Modern APIs
	Old IT operating model (Point to point integrations or tightly coupled)
	Resuable assests, ease of consumption, performance, scalability
	API-led connectivity approach (Experience APIs, Process APIs, System APIs)
	Center for Enablement(c4e) <Central IT, LoB, Innovation teams>
	PaaS as “Anything that is not a business application or systems infrastructure is PaaS”
	API - could be referring to <An API definition file(API Spec), A web service, An API proxy)
	WebService - Soap(Uses HTTP and Soap encoding decoding using xml), REST
		Rest - Architechtural style
			Representation of resources, Stateless, uses HTTP, HTTP methods, URI, URL, All URLs are URIs, but not all URIs are URLs.
			HTTP methods - GET, POST, PUT, PATCH, DELETE
				+---------+------+------------+
				| Method  | Safe | Idempotent |
				+---------+------+------------+
				| CONNECT | no   | no         |
				| DELETE  | no   | yes        |
				| GET     | yes  | yes        |
				| HEAD    | yes  | yes        |
				| OPTIONS | yes  | yes        |
				| POST    | no   | no         |
				| PUT     | no   | yes        |
				| PATCH   | no   | no         |
				| TRACE   | yes  | yes        |
				+---------+------+------------+ 
			Rest testing tools - API portals, Postman, Advanced Rest Client, cURL, Jmeter
			Securing APIs - OAuth, JWT, SAML, Basic Auth, Client Credentials
			HTTP Status Codes - 200 Success, 300 Redirection, 400 Client Error, 500 Server Error
				+---------------------------------+------------------------+----------------------------------------------------------------+---------------------------+
				|             Success             |       Redirection      |                          Client Error                          |        Server Error       |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				| 200=Success                     | 301=Moved Permanently  | 400=Bad Request                   | 408=Request Timeout        | 500=Internal Server Error |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				| 201=Created                     | 302=Found              | 401=Unauthorized                  | 409=Conflict               | 501=Not Implemented       |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				| 202=Accepted (for batch, async) | 307=Temporary Redirect | 402=Payment Required              | 410=Gone                   | 502=Bad Gateway           |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				| 204-No Content                  | 308=Permanent Redirect | 403=Forbidden                     | 411=Length Required        | 503=Service Unavailable   |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				|                                 |                        | 404=Not Found                     | 412=Precondition Failed    | 504=Gateway Timeout       |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				|                                 |                        | 405=Method Not Allowed            | 413=Payload Too Large      |                           |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				|                                 |                        | 406=Not Acceptable                | 414=URI Too Long           |                           |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				|                                 |                        | 407=Proxy Authentication Required | 415=Unsupported Media Type |                           |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
				|                                 |                        |                                   | 429=Too Many Requests      |                           |
				+---------------------------------+------------------------+-----------------------------------+----------------------------+---------------------------+
	API development life cylce (4,2,8)
		Stage 1: Design, Simulate, Feedback, Validate
		Stage 2: Build, Test
		Stage 3: Version, Secure, Deploy & Register, Monitor, Analyze, Troubleshoot, Scale, Respond
		API Specification Phase 5 (API Designer, Exchange(library of assets, central repo, search, REST connect), API Portals, API console, Mocking Service, API Notebook)
		API Implementation Phase (Studio, Munits)
		API Management Phase 5 (API manager, Runtime manager, Anypoint Monitoring(Stats, charts, dashboards), API Analytics (Analyse and report), Visualiser (network nodes visualise)
		Mulesoft web tools (Flow Designer, Composer)
		API Design Approaches - Hand Coding, RAML, Apiary, OAS (Swagger)
			RAML RESTful API Modelling Language (contract) - helps in Autogenerated documentation, validation, reuse, discovery, pattern-sharing, syntax correction, modularization.
