Message Persistence API for PubNub C-Core SDK

Message Persistence provides real-time access to the history of all messages published to PubNub. Each published message is timestamped to the nearest 10 nanoseconds and is stored across multiple availability zones in several geographical locations. Stored messages can be encrypted with AES-256 message encryption, ensuring that they are not readable while stored on PubNub's network. For more information, refer to Message Persistence.

Messages can be stored for a configurable duration or forever, as controlled by the retention policy that is configured on your account. The following options are available: 1 day, 7 days, 30 days, 3 months, 6 months, 1 year, or Unlimited.

You can retrieve the following:

Messages
Message reactions
File Sharing (using File Sharing API)

Fetch History

Requires Message Persistence

This method requires that Message Persistence is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

This function fetches historical messages from one or multiple channels. The include_message_actions flag also allows you to fetch message reactions along with the messages.

It's possible to control how messages are returned and in what order.

if you specify only the start parameter (without end), you will receive messages that are older than the start timetoken
if you specify only the end parameter (without start), you will receive messages from that end timetoken and newer
if you specify values for both start and end parameters, you will retrieve messages between those timetokens (inclusive of the end value)

You will receive a maximum of 100 messages for a single channel or 25 messages for multiple channels (up to 500). If more messages meet the timetoken criteria, make iterative calls while adjusting the start timetoken to fetch the entire list of messages from Message Persistence.

Method(s)

To fetch messages, use the following method(s) in the Objective-C SDK. This method uses the builder pattern; you can omit any optional arguments.

enum pubnub_res pubnub_fetch_history(
    pubnub_t* pb,
    char const* channel,
    struct pubnub_fetch_history_options opt);

Parameter	Type	Required	Description
`pb`	pubnub_t*	Yes	Pointer to PubNub client context. Can't be NULL.
`channel`	`const char*`	Yes	The `string` with the `channel` name to fetch the `history`.
`opt` → `max_per_channel`	`unsigned int`	Yes	Specifies the number of historical messages to return per channel. Maximum value is 100 for a single channel or 25 for multiple channels.
`opt` → `include_meta`	`pubnub_tribool`	No	Whether event metadata should be included in response or not.
`opt` → `include_message_type`	`pubnub_tribool`	No	Indicates whether to retrieve messages with PubNub message type. Default is `YES`. For more information, refer to Retrieving Messages.
`opt` → `include_custom_message_type`	`pubnub_tribool`	No	Indicates whether to retrieve messages with the custom message type. For more information, refer to Retrieving Messages.
`opt` → `include_user_id`	`pubnub_tribool`	No	Pass `YES` to receive the publisher uuid with each history message. Default is `YES`.
`opt` → `include_message_actions`	`pubnub_tribool`	No	Whether event actions should be included in response or not. When `YES`, throws an exception if you call the method with more than one `channel`.
`opt` → `reverse`	`pubnub_tribool`	No	Setting to `YES` traverses the time line in reverse, starting with the oldest message first.
`opt` → `start`	`char const*`	No	Timetoken for oldest event starting from which next should be returned events. Value will be converted to required precision internally.
`opt` → `end`	`char const*`	No	Timetoken for latest event till which events should be pulled out. Value will be converted to required precision internally.

Basic Usage

struct pubnub_fetch_history_options options = pubnub_fetch_history_defopts();
options.include_custom_message_type = true;
// Fetch history and check whether operation started or not.
if (pubnub_fetch_history(ctx, "my_channel1,my_channel2", options) != PNR_IN_PROGRESS) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
    return -1;
}

// Wait for `history` operation completion before trying to get a service response.
enum pubnub_res pbresult = pubnub_await(ctx);
if (pbresult != PNR_OK) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
    return -1;
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Response

This method returns a enum pubnub_res pbresult on success:

enum pubnub_res pbresult = pubnub_await(ctx);
if (pbresult != PNR_OK) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
    return -1;
}

pubnub_chamebl_t response = pubnub_get_fetch_history(ctx);

Other Examples

Fetch messages with metadata

struct pubnub_fetch_history_options options = pubnub_fetch_history_defopts();
options.include_meta = true;

// Fetch history and check whether operation started or not.
if (pubnub_fetch_history(ctx, "my_channel1,my_channel2", options) != PNR_IN_PROGRESS) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
    return -1;
}

// Wait for `history` operation completion before trying to get a service response. 
enum pubnub_res pbresult = pubnub_await(ctx);
if (pbresult != PNR_OK) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
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Fetch messages with actions

struct pubnub_fetch_history_options options = pubnub_fetch_history_defopts();
options.include_message_actions = true;

