Increasingly, developers and architects are disaggregating their architectures to create more scalable and agile applications. As this happens, everything is becoming a programmable endpoint. Ballerina is a new programming language designed around this problem. This deck introduces the challenges and background of why Ballerina has been created, as well as demonstrate the core features of the language.

1. Cloud Native Programming Language that Makes it Easy
to Write Microservices that Integrate APIs
Christopher Davey
April 2019

2. Increasing demand is causing disaggregation

3. Everything is
An Endpoint
Functions
APIs
Data
SaaS apps
Legacy apps
Devices
Disaggregation leads to more endpoints

4. Integration in an increasingly disaggregated world
Transactions
Circuit Breaking
Protocols
Payloads
Events
Security
Workflow
Streams
Compensation

5. ESB, BPMN, EAI
Java / Spring
JavaScript / Node

6. The
Integration
Gap
ESB, BPMN, EAI
Java / Spring
JavaScript / Node

7. AGILE
INTEGRATION SIMPLE

8. Microservice with RESTful API

10. import ballerina/http;
listener http:Listener httpListener = new(9090);
// RESTful service.
@http:ServiceConfig { basePath: "/ordermgt" }
service orderMgt on httpListener {
// Resource that handles the HTTP GET requests that are directed to a specific
@http:ResourceConfig {
methods: ["GET"],
path: "/order/{orderId}"
}
resource function findOrder(http:Caller caller, http:Request req, string
orderId) {
// Implementation
}
// Resource that handles the HTTP POST requests that are directed to the path
@http:ResourceConfig {
methods: ["POST"],
path: "/order"
}
resource function addOrder(http:Caller caller, http:Request req) {
...

11. Service Composition

12. import ballerina/http;
// Service endpoint
listener http:Listener travelAgencyEP = new(9090);
// Client endpoint to communicate with Airline reservation service
http:Client airlineReservationEP = new("http://localhost:9091/airline");
...
// Travel agency service to arrange a complete tour for a user
@http:ServiceConfig {basePath:"/travel"}
service travelAgencyService on travelAgencyEP {
...
// Send a post request to airline service with appropriate payload and get
response
http:Response inResAirline = check airlineReservationEP->post("/reserve",
untaint outReqPayloadAirline);

13. GMail-Google Sheets Integration

14. gsheets4:Client spreadsheetClient = new({
clientConfig: {
auth: {
scheme: http:OAUTH2,
config: {
grantType: http:DIRECT_TOKEN,
config: {
accessToken: accessToken,
refreshConfig: {
clientId: clientId,
clientSecret: clientSecret,
refreshUrl: gsheets4:REFRESH_URL,
refreshToken: refreshToken
function getCustomerDetailsFromGSheet() returns string[][]|error {
//Read all the values from the sheet.
string[][] values = check spreadsheetClient->getSheetValues(spreadsheetId, sheetName);
log:printInfo("Retrieved customer details from spreadsheet id: " + spreadsheetId + " ;
sheet name: "
+ sheetName);
return values;
}

15. Network Abstractions

16. ● Endpoints:
- Listener endpoints - For incoming network interactions
- Protocols
- HTTP/S
- HTTP2
- GRPC
- WebSocket
- JMS ..
- Client endpoints - For outgoing network interactions
- HTTP. WebSub, GRPC
- Database, FTP
- Twitter, Salesforce
Endpoints

17. https://ballerina.io/learn/by-example/
Ballerina by Example
Ballerina by Example enables you to
have complete coverage over the
language, while emphasizing incremental
learning. This is a series of commented
example programs.

18. Network-aware Type System

19. Basic types and other types
○ Simple types
○ (), boolean, int, float, decimal, string
○ Structured types
○ tuple, array, map, record, table, xml
○ Behavioral types
○ error, function, future, object, stream, typedesc

20. Basic types and other types
○ Other types
○ Unions
○ Optional
○ json
○ byte
○ anydata
○ any

21. Union types
○ Type defined by union of two or more other types
○ Remember, a type is name for a set of values
float | string v1 = "John";
float | string v2 = 457.68;
float | string
0.51
1.01
457.68
-11.0
“John”
“name”
“”
“bal”
// The return type of 'post' is a union of 'http:Response' and 'error'
http:Response | error response = orderEP -> post("/create", reqPayload)

22. XML
// Simple XML literal
xml x1 = xml`<name>Pol Katta</name>`;
// XML with namespaces
xmlns "http://wso2.com" as ns0;
xml x2 = xml `<name id="123" status="single">
<ns0:fname>Pol</ns0:fname>
<ns0:lname>Katta</ns0:lname>
</name>`;
// XML literal with interpolation
string lastName = "Katta";
xml x3 = xml`<lname>${lastName}</lname>`;
// Concat XML values
xml x4 = x1 + x2 + x3;

23. JSON
json is just a union - () | int | float | string | map<json> | json[]
// JSON object
json payload = { "orderdata" : { "id": 1, "name": "XYZ", "price": 2500 } };
//Access object values
json orderid = payload.orderdata.id;
//JSON arrays
json orders = {
"orderdata" : [
{ "id": 1, "name": "XYZ", "price": 2500 },
{ "id": 2, "name": "ABC", "price": 3000 }
]
};

24. Sequence Diagram

27. Microservice Deployment

28. import ballerina/http;
import ballerinax/docker;
@docker:Config {
registry:"ballerina.guides.io",
name:"travel_agency_service",
tag:"v1.0"
}
@docker:Expose{}
listener http:Listener travelAgencyEP = new(9090);
// http:Client endpoint definitions to communicate with other services
@http:ServiceConfig {basePath:"/travel"}
service travelAgencyService on travelAgencyEP {
@kubernetes:Ingress {
hostname:"ballerina.guides.io",
name:"ballerina-guides-travel-agency-service",
path:"/"
}
@kubernetes:Service {
serviceType:"NodePort",
name:"ballerina-guides-travel-agency-service"
}
@kubernetes:Deployment {
image:"ballerina.guides.io/travel_agency_service:v1.0",
name:"ballerina-guides-travel-agency-service"
}

29. ● Ballerina natively understand Cloud Native platforms like Docker,
Kubernetes and Istio.
● Ballerina removes gap between developers and Ops.
● Ballerina support agile development to deployment and improve
productivity.
Takeaways

30. How to get involved
Learn more
Open source
Get support
http://ballerina.io
http://github.com/ballerina-platform/
Ballerina Dev Google Group
Ballerina Slack Channel
Stack Overflow #ballerina tag

31. THANK YOU