				Yaml - A human readble data serialisation format (Similar to ASCII format of X.509 Certificates)
				Contains - Resources, methods, URI Parameters, queryParameters, facets and fragments, file references, key words
						Facets (are Action Results) - Request facets(body, types, examples), Response facets(http status codes, body, types, examples), example, examples
						Fragments (are resuable snippets) - DataTypes, ResourceTypes(Reserved Parameters, Parameters Transformers), Traits(behavioral entities), Security Schemes, Examples, Libraries, Documentation, annotations, overlays and extensions
				keywords & annotations- #%RAML 1.0, title:, mediaType:, version, securitySchemes:, traits:, uses:, types:, securedBy: [securityScheme name], resourceTypes:, 
							type:, ?, maxItems:, minItems:,  is: [traits name], description:, responses:, body:, uriParameters:, queryParameters:, default:, 
							required:, example:, enum: -xxx or ["xxx"], additionalProperties:, properties:, items:
				Datatypes - type: <object, array, number, string, boolean, optional, object[], string[], integer, date-only, datetime>
			API Designer - contains File browser, Editor, Shelf, API Console (visual representation of specification, available in API designer, API portals and in studio via APIKit)
Anypoint Studio - Eclipse based IDE using Spring framework used to develop, deploy, test and analyse
	Components - Package explorer, Canvas, Console, Mule palette. Global Elements, Message Flow, Global XML configuration
	Mule palette - Core modules, Other/Featured modules/connectors, modules or connectors from exchange
		Core module - elements are 7
			Batch (3) - Batch Aggregator, Batch Job, Batch Step <processors, aggregators>
			Components (6) - Flow Refs, Logger, Transform message, Parser Template, Invalidate key, Invalidate cache
			Endpoints (1) - Scheduler
			Error Handling (4) - Error handler, On error continue, On error propogate, Raise Error
			Flow Control (4) - Choice, First Successful, Round Robin, Scatter-Gather
			Scopes (7) - Async, Cache, Flow, Subflow, Foreach, Try, Until Successful
			Transformers (3) - Set payload, Set variable, Remove Variable
		Other/Featured modules are 20
			APIKit
			Database - Bulk Insert, Bulk Delete, Bulk Update, Insert, Delete, Update, Select, Execute Script, Execute DDL, On Table Row
			Objectstore - Clear, Contains, Remove, Retrieve, Retrieve all, Retrieve all keys, Store. 
			Java - Invoke, Invoke static, New, Validate Type
			File (not among feature) - Read, Write, Delete, Copy, Rename, Move, List, Create directory, On New or Updated File
			Email
			FTP - Same as File
			SFTP - Same as File
			HTTP
			JMS - Same as VM + "Ack" and "Recover Session"
			VM - Consume, Publish, Publish-Consume, Listener (both inter and intra app)
			Validation
			Scripting - Execute
			OAuth - Retrieve access token, Retrieve expires in, Retrieve refresh token (Resource owner id)
			OAuth 2.0 Provider - Create client, Delete client, Revoke token, Validate token
			Salesforce - create, create batch, create bulk, query
			Sockets -send, receive, send and receive
			Spring
			Web service consumer - Consume
			Service Now - Invoke (soap operation by resource owner id), unathorised (invalidate all tokens of resource id)
			XML
			SAP - Asynchronous RFC, Synchronous RFC, Retieve IDOC, Send IDOC, Document Listener, Confirm Transaction, Function Listener
			AS400 - Read data queue, Write data Queue, Program Call Processor, Command Call, Read data queue processor (program Library, program name, procedure name, Data queue)
		modules or connectors from exchange (secure properties tools, property placeholder editor, cloudhub notifications using alerts)			
	Flow - Event Source, Event Processors, Error Handling
Dataweave (As a functional programming language (Used for code transformation and Data Enrichment))
	1. Type systems (Applied on variables and Functions(all about constraints)
		Categories: Simple - Atomic(String, Boolean, Number, Regex, Null, Temporal(Date, Time, DateTime, LocalTime, LocalDateTime, Period))
			    Composite (Array<T>, Object (Closed, Open) defined by type or {} or {| |}, Functions (T) -> T)
			    Complex (Any, Nothing, Union | on simple types, Intersection & on objects, Literal (string, number, boolean), function overloading
		Type Paramters (Binding Type parameters)fun head<om>(elements: Array<om>): om = elements[1]
		Auto/Default coercion
	2. Data Selectors (Single value, Multi Value, Descendent, key-value pair, index, range, Assert Present, Namespace, XML Attribute, Key Present, Filter
	3. Dataweave Variables
	4. Reserved Variables (and, or, as, is, async, case, default, do, else, if, enum, false, true, for, import, input, 
			       output, ns, type, null, private, throw, unless, var, fun, yield, using)
	5. Script structure
		Header
			import, var, fun, type, ns
			output, input
				Supported Data Formats (reader properties, writer properties (skipNullOn, separator, header, deferred, escape))
					application/{csv,json,java,xml,yaml,dw,flatfile,avro,octet-stream,xlsx,x-www-form-urlencoded}, multipart/form-data, text/plain, text/x-java-properties
