DolphinDB Web API is an API that programs can access DolphinDB server through url (http://IP:port) by posting data in JSON format, which instructs the server to run the specified script and return the result in JSON format.
Any programming language that supports submitting data to a specified url via the http protocol and parsing JSON formatted packets can use DolphinDB web API:
We conduct 1+2=3 in DolphinDB server. Organize a JSON packet like the JavaScript below and post the packet to the url of a data node, such as "http://localhost:8848".
- JavaScript
var paramJson = {...}
var option = {
url: "http://localhost:8848",
async: true,
data: JSON.stringify(paramJson),
type: "POST",
dataType: "json",
success: function (data) {
var resultJson = data; //data={...}
}
}
$.ajax(option);
- Input format
*Note that in the browser environment, special symbols such as "+" need to be url encoded with function encodeURIComponent before sending to DolphinDB server.
var code = "1+2";
codestr = encodeURIComponent(code);
paramJson = {
"sessionID": "942605602",
"functionName": "executeCode",
"params": [{
"name": "script",
"form": "scalar",
"type": "string",
"value": codestr
}]
}
- Output format
resultJson = {
"sessionID": "942605602",
"resultCode": "0",
"msg": "",
"object": [{
"name": "",
"form": "scalar",
"type": "int",
"value": "3"
}]
}In this example, we generate a table on the server side through DolphinDB script select * from table(1..3 as id,'tom' 'bob' 'tony' as name), and return it to the client in JSON format. DolphinDB server stores tables in columns, so the returned JSON is also composed of multiple one-dimensional arrays representing DolphinDB columns.
- Input arameter format
var code = "select * from table(1..3 as id,'tom' 'bob' 'tony' as name)";
code = encodeURIComponent(code);
var paramJson = {
"sessionID": "0",
"functionName": "executeCode",
"params": [{
"name": "script",
"form": "scalar",
"type": "string",
"value": code
}]
};
- Return result format
{
"sessionID": "1130397736",
"resultCode": "0",
"msg": "",
"object": [{
"name": "",
"form": "table",
"size": "3",
"value": [{
"name": "id",
"form": "vector",
"type": "int",
"size": "3",
"value": [1, 2, 3]
}, {
"name": "name",
"form": "vector",
"type": "string",
"size": "3",
"value": ["tom", "bob", "tony"]
}]
}]
}In this example, we use DolphinDB equal join function ej on two tables. The result is also a table.
leftTable: table(1 2 3 as id,'a' 'b' 'c' as name)
rightTable: table(2 3 4 as id,'e' 'f' 'g' as name)
resultTable: table(2 3 as id,'b' 'c' as name,'e' 'f' as rightTable_name)
- Input
var paramJson = {
"sessionID": "0",
"functionName": "ej",
"params": [{
"name": "leftTable",
"form": "table",
"size": "3",
"value": [{
"name": "id",
"form": "vector",
"type": "int",
"size": "3",
"value": [1, 2, 3]
}, {
"name": "name",
"form": "vector",
"type": "string",
"size": "3",
"value": ["a", "b", "c"]
}]
},{
"name": "rightTable",
"form": "table",
"size": "3",
"value": [{
"name": "id",
"form": "vector",
"type": "int",
"size": "3",
"value": [2, 3, 4]
}, {
"name": "name",
"form": "vector",
"type": "string",
"size": "3",
"value": ["e", "f", "g"]
}]
},{
"name": "joincolumn",
"form": "scalar",
"type": "string",
"value": "id"
}]
};
- Output
{
"sessionID": "1358033411",
"resultCode": "0",
"msg": "",
"object": [{
"name": "",
"form": "table",
"size": "2",
"value": [{
"name": "id",
"form": "vector",
"type": "int",
"size": "2",
"value": [2, 3]
}, {
"name": "name",
"form": "vector",
"type": "string",
"size": "2",
"value": ["b", "c"]
}, {
"name": "righttable_name",
"form": "vector",
"type": "string",
"size": "2",
"value": ["e", "f"]
}]
}]
}-
SessionID：specifies the session ID connecting to DolphinDB. The initial session ID is 0. During a user login session, the same server associates the SessionID with the login user.
-
functionName：specifies the name of the function to be called.
-
params: an json array representing the input parameters of the specificed functionName.
-
sessionID： the session ID where the script is executed.
-
resultCode : 0-Normal 1-Exception。
-
msg：wehn resultCode is 1, exception information will be throwed.
-
object： The returned object information after the script execution.
To use the javascript development kit, you need to include DolphinDBConnection.js, DolphinDBEntity.js and jquery development kit.
DolphinDBConnection.js provides the following methods: run, runFunction, login and logout.
- Run Script
Use run(script, [callback]) to run DolphinDB script. For example:
var server = new DolphinDBConnection("http://localhost:8848");
server.run("1+2",function(re){
console.log(var DolphinDBEntity(re).toScalar());
});- Run DolphinDB Functions
Use runFunction(functionName, params, [callback]) to run DolphinDB functions. For example:
var server = new DolphinDBConnection("http://localhost:8848");
var param = [{
"name": "userId",
"form": "scalar",
"type": "string",
"value": "user1"
}, {
"name": "password",
"form": "scalar",
"type": "string",
"value": "passwordstring"
}];
server.runFunction("login", param , function(re){
if (re.resultCode === "1") {
alert(re.msg);
}
});- Login and Logout DolphinDB server
Use login(userId, password, [callback]) to login DolphinDB server and use logout() to logout DolphinDB server.
var server = new DolphinDBConnection("http://localhost:8848");
server.login("user1","pass");
server.logout();Note:
- The javascript development kit depends on javascript library JQuery. It can only be used in a browser environment.
- Web API returns up to 100,000 records at a time.
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