```json
{
"client_id": "123456.7654321",
"events": [
{
"name": "campaign_details",
"params": {
"campaign_id": "google_1234",
"campaign": "Summer_fun",
"source": "google",
"medium": "cpc",
"term": "summer+travel",
"content": "logolink",
"session_id": "123",
"engagement_time_msec": "100"
}
}
]
}
```
While `session_start` is a [reserved event
name](/analytics/devguides/collection/protocol/ga4/reference#reserved_names),
creating a new `session_id` creates a new session without the need to send
`session_start`. Understand how [sessions are
counted](//support.google.com/analytics/answer/9191807).
## Try it
Here's an example you can use to send a [`tutorial_begin`] event to your Google
Analytics server:
```javascript
const measurement_id = `G-XXXXXXXXXX`;
const api_secret = `<secret_value>`;
fetch(`https://www.google-analytics.com/mp/collect?measurement_id=${measurement_id}&api_secret=${api_secret}`, {
method: "POST",
body: JSON.stringify({
client_id: 'XXXXXXXXXX.YYYYYYYYYY',
events: [{
name: 'tutorial_begin',
params: {},
}]
})
});
```
## Override timestamp
The Measurement Protocol uses the *first* timestamp it finds in the following
list for each event in the request:
1. The `timestamp_micros` of the event.
1. The `timestamp_micros` of the request.
1. The time that the Measurement Protocol receives the request.
The following example sends a request-level timestamp that applies to all of
the events in the request. As a result, the Measurement Protocol assigns both the
`tutorial_begin` and `join_group` events a timestamp of
`requestUnixEpochTimeInMicros`.
```javascript
{
"timestamp_micros": requestUnixEpochTimeInMicros,
"events": [
{
"name": "tutorial_begin"
},
{
"name": "join_group",
"params": {
"group_id": "G_12345",
}
}
]
}
```
The following example sends both a request-level timestamp and an event-level
timestamp. As a result, the Measurement Protocol assigns the `tutorial_begin`
event a timestamp of `tutorialBeginUnixEpochTimeInMicros`, and the `join_group`
event a timestamp of `requestUnixEpochTimeInMicros`.
```javascript
{
"timestamp_micros": requestUnixEpochTimeInMicros,
"events": [
{
"name": "tutorial_begin",
"timestamp_micros": tutorialBeginUnixEpochTimeInMicros
},
{
"name": "join_group",
"params": {
"group_id": "G_12345",
}
}
]
}
```
## Limitations
The following limitations apply to sending Measurement Protocol events to Google
Analytics:
Note: For information on the limitations of 360 features, see [Google Analytics
360](//support.google.com/analytics/answer/11202874).
* Requests can have a maximum of 25 events.
* Events can have a maximum of 25 parameters.
* Events can have a maximum of 25 user properties.
* User property names must be 24 characters or fewer.
* User property values must be 36 characters or fewer.
* Event names must be 40 characters or fewer, can only contain alpha-numeric
characters and underscores, and must start with an alphabetic character.
* Parameter names including item parameters must be 40 characters or fewer,
can only contain alpha-numeric characters and underscores, and must start
with an alphabetic character.
* Parameter values including item parameter values must be 100 characters or
fewer for a standard Google Analytics property, and 500 characters or fewer
for a Google Analytics 360 property.
* Item parameters can have a maximum of 10 custom parameters.
* The post body must be smaller than 130kB.
* App Measurement Protocol events sent to Google Analytics 4 don't populate
Search audiences in Google Ads for app users.
For additional requirements of each use case, see [common use cases].