		Body
	6. Operators 5 
		Mathematical (+, -, *, /) # + ,- operates on arrays, objects, dates
		Equality and Relational(<,>,<=,>=,==,~=)
		Logical (not, !, and, or)
		Prepend >>, Append <<, +, - on Arrays
		Scope and Flow Control (do, using, if else, else if)
	7. Core (dw:Core)
		Functions (++, --, filter, filterObject, distinctBy, orderBy, groupBy, joinBy, splitBy, sizeOf, map, mapObject, 
			   pluck, reduce, replace, with, contains, flatMap, flatten, match, matches, read, readUrl, now, keysOf, 
			   valuesOf, namesOf, entriesOf, scan, trim, to, log, mod, find, floor, ceil, abs, avg, round, isInteger, 
			   isEmpty, isBlank, isEven, isOdd, isDecimal, isLeapYear, pow, sqrt, startsWith, min, max, minBy, maxBy,
			   lower, upper, uuid, random, randomInt, zip, unzip)
		Types (Any, Array, Object, CDATA, Binary, Boolean, Date, DateTime, Key, Enum, Null, Number, Range, Regex, Period, LocalDateTime, Time, TimeZone, Type, Uri, Iterator
	8. Modules
		Arrays <dw::core::Arrays>, Binaries<dw::core::Binaries, Core<dw::Core>,Encryption<dw::Crypto>
		Diff<dw::util::Diff>, Objects<dw::core::Objects>, Runtime<dw::Runtime>, Strings<dw::core::Strings>,
		System<dw::System>, URL<dw::core::URL>
	Inline Dataweave, script parameterisation, commenting
	Mule Runtime Functions (p<works on Mule Property Placeholders, System Variables, Envirnoment Variables>, lookup<lookup("anotherFlow", payload)>, causedBy<#[error Mule::causedBy 'HTTP:UNAUTHORIZED']>)(Mule namespace)
Predfined Mule Variables (payload, attributes, vars, app, flow, correlationId, error, message, server, mule)
Mule Events (Mule Message (Payload, Atributes), Variables)
Configuring properties
	Property placeholders, Global properties, Properties files, Supported Files, System properties, File Properties, Environmental variables
	Dynamic properties
	Property Heirarchy (Deployment props > System props > Environment props > application props (configuration props, secured conf props) > Global properties
	import
Mule Message 
	Data Types (Mutable, Immutable), 
	Data Streams (Repeatable, Non Repeatable)
		File Stored Repeatable <file stored<inMemorySize, bufferunit> greater than writes to disk, 
		InMemory Repeatable <initialBufferSize,bufferSizeIncrement,maxinMemorySize,bufferUnit> greater than fails
		File Stored Repeatable (iterable) <inMemoryObjects> greater than writes to disk
		InMemory Repeatable (iterable) <initialBufferSize, bufferSizeIncrement, maxBufferSize>
	Transactions (action: EMPTY, ALWAYS BEGIN, BEGIN_OR_JOIN, INDEFFERENT(default)),(types: local((default), XA),(eligiblity: VM, DB, JMS)
Shared resources and Domains, exported resources and packages
Timeouts (Connection timeout, Response timeout, Request Timeout, Max Idle time)
Reconnection Strategies (none, standard<attempts, frequency>, forever)
Redelivery policy(max retries, objectstore counter, secure hash), and retry mechanisms
Mule Errors
	Error Selectors < #[error.<description,detailedDescription,errorType,cause,errorMessage<payload,attributes<statusCode>>,childErrors>]>
	Error Types <namespace, errorType/identifier>
		ANY
			UNKNWON, TRANSFORMATION, ROUTING, CONNECTIVITY<RETRY_EXHAUSTED>, EXPRESION, SECURITY <CLIENT_SECURITY, SERVER_SECURITY>, VALIDATION
		CRITICAL <FATAL, OVERLOAD>
	Error Handlers <onErrorContinue <type, when>, onErrorPropogate, GlobalErrorHandler>
	Error Mappings <type -> map to custom or common errortype>
Mule Data Processing Exceptions <System Excpetions, Business Exceptions>
Mule SDK
	Classes: (Extension Class, Operations Class, Supporting Classes), dependencies in pom
	Features: apache logger, Scheduled task executor, RouterCallBack Method, Routes and Paramter declaration, flow stop and flow start using mule registry, concurrent wait and input streams, hashmaps, icons
Connector Configuration
	HTTP Listener: (protocol, host, port, tls: <Truststore (Path, password, type, algo), Keystore (Path, type, algo, alias, key-pass, pass), reconn strat, conn-idle-timeout>)
			(conf: mimeType, redelivery, responses<Response,Error Response <Body, Headers, Status Code, Reason phrase>>, advanced<allowed methods, streaming, reconnS)
	HTTP Requestor
	VM (global: queuenames, queueType, maxOutstanding)(conf: queueTimeOut)
	Object Store: (global: Perisistent box, Max Entries, Entry TTL, Entry TTL Unit, Expiration interval, Expiration unit, Config ref)
	Batch Job (max failed records (-1,0,>) on step level, Scheduling strategy, job instance ID, batch block size, max concurrency, target)
	Batch Step (Accept Expression<All, No_FAILURE, ONLY_FAILURES>, Accept Policy) <max concurrency = 1 applies on this>
	Batch Aggregator (Streaming preserve, mime type preserve, Aggregator size)
	Batch job result, status, id #[payload.*] (loadedRecords, failedRecords, processedRecords, successfulRecords, batchJobInstanceId, timeElapsedinMills, Exceptions)
	Batch rules: Complete parallel processing, no batch step will wait, no batch step components will wait, no batch aggregator will wait
		     As soon as a record completes with its previous component it moves on
		     unpredictable processing and logging. Tracking and sequencing is not possible. A batch is similar to async.
