Open(PLU) Request

The Open(PLU) Request message flows from the node to the application. It is used with a PLU connection.

struct Open(PLU) Request {
    PTRBFHDR  nxtqptr;
    PTRBFELT  hdreptr;
    CHAR      numelts;
    CHAR      msgtype;
    CHAR      srcl;
    CHAR      srcp;
    INTEGER   srci;
    CHAR      destl;
    CHAR      destp;
    INTEGER   desti;
    CHAR      ophdr.openqual;
    CHAR      ophdr.opentype;
    CHAR      ophdr.appltype;
    CHAR      ophdr.opluno;
    INTEGER   ophdr.opresid;
    INTEGER   ophdr.icreditr;
    INTEGER   ophdr.icredits;
    CHAR      ophdr.opninfo1;
}; 
 

Element 1

struct Open(PLU) Request {
    PTRBFELT   hdreptr->elteptr;
    INTEGER    hdreptr->startd;
    INTEGER    hdreptr->endd;
    CHAR       hdreptr->trpad;
    CHAR[268]  hdreptr->dataru;
}; 
 

Element 2

struct Open(PLU) Request {
    PTRBFELT  hdreptr->elteptr->elteptr;
    INTEGER   hdreptr->elteptr->startd;
    INTEGER   hdreptr->elteptr->endd;
    CHAR      hdreptr->elteptr->trpad;
    CHAR[ ]   hdreptr->elteptr->dataru;
}; 
 

Members

nxtqptr

Pointer to next buffer header.

hdreptr

Pointer to first buffer element.

numelts

Number of buffer elements (0x02).

msgtype

Message type OPENMSG (0x01).

srcl

Source locality.

srcp

Source partner.

srci

Source index.

destl

Destination locality.

destp

Destination partner.

desti

Destination index.

ophdr.openqual

Open qualifier REQU (0x01).

ophdr.opentype

Open type LUSEC (0x02).

ophdr.appltype

Application program interface type

0x02 (FMI application)

ophdr.opluno

Logical unit number.

ophdr.opresid

Resource identifier.

ophdr.icreditr

Initial credit for flow from application to local node: zero (no flow control).

ophdr.icredits

Recommended initial credit for flow from local node to application:
Pacing window + 1.

ophdr.opninfo1

Negotiable bind indicator

Bind is not negotiable (0x00)
Bind is negotiable (0x01)

Element 1

hdreptr–>elteptr

Pointer to buffer element.

hdreptr–>startd

Start of data in this buffer element (1).

hdreptr–>endd

End of data in this buffer element.

hdreptr–>trpad

Reserved.

hdreptr–>dataru

Data RU, as follows:

dataru[0–9]

Source name.

dataru[10–19]

Destination name.

dataru[20]

Secondary pacing send window.

dataru[21]

Secondary pacing receive window.

dataru[22–23]

Secondary send maximum RU size (see Remarks).

dataru[24–25]

Primary send maximum RU size (see Remarks).

dataru[26]

Secondary send chunk size (in units of elements).

dataru[27]

Primary send chunk size (in units of elements).

Element 2

hdreptr–>elteptr–>elteptr

Pointer to buffer element (NIL).

hdreptr–>elteptr–>startd

Start of data in this buffer element (13).

hdreptr–>elteptr–>endd

End of data in this buffer element.

hdreptr–>elteptr–>trpad

Reserved.

hdreptr–>elteptr–>dataru

Data RU, as follows:

dataru[13]

The BIND RU received from the host.

Remarks

• The Open(PLU) Request message consists of a buffer header, an initial element containing the source and destination names, RU sizes, and so on, followed by a second element containing the BIND RU received from the host.
• The source LPI and the L and P parts of the destination LPI are valid, but the I part of the destination LPI is reserved.
• The two send maximum RU size fields (in dataru[22–25]) are both integer values.
• The BIND RU can be up to 256 bytes in length.
• If the application is using the LUA variant of the FMI (see FMI Concepts), the BIND RU is preceded by its TH and RH; the startd field of the second element points to the TH.
• The LU number matches that allocated to the named application on the Open(SSCP) Response.
• The resource identifier matches the value used by the application on the Open(SSCP) Request.
• If chunking was specified on the Open(SSCP) Request, the icredits (initial credit from local node to application) field specifies the number of chunks, rather than RUs, that can be transmitted. The two send chunk size parameters are specified in units of elements (each element contains up to 256 bytes of RU data). A value of zero indicates that the chunk size is not the limiting factor in determining the size of messages; the limiting factor is the RU size or the segment size, so chunking is not required. In this case, credit will still be used, with the unit of credit being a message.
• The icreditr (initial credit from application to local node) field is not used and must be set to zero.