// Fetch history and check whether operation started or not.
if (pubnub_fetch_history(ctx, "my_channel1,my_channel2", options) != PNR_IN_PROGRESS) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
    return -1;
}

// Wait for `history` operation completion before trying to get a service response. 
enum pubnub_res pbresult = pubnub_await(ctx);
if (pbresult != PNR_OK) {
    printf("Failed to fetch history, error %d\n", pbresult);
    pubnub_free(ctx);
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History

This function fetches historical messages of a channel. Message Persistence provides real-time access to an unlimited history for all messages published to PubNub. Stored messages are replicated across multiple availability zones in several geographical data center locations. Stored messages can be encrypted with AES-256 message encryption ensuring that they are not readable while stored on PubNub's network. It is possible to control how messages are returned and in what order, for example you can:

Limit the number of messages to a specific quantity using the 4th argument parameter.

Method(s)

To run History you can use the following method(s) in the C-Core SDK:

enum pubnub_res pubnub_history (
  pubnub_t *p,
  const char *channel,
  const char *channel_group,
  unsigned count
)

Parameter	Type	Required	Description
`p`	pubnub_t*	Yes	Pointer to PubNub client context. Can't be NULL.
`channel`	const char*	Yes	The `string` with the `channel` name to fetch the `history`
`count`	unsigned	Yes	Maximum number of messages to get. If there are less than this available on the `channel`, you'll get less, but you can't get more.
`include_token`	bool	Yes	If `true`, include the timetoken for every `message`. default: `false`

Basic Usage

Retrieve the last 100 messages on a channel:

// Sync
enum pubnub_res res;

pubnub_history(pn, "history_channel", 10, false);
res = pubnub_await(pn);

if (PNR_OK == res) {
  puts("Got history! Messages:");
  for (;;) {
    const char *msg = pubnub_get(pn);
    if (NULL == msg) {
      break;
    }
    puts(msg);
  }
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Rest Response from Server

An array is returned on success. The pubnub_history() function returns a list of up to 100 messages, the timetoken of the first (oldest) message and the timetoken of the last (newest) message in the resulting set of messages. The output below demonstrates the format for a pubnub_history() response:

[
    ["message1", "message2", "message3",... ],
    "Start Time Token",
    "End Time Token"
]

Extended History

Extended History Options structure

Options for extended history.

Method(s)

Declaration

struct pubnub_history_options {
    bool string_token;
    int count;
    bool reverse;
    char const* start;
    char const* end;
    bool include_token;
}

Members

Member	Type	Description
`string_token`	bool	If `false`, the returned start and end `Timetoken` values will be returned as long ints. If `true`, the start and end `Timetoken` values will be returned as strings. Default is `false`.
`count`	int	The maximum number of messages to return per response. Has to be between 1 and 100 messages. Default is 100.
`reverse`	bool	Direction of time traversal. Default is false, which means timeline is traversed newest to oldest.
`start`	char const*	If provided (not NULL), lets you select a "start date," in `Timetoken` format. If not provided, it will default to current time. Page through results by providing a start OR end timetoken. Retrieve a slice of the time line by providing both a start AND end timetoken. start is `exclusive` – that is, the first item returned will be the one immediately after the start `Timetoken` value. Default is `NULL`.
`end`	char const*	If provided (not NULL), lets you select an "end date," in `Timetoken` format. If not provided, it will provide up to the number of messages defined in the "count" parameter. Page through results by providing a start OR end timetoken. Retrieve a slice of the time line by providing both a start AND end timetoken. End is `exclusive` – that is, if a message is associated exactly with the end `Timetoken`, it will be included in the result. Default is `NULL`.
`include_token`	bool	Pass true to receive a `timetoken` with each history message. Defaults to `false`.

Initialize extended History options

This returns the default options for publish V1 transactions. It's best to always call it to initialize the pubnub_history_options(), since it has several parameters.

Method(s)

Declaration

struct pubnub_history_options pubnub_history_defopts(void)

Parameters

This Method has no arguments.

Basic Usage

struct pubnub_history_options opts = pubnub_history_defopts();

Returns

Type	Value	Description
`struct pubnub_history_options`		The `default` options for here-now.

Extended History

The extended history. It is basically the same as the pubnub_history(), just adding a few options that will be sent.

Method(s)

Declaration

enum pubnub_res pubnub_history_ex(
  pubnub_t* pb,
  char const* channel,
  struct pubnub_history_options opt
)

Parameters

Parameter	Type	Required	Description
`pb`	pubnub_t*	yes	The Pubnub context
`channel`	char const*	yes	The string with the channel name to get history for.
`opt`	struct pubnub_history_options	yes	History options.

