippy). – Leia mais no Livro Oficial do Cargo ### 2.2 Exemplos de Código um pânico? /// Uma operação a ser realizada em duas subexpressões. enum Operation { Add, Sub, Mul, Div, } /// Uma expressão, em forma de árvore. enum Expression { /// Uma operação Expression::Op { op: Operation::Mul, left: Box::new(Expression::Op { op: Operation::Sub, left: Box::new(Expression::Value(3)), right: Box::new(Expression::Value(4))

pánico? /// Operación que se puede llevar a cabo en dos subexpresiones. enum Operation { Add, Sub, Mul, Div, } /// Una expresión en forma de árbol. enum Expression { /// Operación en dos Expression::Op { op: Operation::Mul, left: Box::new(Expression::Op { op: Operation::Sub, left: Box::new(Expression::Value(3)), right: Box::new(Expression::Value(4)) Solución /// Operación que se puede llevar a cabo en dos subexpresiones. enum Operation { Add, Sub, Mul, Div, } /// Una expresión en forma de árbol. enum Expression { /// Operación en dos

management/caching * build scripting * global installation * It is also extensible with sub command plugins as well (such as cargo clippy). – Read more from the official Cargo Book ### 2.2 instead of a panic? /// An operation to perform on two subexpressions. enum Operation { Add, Sub, Mul, Div, } /// An expression, in tree form. enum Expression { /// An operation on two Expression::Op { op: Operation::Mul, left: Box::new(Expression::Op { op: Operation::Sub, left: Box::new(Expression::Value(3)), right: Box::new(Expression::Value(4))