	Batch job phases: load and dispatch, process, oncomplete
	variables and payload only pass between Batch Steps, not between steps and aggregator, or aggregator to steps or Batch jobs to flow.
	SAP conf: IDOC Library, Simple Connection Provider, JCO Library, Username, Password, SAP System number, SAP Client ID, Host<Message Server Host, MS Port, MS Group Name, System ID 
		Advanced: Destination Name, Language Name
	Document Listner: Gateway Host, Gateway Service, Program ID, Connection Count, Idoc regex filters
	Send IDOC: IDOC Name, Payload (same with Retrieve IDoc)
	Syn RFC: Function Name, Payload (not mandatory)
	
Maven
	Contains - Life cycles <clean 3, default 23, site 4>
		 - Phases <clean, compile, deploy, generate-resources, generate-sources, generate-test-resources, generate-test-sources, initialize, package, process-classes, process-resources, process-sources, site, test-compile, undeploy, validate, verify>
		 - Goals (aka Plugin Goals)
	Usage - mvn <PHASE>, mvn <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>.
	Brief points - 1. Build lifecycles consists of Build Phases. Most maven phases has a default goal bindings.
		       2. Build phases consists of Build Goals or Plugin Goals
		       3. Plugins are a collection of Goals also called MOJO (Maven Old Java Object). (Analogy : Plugin is a class and goals are methods within the class)
		       4. When you run a phase, all the phases upto that phase and along with that phase will also run.
		       5. When you run a phase, all goals attached/binded to that phase runs.
		       6. A phase can have multiple goals (zero or more goals). Phase with no goals will not run.
		       7. A goal can be binded to multiple phases. A goal with no phases binding can be directly invoked.
		       8. Phase are meant to run and Goals are meant to be executed.
		       9. A plugin can have more goals specified which can be called upon individually.
		       10. Default bindings for a phase can vary and depend upon the type of packaging specified.
	pom (modelVersion, groupId, artifactId, version, packaging, name, properties, organization, inceptionYear, licenses, developers, distrubtionMangement<repository>,scm, dependencies, 
	     build(resources<resource<directoy, exclude>>, plugins<plugin<g,a,v,extensionm,configuration<classifier>, executions<execution<id,phase,goals-goal,configuration<sources-source,environmentsToTest,placeholderProperties>>>>)
	     repositories-*<id,name,url>, pluginRepositories-*<id,name,url,layout,snapshots-enabled>
	     profiles-*<id, build, dependencies-*>
	List of mule classifiers: mule-plugin, scope: (test, provided)
	packaging: mule-extension, mule-application, pom, jar, maven-plugin
Log4j2
	Logging Levels (ALL < TRACE < DEBUG < INFO < WARN < ERROR < FATAL < OFF )
	Components of Log4j (Appenders, Configuration properties, pattern layout<: %r [%t] %-5p %c{2} %x - %m%n><="%d [%t] ${sys:hostName} %-5p %c - %m%n>, Policies, filters, Aysnc Root-Appender Ref)
	log destinations (local machine, Database, Cloud, Sockets, Console, Cloudwatch, AWS Elastic Search, Amazon S3, kibana, MySQL)
OAuth 2.0 (Authorization Server, Resource Server, Client, Resource Owner)
	Grant Types: Authorization Code, Implicit,Username & password, Client Credential
	Oauth dance: 1. Client Request access token to OAuth server
		     2. Authenicate client at OAuth server
		     3. Return access token to client from OAuth server
		     4. Client requests resource with access token
		     5. Resource server validates access token with OAuth server
		     6. Validated access token response to Resource server
	 	     7. Resource server returns the resource
Archetypes
	project-name
		src/main/resources
			archetype-resources
				src/main/..