Basic Usage

struct pubnub_history_options opt = pubnub_history_defopts();
opt.reverse = true;
pbresult = pubnub_history_ex(pn, "my_channel", opt);

Returns

Type	Value	Description
`enum pubnub_res`	PNR_STARTED	Success.
	other	Indicates the type of error.

Message Counts

Message count per channel structure

Contains channel name (as char memory block, aka Pascal string) and message count for messages received on the channel. The message counts are the number of messages published on one or more channels since a given time.

Used to store information retrieved by pubnub_message_counts() transaction.

Declaration

struct pubnub_chan_msg_count {
    pubnub_chamebl_t channel;
    size_t message_count;
}

Members

Members	Type	Description
`channel`	pubnub_chamebl_t	Channel name as a char memory block (aka `Pascal string`)
`message_count`	size_t	Number of messages for the channel

Count channels in message count response

Returns the number of members (key->value pairs) of JSON object channels in the response to a message count transaction.

Declaration

int pubnub_get_chan_msg_counts_size(pubnub_t* pb)

Parameters

Parameter	Type	Required	Description
`pb`	pubnub_t*	Yes	The Pubnub context in which to parse the response

Basic Usage

int n  = pubnub_get_chan_msg_counts_size(pb);
printf("There are %d channels in the message counts response\n", n);

Returns

Type	Value	Description
`int`	-1	Error (transaction still in progress or other)
	>= 0	The number of members of the `channels` JSON object)

Message Counts transaction

Starts the transaction pubnub_message_counts on the context @p pb for the list of channels @p channel for messages counts starting from @p timeoken which can be a single timetoken, or list of comma-separated timetokens (corresponding to the channel list).

Unlimited message retention

For keys with unlimited message retention enabled, this transaction considers only messages published in the last 30 days.

Declaration

enum pubnub_res pubnub_message_counts(
  pubnub_t* pb,
  char const* channel,
  char const* timetoken
)

Parameters

Parameter	Type	Required	Description
`pb`	pubnub_t*	Yes	The Pubnub context to use for transaction
`channel`	char const*	Yes	The string with the channel name (or comma-delimited list of channel names) to subscribe for.
`timetoken`	char const*	Yes	A single token OR a comma-separated list of tokens. If single, will be used for all channels. If a list, has to have the same number of elements as `@p` channel and each will be used for its channel, in-order.

Basic Usage

/** Obtain message count for
        channel 'one' since 15517035062228243 and
        channel 'two' since 15517035052228243. */
pbres = pubnub_message_counts(pb, "one,two", "15517035062228243,15517035052228243");

Returns

Type	Value	Description
`enum pubnub_res`	PNR_STARTED	Started
	PNR_OK	Finished with a success (can only happen in the sync interface)
	other	Failed, Indicates the type of error

Example: Single token for all channels

/** Obtain message count for channels
        'one' and 'two' since 15517035062228243 */
pbres = pubnub_message_counts(pb, "one,two", "15517035062228243");

Read all channel message counts

On input, @p io_count is the number of allocated counters per channel (array dimension of @p chan_msg_counters). On output(@p io_count), number of counters per channel written. If there are more channel message counters in the answer than there are in the allocated array (can't fit all), that will not be considered an error, they will simply not be written to @p chan_msg_counters. To see how much elements there are (and allocate accordingly), use pubnub_get_chan_msg_counts_size().

This is an alternative to pubnub_get_message_counts(), useful for exploratory usage, as one can get all the channel message counters that are in the report, without keeping track of what were the requested channels.

Unlimited retention

For keys with unlimited message retention enabled, this transaction considers only messages published in the last 30 days.

Declaration

int pubnub_get_chan_msg_counts(
  pubnub_t* pb,
  size_t* io_count,
  struct pubnub_chan_msg_count* chan_msg_counters
)

Parameters

Parameter	Type	Required	Description
`pb`	pubnub_t*	Yes	The Pubnub context to use for transaction
`io_count`	size_t*	Yes	On input, the number of allocated `counters per channel` (array dimension of `@p` `chan_msg_counters`). On output, number of counters per channel written to `@p` `chan_msg_counters`.
`chan_msg_counters`	struct pubnub_chan_msg_count*	Yes	An array of channel message counters, allocated by the caller, filled in by this function.

