PeerGroupOpen function (p2p.h)

The PeerGroupOpen function opens a peer group that a peer has created or joined. After a peer group is opened, the peer can register for event notifications.


  [in]  PCWSTR pwzIdentity,
  [in]  PCWSTR pwzGroupPeerName,
  [in]  PCWSTR pwzCloud,
  [out] HGROUP *phGroup


[in] pwzIdentity

Pointer to a Unicode string that contains the identity a peer uses to open a group. This parameter is required.

[in] pwzGroupPeerName

Pointer to a Unicode string that contains the peer name of the peer group. This parameter is required.

[in] pwzCloud

Pointer to a Unicode string that contains the name of the PNRP cloud in which the peer group is located. If the value is NULL, the cloud specified in the peer group properties is used.

[out] phGroup

Pointer to a handle for a peer group. If this value is NULL, the open operation is unsuccessful. This parameter is required.

Return value

Returns S_OK if the operation succeeds. Otherwise, the function returns one of the following values.

Return code Description
One of the parameters is not valid.
There is not enough memory available to complete the operation.
The cloud specified in pwzCloud cannot be uniquely discovered, for example, more than one cloud matches the provided name.
The cloud specified in pwzCloud cannot be located.
Access to the peer identity or peer group keys is denied. Typically, this is caused by an incorrect access control list (ACL) for the folder that contains the user or computer keys. This can happen when the ACL has been reset manually.

Cryptography-specific errors can be returned from the Microsoft RSA Base Provider. These errors are prefixed with CRYPT_* and defined in Winerror.h.


Multiple applications can open the same group simultaneously. Any application can choose to open a group without subsequently calling PeerGroupConnect. These applications are considered to be offline. However, a second application can open and connect the peer to the group, which means that an application must be ready to connect at any time.


Minimum supported client Windows XP with SP2 [desktop apps only],Windows XP with SP1 with the Advanced Networking Pack forWindows XP
Minimum supported server None supported
Target Platform Windows
Header p2p.h
Library P2P.lib
DLL P2P.dll

See also