				src/test/..
				pom.xml
			META-INF/maven/archetype-metadata.xml
				archetype-descriptor
					fileSets and filters
		src/test
		pom.xml (archetype-packing)
Project Structure and Features
	global.xml
		secure properties tools (filename, key, file level encryption, encrypt alogorithm, encyrpt mode) <can have many><one for env specific, one for global file>
		configuration properties (file name) <one for env specific, one for global file>
		Auto Discovery (API Id, flowName<main flow>)
		import (like common_error_handle.xml taken from project libraries)
	muleDeploy.groovy (appName, env list, apiUri, workerForEnv, autoDiscovery conf, cloudhubApp Properties, azureAD policies<JWT>
	mule-artifact.json (minMuleVersion, secureProperties)
	gdsl, intelliJ

Features
	Azure devops (Pipelines<groovy, yamls, Archetypes, stages, tasks>, git, boards, pull requests)
	Azure AD (app registrations, key-vault, JWT)
		app regis: (application (client) ID, tentant ID, object ID, Application ID URI)
			Certificates & Secrets (Certificates, Client Secrets<secret ID, value, expires)
			API Permissions (other API list to be Executed using Execute, Admin Consent, read, write, execute)
			App Roles (Execute Same API<value=Execute, enable App Role>) for Basic Functionality of API
			Owners (who can edit all the above)
			MANFIEST XML
	Not every PR merge to the master goes to to every stage
	Pipelines (Stages: Build, Dev, QA, Prod)
		Build: Initialize job, Pre-job Downloads, Download secrets from key-vault, Checkout api, Maven repo creds/settings.xml, preserve pom.xml for caching, Cache Maven Packages, Fetch Maven Dependencies, Set Version Number, Run unit tests, Build and deploy, Copy Files to, Publish Artifacts to drop, Post-jobs, Finalize job
		Deploy: Initialize job, Pre-job, Deploy to Cloudhub, Post-job, Finalise job
	JIRA/Boards (Boards, Backlogs, Sprints, Calendar)
	Connector driven connectivity among APIs
	Custom Connectors like Circuit Breakers and Custom Loggers
Integrations taken up
	SAP (IDOCs and RFCs) to LCT, Snowflake to Facebook, Snowflake to LCT, OTM(Transmission XMl) to LCT, OTM to WMS
	Control-M
Best Practices
	Following Widely used Integration Patterns (Migration, Broadcast, Bidirectional sync, Correlation, Aggregation)
	Clean project structure (Separate XMls for Global Elements, Error Handling, Implementation Logic. Different Packages for java, apis, wsdls, examples, test cases etc)
	Naming conventions and Identations
	Use of Conf Props File and Overriding with defaults
	Externalising the scripts rather inline
	Munits coverage standards
Message Brokers -> Kafka, ActiveMQ, AWS SNS, AWS SQS, RabbitMQ, Azure Service Bus
	Message Business Value: Volatile, Durable, Replayable; Semantics: Command, Query, Event
	Queues for P2P, Topics for 1toMany
	Kafka: Higher Throughput, only topics, limited record size, TCP, Permanently stored, Offset, Commit log
		Cluster: group of brokers(server containers); Broker: group of topics; Topic: many partition, Topic duplication, replication factor, Leader 
		Conf: Poll timeout, Acknowledgment mode (Manual, Auto etc), Amount of parallel consumers
		General Conf: bootstrap url, Group ID (aka Consumer GroupID), Topics, SASL/PLAIN(username, password)
		Advanced: Isolation level (READ_COMMITED, READ_UNCOMMITED), Auto offset reset (LATEST, ERROR, EARLIER), Retry backoff timeout, Default send buffer size
			Default receive buffer size, Request timeout, Default record limit, FETCH Conf: Default fetch minimum size
		attributes *consumerCommitKey topic partition offset creationTimestamp
		operation: commit, message listener, publish, consume, batch message, seek
Subflow, Flow, Privateflow

Java 8 Features
	Default and static methods in interface
	Functional interfaces
	Lambda expressions
	Stream API, Date API