## CS 591 K1: Data Stream Processing and Analytics Spring 2020 2/06: Notions of time and progress Vasiliki (Vasia) Kalavri vkalavri@bu.edu ## Mobile game application • input stream: user activity How long do we have to wait before we decide that we have seen all events? ## Watermarks ## Stream progress  http://streamingbook 3b52765752b4fce9120d6/p10_1.jpg) http://streamingbook.net/fig/2-9 • A watermark is a global progress metric that indicates a certain point in time when we are confident that no more delayed events

Mellon University ## Progress guarantees • Progress guarantees are a way to theoretically categorize concurrent algorithms: • Blocking: No guarantee • Obstruction free (progress in isolation): A single to deadlock - Lock free (at least one thread makes progress): At any given time, at least one thread is making progress on its operation • Guarantees system-wide throughput. Some operations are always but individual operations are never guaranteed to ever complete - Wait free (all threads make progress): Every operation completes in a bounded number of steps regardless of other concurrent operations

semantics, and guarantees Vasiliki (Vasia) Kalavri vkalavri@bu.edu ## Today's topics • High-availability and fault-tolerance in distributed stream processing • Recovery semantics and guarantees • Exactly-once primary and $ O' $ the output produced by the secondary after recovery. • Precise recovery guarantees $ O_{f} + O' = O_{e} $ • Rollback recovery allows duplicate tuples downstream: • repeating: identical duplicate tuples ## Processing guarantees and result semantics  Processing guarantees and result semantics ![Image](/

## Why I Was Wrong About TypeScript TJ VanToll Progress $ ^{®} $ DevReach 2013 THE PREMIER DEVELOPER CONFERENCE IN CENTRAL & EASTERN EUROPE ## TypeScript TypeScript Modules Decorators Generics nts/1/8/e/7/18e732be57131655994e4827daf7c7ca/p31_1.jpg) ## Why I Was Wrong About TypeScript ## Progress $ ^{®} $  ![Im Non JS developers that need to write JS code? ## Thanks! @tjvantoll http://bit.ly/DR2017-vantoll Progress $ ^{®} $

## NativeScript UI 100% ## TJ VanToll ☐ @tjvantoll Progress $ ^{®} $  ## Agenda • Introduce {N} UI • Demo □ Raucous ## Welcome to Progress NativeScript UI Pro Progress NativeScript Pro UI a suite of rich-UI components targeting the NativeScript platform. The controls are based on the familiar Progress Telerik UI for for Android and Progress Telerik UI for iOS suites and expose common API for utilizing these suites Android and iOS cross-platform development. The suite offers the following components: ## Calendar •

Specification (Is all about “Guarantees”) System/Subsystem Design (Defines API boundaries and behavior) Implementation details (e.g., “lock-free” and “wait-free” algorithms provide guarantees for system-wide or or per-thread progress) ## Levels of “Knowing” highest Guarantee Always true • Inviolate principle or behavior Rule Exceptions may apply • Highly regarded principle Examples: C++ Language Specification Specification (Is all about “Guarantees”) System/Subsystem Design (Defines API boundaries and behavior) Implementation details (e.g., “lock-free” and “wait-free” algorithms provide guarantees for system-wide or

Exception Handling When to Use Exceptions (And When Not) How to Use Exceptions The Exception Safety Guarantees How to Write Exception-Safe Code How to Refactor Non-Exception-Safe Code ## Content The Exception Exception Handling When to Use Exceptions (And When Not) How to Use Exceptions The Exception Safety Guarantees How to Write Exception-Safe Code How to Refactor Non-Exception-Safe Code ## Why Another Talk preconditions, but using a tool other than exceptions. This paper supports the change, already in progress, to migrate std:: away from throwing exceptions for precondition violations. §4.3: Allocation failure

Broker Issues (Critical Analysis) 1.30 Resource Manager Configuration 1.31 Flow Control 1.32 Guarantees of sends and commits 1.33 Message Redelivery and Undelivered Messages 1.34 Message Expiry 1 system ensures that a copy of each news message is delivered to each subscription. ## Delivery guarantees A key feature of most messaging systems is reliable messaging. With reliable messaging the server the next update on the same stock. The messaging system allows you to configure which delivery guarantees you require. ## Transactions Messaging systems typically support the sending and acknowledgement

Broker Issues (Critical Analysis) 1.30 Resource Manager Configuration 1.31 Flow Control 1.32 Guarantees of sends and commits 1.33 Message Redelivery and Undelivered Messages 1.34 Message Expiry 1 system ensures that a copy of each news message is delivered to each subscription. ## Delivery guarantees A key feature of most messaging systems is reliable messaging. With reliable messaging the server the next update on the same stock. The messaging system allows you to configure which delivery guarantees you require. ## Transactions Messaging systems typically support the sending and acknowledgement

Broker Issues (Critical Analysis) 1.30 Resource Manager Configuration 1.31 Flow Control 1.32 Guarantees of sends and commits 1.33 Message Redelivery and Undelivered Messages 1.34 Message Expiry 1 system ensures that a copy of each news message is delivered to each subscription. ## Delivery guarantees A key feature of most messaging systems is reliable messaging. With reliable messaging the server the next update on the same stock. The messaging system allows you to configure which delivery guarantees you require. ## Transactions Messaging systems typically support the sending and acknowledgement