Session Storage Agent

For sharing data between logic during a task (execution) of a data process.

The session will be purged once the task is completed. This is a very common way to pass data from one logic to the next, including the aggregator logic.

Availability

• ✓ Generic logic
• ✓ Aggregator logic

Write to Session Storage

async sessionStorage.putJson(key: string, value: any): Promise<boolean>
async sessionStorage.putString(key: string, value: string): Promise<boolean>
async sessionStorage.putByteArray(key: string, value: Uint8Array | string): Promise<boolean>

Parameter	Description
key	Key of session data
value	Session data

Write a value into session storage. The key/value pair will be created if not exist.

The functions return a boolean to indicate if the write action is successful.

If value is not valid JSON, the agent will throw an error.

tip

value can be a single number (which is also valid for JSON).

note

The data may not be properly written into session storage without using await.

Example: write JSON object to session storage

const data = {
    name: "Arthur Dent",
    age: 42,
};

await ctx.agents.sessionStorage.putJson("data", data);

Example: write string to session storage

await ctx.agents.sessionStorage.putString("name", "Arthur Dent"");
await ctx.agents.sessionStorage.putString("age", String(age));  // convert number to string

tip

If you want to preserve the types of non-string values in the session storage, it would be better to encapsulate them in a JavaScript object and use putJson.

Example: write Uint8Array to session storage

await ctx.agents.sessionStorage.putByteArray(
    "payload",
    new Uint8Array(ctx.payload.http.body),
);

Read from Session Storage

async sessionStorage.get(key: string): Promise<string | number | object | Uint8Array>

Read a session data. The type depends on how the data was written into session storage.

If the key is not exist, the agent will throw an error.

Example

const name = await ctx.agents.sessionStorage.get("name");
const data = await ctx.agents.sessionStorage.get("data");

Remove from Session Storage

async sessionStorage.delete(key: string)

// or
async sessionStorage.remove(key: string)