Basic Usage

struct pubnub_chan_msg_count chan_msg_count[CHAN_COUNT];
size_t count = CHAN_COUNT;
int rslt = pubnub_get_chan_msg_counts(pb, &count, chan_msg_count);
if (0 == rslt) {
    size_t i;
    for (i = 0; i < count; ++i) {
        printf("  Channel    = '%.*s'\n", (int)chan_msg_count[i].channel.size, chan_msg_count[i].channel.ptr);
        printf("  Message count  = %z'\n", chan_msg_count[i].message_count);
    }
}

Returns

Type	Value	Description
`int`	0	Success (even if there are more channel message counts than is possible to write to `@p` `chan_msg_counters`)
	-1	Error, messages not read (transaction still in progress, format error...)

Example: Make sure we have room for all the channel message counters

int n  = pubnub_get_chan_msg_counts_size(pb);
if (n > 0) {
    struct pubnub_chan_msg_count *pchmsc = malloc(n * sizeof *pchmsc);
    if (pchmsc != NULL) {
        size_t count = n;
        int rslt = pubnub_get_chan_msg_counts(pb, &count, pchmsc);
        if (0 == rslt) {
            printf("Got %z counters, should be the same as %d\n", count, n);
        }
        free(pchmsc);
    }
}

Read counters for channels

Reads message counters for the given channels (in @p channel) from the PubNub response to pubnub_message_counts().

Array dimension for @p o_count is the number of channels from the comma-separated channel list @p channel and it (@p o_count array) is allocated by the caller.

Message counts order in @p o_count is corresponding to channel order in @p channel list respectively, even if the answer itself has the channels in a different order. If a requested channel is not found in the PubNub response, the message counter in the respective @p o_count array member has a negative value.

If there is a channel name in the answer, not to be found in requested @p channel list, that is not considered an error.

This is an alternative to pubnub_get_chan_msg_count(), useful if we already maintain the list of channels and just want to get the message counters.

Unlimited message retention

For keys with unlimited message retention enabled, this transaction considers only messages published in the last 30 days.

Declaration

int pubnub_get_message_counts(
  pubnub_t* pb,
  char const*channel,
  int* o_count
)

Parameters

Parameter	Type	Required	Description
`pb`	pubnub_t*	Yes	The Pubnub context to use for transaction
`channel`	char const*	Yes	A comma-separated list of channels to read message counters from
`o_count`	int*	Yes	An array of message counters, allocated by the caller, filled in by this function.

Basic Usage

int msg_count[2];
int rslt = pubnub_get_message_counts(pb, "one,two", msg_count);
if (0 == rslt) {
    printf("message counts: one -> %d, two -> %d\n", msg_count[0], msg_count[1]);
}

Returns

Type	Value	Description
`int`	0	Success (even if there are channel message counts int `@p` channel that are not there in the response or vice-versa)
	-1	Error, messages not read (transaction still in progress, format error...)

Fetch History​

Requires Message Persistence

Method(s)​

Basic Usage​

Response​

Other Examples​

Fetch messages with metadata​

Fetch messages with actions​

History​

Method(s)​

Basic Usage​

Rest Response from Server​

Extended History​

Extended History Options structure​

Method(s)​

Declaration​

Members​

Initialize extended History options​

Method(s)​

Declaration​

Parameters​

Basic Usage​

Returns​

Extended History​

Method(s)​

Declaration​

Parameters​

Basic Usage​

Returns​

Message Counts​

Message count per channel structure​

Declaration​

Members​

Count channels in message count response​

Declaration​

Parameters​

Basic Usage​

Returns​

Message Counts transaction​

Unlimited message retention

Declaration​

Parameters​

Basic Usage​

Returns​

Example: Single token for all channels​

Read all channel message counts​

Unlimited retention

Declaration​

Parameters​

Basic Usage​

Returns​

Example: Make sure we have room for all the channel message counters​

Read counters for channels​

Unlimited message retention

Declaration​

Parameters​

Basic Usage​

Returns​

Fetch History

Method(s)

Basic Usage

Response

Other Examples

Fetch messages with metadata

Fetch messages with actions

History

Method(s)

Basic Usage

Rest Response from Server

Extended History

Extended History Options structure

Method(s)

Declaration

Members

Initialize extended History options

Method(s)

Declaration

Parameters

Basic Usage

Returns

Extended History

Method(s)

Declaration

Parameters

Basic Usage

Returns

Message Counts

Message count per channel structure

Declaration

Members

Count channels in message count response

Declaration

Parameters

Basic Usage

Returns

Message Counts transaction

Declaration

Parameters

Basic Usage

Returns

Example: Single token for all channels

Read all channel message counts

Declaration

Parameters

Basic Usage

Returns

Example: Make sure we have room for all the channel message counters

Read counters for channels

Declaration

Parameters

Basic Usage

Returns