A modern programming language focused on integration - PowerPoint Presentation

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A modern programming language focused on integration

Sanjiva Weerawarana, Ph.D.Founder, Chairman & Chief Architect; WSO2

Joint work with Sameera

Jayasoma, WSO2; Hasitha Aravinda, WSO2; Dr. Srinath Perera, WSO2; and Prof. Dr. Frank Leymann; Univ. of Stuttgart

June 22, 2018; Univ. of Thessaly, Volos, Greece

James Clark

Independent

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Agenda

MotivationType systemNetwork awareness, security & resiliencyMore than the language

ImplementationFuture work

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Motivation: Why yet another language?

Digital transformation

Everything is a network serviceProduce, not just consume network servicesEvery business has to become a software company

Minimalization of computingHardware  VMs  Containers  ServerlessSOA  MicroservicesESB  Service meshesMiddleware is dead; middleware is everywhereServers to sidecars to code

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Design inspirations

London 2012 Olympics opening

Sequence diagramsMany existing languages, including Java, Go, C, C++,

Rust, Haskell, Kotlin, Dart, Typescript, Javascript, Flow, Swift, RelaxNG6/22/18

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Source: 

https://stillmed.olympic.org/Global/Images/News/2012-07/27/opening_country.jpg

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Design principles

Code, not config, with both text and graphic syntaxes

Do not try to hide the networkFirst class support for network data types

No room for best practices or “findbugs”Make programs secure by defaultMake programs network resilient by defaultNo dogmatic programming paradigmMainstream concepts & abstractions, not research

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Unusual aspects of Ballerina

First-class nature of application level network abstractions

Structural type system with network friendly types and unionsSequence diagram based parallelism model

Language extensibility with environment binding and compilation extensibility6/22/186

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Hello, World from Ballerina

import ballerina/

io

;function main (string... args) {

worker w1 { io:println

("Hello, World! #m");

}

worker w2 {

io:println

("Hello, World! #n");

}

worker w3 {

io:println

("Hello, World! #k");

}

}

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Ballerina graphical notation

Sequence diagrams focused on showing worker and endpoint interactionsEndpoints represent network services

Each worker is sequential codeWe can zoom in graphically but its really just code

Not meant to be used for low-code / no-code or by non-programmersMeant to make it easier to understand complex distributed interactions6/22/18

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Ballerina, the language

Program & lexical structure

Values, types & variablesExpressions

StatementsWorkers, Functions, Endpoints & ServicesTables & streamsAnnotationsComments & documentationSecurity

Distributed resilience6/22/18

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Programs

Modularity in 4 levelsPackage repository

OrganizationPackageObject, but not mandatory

PackageCollection of files that contribute symbols, like GoFile names not relevantUnit of compilation & executionObjectUsual kind of object6/22/18

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Values, types & variables

Structurally typed, defined in terms of values

Type is a label for a set of values, same value can be of many typesKinds of valuesSimple values: (),

boolean, int, float, decimal, string, byteStructured values: tuple, array, map, record, table, xmlBehavioral values: function, future, object, stream, typedescTypesBasic types (one of the above)OthersFinite types, unions, optional, any, json

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Mapping types

Mappings are collections of (name, value) pairs

VariationsOpen vs. closed mappingsRequired vs. optional fields

“record” type constructorCollection of mandatory and optional named fields of any typesOpen if desired“map” type constructorAny fields but all values of a single typeAlways openCovariant subtypesStorage type

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json

json is just a union

() | int | float | string | map<json> | json

[]json objects are most commonly usedmap<json>, but subtyped to an open record with non-mandatory fields in most casesVery useful for man-in-the-middle network scenariosWith json being within the type system, no data binding concept needed for json

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XML

Minimalistic but powerful native xml type

Non-traditional XML architecturexml is sequence of things that appear in XML (elements, comments, text, ..)Elements do not contain references to parent or siblings and same element can appear in multiple xml values

No node identity, no text nodes (just strings)Namespaces married to Ballerina qualified name architectureLiteral XML values, reading/writing6/22/18

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Tables

Tabular dataProgrammatically generated & manipulated

Database connectors to load/store tablesIntegrated SQL-like query, ala C# LINQIn-memory database

Table rows are just records (no ORM)6/22/1815

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Streams and streaming query

Stream is a distributor of any type of events within a BVM

Can be attached to network sources as wellStreaming SQL-like queries attach to some number of streamsComplex event processing

Event stream processingMarrying Siddhi CEP engine6/22/1816

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Type matching

Union typed expressions have to be separated out before use:

match expression {

pattern [var] => statement;

pattern [var

] => statement;

..

