Working with Threads

Threads allow users to communicate using topic-specific communication channels. Each Context can contain any number of Threads with a unique identifier (threadId) used to distinguish them. Threads do not need to have unique names or assigned public keys.

Permissions

Threads differentiate two types of users - Managers and Regular Users. The table below shows the differences in their permissions:

Activity	User	Manager
Sending messages	yes	yes
Editing Thread	no	yes
Deleting messages	only their own	all messages

The values above are the default policy values defined by PrivMX. To read more about Policies and learn how to modify them, go to Policies.

Before working with Threads, follow our Getting Started Guide. It will show you how to set up your project to work with PrivMX Bridge. Sample code on this page is based on the initial assumptions.

When working with Threads, you will use the following:

ThreadApi - provides methods used to manage Threads in given Context

Let's modify the program from the First App chapter to connect to the Bridge server, create a Thread, and send the first message in it.

CMakeLists.txt

...
target_link_libraries(test_program PUBLIC 
		privmxendpoint::privmxendpointcore
        privmxendpoint::privmxendpointthread
		privmxendpoint::crypto
)

main.cpp

C++

// setup some defaults
core::PagingQuery defaultListQuery = {.skip = 0, .limit = 100, .sortOrder = "desc"};

// initialize Endpoint connection and Threads API
auto connection {core::Connection::connect(USER1_PRIVATE_KEY, SOLUTION_ID, BRIDGE_URL)};
auto threadApi {thread::ThreadApi::create(connection)};

// ...

Creating Threads

Creating a basic, unnamed Thread, which can act as an encrypted data container:

C++

// ...

std::vector<core::UserWithPubKey> managers {
    {.userId = USER1_ID, .pubKey = USER1_PUBLIC_KEY}
};

std::vector<core::UserWithPubKey> users {
    {.userId = USER1_ID, .pubKey = USER1_PUBLIC_KEY},
    {.userId = USER2_ID, .pubKey = USER2_PUBLIC_KEY}
};

// create a new Thread with access for USER_1 as manager and USER_2 as regular user
auto threadId {threadApi.createThread(
    CONTEXT_ID, 
    users, managers, 
    core::Buffer::from("some thread's public meta-data"), 
    core::Buffer::from("some thread's private meta-data")
)};

// ...

Hint: You can assign any data to private and public meta fields (e.g. the Thread's name), as long as it is serialized and can be given as the core::Buffer.

Fetching Threads

Getting a list of Threads available for the user in the given Context:

C++

// ...

auto threadsList = threadApi.listThreads(CONTEXT_ID, defaultListQuery);

// ...

As a result you will receive an object:

C++

// threadsList:
{
    readItems: [<threadObject1>, <threadObject2>,..., <threadObjectN>],
    totalAvailable: <number_of_all_threads>
}

Getting a single Thread:

C++

// ...

auto thread = threadApi.getThread(threadId, defaultListQuery);

// ...

A detailed description of the Thread object fields can be found in API Reference.

Modifying Threads

To update a Thread you must always provide a full list of parameters.

The updateThread(...) method needs all the parameters as in the createThread(...) method and a few more. If you want to update one of the parameters – provide it in a new modified form. If, on the other hand, you want to leave the parameter unchanged – provide it as it was before.

C++

// ...
auto currentThread {threadApi.getThread(threadId, defaultListQuery)};

std::vector<core::UserWithPubKey> managers {
    {.userId = USER1_ID, .pubKey = USER1_PUBLIC_KEY}
};

std::vector<core::UserWithPubKey> users {
    {.userId = USER1_ID, .pubKey = USER1_PUBLIC_KEY}
};

// update a new Thread with access for USER_1 as the only user.
auto threadId {threadApi.updateThread(
    threadId, 
    users, managers, 
    currentThread.publicMeta, 
    currentThread.privateMeta,
    currentThread.version, // <- pass the version of the Thread you will perform the update on
    false, // <- force update (without checking version)
    false // <- force to regenerate a key for the Thread
)};

// ...

Deleting a Thread

To delete a Thread, you need to use the deleteThread(...) method.

C++

// ...
threadApi.deleteThread(threadId);
// ...

Working with Threads

Permissions