fetch price updates guide

Author: aditya520

pages/lazer/_meta.json

@@ -16,6 +16,7 @@
     "type": "separator"
   },
 
+  "fetch-price-updates": "Fetch Price Updates",
   "integrate-as-consumer": "Integrate as a Consumer",
   "integrate-as-publisher": "Integrate as a Publisher",
 

pages/lazer/fetch-price-updates.mdx

@@ -0,0 +1,122 @@
+import { Callout, Steps } from "nextra/components";
+
+# How to Fetch Price Updates from Pyth Lazer
+
+Pyth Lazer provides a [websocket API (TODO: Prod)](https://pyth-lazer-staging.dourolabs.app/docs) to fetch price updates. 
+
+
+This guide explains how to **fetch** price updates, explore various **properties** of these updates, and configure the channel for **update frequency**. (TODO: Rewrite maybe)
+
+Fetching price updates is a three-step process:
+
+1. **Acquire** an access token.
+2. **Adjust** subscription parameters.
+3. **Subscribe** to the price updates via websocket API.
+
+The websocket server is available at `wss://pyth-lazer-staging.dourolabs.app/v1/stream`.
+TODO: Add the prod URL.
+
+<Steps>
+
+### 1. Acquire an access token
+
+Please fill out [this form](https://tally.so/r/nP2lG5) to contact the Pyth team and get the access token.
+
+Use the access token to authenticate the websocket connection as a `Bearer {token}{:bash}`.
+
+
+### 2. Adjust subscription parameters
+
+One can configure the request/subscription parameters to customize the received price updates. A sample request is shown below:
+
+```json
+  client.send({
+    type: "subscribe",
+    subscriptionId: 1,
+    priceFeedIds: [1, 2],
+    properties: ["price"],
+    chains: ["solana"],
+    channel: "fixed_rate@200ms",
+  });
+```
+Here:
+
+- `subscriptionId` is an arbitrary numeric identifier one can choose for a subscription. It will eb returned back in response by the server. It doesn not affect the signed payload.
+- `priceFeedIds` is the list of price feeds one like to receive. Data for all price feeds will be present in the signed price updates generated. Refer to the [Price Feed IDs list](./price-feeds.mdx) for the supported price feeds.
+- `properties` is the list of properties one can request, such as **price**, **bestBidPrice**, **bestAskPrice**, etc. TODO: Find more properties.
+- `chains` is the list of chains for which one need a signed payload, such as **evm**, **solana**, etc.
+- `channel` allows to configure the update rate: updates in the **real_time** channel are sent as frequently as possible, while **fixed_rate@200ms** and **fixed_rate@50ms** channels are updated at fixed rates.
+
+There are also a few other parameters one may use. Refer to the [API documentation](https://pyth-lazer-staging.dourolabs.app/docs) for more details.
+
+### 3. Subscribe to the price updates
+
+To subscribe to the price updates, one needs to send the request to the websocket server. The server will respond with a signed price update.
+
+1. Pyth Lazer provides a [SDK](https://github.com/pyth-network/pyth-crosschain/tree/main/lazer/sdk/js) to seamlessly integrate the websocket API into your application. 
+It can be installed using the following command:
+
+```bash
+npm install --save @pythnetwork/pyth-lazer-sdk
+```
+
+2. Then create a [`PythLazerClient`](https://github.com/pyth-network/pyth-crosschain/blob/main/lazer/sdk/js/src/client.ts#L32) object using the URL and the access token requested from the Pyth team in the first step.
+
+```js
+import { PythLazerClient } from "@pythnetwork/pyth-lazer-sdk";
+
+const client = new PythLazerClient("wss://pyth-lazer-staging.dourolabs.app/v1/stream", "ctoken1");
+```
+
+3. After the client is created, one can adjust the subscription parameters and subscribe to the price updates.
+
+```js
+client.ws.addEventListener("open", () => {
+  client.send({
+    type: "subscribe",
+    subscriptionId: 1,
+    priceFeedIds: [1, 2],
+    properties: ["price"],
+    chains: ["solana"],
+    channel: "fixed_rate@200ms",
+  });
+});
+```
+
+4. One the connection is established, the server will start sending the price updates to the client.
+
+```js
+client.addMessageListener((message) => {
+  console.log(message);
+});
+```
+
+By default, price updates contain the `parsed` field that one can use to easily interpret the update in their backend or frontend, as well as evm and/or solana fields that contain data that one should include in the on-chain transaction:
+
+```json
+{
+  "type": "streamUpdated",
+  "subscriptionId": 1,
+  "parsed": {
+    "timestampUs": "1730986152400000",
+    "priceFeeds": [
+      {
+        "priceFeedId": 1,
+        "price": "1006900000000"
+      },
+      {
+        "priceFeedId": 2,
+        "price": "2006900000000"
+      }
+    ]
+  },
+  "solana": {
+    "encoding": "hex",
+    "data": "b9011a82d239c094c52016990d6ca2b261dbb1157ad503cbd3ea0679493316150cf3457624d19ec3f6e0a0e94373ab0971e39d939beda15cc02eb3c5454eb700f1f7310df65210bee4fcf5b1cee1e537fabcfd95010297653b94af04d454fc473e94834f2a0075d3c7938094b99e52260600030201000000010000b5ea6fea00000002000000010000c58f44d3010000"
+  }
+}
+```
+
+
+
+</Steps>

pages/lazer/integrate-as-consumer/evm.mdx

@@ -10,7 +10,6 @@ Integrating with Pyth Lazer in your smart contracts as a consumer is a three-ste
 2. **Subscribe** to Pyth Lazer websocket to receive price updates on your backend or frontend.
 3. **Include** the price updates into your smart contract transactions.
 
-
 <Steps>
 
 ### Integrate Pyth Lazer SDK into your smart contracts
@@ -26,4 +25,10 @@ TODO: requiremnts.txt
 ```bash
 pyth-lazer-sdk/=lib/pythnet/pyth-crosschain/lazer/contracts/evm
 ```
+
 </Steps>
+
+### Modify the smart contract to TODO:
+
+1. Import
+2. State Variables.