}

Or within an expression:

expression but { pattern [

var

] => expression }

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Errors and error lifting

Errors are its own value space

Can be returned or thrownOften returned as T | errorThrowing is discouraged and meant to be used rarely

Error liftingMany functions return ResultType | errorCheck expression: check expressionIf error return immediately, else error is eliminated from type set6/22/18

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Nil & error lifting navigation

Navigating deep hierarchies is common in integration code

Navigating through optional types are nil-lifted by “.” operator: a.b.cNavigation is both nil and error lifted by “!” operator:

a!b!cWhy?Combination of optional types and type matching makes it impossible to have a null reference in BallerinaNil & error lifting make those rules palatable6/22/18

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Local & distributed transactions

One service calling another over HTTP is very common in enterprise applications

But lack of distributed resiliency leads to fragile codeBallerina micro transaction protocolAllows any piece of code to initiate a distributed transaction with its own built-in coordinator

Transaction ID is transparently infected to other nodes in the distributed systemThey join and participate in transaction protocolSee: transaction { .. } statement6/22/18

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Writing (more) secure programs

ObjectivesProvide integrated authentication and authorization architecture

Prevent potentially dangerous data from getting into the systemPropagate security contexts to downstream bits Make it easier to monitor access patterns for abuse

ArchitectureRuntime context with principal and permissions set by inbound endpointsPluggable authentication and authorization frameworkTaint assertions and checking6/22/18

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Functions, methods and resources

Unit of execution: One sequence diagramDefines a set of workers who startin parallel whenunit is invoked

Any worker can causecaller to be releasedOther workers

continue6/22/1822

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Function invocation

Initialization: start endpoints

Start concurrent workersFirst one to return will release callerOthers continue to completion

If no one completes (e.g. due to failures) function call fails with “call failed” exception6/22/1823

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Futures & non-blocking invocation

Any function can be called in a non-blocking way:

future<T> f = start

functionName (args)Wait for completion, cancel, get return values via typed future

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Worker to worker communication

Via anonymous channels, non-blocking for send, blocking for receive

Attempt at deadlock preventionComing soon: named channels

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Network abstraction: endpoint

Endpoints represent network termination points for incoming network interactions or outgoing network interactions

More than a socketService endpoints are network entry points to a BVM via a registered serviceCalls are delivered to a particular resource in a service

Code can reply/message with provided endpoint, no returning valuesClient endpoints represent remote systemsOffer a set of actions for interaction with them6/22/18

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Services & resources

Service is a collection of resources where each resource is network invokable

Services must be attached to an endpoint to be invokedResponses must be via endpoint and not by returning values

Responses may not go6/22/1827

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Network calls

Programmer needs to be made aware that this is a network callGraphically line from a worker to an endpoint

Textually:

var result = epName->actionName (

args);If any errors occur they need to be type matched and handled

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Outbound resiliency

Failure is normal in network interactions

Endpoints are logicalGroup them for load balancing, failover or other behaviorsCircuit breaking, bulk-heading, timeouts, load management all part of endpoint architecture

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Comments and documentation

Documentation is a first class aspect of BallerinaWritten in markdown+

Mandatory for public symbolsComments and disabling code

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Annotations

For everything about the code

Compile-time processable with compiler extensionsE.g.: Docker and K8s annotations

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Beyond the language

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Standard Library

ballerina/auth

ballerina/cacheballerina/config

ballerina/cryptoballerina/fileballerina/grpcballerina/h2ballerina/httpballerina/internalballerina/ioballerina/jdbcballerina/jmsballerina/log

ballerina/math

ballerina/mb

ballerina/mime

ballerina/mysql

ballerina/reflect

ballerina/runtime

ballerina/sql

ballerina/swagger

ballerina/system

ballerina/task

ballerina/test

ballerina/time

ballerina/transactions

ballerina/websub

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Programming is more than just code

Editing & debugging

TestingObservabilityDependencies, versions and building

DocumentationSharing6/22/18

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Implementation

Compiler produces BVM instructions into library (.balo

) or linked binary (.balx)Portable object and executable format

Extensible architecture for compiler to allow 3rd party annotation processing to become part of compilation process, e.g. Docker/K8sIDEs supported via Language Server ProtocolPlugins for VS Code, IntelliJ and standalone browser-based ComposerCompiler & BVM currently written in Java6/22/18

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Future work

Forward recoverabilityCompensationCheckpoint and restart

Docker / Kubernetes compositionsMerging / collapsing sequence diagramsInternationalizing the grammar

Greek, anyone?ImplementationNative compilation via LLVMAlso WebASM, CLR6/22/18

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Summary

Ballerina is an attempt to build a modern industrial grade programming language

For future with lots of network endpointsType system is designed to make network data processing easier

First class network services along with functions/objectsFramework to encourage more secure codeFully open source and developed openly6/22/18

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Questions?

Contact: sanjiva@wso2.com

Download?v0.970.0 released May 1stv0.975.0 about to be released

v0.980.0 due in mid-Julyv1.0 ETA Nov/Dec 2018http://ballerina.io/CommunityEmail: ballerina-dev@googlegroups.comSlack: ballerina-platform.slack.com#generalTwitter: @ballerinaplat

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